BIOL 1220 Complete Study Guide PDF

BIOL 1220 OBJECTIVES AND KEY TERMS Chapter 1: The Human Body – An Orientation Key Terms: Anatomy: study of the structure of living organisms Physiology: study of the function of living organisms Gross anatomy: branch of anatomy that deals with the structure of organs and tissues that are visible to...

BIOL 1220 OBJECTIVES AND KEY TERMS Chapter 1: The Human Body – An Orientation Key Terms: Anatomy: study of the structure of living organisms Physiology: study of the function of living organisms Gross anatomy: branch of anatomy that deals with the structure of organs and tissues that are visible to the naked eye Microscopic anatomy: study of normal structure of an organism under the microscope Cytology: examination of cells from the body under a microscope Histology: branch of anatomy dealing with the microscopic structure of tissues Atoms: smallest particle of an elemental substance that exhibits the properties of that element; composed of protons, neutrons, and electrons Molecules: particle consisting of two or more atoms joined by chemical bonds Organelles: smaller subcellular structures that perform specific functions for the cell as a whole Cells: structural units of all living things Tissues: a group of similar cells and their intercellular substance specialized to perform a specific function; primary tissue types of the body are epithelial, connective, muscle, and nervous tissue Organs: a part of the body formed of two or more tissues and adapted to carry out a specific function Organ systems: a group of organs that work together to perform a vital body function Organism: the living animal or plant, which represents the sum total of all its organ systems working together to maintain life; also applies to microorganism Homeostasis: a state of body equilibrium or stable internal environment of the body Variable: parameters that are monitored and controlled or affected by the feedback system Receptor: a cell or nerve ending of a sensory neuron specialized to respond to particular types of stimuli Stimulus: an excitant; a change in the environment that evokes a response Control centre: body structure that determines the normal range of the variable, or set point Effector: muscle or gland (or other organ) capable of being activated by nerve endings Negative feedback: the most common homeostatic control mechanism. The net effect is that the output of the system shuts off the original stimulus or reduces its intensity. Positive feedback: feedback that tends to cause the level of a variable to change in the same direction as an initial change. Anatomical position: in this position, a person is standing upright with the lower limbs together or slightly apart, feet flat on the floor and facing forward, upper limbs at the sides with the palms facing forward and thumbs pointing away from the body, and head and eyes directed straight ahead Axial part: relating to the head, neck, and trunk Appendicular part: relating to the limbs Sagittal plane: vertical plane that divides the body or any of its parts into right and left portions Midsagittal: sagittal plane that lies directly in the middle Parasagittal: sagittal plane that offsets the midline Frontal (coronal) plane: vertical plane that divides the body or an organ into anterior and posterior parts Transverse (horizontal) plane: plane running from right to left, dividing the body or an organ into superior and inferior parts Transverse section (cross section): cross section obtained by slicing, actually or through imaging techniques, the body or any part of the body structure, in a horizontal plane, that is, a plane that intersects the longitudinal axis at a right angle Oblique section: cut made diagonally between the horizonal and vertical plane of the body or an organ Superior (cranial): toward the head or upper regions of the body Inferior (caudal): pertaining to a position toward the lower or tail end of the long axis of the body Ventral (anterior): pertaining to the front Dorsal (posterior): pertaining to the back Medial: toward the midline of the body Lateral: away from the midline of the body Intermediate: between Proximal: toward the attached end of a limb or the origin of a structure Distal: away from the attached end of the limb or the origin of the structure Superficial: located toward or on the body surface Deep: further into the body Dorsal body cavity: a fluid filled space which surrounds the brain and spinal cord of vertebrates. The dorsal cavity is usually considered as two semi-separate spaces, the cranial cavity and the spinal cavity, housing the brain and spinal cord, respectively Cranial cavity: cavity housing the brain Vertebral (spinal) cavity: cavity housing spinal cord Ventral body cavity: human body cavity that is in the anterior (front) aspect of the human body. It is made up of the thoracic cavity (enclosed by rib cage, has lungs and the heart), and the abdominopelvic cavity (largest cavity). Viscera: internal organs in the main cavities of the body, especially those in the abdomen Thoracic cavity: more superior subdivision of the anterior cavity and is enclosed by the rib cage. It contains the lungs in the pleural cavity and the heart inf the pericardial cavity. Abdominopelvic cavity: largest cavity in the body that is more inferior. It primarily houses the digestive organs. Objectives: 1. Name and define in order of increasing complexity the levels of organization that make up the human body. a. Chemical: simplest level, where tiny building blocks of matter- atoms - combine to form molecules which eventually form organelles – the basic components of cells. Cells are the smallest units of living things. b. Cellular: composed of organelles. Cells are extremely various and have many different functions. c. Tissue: composed of groups of similar cells that have a common function. There are four basic tissue types – epithelial, muscle, connective, and nervous. d. Organ: at the organ level, at least two tissue types (four is more common) are composed together to perform specific functions. For example, the stomach is an organ comprised of a lining of epithelial tissue, muscle tissue and connective tissue, all which help digest/break down food and reinforce the stomach. Nerve fibers also play a role by stimulating the stomach to contract. e. Organ system level: organs working together to fulfill a purpose – for example, the heart and blood vessels of the CVD system circulate blood and carry oxygen. There are 11 organ systems. f. Organismal: represents the sum total of all structural levels working together. 2. List the 11 organ systems of the body. Briefly identify the components and major functions of each. (See Figure 1.4) a. Integumentary: - Forms external body covering - Protects deeper tissues from damage - Synthesizes vit. D - Houses pain/pressure receptors, and sweat and oil gland - E.G. hair, skin, nails b. Skeletal: - Protects and supports body organs - Provides a framework muscles use to cause movement - Blood cells formed here - Store minerals - E.G. bones c. Muscular: - Manipulation of environment - Locomotion - Facial expressions - Maintains posture - Produces heat - E.G. skeletal muscles d. Nervous: - Control system of the body - Activates appropriate muscles and glands in response to internal/external changes - E.G. brain, spinal cord, nerves e. Endocrine: - Secrete hormones that regulate growth, reproduction, nutrient use - E.G. pineal gland, pituitary gland, ovary, testis f. CV: - Blood vessels transport blood which carries oxygen, carbon dioxide, nutrients, waste, etc. - Heart pumps the blood - E.G. heart, blood vessels g. Lymphatic/Icaenmmunity: - Returns fluid leaked from blood vessels back to the blood - Disposes of debris - Houses white blood cells  - Immune response attacks foreign substances - E.G. lymph nodes, thymus, h. Respiratory: - Keeps blood supplied with oxygen - Removes carbon dioxide - E.G. lungs, larynx, trachea i. Digestive: - Breaks down food into usable unites - Eliminates indigestible foods as feces - E.G. large intestine, stomach, rectum j. Urinary: - Eliminates nitrogenous waste from body - Regulates water, electrolyte, balances blood - E.G. kidney, urinary bladder k. Male Reproductive: - Production of offspring - Produce sperm and male sex hormone - E.G. penis, prostate l. Female Reproductive: - Production of offspring - Ovaries produce eggs - Mammary glands produce milk - E.G. mammary glands, vagina, uterus 3. Define homeostasis and explain its significance. - Homeostasis indicated a dynamic state of equilibrium in which internal conditions vary, but within narrow limits. The body is in homeostasis – or functioning properly – when needs are met and the body is functioning smoothly. Homeostasis is significant because without our body’s ability to adjust, out body’s will start to break down. - Homeostatic control: Variable is the factor or event being regulated Receptor is the first component, that responds to stimuli (changes) by sending information (input) along a pathway to the control centre The control center determines the set point that needs to be maintained. It analyzes and comes up with an appropriate response. Information flows along the efferent pathway to the effector. The effector carries out the control center’s response to the stimulus, and the results feed back to influence the stimulus 4. Describe how negative feedback systems are involved in maintaining homeostasis. - In negative feedback systems, the output shuts off the effect of the stimulus or reduces its intensity. Positive feedback systems do the opposite. - Example: regulation of blood sugar (glucose) by insulin:  Blood sugar rises, and the receptors sense this Pancreas (control center) detects this and secretes insulin into the blood This change prompts body cells to absorb more glucose and remove it from the bloodstream Once blood sugar falls, the stimulus for insulin release ends 5. Use correct anatomical terms to describe body directions, regions, planes or sections and the major body cavities. - Body directions: Anatomical position (reference point): body is erect, feet slightly apart, palms face forward, eyes forward, feet flat and down. Superior (cranial): toward the top of the head (think better!) Inferior (caudal): away from the head (like looking down because you are less) Anterior (ventral): toward the front (look down and see ants on your chest) Posterior (dorsal): toward the back of the body Medial: midline of the body Lateral: outer side of the body (like the parts of a ladder) Intermediate: between a more medial and lateral structure (like the collarbone being intermediate b/w the breastbone and shoulder) Proximal: closer to the origin of the body part or the point of attachment to the body Distal: further away from the origin Superficial (external): body surface Deep (internal): more internal, away from surface - Regional terms: the axial part makes up the main part of our body – the head, neck, and trunk. The appendicular part is our limbs. Regional terms designate specific areas within the body.  - Body planes/sections: Sagittal: vertically divides the body into right and left halves (identical, like the “tt’s” Median/midsagittal: directly in the middle Parasagittal: offset sagittal plane Frontal: divides the body into front and half – anterior and posterior (coronal plane) Transverse: runs horizontally from right to left, dividing the body into superior and inferior parts Oblique: cuts made diagonally between the horizontal and vertical planes - Body Cavities: a. Dorsal: protects the fragile nerve system organs, covered by meninges 1. Cranial: encases the skull and brain 2. Vertebral/spinal: encases the spinal cord b. Ventral: houses internal organs collectively called the viscera, or visceral organs 1. Thoracic: more superior, surrounded by the rubs and muscles of the chest. Contains the heart and lungs. 2. Abdominopelvic: more anterior, separated from the thoracic by the diaphragm. The abdominal cavity section contains the stomach, intestines, spleen, liver, etc. The inferior part – pelvic cavity 0 contains the urinary bladder and some reproductive organs. Chapter 2: Chemistry Comes Alive Key Terms: Kinetic energy: energy of motion or movement Potential energy: stored or inactive energy Ionic bond: chemical bond formed by electron transfer between atoms Cation: ion with a positive charge Anion: ion with a negative charge Covalent bond: chemical bond created by electron sharing between atoms Hydrogen bond: weak bond in which a hydrogen atoms forms a bridge between two electron hungry atoms. Important intramolecular bond. Organic compounds: any compound composed of atoms (with carbon) held together by covalent bonds Inorganic compounds: chemical substances that do not contain carbon, including water, salts, acids, and bases Hydrolysis: process in which water is used to split a substance into smaller parts Dehydration synthesis: process by which a large molecule is synthesized by removing water and covalently bonding smaller molecules together Electrolytes: chemical substances, such as salts, acids, and bases, that ionize and dissociate in water and are capable of conducting and electrical current Acid: a substance that releases hydrogen ions when in solution; proton donor Base: substance capable of binding with hydrogen ions; proton acceptor Hydroxyl ions: an ion liberated when a hydroxide is dissolved in water pH: measure of the relative acidity or alkalinity of a solution Buffer: chemical substance or system that minimizes changes in pH by releasing or binding hydrogen ions Bicarbonate buffer system: chemical system that helps maintain pH homeostasis of the blood Carbonic acid: chemical compound with the chemical formula H2CO3 (equivalently: OC(OH)2). It is also a name sometimes given to solutions of carbon dioxide in water (carbonated water), because such solutions contain small amounts of H2CO3. Bicarbonate: a byproduct of your body's metabolism. Your blood brings bicarbonate to your lungs, and then it is exhaled as carbon dioxide. Your kidneys also help regulate bicarbonate. Bicarbonate is excreted and reabsorbed by your kidneys. This regulates your body's pH, or acid balance Polymer: substance of high molecular weight with long, chain like molecules consisting of many similar units Carbohydrate: organic compound composed of carbon, hydrogen, and oxygen. Includes starches, sugars, cellulose. Monosaccharide: one sugar; building block of CHO; glucose Disaccharide: two sugars, sucrose, and lactose Polysaccharide: many sugars; starch and glycogen Lipid: hydrophobic organic compound formed of carbon, hydrogen, and oxygen Triglyceride: fats and oils composed of fatty acids and glycerol; most concentrated source of energy fuel Glycerol: modified simple sugar; building block of fat Fatty acid: linear chains of carbon and hydrogen atoms with an organic acid group at one end Saturated fatty acid: derived from both animal fats and plant oils. Rich sources of dietary saturated fatty acids include butter fat, meat fat, and tropical oils (palm oil, coconut oil, and palm kernel oil). Saturated fatty acids are straight-chain organic acids with an even number of carbon atoms Unsaturated fatty acid: a fat or fatty acid in which there is one or more double bond in the fatty acid chain. A fat molecule is monounsaturated if it contains one double bond, and polyunsaturated if it contains more than one double bond. Where double bonds are formed, hydrogen atoms are eliminated Phospholipid: modified lipid, contains phosphorus Steroid: a class of lipids derived from (and including) cholesterol; act as hormones and as constituents of phospholipid bilayer membranes Cholesterol: steroid found in animal fats as well as in most body tissues; made by the liver Prostaglandins: a lipid-based chemical messenger synthesized by most tissue cells Proteins: organic compound composed of carbon, oxygen, hydrogen, and nitrogen; types includes enzymes, structural components, 10-30% of cell mass Amino acids: organic compound containing nitrogen, carbon, hydrogen, and oxygen; building blocks of protein Denaturation: in biology, process modifying the molecular structure of a proteins Enzyme: a protein that acts as a biological catalyst to speed up a chemical reaction Substrate: a reaction on which an enzyme acts to cause a chemical action to proceed Active site: region on the surface of a functional (globular) protein where it binds and interacts chemically with other molecules of complementary shape and charge Nucleic acids: class of organic molecules that includes DNA and RNA DNA: nucleic acid found in all living cells; it carries the organism’s hereditary information RNA: nucleic acid that contains ribose and the base A, G, C, and U. Carries out DNA’s Nucleotides: building block of nucleic acid; consists of a sugar, a nitrogen-containing base, and a phosphate group Adenine: one of the two major purines found in both RNA and DNA, as well as ATP Guanine: one of the two major purines occurring in all nucleic acids Cytosine: nitrogen-containing base that is part of a nucleotide structure Thymine: single ring base in DNA Uracil: a smaller, single ring base found in RNA Adenine triphosphate (ATP): organic molecule that stores and releases chemical energy for use in body cells Phosphorylation: a chemical reaction in which a phosphate molecule is added to a molecule (e.g. phosphorylation of ADP yields ATP) Objectives: 1. List the four elements that form the majority of the body. Carbon, Oxygen, Hydrogen, and Nitrogen make up 96% of the body 2. Distinguish between kinetic energy and potential energy and give examples of each. - Kinetic: energy in motion/action that does work by moving objects. An example of kinetic energy is the rushing of water out of a dam. - Potential: energy that is stored/inactive, but has the potential to do work. An example is the batteries in an unused toy – they have the potential to do energy. 3. Describe and compare and contrast covalent, ionic, and hydrogen bonds. - Covalent: covalent bonds are chemical bonds that are formed when electrons are shared. If the electrons are shared equally, a nonpolar covalent bond forms. If the electrons are shared unequally, a polar covalent bond forms. Covalent bonds always have a three-dimensional shape. An example is water (polar) and carbon dioxide (nonpolar). Strongest - Ionic: ionic bonds are chemical bonds between atoms that are formed by the transfer of one or more electrons from one atom to another due to attraction between two oppositely charged ions. They involve a complete transfer of electrons, separate ions (charged particles) are formed. An example is the formation of sodium chloride. Sodium achieves stability when it loses an electron (becoming a cation) and chlorine accepts this electron (to become an anion). Intermediate strength - Hydrogen: hydrogen bonds are formed when a hydrogen atom carrying a partial positive charge is attracted by an electron hungry atom with a slightly negative charge, so a bridge forms between them. It is common between dipoles and are more like attractions than a true bond. An example is how surface tension  happens due to the hydrogen bonds in water causing water molecuels to cling together. Weakest strength 4. Define acid and base, and explain the concept of pH. - Acids: Have a sour taste React with many metals Proton donors Substance that releases hydrogen ions when dissolved in water pH: 0-7 - Bases: Bitter taste Feel slippery Proton acceptors (take up hydrogen ions) pH: 7-14 When bases are dissolved in water, hydroxyl ions and cations are released - pH: the more hydrogen ions in a solution, the more acidic it is. The greater the concentration of hydroxyl ions (lower amounts of hydrogen ions) indicates something is more basic. Buffers prevent excessive changes of pH in our bodies. - The pH scale is logarithmic and is based on the concentration of hydrogen ions in a solution - Neutralization occurs when acids and bases are mixed – a displacement reaction occurs to form water and salt - Buffers: resist abrupt swings of pH by releasing hydrogen ions when the pH rises and by binding hydrogen ions when the pH lowers - Important concepts: 1. The acidity of a solution reflects only the free hydrogen ions, not the ones bound 2. Acids that dissolve completely and irreversibly are strong acids because they dramatically change pH 3. Acids that do not dissolve completely are weak 4. Strong bases dissociate easily and water and quickly tie up H+ 5. Bases that accept relatively few protons are weak bases 5. Describe and compare the building blocks, general structures, and biological functions of carbohydrates, lipids, proteins and nucleic acids. - Carbohydrates: Contain carbon, oxygen, hydrogen, in which hydrogen and oxygen atoms occur in a 2:1 ratio Classified by size as either a monosaccharide (one sugar), disaccharide (two sugars), or polysaccharide (many sugars) Monosaccharides are the monomers of the other carbohydrates (include glucose, fructose, and galactose, disaccharides are sucrose, maltose, and lactose)  Provide an easily used energy source for the body: glucose is broken down and oxidized in cells, which causes electrons to be transferred and the bond energy stored in glucose to be released Synthesizes ATP Dietary carbohydrates are converted to glycogen or fat to be stored Only small amounts are used for structural purposes Examples: starch (storage form used by plants) and glycogen (storage form used by animals) - Lipids: Insulate body organs, build cell membranes, provide stored energy Contain carbon, oxygen, and hydrogen, along with phosphorus Triglycerides: fats when solids, oil when liquid. Provide the body with an efficient and compact form of stored energy, and are composed of fatty acids and glycerol. They are found mainly beneath the skin. o Saturated: fatty acids with one covalent bond, solid at room temperature due to the close packing of molecules o Unsaturated: double bonds cause a kink, which causes them to be liquid at room temperature Phospholipids are chief components of cell membranes due to their hydrophilic and hydrophobic ends Steroids: component of cell membranes, necessary for growth, include cholesterol, bile salts, etc. Eicosanoids: diverse lipids, chiefly derived from 20-carbon fatty acid. Prostaglandins are the most important, that regulate blood pressure, inflammation, labour contractions, etc. - Proteins: Compose 10-30% of cell mass, basic structure material in the body Have many roles: mechanical support, catalysis (enzymes – speed up reactions without being used up), transportation, movement, transmitting signals between cells, protection against disease Amino acids: building blocks of proteins which can be either acids or bases. The R group of an amino acid determines it chemical composition. Enzymes: o Act as catalysts o Regulate and speed up the rate of biochemical reactions without being used up or changed o Action: requires a certain amount of energy – activation energy – to have reaction, enzymes lower this o Three steps of enzyme action: 1. Substrate binds to enzyme’s active site, temporarily forming an enzyme-substrate complex 2. Enzyme-substrate complex undergoes internal rearrangements to form a product 3. Enzyme releases the product of the reaction Structural levels of proteins: 1. Primary: linear sequence of amino acids forming a polypeptide chain  2. Secondary: primary cells twists or bending upon themselves to form an alpha helix or beta-pleated sheet 3. Tertiary: superimposed on secondary structure, alpha helixes and beta sheets are formed up to form a compact globular molecule held by intramolecular bonds 4. Quaternary: two or more polypeptide chains combining to form a functional protein - Nucleic Acids: DNA Found in the nucleus Constitutes the genetic material – called genes/genomes Two roles: replicates itself before a cell divides, and provides basic instruction for building every protein in the body Double chain of nucleotides Bases: A G C T (A + T, G + C) - Nucleic Acids: RNA Located outside the nucleus Considered a “molecular slave” of DNA Carries out the orders for protein synthesis issued by DNA Single chain of nucleotides Bases: A G C U (A + U, G + C) Three varieties: 1. Messenger RNA (mRNA) 2. Ribosomal RNA (rRNA) 3. Transfer RNA (tRNA) 6. Describe how ATP drives cellular work. - ATP is the primary energy transferring molecule in cells and it provides a form of energy that is immediately usable by all body cells - Adenine- containing RNA nucleotide in which two additional phosphate groups have been added - ATP can store energy because its three negatively charged phosphate groups are closely packed and repel each other. When its terminal high-energy phosphate bond is broken, the chemical “spring” relaxes and the molecule becomes more stable Chapter 3: Cells – The Living Units Plasma membrane (cell membrane): membrane, composed of phospholipids, cholesterol, and proteins, that encloses cell contents Lipid bilayer: biological membrane consisting of two layers of lipid molecules Phospholipids: modified lipid, contains phosphorus Cholesterol: steroid found in animal fats as well as in most body tissues; made by the liver Intracellular fluid (ICF): fluid within the cell Extracellular fluid (ECF): internal fluid located outside cells; includes blood plasma and cerebrospinal fluid Fluid mosaic model: a depiction of the structure of the membranes of a cell as phospholipid bilayers in which proteins are dispersed Hydrophobic: refers to molecules, or portions of molecules, that interact only with nonpolar molecules Hydrophilic: refers to molecules, or portions of molecules, that interact with water and charged particles Integral proteins: sometimes referred to as an integral membrane protein, is any protein which has a special functional region for the purpose of securing its position within the cellular membrane (enter hydrophobic space) Peripheral proteins: or peripheral membrane proteins, are a group of biologically active molecules formed from amino acids which interact with the surface of the lipid bilayer of cell membranes (do not enter hydrophobic space) Glycolipids: a lipid with one or more covalently attached sugars Glycoproteins: any of a class of proteins that have carbohydrate groups attached to the polypeptide chain. Also called glycopeptide. Tight junctions: area where plasma membranes of adjacent cells are rightly bound together, forming an impermeable barrier Desmosomes: cell junction composed of thickened plasma membranes joined by filaments Gap junctions: a passageway between two adjacent cells; formed by transmembrane proteins called connexons Interstitial fluid: fluid between cells Selectively permeable: a membrane that allows certain substances to pass while restricting the movement of others; also called differentially permeable membrane Simple diffusion: the unassisted transport across a plasma membrane of lipid soluble or very small particle Osmosis: diffusion of a solvent through a selectively permeable membrane from a dilute solution into a more concentrated one Aquaporins: transmembrane proteins that form water channels Osmolarity: the number of solute particles present in 1 liter of solution Tonicity: a measure of the ability of a solution to cause a change in cell shape or tone by promoting osmotic flows of water Hypertonic: excessive, above normal. Tone or tension Hypotonic: below normal tone or tension Isotonic: denoting or relating to a solution having the same osmotic pressure as some other solution, especially one in a cell or a body fluid Facilitated diffusion: passive transport process used by certain large or charged molecules that are unable to pass through the plasma membrane unaided. Involves movement through channels or movement facilitated by a membrane carrier. Primary active transport: a type of active transport in which the energy needed to drive the transport process is provided directly by hydrolysis of ATP Na+-k+ pump (Na+-K+ ATPase): main function of the N+/K+ ATPase pump is to maintain resting potential so that the cells will be keeping in a state of a low concentration of sodium ions and high levels of potassium ions within the cell (intracellular). The sodium-potassium pump is an antiporter transport protein Secondary active transport (contransport): a type of active transport in which the energy needed to drive the transport process is provided by the electrochemical gradient of another molecule. Also called cotransport or symport (when two transported molecules move in the same direction), or antiport (moving in opposite direction) Vesicular transport: transport of large particles and macromolecules into or out of a cell or between its compartments in membrane bound sacs Exocytosis: mechanism by which substances are moved from the cell inferior to the extracellular space as a secretory vesicle fuses with the plasma membrane Endocytosis: means by which fairly large extracellular molecules or particles enter cells Phagocytosis: engulfing of solids by phagocytic cells Membrane potential: voltage across the plasma membrane Resting membrane potential (RMP): the voltage that exists across the plasma membrane during the resting state of an excitable cell; typically ranges from -50 to -90 millivolts Membrane receptors: a large, diverse group of integral proteins that serve as binding sites for signaling molecules Ligand: signalling chemical that binds specifically to membrane receptors Neurotransmitters: chemical messenger released by neurons that, upon binding to receptors of neurons or effector cells, stimulate or inhibit those neurons or effector cells Hormones: steroidal or amino-acid based molecules release to the blood that act as chemical messengers to regulate specific body functions Paracrine: a chemical messenger that acts locally within the same tissue and is rapidly destroyed G protein: protein that relays signals between extracellular first messengers (e.g. hormones and neurotransmitters) and intracellular second messengers (e.g. cyclic AMP) via an effector enzyme Second messenger: intracellular molecule generated by the binding of a chemical to a receptor protein; mediates intracellular responses to the chemical messenger Cyclic AMP (cAMP): intracellular second messenger that mediates the effects of the first (extracellular) messenger; formed from ATP by a plasma membrane enzyme Cytoplasm: the cellular material surrounding the nucleus and enclosed by the plasma membrane Cytosol: viscous, semi-permanent fluid substance of cytoplasm in which other elements are suspended Nucleus: (1) control center of the cell; contains genetic material; (2) clusters of neuron cell bodies in the CNS; (3) center of an atom; contains protons and neutrons Nucleolus: a round body located inside the nucleus of a eukaryotic cell. It is not surrounded by a membrane but sits in the nucleus. The nucleolus makes ribosomal subunits from proteins and ribosomal RNA, also known as rRNA Chromatin: strands of DNA (genes) and associated proteins; forms chromosomes when condensed Mitochondria: POWERHOUSE OF THE CELL – cytoplasmic organelles responsible for s generation for cellular activities Ribosomes: cytoplasmic organelles at which proteins are synthesized Rough endoplasmic reticulum: series of connected flattened sacs, part of a continuous membrane organelle within the cytoplasm of eukaryotic cells, that plays a central role in the synthesis of proteins (bound by ribosomes) Smooth endoplasmic reticulum: a membranous organelle found in most eukaryotic cells.... Its main functions are the synthesis of lipids, steroid hormones, the detoxification of harmful metabolic by-products and the storage and metabolism of calcium ions within the cell (not bound by ribosomes) Golgi apparatus: membranous system close to the cell nucleus that packages protein secretions for export, packages enzymes into lysosomes for cellular use, and modifies proteins destined to become part of cellular membranes Lysosomes: organelles that originate from the Golgi apparatus and contain strong digestive enzymes Peroxisomes: membranous sacs in cytoplasm containing powerful oxidase enzymes that use molecular oxygen to detoxify harmful or toxic substances, such as free radicals Cytoskeleton: cell skeleton; an elaborate series of structural proteins running through the cytosol, supporting cellular structures, and providing the machinery to generate various cell movements Microtubules: one of three types of cytoskeletal elements; hollow tubes made of spherical protein tubulin Microfilaments: one of three types of cytoskeletal elements; thin strands of protein actin Intermediate filaments: one of the three types of cytoskeletal elements; provide mechanical support for the plasma membrane where it encounters other cells or with the extracellular matrix. Unlike microfilaments and microtubules, intermediate filaments do not participate in cell motility Centrioles: minute body found in pairs near the nucleus of the cell; active in cell division Cilia: tiny, hair like projections of a cell; may move in a wave like manner to propel substances across the exposed cell surface Flagella: long, whip like cellular extensions containing microtubules; propels sperm and some single-celled eukaryotes Microvilli: tiny projections on the free surfaces of some epithelial cells; increases surface area for absorption G1 phase: intermediate phase occupying the time between the end of cell division in mitosis and the beginning of DNA replication during S phase. During this time, the cell grows in preparation for DNA replication, and certain intracellular components, such as the centrosomes undergo replication. G2 phase: last part of interphase is called the G2 phase. The cell has grown, DNA has been replicated, and now the cell is almost ready to divide. This last stage is all about prepping the cell for mitosis or meiosis. During G2, the cell has to grow some more and produce any molecules it still needs to divide Go phase: resting phase is a period in the cell cycle in which cells exist in a quiescent state. G0 phase is viewed as either an extended G1 phase, where the cell is neither dividing nor preparing to divide, or a distinct quiescent stage that occurs outside of the cell cycle. S phase: synthetic phase; the part of the interphase period of the cell cycle in which DNA replicates itself, ensuring that the two future cells with receive identical copies of genetic material Interphase: on of the two major periods in the cell life cycle; includes the period from cell formation to cell division Mitosis: process during which the chromosomes are redistributed to two daughter nuclei; nuclear division. Consists of prophase, metaphase, anaphase, and telophase. Prophase: first stage of mitosis, meiosis I, and meiosis II. The chromosomes become visible, the nuclear envelope breaks down, and a spindle forms. Metaphase: second stage of mitosis, meiosis I, and meiosis II Anaphase: third stage of mitosis, meiosis I, and meiosis II in which chromosomes move toward each pole of a cell Telophase: final stage of mitosis, meiosis I, and meiosis II; begins when migration of chromones to the poles of the cell has been completed and ends with the formation of two daughter nuclei Cytokinesis: the division of cytoplasm that occurs after the cell nucleus has been divided Cell differentiation: the development of specific and distinctive features in cells; from a single cell (fertilized egg) to all the specialized cells (of adulthood) Apoptosis: a process of controlled cellular suicide; eliminates cells that are unneeded, stressed, or aged Objectives: 1. Describe the fluid mosaic model of cell membrane structure. Include a description of the functions of each of lipids, proteins and carbohydrates in membranes. (See Focus Figure 3.1 on pp. 64-65.) The fluid mosaic model of a membrane structure shows the structure as very thin and composed of bilayer lipid molecules with protein molecules “plugged into” or dispersed in it. It is named after the way the proteins float in the fluid lipid bilayer, which results in a constantly changing mosaic look. Functions of each part of the membrane: - Lipids: Phospholipids: form basic structure of the membrane, hydrophobic tails prevent water-soluble substances from crossing, which forms a boundary Cholesterol: stiffens the membrane, decreases solubility of the membrane - Proteins: Determine what functions the membrane performs Many roles (e.g. transportation) Proteins with different shapes have different functions - Carbohydrates: Act as identity molecules that recognize who is who so that cells can sort themselves into tissues and organs, and also allows immune cells to recognize their own cell VS. a pathogen Only found on the outer surface 2. Explain how membrane structure influences the ability of lipid and non-lipid molecules to pass through a membrane. - Phospholipids form the main part of the cell membrane. They have polar, hydrophilic heads that are attracted to water. These polar heads face the water inside and outside of the cell. In between these points lie the nonpolar, hydrophobic tails that form a sandwich like layer between the heads. Since the tails are hydrophobic, they resist water, which prevents water-like substances to pass through – essentially forming a boundary. 3. Describe six different functions of cell membrane proteins (See Fig. 3.3.)  a. Transport: some proteins form a hydrophilic channel across the membrane that is particular to certain substances, other proteins are transport proteins that hydrolyze substances across the membrane b. Receptors for signal transduction: a membrane protein outside of the cell may have a binding site that fits the shape of a specific chemical messenger, and when bound, the chemical messenger may cause a change in shape in the protein that initiates a chain of chemical reactions in the cell c. Enzymatic activity: membrane protein may be an enzyme with its active site exposed to substances in adjacent solution, and a team of several enzymes may catalyze sequential steps of a metabolic pathway d. Cell-cell recognition: some serve as identification tags that are specifically recognized by other cells e. Attachment to the cytoskeleton and extracellular matrix (ECM): elements of the cytoskeleton and extracellular matrix may anchor to proteins, which helps maintain cell shape, fixes the location of certain membrane proteins, and plays a role in cell movement f. Cell-cell joining: membrane proteins of adjacent cells may be hooked together and some membrane proteins provide temporary binding sites that guide cell migration and other cell-cell interactions 4. Compare and contrast the functions of tight junctions, desmosomes and gap junctions. Give one example of where you might find each type of junction. - Tight junctions: series of integral protein molecules in the plasma membranes of adjacent cells fuse together like a zipper, which forms an impermeable junction that circles the cell and separates one fluid-filled compartment from another. Overall, they prevent molecules from passing through extracellular space and restrict the movements of membrane proteins. An example of a tight junction in the body are the junctions between epithelial cells lining the digestive tract, that keeps digestive enzymes and microorganisms from seeping into the bloodstream. - Desmosomes: serve as anchoring junctions that prevents the separation of adjacent cells – they bind neighbouring cells together into sheets and contribute to a continuous internal network of strong fibers acting a “guy wires”. These “guy wires” redistribute tensions throughout the cellular sheet and reduce chances of tearing. An example of where desmosomes are found are in skin and the heart muscles.  - Gap junctions: a gap junction is a communicating junction between adjacent cells. Plasma membranes are very close in gap junctions and the cells are connected by hollow cylinders composed of transmembrane proteins. Gap junctions are present in electrically excitable tissues, like the heart and smooth muscle, where ion passage from cell to cell helps synchronize electrical activity. 5. Describe the differences between active and passive transport mechanisms with respect to energy sources, mechanisms, and direction of transport. Passive: passive transport requires no energy, and substances move from high to low concentration (down the concentration gradient). It is affected by the concentration (greater difference = more collisions = faster diffusion), molecular size (smaller = faster), and temperature (high temps = higher speeds = faster diffusion). Specificity and saturability are both important characteristics of passive transport. - Energy source: intrinsic kinetic energy of the molecules. The constant random and high speed motion of molecules and ions results in collisions, which causes particles to bounce off one another and disperse throughout the environment. - Direction of transport: high to low concentration (down gradient) - Kinds of passive transport/mechanisms: a. Simple diffusion: unassisted diffusion of lipid-soluble or very small particles across the membrane. Need to be small, nonpolar molecules that readily dissolve (include gases, hormones, fatty acids). Not specific or saturable. b. Facilitated diffusion: transported substance either (1) bind to carrier proteins in the membrane or (2) move through water filled channel proteins. In carrier mediated facilitated diffusion, carriers are specific for transporting certain polar molecules or classes of molecules. In channel mediated diffusion, channels open. They are selective due to pore size and the charges of an amino acid. Saturable. c. Osmosis: osmosis is the diffusion of a solvent through a selectively permeable membrane, and is very important in determining the distribution of water in various fluid-containing compartments. Osmosis occurs whenever the water concentration differs on the two sides of a membrane. Process Energy Description Membrane Specific and Examples Source Transport Saturable  Protein Required? Simple Kinetic Net movement of No No Lipids, diffusion energy molecules down oxygen, concentration gradient carbon (from high to low) dioxide Facilitated Kinetic Same as simple, but Yes Yes – Glucose, diffusion the diffusing substance specificity Na+, K+ is attached to a depends on membrane protein or shape inside moves through a transport channel protein protein Osmosis Kinetic Diffusion of water No, except No Water through a selectively for permeable membrane; movements can occur directly of aquaporins through the lipid bilayer or via membrane channels Active transport: active transport requires transport proteins and combine specifically and reversibly with the transported substance. Active transporters move solutes “uphill” against a concentration gradient from low to high. These processes are distinguished according to their source of energy: - Primary active transport: energy to do work comes directly from hydrolysis of ATP by transport proteins called pumps - Secondary active transport: driven by energy stored in concentration gradients of ions created by primary active transport pumps. 6. Compare and contrast simple diffusion, facilitated diffusion, primary active transport, and secondary active transport. Differentiate clearly between these transport processes with respect to their energy sources, specificity, and saturability. a. Simple diffusion: substances diffuse directly though the lipid bilayer. Substances are usually small, nonpolar molecules that dissolve readily in lipids (relies on size and lipid saturability). Energy sources: kinetic Specificity: small, lipid soluble Saturability: no b. Facilitated diffusion: transported substance either (1) binds to carrier proteins in the membrane and is ferried across or (2) moves through water-filled channel proteins. Energy sources: kinetic Specificity: specificity depends on shape inside transport protein Saturability: yes c. Primary Active Transport: the hydrolysis of ATP causes the protein to change its shape in such a manner that it pumps the bound solute across the membrane. Energy sources: hydrolysis of ATP by transport proteins called pumps Specificity: bind to certain molecules Saturability: yes d. Secondary Active Transport: transport is driven by energy stored in concentration gradients of ions created by primary active transport pumps – use cotransport proteins Energy sources: the concentration gradient that is create by primary active transport Specificity: use cotransport proteins Saturability: yes 7. Define osmosis. Explain how solute concentrations of the ICF and ECF influence the direction of osmosis. Osmosis is the diffusion of a solvent through a selectively permeable membrane, and is extremely important in determining the distribution of water in the various fluid-containing compartments. Osmosis occurs whenever the water concentration differs on the two sides of a membrane: - Distilled water present on both sides of the membrane: no net osmosis - Membrane permeable to water and solutes: both the solute and water will move down their concentration gradients – water toward the solution with higher osmolarity (total concentration of all solute particles in a solution), and the solute toward the solution with lower osmolarity (lower solute concentration). This establishes equilibrium. - Membrane permeable to water, impermeable to solutes: water will move through the selectively permeable membrane from an area of higher water concentration to lower water concentration (lower to high solute concentration). This changes the volume on each side as water can move but the solute can’t, and results in equilibrium.  Tonicity: ability of a solution to change the shape of cells by altering the cells inner volumes - Isotonic: cells retain normal size and shape - Hypertonic: cells lose water by osmosis and shrink, because they have a higher concentration of nonpenetrating solutes - Hypotonic: cells gain water and become bloated, possibly bursting because they have a lower concentration of nonpenetrating solutes inside the cell 8. State the functions of vesicular transport and the mechanisms underlying the specificity of some types of vesicular transport. In vesicular transport, fluids containing large particles and macromolecules are transported across cellular membranes in side bubble-like, membranous sacs called vesicles. It moves substances into the cell (endocytosis) and out of the cell (exocytosis). - Endocytosis: begins with a coated pit/infolding of the membrane Phagocytosis: cell engulfs some relatively large or solid material, like bacteria and debris. In the human body, only macrophages and certain white blood cells are experts at this. Pinocytosis: a bit of infolding plasma membrane surrounds a very small volume of extracellular fluid containing dissolved molecules. Unlike phagocytosis, pinocytosis is a routine activity that is primary important in cells that absorb nutrients. Receptor-mediated endocytosis: main mechanism for the specific endocytosis and transcytosis (moves substances into, across, and out of the cell). Allows cells to concentrate material that is present only in small amounts in the extracellular fluid.  - Exocytosis: vesicular transport processes that eject substances from the cell interior into the extracellular fluid. It is typically stimulated by a cell-surface signal such as binding of a hormone to a membrane receptor or a change in membrane voltage. It accounts for hormone secretion, neurotransmitter release, mucus secretion, and sometimes the ejection of wastes. The substance being removed is first enclosed in a protein-coated membranous sac called a secretory vesicle. 9. Define membrane potential and explain how the resting membrane potential is established and maintained. (See also Focus Figure 11.1 on p. 402.) Membrane potential is the voltage across a membrane. This is extremely important for nerve and muscle cells because they use changes in membrane potential as a form of communication. A voltage is electrical potential energy resulting from the separation of oppositely charged particles. Resting membrane potential: - The state plasma body cells exhibit while resting - Ranges from -50—90 millivolts - Cells are said to be electrically polarized - Minus sign before the voltage indicates that the inside of the cell is negative compared to the outside - Voltage exists only at the membrane - How it develops/is maintained: diffusion causes ionic imbalances that polarize the membrane, and active transport processes maintain the membrane potential K+ helps generate resting membrane potential by: (1) diffusing down their steep concentration gradient vita leakage channels. This loss causes a negative charge on the inner plasma membrane face. (2) K+ then moves into the cell because they are attracted to the negative charge established on the inner plasma membrane face. (3), finally a negative membrane potential is established when the movement of K+ out of the cell equals K+ movement into the cell – at this point, the concentration gradient promoting K+ exit exactly opposes the electrical gradient for K+ entry. Active transport processes maintain the membrane to keep the cell steady: if more Na+ enters, more is pumped out to maintain equilibrium 10. Name and briefly describe three different types of chemical messengers Chemical signalling is the process in which a ligand – the chemical messenger – binds a specific receptor and initiates a response. Ligands include most neurotransmitters, hormones, and paracrines. a. G protein: regulatory molecule that acts as a middleman or relay to activate (or inactivate) a membrane-bound enzyme or ion channel. This in turn generates second messengers. b. Second messengers: connect plasma membrane events to the internal metabolic machinery of the cell. They include (1) cyclic AMP and (2) ionic calcium, both which activate protein kinase enzymes Process: 1. Ligand binds to the receptor, which change shape and activates 2. Activated receptor binds to the G protein and activates it, which causes a release of GDP and bind GTP (energy source) 3. Activated G protein activates (or inactivates) an effector protein by causing its shape to change 4. Activated effector enzymes catalyze reactions that produce second messengers in the cell (cyclic AMP and ionic calcium) 5. Second messengers activate other enzymes or ion channels (cyclic AMP typically activates kinase protein) 6. Kinase enzymes activate other enzymes 11. Briefly describe the structure and function of each of the following components of the cytoplasm: mitochondria, ribosomes, rough endoplasmic reticulum, smooth endoplasmic reticulum, Golgi apparatus, lysosomes, peroxisomes, microtubules, microfilaments, intermediate filaments, centrioles, cilia, flagella, nucleus. (See Table 3.4 and Figure 3.2.) - Mitochondria: Shape: bean shaped membranous organelles with a smooth outer membrane and a folded inner membrane Function: power plant of the cell, providing most of the ATP supply, contain and produce their own DNA, RNA, and ribosomes and can reproduce themselves - Ribosomes: Shape: dark, small granules composed of proteins and a variety of RNA’s called ribosomal RNA’s Function: sites of protein synthesis – free ribosomes make soluble proteins that function in the cytosol, and membrane-bound ribosomes are attached to membranes that synthesize proteins destined for incorporation into cell membranes or lysosomes - Rough endoplasmic reticulum: Shape: folded shape embedded with ribosomes  Function: manufacture all proteins secreted from cells, and is the cell’s “membrane factory” where integral proteins and phospholipids that form part of all cellular membranes are manufactured - Smooth endoplasmic reticulum: Shape: folded shape with no ribosome embedding Function: metabolize lipids, synthesize cholesterol and phospholipids, and synthesize lipid components of lipoproteins. They synthesize steroid-based hormones, detoxify drugs, break down stored glycogen to form free glucose, and store calcium ions in most cell types - Golgi apparatus: Shape: stacked and flattened membranous sacs, shaped like hollow dinner plates associated with swarms of tiny membranous vesicles Function: “traffic director” for cellular proteins – major function is to modify, concentrate, and package the proteins and lipids made at the rough ER and destined for export from the cell - Lysosomes: Shape: spherical membranous organelles, large and abundant in phagocytes Function: can digest almost all kinds of biological molecules – function as the demolition crew that digests particles, degrades stressed or dead cells, performs metabolic functions, and breaks down bones to release calcium ions into the blood - Peroxisomes: Shape: resemble small lysosomes, spherical sacs containing powerful enzymes Function: oxidases in them use molecular oxygen to detoxify harmful substance, and most importantly neutralize free radicals. - Microtubules: Shape: hollow tubes made of spherical protein subunits called tubulin Function: determine the overall shape of the cell and distribute cellular organelles. Form centriole and cilia and flagella if present. - Microfilaments: Shape: fine filaments composed of the protein actin Function: muscle contraction and intracellular movement, help form the cell’s cytoskeleton - Intermediate filaments: Shape: protein fibers, composition varies, generally resembles twisted rope Function: stable cytoskeletal elements, resist mechanical forces acting on the cell - Centrioles: Shape: paired cylindrical bodies, each composed of nine triplets of microtubules Function: organize the microtubule network, form spindle and asters during mitosis; as basal bodies, form the bases of cilia and flagella - Cilia: Shape: short cell-surface projections; hair like  Function: coordinated movement creates an unidirectional current that propels substances across cell surfaces - Flagella: Shape: like cilium, but longer, only example in the human body is the tail of sperm Function: propels the cell - Nucleus: Shape: largest organelle surrounded by the nuclear envelop, contains fluid nucleoplasm, nucleoli, and chromatin Function: control center of the cell – responsible for transmitting genetic information and providing the instructions for protein synthesis 12. List in order the stages of the cell cycle and mitosis and briefly describe what happens during each one. a. Interphase: period from cell formation to cell division, metabolic phase or growth phase - G1 (gap 1 subphase): cell is metabolically active, synthesizing proteins rapidly and growing at a fast rate. Cells that stop dividing are in the G0 phase. - S phase: DNA is replicated, ensuring the two future cells being created with receive identical copies of the genetic material - G2 (gap 2 subphase): brief phase in which the enzymes and other proteins needed for division are synthesized and moved to their proper sites. By the end of this, centriole replication is complete. b. DNA replication: before a cell divides, its DNA has to be replicated exactly so that identical copies of the genes can be passed on. - Uncoiling: enzymes unwind DNA, forming a replication bubble - Separation: two DNA strands separate as the hydrogen bonds are broken. The points at which the strands unzip is known as the replication fork. - Assembly: DNA polymerase positions complimentary free nucleotides along the template strands, forming tow new strands, called leading and lagging strand. Two new DNA molecules result from one parental DNA molecule. - Restoration: ligase enzyme splice short segments of DNA together, reforming helix c. Mitosis: - Prophase: Chromatin coils and condense, forming chromosomes Each chromosome has two identical threads called sister chromatids Nucleoli disappear, and the two centrosomes separate from one another Nuclear envelope breaks up, allowing spindles to interact with chromosomes Some of the spindles attach to chromosomes centromere’s (center) Spindle fibres begin to pull on each chromosome from both poles and draw the chromosomes to the center of the cell - Metaphase: Two centrosomes are at opposite poles of the cells Chromosomes cluster in the middle of the cell  Enzymes that will act to separate the chromatids from each other are triggered - Anaphase: Begins as the centromeres split simultaneously, each becoming its own chromosome Microtubules shorten, pulling each chromosome toward pole faces Moving chromosomes look v shaped - Telophase: Begins as soon as chromosomal movement stops Identical sets of chromosomes at each pole begin to uncoil and resume their threadlike chromatin form New nuclear envelop appears around each chromatin mass d. Cytokinesis: begins during late anaphase and continues through and beyond telophase. The cleavage furrow forms and pinches the cell apart. Chapter 4: Tissue – the Living Fabric Epithelial tissue: pertaining to a primary tissue that covers the body surface, lines its internal cavities, and forms glands Apical surface: surface of epithelial cell that is exposed to the body exterior or to the cavity of an internal organ Basal surface: the surface near the base or interior of a structure; nearest the lower se or bottom of a structure Basement membrane: extracellular material consisting of a basal lamina secreted by epithelial cells and a reticular lamina secreted by underlying connective tissue cells Squamous: a large flattened cell with abundant cytoplasm and small round central nucleus Cuboidal: consists of a single layer cells that are as tall as they are wide. The important functions of the simple cuboidal epithelium are secretion and absorption. This epithelial type is found in the small collecting ducts of the kidneys, pancreas, and salivary glands. Columnar: are taller than they are wide: they resemble a stack of columns in an epithelial layer, and are most commonly found in a single-layer arrangement Simple: consists of a single layer of cells. They are typically where absorption, secretion and filtration occur. The thinness of the epithelial barrier facilitates these processes. Simple epithelial tissues are generally classified by the shape of their cells Stratified: is a type of epithelial tissue that is composed of more than one layer of epithelial cells. The basal layer is the only one that is in contact with the basal lamina. This layer is also the one that undergoes mitotic division producing cells in the upper layers. Pseudostratified: a type of epithelium that, though comprising only a single layer of cells, has its cell nuclei positioned in a manner suggestive of stratified epithelia Transitional: is a type of stratified epithelium. This tissue consists of multiple layers of epithelial cells which can contract and expand in order to adapt to the degree of distension needed. Gland: organ specialized to secrete substances for further use in the body or excrete substances for elimination Secretion: (1) the passage of material formed by a cell to its exterior; (2) cell product that is transported to the exterior of a cell Duct: a canal or passageway; a tubular structure that provides an exit for the secretions of a gland, or for conducting any fluid Endocrine gland: ductless glands that empty their hormonal products directly into the blood Exocrine gland: glands that have ducts through which their secretions are carried to a particular site Goblet cells: individualized cells (unicellular glands) that produce mucus Merocrine: glands that produce secretions intermittently; secretions do not accumulate in the gland Holocrine: glands that accumulate their secretions within their cells; secretions are discharged only upon rupture and death of the cell Connective tissue: a primary tissue; form an function may vary extensively; functions include support, storage, and protection Mesenchyme: common embryonic tissue from which all connective tissue arises Extracellular matrix (ECM): nonliving material in connective tissue consisting of ground substance and fibers; separates living cells Ground substance: an amorphous gelatinous material. It is transparent, colourless, and fills the spaces between fibres and cells. It actually consists of large molecules called glycosaminoglycans (GAGs) which link together to form even larger molecules called proteoglycans. Collagen fibers: the most abundant of the three types of protein fibers found in the extracellular matrix of connective tissue Elastic fibers: fiber formed form the protein elastin, which gives a rubbery and resilient quality to the matrix of connective tissue Elastin: a key protein of the extracellular matrix. It is highly elastic and present in connective tissue allowing many tissues in the body to resume their shape after stretching or contracting. Elastin helps skin to return to its original position when it is poked or pinched. Reticular fibers: or reticulin is a type of fiber in connective tissue composed of type III collagen secreted by reticular cells. Reticular fibers crosslink to form a fine meshwork (reticulin). Fibroblasts: young, actively mitotic cell that forms the fibers of connective tissue Chondroblasts: actively mitotic cell of cartilage Osteoblasts: bone-forming cells Hematopoietic stem cell: bone marrow cell that gives rise to all the formed elements of blood; hemocytoblast Macrophage: immune cell type common in connective tissue, lymphoid tissue, and many body organs; phagocytizes tissue cells, bacteria, and other foreign debris; present antigens to T cells in the immune response Connective tissue proper: consists of loose connective tissue and dense connective tissue (which is further subdivided into dense regular and dense irregular connective tissues.) Loose and dense connective tissue are distinguished by the ratio of ground substance to fibrous tissue Loose connective tissue: a category of connective tissue which includes areolar tissue, reticular tissue, and adipose tissue. Loose connective tissue is the most common type of connective tissue in vertebrates. It holds organs in place and attaches epithelial tissue to other underlying tissues Areolar connective tissue: type of loose connective tissue Adipose tissue: areolar connective tissue modified to store fat; a connective tissue consisting chiefly of adipocytes Adipocyte: an adipose, or fat, cell Reticular connective tissue: connective tissue with a fine network of reticular fibers that form the internal supporting framework of lymphoid organs Dense connective tissue: a type of connective tissue with fibers as its main matrix element. The fibers are mainly composed of type I collagen. Crowded between the collagen fibers are rows of fibroblasts, fiber-forming cells, that generate the fibers. Cartilage: one of the four types of connective tissue – avascular and not innervated Chondrocyte: mature cell of cartilage Lacunae: a small space, cavity, or depression; lacunae in bone or cartilage are occupied by cells Hyaline cartilage: the most abundant cartilage type in the body; provides firm support with some pliability Elastic cartilage: cartilage with abundant elastic fibers; more flexible than hyaline cartilage Fibrocartilage: the cartilage most resistant to compression and stretch. Forms vertebral discs and knee joint cartilages. Osteocytes: mature bone cell Nervous tissue: the term for groups of organized cells in the nervous system, which is the organ system that controls the body's movements, sends and carries signals to and from the different parts of the body, and has a role in controlling bodily functions such as digestion. Neurons (nerve cell): cell of the nervous system specialized to generate and transmit electrical signals Skeletal muscle: muscle composed of cylindrical multinucleate cells with obvious striations; the muscle(s) attached to the body’s skeleton; voluntary muscles Cardiac muscle: specialized muscle of the heart Smooth muscle: spindle-shaped cells with one centrally located nucleus and no externally visible striations. Found mainly in the walls of hollow organs. Cutaneous membrane: multi-layered membrane composed of epithelial and connective tissues. The apical surface of this membrane exposed to the external environment and is covered with dead, keratinized cells that help protect the body from desiccation and pathogens. The skin is an example of a cutaneous membrane Mucous membrane: membranes that form the linings of body cavities open to the exterior Serous membrane (serosa): the moist membrane found in closed ventral body cavities \ Objectives: 1. List the four basic tissue types in the human body: - Tissues are groups of cells that are similar in structure and perform a common or related function. The four types are as follows: a. Epithelial: covers  b. Connective: supports c. Muscle: moves d. Nervous: controls 2. State the functions and some of the characteristics of epithelial tissues: Epithelial tissue is a sheet of cells that covers a body surface or lines a body cavity. There are two forms of epithelial tissue in the body: 1. Covering and lining epithelium: forms the outer layer of the skin, dips into and lines the open cavities of the urogenital, digestive, and respiratory systems, and covers the walls and organs of the closed ventral body cavity 2. Glandular epithelium: fashions the glands of the body Epithelial tissue accomplishes many functions: - Protection - Absorption - Filtration - Excretion - Secretion - Sensory reception Characteristics of Epithelium: 1. Polarity: the apical surface is not attached to surrounding tissue and is exposed to either the outside of the body or the cavity of the internal organ. The basal surface is attached to the underlying connective tissue. For this reason, we say that epithelia exhibit apical-basal polarity. Most apical surfaces are smooth and slick and most have microvilli that increase the exposed surface area Adjacent to the basal surface of an epithelium is a thin supporting sheet called the basal lamina, that is a noncellular, adhesive sheet consisting largely of glycoproteins secreted by the epithelial cells. The basal lamina also acts as a selective filter and a scaffolding along with epithelial cells can migrate to repair a wound. 2. Specialized contacts: epithelial cells fit closely together to form continuous sheets tied together by tight junctions and desmosomes 3. Supported by connective tissue: in between the epithelial and connective tissues is a basement membrane that reinforces the epithelial sheet, helps resist stretching and tearing, and defines the epithelial boundary. The basement membrane has two layers: Basal lamina Reticular lamina: deep to basal lamina, consists of a layer of extracellular material containing a fine network of collagen fibers 4. Avascular but innervated: although epithelium is avascular (containing no blood vessels), it is also innervated (supplied by nerve fibers). They are nourished by substances diffusing from blood vessels in the connective tissue that underlies it. 5. Regeneration: epithelium has high regenerative capacity – reproduce themselves rapidly if damage occurs 3. Compare and contrast exocrine and endocrine glands: Summary of glands: a gland consists of one or more cells that make and secrete a particular product. This product, which is called secretion, generally contains proteins. The process of secretion is active. Glands are classified according to where they release their produce and the number of cells they have. Exocrine glands: - Secrete their products onto body surfaces or into body cavities - Unicellular - Secretion takes place through exocytosis - Exocrine glands are diverse, and include the liver (secreting bile), pancreas (synthesizes digestive enzymes), mucous, sweat, oil, and salivary glands, etc. - Unicellular exocrine glands: Mucous cells and goblet cells are the most important unicellular exocrine glands These glands produce mucin, which is a complex glycoprotein that dissolves in water when it is secreted. When it is dissolved, it forms mucus. In goblet cells, mucin distends the top of the cell, making it look like a glass with a stem. This does not occur in mucous cells. - Multicellular exocrine glands: structurally more complex than unicellular glands and have two basic parts – (1) an epithelium derived duct and (2) a secretory unit with secretory cells. Supportive connective tissue surrounds the secretory unit, and supplies it with blood vessels and nerve fibers, as well as divides it into lobes. Structural classification: o Simple glands have an unbranched duct, compound glands have a branched duct o Tubular: secretory cells form tubes o Alveolar: secretory cells for small, flask like sacs o Tubuloalveolar: both tubular and alveolar Modes of secretion: o Merocrine: secrete their products by exocytosis when they are produced o Holocrine: accumulate their products within them until they rupture o Apocrine: accumulate products but only just beneath the free surface Endocrine glands: - Lose their ducts during development (ductless) - Produce hormones that they secrete by exocytosis directly into extracellular space - Structurally diverse - Diffuse endocrine system 4. Describe the classification of epithelial tissue: Simple epithelia: most concerned with absorption, secretion, and filtration, and consist of a thin, single layer. - Simple squamous epithelium: flattened laterally with sparse cytoplasm. Found where filtration or the exchange of substances by rapid diffusion is a priority. There are two simple squamous epithelia in the body: 1) Endothelium: slick, friction reducing lining in lymphatic vessels and in all hollow organs of the CVD system. Capillaries consist almost exclusively of these. 2) Mesothelium: epithelium found in serous membranes, the membranes lining the ventral body cavity and covering its organs - Simple cuboidal epithelium: consists of a single layer of cells as tall as they are wide. Their important functions are secretion and absorption. They form the walls of the smallest ducts of glands and of many kidney tubules. - Simple columnar epithelium: single layer of tall, closely packed cells, aligned like soldiers in a row. It lines the digestive tract from the stomach to the rectum and are mostly associated with absorption and secretion. The digestive tract has tow distinct modifications: 1) Dense microvilli on the apical surface of absorptive cells 2) Tubular glands made primarily of cells that secrete mucus containing intestinal juice - Pseudostratified columnar epithelium: vary in height. All of its cells rest on the basement membrane, and only the tallest reach the free surface of the epithelium. It secretes and absorbs substances, particularly mucus by ciliary action. It is generally located in the trachea and most of the upper respiratory tract. Stratified epithelia: contain two or more cell layers that regenerate from below by the basal cells dividing and pushing apically to replace the older surface cells. They are considered more durable than simple epithelia cells, and protection is a major role. - Stratified squamous epithelium: most widespread, composed of several layers. Thick and well suited for protective role. The free surface cells are squamous, and the cells of the deeper layers are cuboidal or columnar. They are found in any location of the body that is subjected to tearing and rubbing (nonkeratinized locations like the mouth, vagina, etc.) - Stratified cuboidal and columnar epithelia: Cuboidal: rare in the body, mostly found in the ducts of some of the larger glands. Typically has two layers of cuboidal.  Columnar: limited distribution in the body, small amounts found in the pharynx, male urethra, lining of some glandular ducts. Only its apical layer of cells is columnar. - Transitional epithelium: forms the lining of hollow urinary organs, which stretch as they fill with urine. Cells of the its basal layer are cuboidal or columnar. The apical cells vary in appearance depending on the degree of distension. 5. Describe the common characteristics of connective tissue and describe its structural elements: Common characteristics: - Extracellular matrix: connective tissues consist largely of non-living extracellular matric, which separates the living cells of the tissue. The connective tissue can bear weight because of the matrix, as well as withstand great tension, endure abuses. - Common origin: all connective tissues arise from mesenchyme (an embryonic tissue) Structural components: 1. Ground substance: unstructured material that fills the space between the cells and contains fibers. It has three parts: a. Interstitial fluid: large amounts of fluid that functions as a molecular sieve through which nutrients and other dissolved substances can diffuse between the blood capillaries and the cells b. Cell adhesion proteins: serve as connective tissue glue that allows connective tissue cells to attach to the extracellular matrix c. Proteoglycans: consist of a protein core to which large polysaccharides are attached. 2. Fibers: provide support; three types of fibers, by which collagen is the most abundant a. Collagen: collagen molecules are secreted into extracellular space, where they assemble spontaneously into cross-linked fibrils, which in turn are bundled  together into thick collagen fibers. They are extremely tough and provide high tensile strength. b. Elastic: long, thin, elastic fibers form branching networks in the extracellular matrix. They contain a rubber like protein called elastin, that helps them stretch and recoil. They are found in the skin, lungs, and blood vessel walls. c. Reticular: short, fine fibers that connect to the coarser collagen fibers and branch to form delicate networks. These networks surround small blood vessels and support small tissue of organs and are abundant where connective tissue is next to other tissue types. They allow more stretch than larger collagen fibers. 3. Cells: each major class of connective tissue has a resident cell type that exists in immature (-blast) and mature (-cyte) forms, like fibroblasts becoming fibrocytes. - Immature blast cells are mitotic, and once they synthesize the matrix, they assume their mature form. Mature cells maintain the health of the matrix. Blood is the only exception to this. - Connective tissue is home to many cell types, including: adipocytes (fat), white blood cells, mast cells (cluster along blood vessels, detect foreign microorganisms), and macrophages (devour foreign material). 6. Describe the types of connective tissue found in the body and their characteristic functions and locations: Mature connective tissues arise from mesenchyme that arises during the early weeks of embryonic development. All mature connective tissues except for bone, cartilage, and blood are connective tissue proper.  Connective Tissue Proper: a. Loose connective tissue: - Areolar: most widely distributed connective tissue in the body and serves as a universal packing material between other tissues. It binds parts together while allowing them to move freely. The functions include: Supporting and binding other tissues (fibers) Holding body fluids (ground substance role) Defending against infection (via white blood cells and macrophages) Storing nutrients as fat in adipocytes (fat cells) - Adipose: similar to areolar in structure and function, but it has a much stronger nutrient-storing ability. It is richly vascularized, indicating its high metabolic activity. It usually accumulates in the subcutaneous tissue, where it acts as a shock absorber, as insulation, and as an energy storage site. It is sometimes called white fat to distinguish it from brown fat. - Reticular: resembles areolar connective tissue, but the only fibers in its matrix are reticular fibers. These fibers form a delicate network along which fibroblasts called reticular cells are scattered. They form an internal framework that can support many free blood cells. b. Dense connective tissues: often called fibrous connective tissues - Dense regular connective tissue: contains closely packed bundles of collagen fibers running in the same direction, parallel to the direction of the pull. This results in white, flexible structures with great resistance to tension. Dense regular tissue forms: Tendons: cords that attach to muscles and bones Aponeuroses: flat, sheet like tendons that attach muscles to other muscles or to bones Ligaments: bind bones together at joints - Dense irregular tissues: the bundles of collagen fibers are thicker and are arranged irregularly – run in all directions. It forms sheets in body areas where tension is exerted from many different directions, and is found in the skin as the leathery dermis, and forms fibrous joint capsules and the fibrous coverings that surround some organs. - Elastic: dense regular connective tissue containing a high proportion of elastic fibers that make it stretch and allow tissue to recoil. Specialized Connective Tissue: a. Cartilage: stands up to compression and tension and is tough but flexible. It lacks nerve fibers and is avascular, and receives nutrients by diffusion from blood vessels located in the connective tissue layer surrounding it. - Hyaline cartilage: most abundant cartilage in the  body, that appears glassy blue white. It is found in several key places: Covers the ends of long bones, which provides springy pads that absorb compression at joints Supports the tip of the nose Connects the ribs to the sternum Supports most of the respiratory system passages Makes up most of the embryonic skeleton before bones form - Elastic cartilage: nearly identical to hyaline cartilage, except it has more elastic fibers. - Fibrocartilage: intermediate between hyaline cartilage and dense connective tissues. Its rows of chondrocytes alternate with rows of thick collagen fibers. It resists both compression and tension well, and is found where strong support and the ability to withstand heavy pressure is required. b. Bone (osseous tissue): bone can support and protect body structures. They also provide cavities for storing fat and synthesizing blood cells. c. Blood: does not connect things or give mechanical support. It is classified as connective because it develops from mesenchyme and consists of blood cells, surrounded by a nonliving fluid matrix called blood plasma. 7. Describe the basic characteristics of nervous and muscle tissue: Nervous: specialized tissue of the nervous system - Main component of brain, spinal cord, and nerves, which regulate and control body functions - Contain two major cell types: neurons and supporting cells - Neurons generate and conduct nerve impulses, and their branching cells with cytoplasmic extensions enable them to respond to stimuli (through dendrites) and transmit electrical impulses over substantial distances in the body (through axons) - Supporting cells support and protect the neurons Muscle: responsible for body movement. Muscle cells possess myofilaments that bring about movement and contraction in all cells. - Skeletal muscles: Voluntary muscle (under conscious control) Used in locomotion, manipulation of environment, and facial expression Packaged by connective tissue sheets into organs called skeletal muscle that are attached to the bones of the skeleton Long, cylindrical cells that contain many peripheral located nuclei - Cardiac muscles: Found only in the walls of the heart  Contractions help propel blood through the blood vessels to all parts of the body Generally uninucleate (one nucleus) with the nucleus central Branching cells that fit together tightly at unique functions called intercalated discs - Smooth muscle: Cells have no visible striations Individual smooth muscle cells are spindle shaped and contain one centrally located nucleus Found mainly in the walls of hollow organs other than the heart Chapter 5 – The Integumentary System: Key Terms: Integumentary system: skin and its derivatives; provides the external protective covering of the body Epidermis: superficial layer of skin; composed of keratinized stratified squamous epithelium Dermis: layer of skin deep to the epidermis; composed mostly of dense irregular connective tissue Subcutaneous tissue (Hypodermis): tissue just deep to the skin; consists of adipose plus some areolar connective tissue. Also called the hypodermis or superficial fascia. Keratinocytes: he primary type of cell found in the epidermis, the outermost layer of the skin. In humans they constitute 90% of epidermal skin cells. Melanocytes: melanin-producing neural crest-derived cells located in the bottom layer (the stratum basale) of the skin's epidermis, the middle layer of the eye (the uvea), the inner ear, vaginal epithelium, meninges, bones, and heart. Melanin is a dark pigment primarily responsible for skin color. Dendritic cells: protective cells that engulf antigens, migrate to lymph nodes, and present the antigen to T cells, causing them to activate and mount an immune response; those in the skin are sometimes called the Langerhans cells Tactile epithelial (merkel cell): oval-shaped mechanoreceptors essential for light touch sensation and found in the skin of vertebrates Stratum basale: the deepest layer of the five layers of the epidermis, the external covering of skin in mammals. The stratum basale is a single layer of columnar or cuboidal basal cells. Stratum spinosum: a layer of the epidermis found between the stratum granulosum and stratum basale. Their spiny (Latin, spinosum) appearance is due to shrinking of the microfilaments between desmosomes that occurs when stained with H&E. Stratum granulosum: thin layer of cells in the epidermis. Keratinocytes migrating from the underlying stratum spinosum become known as granular cells in this layer. Stratum lucidum: a thin, clear layer of dead skin cells in the epidermis named for its translucent appearance under a microscope. It is readily visible by light microscopy only in areas of thick skin, which are found on the palms of the hands and the soles of the feet. Stratum corneum: the outer layer of the skin (epidermis). It serves as the primary barrier between the body and the environment. Papillary dermis: the uppermost layer of the dermis. It intertwines with the rete ridges of the epidermis and is composed of fine and loosely arranged collagen fibers. The papillary region is composed of loose areolar connective tissue. Dermal papillae: small, nipple-like extensions (or interdigitations) of the dermis into the epidermis. At the surface of the skin in hands and feet, they appear as epidermal or papillary ridges (colloquially known as fingerprints). Reticular dermis: lower layer of the dermis, found under the papillary dermis, composed of dense irregular connective tissue featuring densely packed collagen fibers. It is the primary location of dermal elastic fibers. The reticular region is usually much thicker than the overlying papillary dermis. Sweat (sudoriferous) glands: epidermal glands that produce sweat Eccrine (merocrine) sweat glands: sweat glands abundant on the palms, soles of the feet, and the forehead Apocrine sweat glands: less numerous type of sweat gland; produces a secretion containing water, salts, proteins, and fatty acids Sebaceous (oil) glands: epidermal glands that produce an oily secretion called sebum Sebum: oily secretion of the sebaceous glands Thermoregulatory centers: A center in the hypothalamus that regulates heat production and heat loss, esp. the latter, so that a normal body temperature is maintained. It is influenced by nerve impulses from cutaneous receptors and by the temperature of the blood flowing through it. Peripheral thermoreceptors: present in skin as free nerve endings of A and C type fibres Central thermoreceptors: two types of receptor are found in the preoptic area of the anterior hypothalamus Objectives: 1. Name the cells that make up the epidermis and briefly describe the function(s) of each. Describe the changes that occur in the cells as they migrate through the epidermis. Keratinocytes: - Keratin cells - Chief role is to produce keratin, which gives the epidermis its protective properties - Most epidermal cells are keratinocytes - Tied together by desmosomes for strength and, in some layers, by tight junctions to hinder movement of water between cells - Arise in the deepest part of the epidermis from the stratum basale – these cells undergo almost continuous mitosis. Newly formed keratinocytes are pushed upward throughout the body, and by the time they reach the surface, they are dead, scale-like flat sacs completely filled with keratin. Melanocytes: - Spider shaped epithelial cells that synthesize the pigment melanin - Found in the deepest layer of the epidermis - Made in membrane bound granules called melanosomes and then transferred through the cell processes to nearby keratinocytes. This results in the basal keratinocytes carrying more melanin than melanocytes - Protect the nucleus from damaging effects of UV radiation in sunlight Dendritic cells: - Star shaped cells - Arise from bone narrow and migrate to the epidermis - Also called Langerhans cells - Ingest foreign substances and are key activators of our immune system - Form a continuous network Tactile epithelial cells: - Merkel cells - Present at the epidermal-dermal junction - Shaped like a spiky hemisphere - Functions as a sensory receptor for touch 2. Name the tissue types composing the epidermis and dermis, Describe the major layers of each. Subcutaneous tissue: lies just deep to the skin but its no part of the skin, although it shares some of the skin’s protective functions. It anchors the skin to the underlying structures. Layers and Tissues of the Epidermis: outermost layer of the cell 1. Stratum Basale (Basal Layer): - Deepest epidermal layer - Attached to the underlying dermis - Consists of a single row of stem cells – a continually renewing cell population – representing the youngest keratinocytes - Around 10-25% are melanocytes, which branch into the stratum spinosum layer 2. Stratum Spinosum (Prickly Layer): - Several cell layers thick - Spinelike extensions in keratinocytes are not existent in living cells, but are artifacts created during tissue preparation because the cells shrink while holding tightly to their desmosomes. - Cells contain thick bundles of intermediate filaments, which consist of tension-resisting proteins, pre-keratin 3. Stratum Granulosum (Granular Layer): - 1-5 cell layers in which keratinocyte appearances changes drastically and the process of keratinization begins - Cells flatten and their nuclei and organelles begin to disintegrate, accumulating two kinds of granules: a) Keratohyalin granules: help form keratin in upper layers b) Lamellar granules: slows water loss from epidermis via water-resistant glycolipids - Touch and water resistance cells - Release lipids 4. Stratum Lucidum (Clear Layer): - Found only in thick skin - Visible through a light microscope as a thin translucent band just above the stratum granulosum - Consists of a few rows of flat, dead keratinocytes 5. Stratum Corneum (Horny Layer): - 20-30 cell layers thick that account for up to ¾ of the epidermal thickness - Cells shed regularly - Flat membranous sacs filled with keratin - Glycolipids in extracellular spaces Layers and Tissues of the Dermis: The dermis is made up of strong, flexible connective tissue. Its cells are typical of those found in any connective tissue proper: fibroblasts, macrophages, and occasional mast cells and white blood cells. 1. Papillary Dermis: - Areolar connective tissue in which fine interlacing collagen and elastic fibers form a loosely woven mat with many small blood vessels. This looseness allows phagocytes and other cells to wander freely as they look for bacteria. - Dermal papillae: peg like projections that contain capillary loops or free nerve endings, as well as touch receptors 2. Reticular Dermis: - Accounts for around 80% of the dermis - Coarse, dense, irregular connective tissue containing a network of blood vessels that nourish the layer - Contains thick bundles of interlacing collagen fibers which form cleavage lines in the skin