Chapters 1-4 Study Guide PDF

Chapter one: - Anatomy: structure of body parts and relationships to each other - Physiology: functions of the body; how parts carry out life-sustaining activities. - Gross anatomy: study of large body structures (lungs, heart) \- regional anatomy: all structures in particular regi...

Chapter one: - Anatomy: structure of body parts and relationships to each other - Physiology: functions of the body; how parts carry out life-sustaining activities. - Gross anatomy: study of large body structures (lungs, heart) \- regional anatomy: all structures in particular region are examined (same time) \- systemic anatomy: studied system by sys tem. \- surface anatomy: internal structures how they relate to the skin surface Microscopic anatomy: structures too small to be seen Developmental: traces structural changes that occur through life span Palpate: feel organs w/ hands Auscultate: listen to organ sounds - Anatomy & physiology are inseparable \- function reflects structure \- structures function depends on form \- principle of complementarity of structure & function STUCTURAL ORGANIZATION \- Chemical level: atoms, molecules, organelles \- Cellular level: single cell \- Tissue level: group of similar cells \- Organ level: two or more types of tissue \- Organ System level: organs work close together \- Organismal level: systems combine to make organism **Maintaining boundaries**: keep internal environment from external environment. **Movement:** activities promoted by muscular system. Ex: running. **Responsiveness:** ability to sense changes (stimuli) in the environment and respond. **Digestion**: breakdown of ingested food to simple molecules. **Metabolism: (state of change)**. All chemical reactions that occur within body cells. Includes catabolism and anabolism; uses nutrients and oxygen for creation of ATP. \- catabolism: breakdown of substances into simpler building blocks \- anabolism: synthesizing of more complex substances from simple building blocks. **Excretion**: waste removal from body. **Reproduction**: occurs at cellular and organismal level. **Growth**: increase in size of a body part or the organism as a whole. ORGAN SYSTEMS: - Integumentary: forms external body covering. Synthesizes vitamin D. houses sweat and oil glands. - Skeletal: protects&supports organs and provides framework for muscle movement; blood cells formed in bones; stores minerals - Muscular: allows manipulation of environment & facial expression; maintains posture; produces heat - Nervous: fast-acting control system of body. Responds to internal and external changes by activating appropriate muscles/glands. - Endocrine: glands secrete hormones that regulate growth processes, reproduction, and metabolism - Cardiovascular: blood vessels transport blood, which carries oxygen, carbon dioxide, nutrients, wastes, etc. - Lymphatic/Immunity: picks up fluid leaked from blood vessels and return it to blood. Houses white blood cells involved in immunity. - Respiratory: keeps blood supplied w/ oxygen; removes carbon dioxide - Digestive: breaks down food to absorbable units that enter blood to be distributed to cells - Urinary: eliminates nitrogenous waste from body. Regulates water, electrolyte, and acid-base balance of blood. - Male&Female Reproductive: production of offspring. Testes produce sperm and male sex hormone; ovaries produce eggs and female sex hormones. SURVIVAL NEEDS\ - Nutrients: contain chemical substances used for energy and cell building. \- carbohydrates are the MAJOR energy fuel for body cells. Proteins are essential for building cell structures. - Oxygen: 20% of air we breathe. Chemical reactions that release energy from food requires oxygen. - Water: 50-60% of body weight. Single most abundant chemical substance in body. - Normal Body Temperature: metabolic reactions become slower until stopped as temp decreases; when temp is too high, chemical reactions occur at frantic pace and systems stop functioning. - Appropriate Atmospheric Pressure: the force that air exerts on the body. HOMEOSTASIS - Maintenance of stable internal conditions. - Dynamic state of equilibrium. Maintained by contributions of all organ systems HOMEOSTATIC CONTROL The three components that work to regulate the variable: - Receptor: a sensor that monitors environment. Responds to stimuli by sending info to the control center along the afferent pathway - Control Center: determines the set point (range of levels that the variable must be maintained. Analyzes input that it receives and flows to the effector along the efferent pathway. - Effector: carries out control center's response to stimulus. The results feed back to influence effect of the stimulus. Either shutting off the process or enhancing it. NEGATIVE FEEDBACK MECHANISMS - The output shuts off the original effect of the stimulus or reduce intensity. This causes the variable to change in a direction opposite to that of the initial change. - Endocrine system is importantant in maintaining homeostasis. (ex. Control of blood sugar by insulin. - Negative feedback mechanisms prevent severe changes in body. POSITIVE FEEDBACK MECHANISMS\\ - The initial repsonse enhances the original stimulus so that further responses are greater. "positive" because the change that results proceeds in the same direction as the initial change. - Ex. Enhancement of labor contractions w/ oxytocin and blood clotting. ANATOMICAL POSITIONS & DIRECTIONAL TERMS - Standard Anatomical Position \- Body erect, feet slightly apart, palms facing forward w/ thumbs pointing away from body. - Directional Terms: describe one body structure in relation to another body structure. **Superior (cranial):** toward the head end of upper part of a structure; above. (ex. Head is superior to abdomen) **Inferior (caudal)**: away from the head end or toward the lower part of structure; below. (ex. Navel is inferior to chin) **Anterior (ventral):** toward or at the front of the body; in front of. (ex: breastbone is anterior to the spine. **Posterior (dorsal):** Toward or at the back of the body; behind. (ex: the heart is posterior to the breastbone. **Medial:** toward or at the midline of the body; on the inner side of. (ex. The heart is medial to the arm) **Lateral:** away from the midline of the body; on the outer side of. (ex. The arms are lateral to the chest.) **Intermediate:** between a more medial and a more lateral structure. (ex. Collarbone is intermediate between the breastbone and shoulder. **Proximal:** closer to the origin of the body part or the point of attachment of a limb to a body trunk. (ex. The elbow is proximal to the wrist). **Distal**: Farther from the origin of the body part or the point of attachment of a limb. (ex. The knee is distal to the thigh.) **Superficial (External):** toward or at the body surface. (ex. The skin is superficial to the skeletal muscles.) **Deep (Internal):** away from the body surface; more internal. (ex. The lungs are deep to the skin. REGIONAL TERMS - Two divisions are: \- Axial: makes up the main axis of the body; includes head, neck, trunk. \- Appendicular: appendages, or limbs which are attached to the axis. BODY PLANES & SECTIONS - Sagittal plane: vertical plane that divides body into right and left. \- Median/Midsaggital plane: lies exactly in midline \- Parasaggital plane: offset from midline - Frontal Planes: lie vertically. Divide body into anterior and posterior. Also called a coronal plane. - Transverse Plane: runs horizontally from right to left, dividing into superior and inferior parts. Transverse sections is also called a cross section. ' - Oblique sections: cuts made diagonally between the horizontal and the vertical planes. DORSAL BODY CAVITY: - Protects nervous system organs. - Has two **subdivisions**: \- cranial cavity: in skull, encases brain. \- vertebral or spinal cavity: encloses the spinal cord. \- these cavities are continuous w/ each other. VENTRAL BODY CAVITY - The more anterior and larger of the closed body cavities. - Houses internal organs called the viscera or visceral organs. - Has two major **subdivisions**: \- Thoracic Cavity: the superior. Surrounded by ribs and chest muscles. It is further divided into lateral pleural cavities (each enveloping a lung and the medial mediastinum.) The mediastinum contains the pericardial cavity. \- Pericardial Cavity encloses the heart and surrounds the remaining thoracic organs (esophagus, trachea, and others). ABDOMINOPELVIC CAVITY - Contains two parts: \- **abdominal cavity**, the superior portion, (contains stomach, intestines, spleen, liver \- **pelvic cavity**, the inferior part; lies in the bony pelvis, (contains bladder, the rectum, and some reproductive organs.) MEMBRANES IN VENTRAL BODY CAVITY - Serous membrane: thin, double-layered membrane that lines organs and the walls of the ventral cavity. - The part lining the walls is called the parietal serosa. (parie=wall.) - The visceral serosa covers the organs in the cavity. ABDOMINOPELVIC REGIONS AND QUADRANTS - **Four quadrants** result from a transverse & median plane pass through the umbilicus at right angles: \- Right Upper Quadrant \- Left Upper Quadrant \- Right Lower Quadrant \- Left Lower Quadrant - Two transverse and two parasagittal planes divide the cavity into **nine regions**: \- Umbilical Region: centermost region deep to and surrounding the navel. \- Epigastric Region: located superior to the umbilical region. \- Pubic (Hypogastric) Region: located inferior to the umbilical region. \- Right &Left Inguinal or Iliac Regions: located lateral to the hypogastric region. \- Right & Left Lateral (Lumbar) Regions: lie lateral to the umbilical region. \- Right & Left Hypochondriac Regions: lie lateral to the epigastric region and deep to the ribs. Chapter two: - chemistry underlies all physiological reactions. \- movement, digestion, nervous system, pumping of heart. - Chemistry can be broken down into: \- Basic chemistry: general chemistry \- Biochemistry: more of chemistry for the body MATTER: - Anything that has mass; occupies space - Can be seen, felt, smelled - Weight is mass plus the effects of gravity STATES OF MATTER: - Exists in three possible states \- solid: definite shape and volume \- liquid: changeable shape; definite volume \- gas: changeable shape and volume ENERGY: - Capacity to do work; put matter into motion - Does not take up space; does not have mass - The greater the work done, the more energy used up KINETIC VS. POTENTIAL - Exists in two forms: \- Kinetic: energy in action \- Potential: stored (inactive) energy - Can be transformed from potential to kinetic - Chemical energy: stored in bonds of chemical substances - Electrical energy: results from movement of charged particles - Mechanical energy: directly involved in moving matter - Radiant or electromagnetic energy: travels in waves (ex. Heat) - Energy cannot be created or destroyed. - Can be converted from one form to another. - Energy conversion is inefficient. Some energy is "lost" as heat. ATOMS & ELEMENTS Elements: substances that cannot be broken down into simpler substances by ordinary chemical methods. - All matter is composed of elements. - All elements are made of atoms which are: \- unique building blocks for each element \- smallest particles of an element \- what give each element its physical & chemical properties. - FOUR elements make up 96% of the body: \- carbon, oxygen, hydrogen, and nitrogen - Atomic symbol: One or two letter chemical shorthand for each element. STRUCTURE OF ATOMS: - Atoms are composed of three subatomic particles: Protons, Neutrons, Electrons. \- Protons: \- positive charge (+) \- weigh 1 atomic mass unit (amu) \- Neutrons: \- no electrical charge \- weigh 1 amu \- Electrons: \- negative charge (-) \- so small, no weight -Number of positive protons is balanced by number of negative electrons. -Atoms are electrically neutral. \- Protons and Neutrons are found in nucleus. 2 models of how subatomic particles are put together: Planetary Model & Orbital Model - Planetary: outdated; incorrectly depicts electrons - Orbital: current model; depicts orbitals: probable region where electron is likely to be located. (shading in regions w/ electron cloud) IDENTIFYING ELEMENTS - Atomic \#: number of protons in nucleus; written as subscript to left of atomic symbol. - Mass \#: total number of protons and neutrons in nucleus; written as superscript to atomic symbol. - Isotopes: structural variations of same element; contain same number of protons but different number of neutrons. Atomic numbers are the same, but mass numbers different. - Atomic weight: average of mass numbers of all isotope forms of an atom. RADIOISOTOPES: - Isotopes that decompose to more stable forms. \- atom loses various subatomic particles. Loss sometimes results in isotopes becoming different elements. - When isotope decays, subatomic particles being given off release a little energy called radioactivity. - Valuable tool for biological research and medicine. - Can damage living tissue. MOLECULES AND COMPOUNDS - Most atoms chemically combine w/ other atoms to form molecules & compounds. - **Molecule**: 2 or more atoms bonded together. (H2 or 02) - **Compound**: specific molecule that has 2 or more different kinds of atoms bonded together. (ex. C6H12O6) MIXTURES: **Mixtures**: two or more components that are physically intermixed. - Three basic mixture types: \- Solutions \- Colloids \- Suspensions **1. SOLUTIONS**: homogenous mixtures; particles are evenly distributed throughout. \- **Solvent**: substance present in greatest amount. (ex. Usually liquid.) \- Water is the Universal Solvent **-solute(s)**: substance dissolved in solvent. \- present in smaller amounts. (ex. Glucose is solute, blood (plasma) is solvent. - True solutions are usually transparent (don't deflect light). - Concentration of true solutions: \- Three common ways to express concentrations: 1. Percent of solute in total solution 2. Milligrams per deciliter 3. Molarity **2. COLLOIDS**: \- Heterogenous mixtures; not evenly distributed throughout mixture. \- can see large solute particles in solution, these DO NOT settle. \- gives milky or cloudy look. \- Some undergo sol-gel (solution to gel) transformations. (ex. Jell-O goes from liquid to gel.) (Cytosol of cell is also sol-gel type solution. **3. SUSPENSIONS:** \- Heterogenous mixtures that contain large, visible solutes that DO settle out. (ex. Mixture of water and sand.) \- Blood is considered a suspension because if left in a tube, the blood cells settle out, Three main differences between Compounds and Mixtures: \- Unlike compounds, mixtures DO NOT involve chemical bonding between components. \- Mixtures can be separated by physical means, compounds can be separated only by breaking chemical bonds. \- Mixtures can be heterogeneous or homogeneous; compounds are **only** homogenous. CHEMICAL BONDS - Chemical bonds are "energy relationships" between electrons of reacting atoms \- bonds are not actual physical structures. - Electrons are the subatomic particles that are involved in all chemical reactions. \- determine chemical reaction and what type of bond is formed. ROLE OF ELECTRONS IN CHEMICAL BONDING - Electrons occupy electron shells (areas around the nucleus). \- each shell has electrons that have a certain amount of kinetic and potential energy; shells are referred to as **energy levels**. \- depending on size, an atom can have up to 7 electron shells \- shells can only hold a specific number of electrons; the shell closest to nucleus is filled first. \- shell 1 holds only 2 electrons, shell 2 holds a maximum of 8 electrons, and shell 3 holds maximum of 18. - Outermost shell- Valence Shell \- electrons in valence have the most potential energy because they are farthest from nucleus. \- these are electrons that are involved in chemical reactions. - Octet Rule (Rule of eights) \- atoms desire 8 electrons in valence shell. \- exceptions: smaller atoms want only 2 in shell 1. \- desire to have 8 electrons is the driving force of chemical reactions. \- most atoms do NOT have full valence shells. \- atoms gain, lose, or share electrons (form bonds) w/ other atoms to achieve stability of 8 electrons in valence shell. THREE MAJOR TYPES OF CHEMICAL BONDS - Ionic Bonds - Covalent Bonds - Hydrogen Bonds IONIC BONDS: \- **ions** are atoms that have gained or lost electrons and become charged. (number of protons does not equal number of electrons). - Ionic bonds involve the transfer of valence shell electrons from one atom to another, resulting in ions. \- one becomes **anion (negative charge)**: atom that gained one or more electrons \- one becomes **cation (positive charge):** atom that lost one or more electrons - Attracting of opposite charges results in ionic bond. - Most ionic compounds are salts. COVALENT BONDS: - formed by sharing of two or more valence shell electrons between two atoms. - Allows each atom to fill the valence shell for part of the time. ("Co" means share!) - Sharing of 2 electrons is a SINGLE bond. - Sharing of 4 electrons is a DOUBLE bond - Sharing of 6 electrons is a TRIPLE bond. TWO TYPES OF COVALENT: - Polar & Nonpolar Covalent Bonds NONPOLAR -- Equal sharing of electrons between atoms; results in electrically balanced, nonpolar molecules. (ex. CO2) (Electrically balanced because the electrons are on both molecules, around both molecules EQUALLY.) POLAR -- Unequal sharing of electrons between 2 atoms; results in electrically polar molecules. - Unequal sharing because of the atom's different electron-attracting abilities. \- atoms w/ greater electron-attracting ability are **electronegative** and those w/ less are **electropositive**. - Dipole: having two different charges. HYDROGEN BONDS: - attractive force between electropositive hydrogen of one molecule and an electronegative atom of another molecule. - Not a true bond; weak magnetic attraction. - Hydrogen bond is what makes water liquid TYPES OF CHEMICAL REACTIONS: 1. Synthesis Reactions: (combination) reactions involve atoms/molecules combining to form larger more complex molecules. - Used in anabolic (building) processes. 2. Decomposition Reactions: involve breakdown of molecule into smaller molecules. (reverse of synthesis). - Involve catabolic (bond-breaking) reactions. 3. Exchange Reactions: involve synthesis and decomposition. - Bonds are made and broken Reduction-oxidation or Redux reactions -- atoms are **reduced** when they **gain** electrons, **oxidized** when they **lose** electrons. - All chemical reactions are Exergonic or Endergonic. \- EXERGONIC: result in net release of energy; catabolic & oxidative reactions. (give off energy). \- ENDERGONIC: result in net absorption of energy; anabolic reactions. (use up energy) The speed of chemical reactions can be affected by: temp. (increased temp=increased reaction rate), concentration of reactants (increased concentration=increased reaction rate), particle size (smaller particles=increased reaction rate). - Catalysts: increase the rate of reaction only if it is natural; biological catalysts. They lower the amount of energy needed for A+B to become AB. INORGANIC COMPOUNDS: water, salts, many acids and bases. (no carbon) ORGANIC COMPOUNDS: lipids, proteins, carbohydrates, and nucleic acids. contain carbon; covalently bonded. ACIDS - Proton **donors** - Release hydrogen ions BASES - (or alkaline) are proton **acceptors**. - Pick up hydrogen ions PH: - Ph scale: measurement of concentration of hydrogen ions - The more hydrogen ions, the more acidic the solution. - Acidic ph range is 0-6.99 - Neutral is 7. (water) - Alkaline ph range is 7.01-14. - Buffers: resist abrupt and large swings in ph; convert strong acids or bases into weak ones. [CARBOHYDRATES:] - Include sugar & starches - Contain carbon, hydrogen, and oxygen - Three classes: monosaccharides, disaccharides, and polysaccharides. **Monosaccharides**: one single sugar; contains 3-7 carbon atoms. \*Important monosaccharides: (Pentose sugars: Ribose & Deoxyribose) and (Hexose sugars: glucose.) - Monomers: smallest unit of carbohydrate. **Disaccharides**: two sugars; too large to pass through cell membranes. (sucrose, maltose, lactose); formed through dehydration synthesis. **Polycaccharides**: many sugars; polymers of monosaccharides. (ex. Glycogen & starch.); not soluble. [LIPIDS: ] - Contain carbon, oxygen, and hydrogen, but LESS than carbohydrates. - Insoluable in water - Main types: phospholipids, triglycerides, steroids Triglycerides: - Main function: energy storage, insulation, protection. - Composed of THREE fatty acids bonded to glycerol molecule - Saturated Fats: molecules pack closely together by SINGLE covalent bonds forming solid at room temperature. - Unsaturated Fats: liquid at room temperature; DOUBLE bonds cause molecules to be unable to pack close together Phospholipids: - Modified triglycerides. - TWO fatty acids and glycerol plus a phosphorus containing group. \- head is polar and hydrophillic (attracted to water) \- tail is nonpolar and hydrophobic (repelled by water) [PROTEINS: ] - 20-30% of cell mass. - Polymers of amino acid monomers held together by **peptide bonds.** - All proteins made from 20 types of amino acids. \- joined by covalent bonds called peptide bonds. \- contain amine and acid group - Shapes of Proteins: \- Fibrous (structural proteins): strand-like; insoluble, stable \- most have 3D structure \- (collagen, keratin, elastin) \- Globular (functional): compact, water-soluble. \- antibodies, hormones, enzymes. ENZYMES - Globular proteins that are biological catalysys. - Increase speed of chemical reactions - Lower energy needed to initiate chemical reaction. - Names usually end in --ase. - Three steps of enzyme action: 1\. substrate binds to enzyme active site (form enzyme-substrate complex). 2\. rearrangement of substrate, results in final product 3\. product is released from enzyme. NUCLEIC ACIDS: - Largest molecules in the body. - Nucleotides are the monomers that make up nucleic acid polymers. \- composed of nitrogen base, pentose sugar, and phosphate group. - Two major classes: \- Deoxyribonucleic acid (DNA) \- Ribonucleic acid (RNA) - DNA holds genetic blueprint for synthesis of proteins \*PURINES\*: Adenine (A), Guanine (G). \*PYRIDAMINES\*: Cytosine (C), Thymine (T) RNA: - Slightly different from DNA: contains ribose sugar NOT deoxyribose. - Thymine is replaced with Uracil (U) - Three varieties of RNA: \- messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). ATP: - Adenosine Triphosphate. - Chemical energy is released as this when glucose is broken down - Directly powers chemical reactions in cells. - When we want to make ATP, we get the energy from glucose and add phosphorous groups. Chapter 3: CELLS: - 3 basic parts: \- plasma membrane: flexible outer boundary \- cytoplasm: intracellular fluid; contains organelles \- nucleus: DNA containing control center Interstitial fluid: cells are submersed in this Blood plasma: fluid of blood Cerebrospinal fluid: fluid surrounding nervous system organs - Extracellular matrix: substance that acts as glue to hold cells together; nonfluid portion of extracellular material. - Cellular secretions: (ex. Mucus, saliva) PLASMA MEMBRANE - Separates intracellular fluid from extracellular fluid; controls what enters and leaves the cell - Also known as Cell Membrane - Consists of membrane lipids that form flexible lipid bilayer. Lipid bilayer: made up of 75% phospholipids which have 2 parts: \- phosphate heads: polar (charged) so are hydrophilic. \- fatty acid tails: nonpolar (no charge) so are hydrophobic MEMBRANE PROTEINS - Integral proteins: \- firmly inserted into membrane; span membrane; have hydrophobic & hydrophilic areas; function as transport proteins, enzymes, or receptors - Peripheral proteins: \- loosely attached to integral proteins; filaments on intracellular surface for membrane support; function as cell-to-cell connections, motor proteins for shape change during cell division, and enzymes GLYCOCALYX - Consists of sugars (carbohydrates) sticking out of cell surface - Cell types have different patterns of this "sugar coating;" allows immune system to recognize self v nonself CELL JUNCTIONS - Some cells are free (not bound to any cells.) (ex. Sperm cells, blood cells) - Most cells are bound together to form tissues and organs - Three ways cells can be bound: \- **Tight Junctions**: integral proteins on close cells fuse to form impermeable junction that encircles whole cell; prevents fluid and molecules from moving in between cells. \- **Desmosomes**: linker proteins interlock w/ neighboring cells like teeth of a zipper; allow give in between cells. Linker protein is anchored to plaque. \- **Gap Junctions**: proteins that span membrane form tunnels that allow small molecules to pass from cell to cell; allows electrical signals to be passed quickly between cells. Plasma membrane is selectively permeable. Two ways substances can cross: - Passive transport: no energy required - Active transport: energy (ATP) is required. PASSIVE MEMBRANE TRANSPORT NO energy input. Types of passive transport. - Simple diffusion - Facilitated diffusion - Osmosis - **Diffusion**: natural movement of molecules from high concentration to low. - All molecules have random, high-speed movement due to intrinsic kinetic energy Speed of diffusion influenced by 3 factors: - The greater concentration, the faster diffusion - The smaller the molecule, the faster diffusion - The higher the temp, the faster diffusion. \- S**imple diffusion:** Lipid-soluble and nonpolar substances passively diffuse through membrane. Very small molecules that can pass through membrane. (Oxygen, carbon dioxide, fatty acids.) \- **Facilitated diffusion**: larger or nonlipid soluble or polar molecules cross w/ **assistance** of carrier molecules. (Glucose, amino acids, and ions) \- Carrier Mediated: substances bind to protein carriers \- Channel Mediated: substances move through water-filled channels. \- Leakage channels: always open \- Gated channels: controlled by chemical or electrical signals. \- **Osmosis**: movement of solvent (usually water), not molecules. \- flow occurs when solvent concentration is different on the two sides of the membrane. Osmolarity: measures the concentration of the number of solute particles in solvent. \- When solute concentration goes up, water concentration goes down. Vice-versa. \- Equilibrium: same concentration of solutes & water molecules on both sides, w/ equal volume. Movement of water includes pressures: - Hydrostatic pressure (back pressure): outward pressure on cell side of membrane from increases in volume of cell from osmosis - Osmotic pressure: inward pressure from tendency of water to be "pulled" into a cell w/ higher osmolarities. Tonicity: ability of a solution to change shape of cells by altering internal water volume ISOTONIC SOLUTION: same osmolarity as inside of cell; volume remains unchanged HYPERTONIC SOLUTION: higher osmolarity than inside cell; water flows out resulting in shrinking. (crenation) HYPOTONIC SOLUTION: lower osmolarity than inside cell; water flows into cell resulting in swelling ACTIVE MEMBRANE TRANSPORT - Two major types: \- active transport \- Vesicular transport - Both require ATP to move solutes across plasma membrane \- Active transport requires: carrier proteins (solute pump) and moves solutes against concentration gradient (low to high) \- Antiporters: transport one substance into cell while transporting another substance out of cell. \- Symporters: transport 2 different substances in the same direction. - **Primary active transport:** energy comes DIRECTLY from ATP hydrolysis; causes change in shape of transport protein, which causes solutes bound to protein to be pumped across membrane. - **Sodium-potassium pump:** basically an enzyme that pumps Na+ out of cell and K+ back into cell against their concentration gradients. \- located in all plasma membranes. \- most important pump in our bodies. \- leakage channels result in leaking of Na+ INTO cell, and K+ OUT of cell. SECONDARY ACTIVE TRANSPORT - Obtained INDIRECTLY **from ionic gradients** created by primary active transport. - Energy stored in gradients is used indirectly to drive transport of other solutes. VESICULAR TRANSPORT - Transport of LARGE particles, macromolecules, and fluids in membranous sacs called **VESICLES**. - Requires cellular energy (usually ATP) Includes: - **Endocytosis**: transport INTO cell. Involves formation of protein-coated vesicles; usually involves receptors so it is very selective process. When inside, may either fuse w/ lysosome or undergo transcytosis. \- 3 types: phagocytosis, pinocytosis, and receptor-mediated endocytosis PHAGOCYTOSIS: "cell eating." The formed vesicle is called a phagosome. - Cell engulfs large particle by forming projecting pseudopod around it and enclosing it in phagosome which is pulled into the cell. PINOCYTOSIS: referred to as "cell drinking" or fluid phase of endocytosis. - Cell "gulps" drop of extracellular fluid containing solutes into vesicles. RECEPTOR-MEDIATED ENDOCYTOSIS: extracellular substances bind to specific receptor proteins allowing cell to ingest and concentrate specific substances in protein-coated vesicles. - **Exocytosis**: transport OUT of cell. \- substance being ejected is enclosed in **secretory vesicle.** **-** secretory vesicle migrates towards plasma membrane. There, proteins at the vesicle surface (V-snares) bind w/ T-snares (plasma membrane proteins). Then the vesicle and plasma membrane fuse and a pore opens up. Finally, vesicle contents are released to cell exterior. - **Transcytosis**: transport across, into, and out of cell. RESTING MEMBRANE POTENTIAL: - Electrical potential energy produced by separation of oppositely charged particles across plasma membrane in all cells. \- **Voltage** is the difference in electrical charge between two points. Only occurs at membrane surface. The rest of the cell and extracellular fluid are neutral \- Membrane voltages range from --50 to --100 mV. Negative sign indicates inside of cell is more negative than outside of cell. \- cells that have a charge are polarized. K+ IS KEY PLAYER IN RMP - Sodium (K+) diffuses out of cell through K+ leakage channels down its concentration gradient. - Negatively charged proteins cannot leave; cytoplasmic side of cell membrane becomes more negative - K+ is then pulled back by the more negative interior bc of its electrical gradient. - When drive for K+ to leave cell is balanced by its drive for stay, RMP is established. \- most cells have RMP around --90. - Electrochemical gradient of K+ sets RMP - NA+ can also affect RMP because of its negative charge but membrane is more permeable to K+ so K+ has the primary influence on RMP. - RMP is maintained through action of the NA+-K+ pump, which continuosly ejects 3 NA+ out of cell and brings 2 K+ back inside. CELL-ENVIRONMENT INTERACTIONS - Cells interact w/ environment by responding directly to other cells, or indirectly to extracellular chemicals. - Interactions always involve GLYCOCALYX \- Cell Adhesion Molecules (CAMs) \- Plasma Membrane Receptors ROLE OF CELL ADHESION MOLECULES: - Every cell has thousands of sticky glycoprotein CAMs projecting from membrane. - Functions: \- anchor cell to extracellular matrix or to each other \- assist in movement of cells past each other \- attract white blood cells to injured or infected areas \- stimulate synthesis or degradation of adhesive membrane junctions (ex. Tight junctions) - Membrane receptor proteins serve as binding sites for several chemical signals. \- CONTACT SIGNALING: cells that touch recognize each other by membrane receptors (used in normal development & immunity). \- CHEMICAL SIGNALING: interaction between receptors and **ligands** (chemical messengers) that cause changes in cellular activities \- Examples of **Ligands**: neurotransmitters and hormones. \- same ligand can cause different responses in different cells depending on chemical pathway \- when ligand binds, receptor protein changes shape and becomes activated \- some activated receptors become enzymes; others act to directly open or close ion gates. \- Activated G protein-linked receptors indirectly cause cellular changes by activating G proteins, which can affect ion channels, activate other enzymes, or cause release of internal second messenger chemicals such as cyclic AMP or calcium. CYTOPLASM: All cellular material located between plasma membrane and nucleus. - Composed of: \- cytosol: gel-like solution made up of water and soluble molecules such as proteins, salts, sugars \- inclusions: insoluble molecules; vary w/ cell type \- organelles: metabolic machinery structures of cell, each w/ specialized function; either membranous or nonmembranous. CYTOPLASMIC ORGANELLES - Membranous: \- mitochondria \- endoplasmic reticulum \- golgi apparatus \- lysosomes - Nonmembranous: \- ribosomes \- cytoskeleton \- centrioles MITOCHONDRIA - "powerhouse of cell." produces most of ATP via aerobic cellular respiration - Enclosed by double membranes; has many folds called **cristae** - Contains its own DNA, RNA, and ribosomes - Are able to reproduce themselves; use cell division called **fission** RIBOSOMES - Nonmembranous; site of protein synthesis - Made of protein and rRNA (ribosomal rna) - **Free ribosomes**: free floating; site of synthesis for soluble proteins that function in cytosol or other organelles - **Membrane-Bound ribosomes**: attached to membrane of endoplasmic reticulum; site of synthesis for proteins to be incorporated into membranes of lysosomes, or exported; form Rough ER. ENDOPLASMIC RETICULUM - Consists of series of parallel, interconnected **cisterns-** flattened membranous tubes that enclose fluid filled interiors. - Continuous with outer nuclear membrane. - Two varieties: ROUGH ER and SMOOTH ER ROUGH ER: - Surface appears rough because it is studded with ribosomes \- site of synthesis of proteins that will be secreted from cell \- site of synthesis of many plasma membrane proteins & phospholipids - Proteins enter cisterns when they are synthesized and are modified as they go through the tubes. - Final protein is enclosed in vesicle and sent to golgi apparatus SMOOTH ER: - Network of looped tubules continuous w/ rough er. - Enzymes found in its plasma membrane (integral proteins) function in: \- lipid metabolism; cholesterol and steroid-based hormone synthesis; making lipids for lipoproteins. \- absorption, synthesis, and transport of fats \- converting of glycogen to free glucose \- storage and release of calcium GOLGI APPARATUS - Stacked and flattened membranous cistern sacs. (shaped like hollow dinner plates) - Modifies, concentrates, and packages proteins and lipids received from Rough ER. - Three steps: \- Transport vesicles from ER fuse w/ **cis (inner)** face of Golgi \- Proteins or lipids taken inside are further modified, tagged, sorted, and packaged. \- Golgi is the traffic director; controls which pathway final products will take when new transport vesicles pinch of **trans (outer)** face. - Can take three pathways: \- Pathway A: Secretory vesicles containing proteins to be used outside of cell fuse w/ plasma membrane and exocytosis contents \- Pathway B: Vesicles containing lipids or transmembrane proteins fuse w/ plasma membrane, inserting contents directly into destination membrane. \- Pathway C: Lysosomes containing digestive enzymes remain in cell, holding contents until needed. PEROXISOMES - Membranous sacs that containing powerful detoxifying substances that neutralize toxins. \- Free Radicals: toxic, highly reactive molecules that are natural by-products of cellular metabolism \- Two main detoxifiers: \- OXIDASE: uses oxygen to convert toxins to hydrogen peroxide, which is still toxic, but peroxisome also contains catalase, which converts hydrogen peroxide to water - Also play role in breakdown and synthesis of fatty acids LYSOSOMES - Spherical membranous bags containing digestive enzymes (acid hydrolases) - "safe" sites because they isolate harmful intracellular digestion from rest of cell - Digest ingested bacteria, viruses, and toxins - Work best in acidic conditions - Metabolic functions: breakdown and release calcium ions from bone ENDOMEMBRANE SYSTEM - Consists of the ER's, Golgi apparatus, secretory vesicles, lysosomes, and nuclear and plasma membranes - They work together to: \- produce, degrade, store, and export molecules \- degrade potentially harmful substances CYTOSKELETON - "Cell skeleton." - Three types: \- Microfilaments, intermediate filaments, and microtubules MICROFILAMENTS: - Thinnest of all cytoskeletal elements - Semi-flexible strands of protein ACTIN - Dense, cross linked network of microfilaments attached to cytoplasmic side of plasma membrane; strengthens cell surface and helps resist compression - Some are involved in endocytosis and exocytosis, cell motility, and shape changes INTERMEDIATE FILAMENTS: - Size is in between microfilaments and microtubules - Tough, insoluble ropelike protein fibers - Composed of tetramer (4) fibrils twisted together, resulting in one strong fiber - Helps cell resist pulling forces - Most stable and permanent of elements MICROTUBULES: - **Largest** of cytoskeletal elements; consist of hollow tubes composed of protein subunits called **tubulins,** which are constantly assembled and disassembled. - Determine overall shape and distribution of organelles. \- many organelles are tethered to microtubules to keep in place \- many substances are moved throughout cell by motor proteins, which use microtubules are tracks. Motor proteins: complexes that function in motility; helps in movement of organelles and other substances around cell, powered by ATP. CENTROSOME & CENTRIOLES - **Centrosome**: located near nucleus, means "cell center." - It is a microtubule organizing center, consisting of granular matrix and **centrioles.** - **Centrioles**: pair of barrel-shaped microtubular organelles that lie at right angles to each other; form the basis of cilia and flagella. - Newly assembled microtubules radiate from centrosome to rest of cell CELLULAR EXTENSIONS: [CILLIA AND FLAGELLA] - Some cells have structures that extend from cell surface: \- Cilia: whiplike, motile extensions on surfaces of certain cells; thousands of cilia work together in sweeping motion to move substances across cell surfaces in one direction. \- Flagella: **longer** extensions that propel the whole cell (ex. Sperm). - Cilia and Flagella have a 9+2 pattern of microtubules. (9 sets of double tubes surrounding a central pair of doublets.) - Cilia movements alternate between power stroke and recovery stroke. \- **Power Stroke**: it is nearly straight and moves in an arc. \- **Recovery Stroke**: it bends and returns to initial position \- **Cilia** and **Flagella** aid in movement of the cell or of materials across surface of the cell. [MICROVILLI] - Tiny, fingerlike extensions of plasma membrane that project from surface of select cells; used to increase surface area for absorption; have a core of actin microfilaments NUCLEUS: - LARGEST organelle; contains genetic blueprints for synthesis of nearly all cellular proteins \- contain instructions to build nearly all the body's proteins - **Uninucleate**: one nucleus - **Multinucleate**: (many nuclei) (ex. Some bone cells, skeletal muscle, and some liver cells). - **Anucleate**: no nucleus (ex. Red blood cells). - THREE main structures: \- Nuclear envelope \- Nucleoli \- Chromatin [NUCLEAR ENVELOPE:] - Double-membrane barrier; encloses jelly-like fluid, the nucleoplasm \- Outer Layer is continuous w/ rough ER and it is studded w/ ribosomes \- Inner Layer, called **nuclear lamina**, is a network mesh of proteins that maintains nuclear shape and organizes DNA in nucleus. - Nucleus is **bounded** by nuclear envelope [NUCLEOLI:] - Dark-staining spherical bodies within nucleus; involved in ribosomal RNA synthesis and ribosome subunit assembly. - Usually, 1 or 2 per cell. [CHROMATIN:] - Consists of 30% threadlike strands of DNA, 60% histone proteins, and 10% RNA - Arranged in fundamental units called **nucleosomes**, which consist of DNA wrapped around histones - **Chromosomes** are [condensed] chromatin \- condensed state protects fragile chromatin threads during cell division. - "Beads on a string" structure w/ nucleosomes. Two major periods of cell cycle: - Interphase: cell grows and carries on usual activities; period from cell formation to cell division; nuclear material is in uncondensed chromatin state. - Cell division (mitotic phase): cell divides in two 3 SUBPHASES OF INTERPHASE: - G1 (gap 1): vigorous growth and metabolism; as it ends, centrioles start to replicate in preparation for division. - S (synthetic): DNA replication occurs - G2 (gap 2): preparation for division DNA replication: - Prior to division, cell makes copy of DNA - Double-stranded DNA helices unwind and unzip. \- **Replication Fork**: point where strands separate. \- **Replication Bubble:** active area of replication \- Each strand acts as a template for a new complementary strand. - DNA polymerase: adds nucleotides to primer and forms new strand \- DNA polymerase synthesizes both new strands at one time (one leading and one lagging strand). \- They are synthesized in opposite directions - DNA ligase: splices short segments of discontinuous lagging strand together which **restores the double helix.** - End result: two identical "daughter" DNA molecules formed from original; one complete copy is given to new cell, while one is retained in original. - **Semiconservative Replication**: each new double-stranded DNA is composed of one old strand and one new strand MITOSIS: - The division of the nucleus, in which the duplicated DNA is distributed to new daughter cells. - Four stages of Mitosis: Prophase, Metaphase, Anaphase, Telophase. PROPHASE: - [Early Prophase] - Chromatin condenses, forms visible chromosomes. - Each chromosome and duplicate are held together by a centromere. - Centrosome and its duplicate begin synthesizing microtubules that push each centrosome to opposite poles of cell. \- called the **mitotic spindle.** \- other microtubules called **asters** radiate from centrosome. - [Late Prophase ] - Nuclear envelope breaks up. - Special microtubules attach to specific area on centromeres called kinetochore and serve to pull chromosomes to center of cell. METAPHASE: - Centromeres of chromosomes are precisely aligned at cell's equator. ANAPHASE: - Shortest of all phases. - Centromeres of chromosomes split and each sister chromatid becomes a separate chromosome and are pulled toward their respective poles TELOPHASE: - Begins when chromosome movement stops. - Each set of chromosomes uncoils to form chromatin. - Nucleoli reappear; spindle disappears. CYTOKINESIS: - Begins during late anaphase and continues through mitosis - Ring of protein actin microfilaments contracts to form **cleavage furrow** - Two daughter cells are pinched apart when the furrow deepens. \- Two groups of proteins are crucial to enter mitosis: - Cyclins: regulatory proteins that accumulate during interphase - Cdks (Cyclin- dependent kinases): that activate cyclins when they bind to them. - Cyclin-Cdk complex activates enzyme cascades that prepare cell for division \- **GENE**: segment of DNA that holds the code for one polypeptide. - Proteins are composed of polypeptide chains, which in turn are made up of amino acids - Genes are composed of **exons** and **introns** - **Exons** are part of the gene that actually codes for amino acids - **Introns** are noncoding segments interspersed amongst exons. THE ROLE OF RNA: - RNA is the "go between" molecule that links DNA to proteins \- RNA copies the DNA code in nucleus, then carries it into cytoplasm to ribosomes. - All RNA is formed in the nucleus. - RNA differs from DNA: \- Uracil is substituted for Thymine \- RNA has ribose instead of deoxyribose sugar - Three types: \- Messenger RNA (mRNA) \- Ribosomal RNA (rRNA) \- Transfer RNA (tRNA) - Single stranded - Code from DNA template strand is copied w/ complementary base pairs, resulting in a strand of mRNA \- process is referred to as **Transcription** - MRNA maintains the triplet code (codon) from DNA - Structural component of ribosomes, the organelle where protein synthesis occurs. - Along w/ tRNA, helps to translate message from mRNA into polypeptide - Carrier of Amino Acid - Have special areas that contain a specific triplet code (anticodon) that allows each tRNA to carry only a specific amino acid - Anticodon of tRNA will complementary base pair w/ codon of mRNA at ribosome, adding its specific amino acid to growing polypeptide chain \- process is referred to as **Translation** **Protein synthesis occurs in two steps:** - Transcription: DNA information coded in mRNA - Translation: mRNA decoded to assemble polypeptides 3 PHASES OF TRANSCRIPTION: 1. Initiation: RNA polymerase separates DNA strands 2. Elongation: RNA polymerase adds complementary nucleotides to growing mRNA matching sequence of bases on DNA template strand 3. Termination: transcription stops when RNA Polymerase reaches special termination signal code. - Processing of mRNA: Newly formed mRNA is then edited and processed before translation can begin. (referred to as pre mRNA). \- Introns are removed by special proteins called spliceosomes, leaving only exon coding regions \- Genetic Code: \- There are 64 possible codons. (complementary 3-base sequence). TRANSLATION: - The language of nucleic acids (base sequence) is translated into the language of proteins (amino acid sequences). - tRNA binds a specific amino acid at one end (stem) - Anticodon at other end (head) is triplet code that determines which amino acid will be bound at stem. - Ribosomes coordinate coupling of mRNA and tRNA. **Apoptosis**: programmed cell death, causes cells to neatly destruct. **Ubiquitin-Proteasome Pathway**: unneeded, misfolded, or damaged proteins can be marked for destruction by protein called ubiquitin. Proteasomes disassemble ubiquitin-tagged proteins, recycling the amino acids and ubiquitin. **Autophagy**: (self-eating) the process of disposing of nonfunctional organelles and sweeping up cytoplasmic bits by forming autophagosomes, which are then degraded by lysosomes. Chapter 4: EPITHELIAL TISSUE - (epithelium) is a sheet of cells that covers body surfaces or cavities. - Two main forms: - **Covering and Lining Epithelia**: on external and internal surfaces (ex. Skin) - **Glandular Epithelia**: secretory tissue in glands (salivary glands). - Main functions: protection, absorption, filtration, excretion, secretion, and sensory reception. - Five distinguished characteristics: - Polarity - Specialized contacts - Supported by connective tissues - Avascular, but innervated - Regeneration POLARITY: - Cells have polarity (top & bottom) - **Apical surface**, upper free side, is exposed to surface or cavity \- Most Apical surfaces are smooth, but some have microvilli - **Basal surface**, lower attached side, faces inwards towards body \- Attaches to **basal lamina**, an adhesive sheet that holds basal surface of epithelial cells to underlying cells. SPECIALIZED CONTACTS: - Epithelial tissues need to fit closely together. \- many form continuous sheets - Specialized contact points bind adjacent epithelial cells together \- Lateral contacts include: \- Tight junctions \- Desmosomes SUPPORTED BY CONNECTIVE TISSUES: - All epithelial sheets are supported by connective tissue. - Reticular lamina: deep to basal lamina; consists of network of collagen fibers. - Basement membrane: - Made up of basal and reticular lamina - Reinforces epithelial sheet - Resists stretching and tearing - Defines epithelial boundary AVASCULAR BUT INNERVATED: - No blood vessels are in epithelial tissue - Are supplied by nerve fibers REGENERATION: - Have high regenerative capacities CLASSIFICATION OF EPITHELIA: - All epithelial tissues have two names: - First name indicates number of cell layers \- Simple Epithelia: single layer thick \- Stratified Epithelia: 2 or more layers thick and involved in protection (ex. Skin) - Second name indicates shape of cells \- Squamous: flattened and scale-like \- Cuboidal: box-like, cube \- Columnar: tall, column-like - In **stratified** epithelia, shape can vary in each layer, so cell is named according to the shape in **apical layer (top)** - [Simple Epithelia: ] - Involved in absorption, secretion, or filtration processes. - **Simple Squamous Epithelium --** resemble fried eggs. \- Cells are flattened laterally, and cytoplasm is sparse. \- Function where rapid diffusion is priority. (ex. Kidneys, lungs) - Two special simple squamous epithelia are based on locations \- **Endothelium**: lining of lymphatic vessels, blood vessels, and heart \- **Mesothelium**: serous membranes in the ventral body cavity - **Simple Cuboidal** - Single layer of cells - Involved in secretion and absorption - Forms walls of the smallest ducts of glands and many kidney tubules - **Simple Columnar** - Single layer of tall, closely packed cells. \- some layers have microvilli, some have cilia. - Involved in absorption and secretion of mucus, enzymes, and other substances \- ciliated cells move mucus. - Found in digestive tract, gallbladder, ducts of some glands, bronchi, and uterine tubes. - **Pseudostratified Columnar** - Appear to be multi-layered and stratified, but it is single-layered simple epithelium. - Pseudo means false! - Many cells are ciliated - Involved in secretion, particularly mucus. - Located mostly in upper respiratory tract, ducts of large glands, and tubules in testes. - Stratified Epithelial Tissues - Involve 2 or more layers of cells - New cells regenerate from below - Basal cells divide and migrate towards surface - More **durable** than simple epithelial because protection is its major role. - **Stratified Squamous:** - Most widespread of stratified epithelia. - Located in areas of high wear and tear (skin). - Stratified Cuboidal: - Rare - Found in some sweat and mammary glands - Typically only 2 cell layers thick - **Stratified Columnar:** - Also very limited distribution in body. - Usually occurs at transition areas between 2 other types of epithelia - **Transitional Epithelia:** - Forms lining of hollow urinary organs. (they stretch as they fill w/ urine) - Ability of cells to change shape when stretched allows for increased flow of urine, and more storage space for bladder. GLANDULAR EPITHELIA: - **Gland**: one or more cells that makes and secretes an aqueous fluid called a **secretion**. - Classified by: - Site of product release: - Endocrine: internally secreting (ex. Hormones). - Exocrine: externally secreting (ex. Sweat) - Relative number of cells forming gland - **Endocrine Glands:** - **Ductless** glands - Secretions are not released into duct; are released into surrounding interstitial fluid, which is picked up by circulatory system. - Secrete by (exocytosis) hormones, messenger chemicals that travel through lymph or blood to their specific target organs. - Target organs respond in some characteristic way. - **Exocrine Glands:** - Secretions are released onto body surfaces, such as skin, or into body cavities. - More numerous than endocrine glands - Secrete products into ducts - Ex. Mucous, sweat, oil, and salivary glands - Can be unicellular or multicellular. - **Unicellular** Exocrine Glands: - Only important unicellular glands are mucous cells and goblet cells. All produce mucin, which forms mucus. - **Multicellular** Exocrine Glands: - Composed of a duct and a secretory unit - Classified by: Structure and Mode of Secretion \- **Structure**: [simple] exocrine glands have [unbranched] ducts, but [compound] glands have [branched] ducts. \- Tubular Gland: secretory cells form a duct. \- Alveolar Gland: secretory cells form sacs. \- Tubuloalveolar glands have [both] types. \- Mode of Secretion: \- **Merocrine**: most secrete products by exocytosis as secretions are produced. \- Holocrine: accumulate products within, then rupture. (Ex. sebaceous oil glands.) CONNECTIVE TISSUE: - Most abundant and widely distributed of primary tissues - Major functions: binding and support, protecting, insulating, storing reserve fuel, and transporting substances (blood). - Four main classes: - Connective tissue proper: consists of all connective tissue except for bone, cartilage, and blood - Cartilage - Bone - Blood - 3 characteristics that make it different from other primary tissues: - All have common embryonic origin; all arise from mesenchyme tissue - Have varying degrees of vascularity - Cells are suspended/embedded in extracellular matrix; connective tissue consists largely of nonliving extracellular matrix. - Matrix supports cells so they can bear weight, withstand tension, endure abuse - Connective tissues three main elements: - Ground substance - Fibers - Cells - The extracellular matrix is made of **ground substance** and **fibers**. Ground Substance: - Unstructured gel-like material that fills space between cells - Components: - Interstitial fluid - Cell Adhesion Proteins: ("glue" for attachment). - Proteoglycans: (sugar proteins), made of protein core + large polysaccharides. Fibers: - Three types of fibers provide support - Collagen: strongest and most abundant type; tough, provides high tensile strength - Elastic Fibers: networks of long, thin, **elastin** fibers that allow for stretch and recoil - Reticular: short, fine, highly branched collagenous fibers; branching forms networks that offer more "give" Cells: - "Blast" cells - Immature form of cell that actively secretes ground substance and ECM fibers - **Fibroblasts** found in connective tissue proper - **Chondroblasts** found in cartilage - **Osteoblasts** found in bone - "Cyte" cells - Mature, less active form of "blast" cell that becomes part of and helps maintain health of matrix. - Other cell types in connective tissues: - Fat cells: store nutrients - White blood cells: tissue response to injury - Mast cells: initiate inflammatory response against foreign microorganisms - Macrophages: phagocytic cells that "eat" dead" cells and microorganisms; function in immune system CONNECTIVE TISSUE PROPER: - Consists of all connective tissues except bone, cartilage, and blood - Two subclasses: - Loose (large spaces in between) Connective: - Areolar: most widely distributed; supports & binds other tissues; universal packing material between other tissues - Adipose: great nutrient storage; functions in shock absorption, insulation, and energy storage - Reticular: thin reticular fibers that are made of thin collagen - Dense (large amount of fiber in bundles) connective: - Dense regular: very high tensile strength; closely packed bundles; fibers slightly wavy; poorly vascularized. - Dense irregular: same elements as dense regular, but thicker bundles of collagen and irregularly arranged; forms **sheets** rather than bundles. - Elastic: contains high proportion of elastic fibers CARTILAGE: - Matrix secreted from chondroblasts (during growth) and chondrocytes (adults) - Chondrocytes found in cavities called lacunae. - Tough yet flexible material that **lacks nerve fibers.** - Avascular - Three types of cartilage: - Hyaline cartilage: most abundant; appears as shiny blueish glass. (ex. Nose, trachea, and larynx.) - Elastic cartilage: similar to hyaline but w/ more elastic fibers. (found in ears). - Fibrocartilage: properties between hyaline and dense regular tissue - Strong, so it is found in knee BONE: - Also called **osseous** tissue. - Supports and protects body structures - Synthesizes blood cells in cavities - Has more collagen than cartilage - Richly vascularized. MUSCLE TISSUE: - Highly vascularized - Responsible for most types of movement - Possess myofilaments that bring about contraction - Three types of muscle tissue: - Skeletal muscle - Cardiac muscle - Smooth muscle SKELETAL MUSCLE TISSUE: - Attached to and causes movement of bones. Also called voluntary muscle; can be consciously controlled - Cells are called muscle fibers - Contain multiple nuclei; appear striated or banded. CARDIAC MUSCLE TISSUE: - Found only in walls of heart - Involuntary muscle - Contains striations; only one nucleus - Intercalated discs: special joints where cardiac cells are joined. SMOOTH MUSCLE TISSUE: - Found mainly in walls of hollow organs (other than heart) - Involuntary muscle - No visible striations - Spindle-shaped; one nucleus NERVOUS TISSUE: - **Main** component of nervous system - Regulated and controls body functions - Made up of two specialized cells: - **Neurons**: specialized nerve cells that generate and conduct nerve impulses. - Supporting cells that support, insulate, and protect neurons. COVERING AND LINING MEMBRANES: - Composed of 2 primary tissue types: an epithelium bound to underlying connective tissue proper layer. - Three types: - **Cutaneous Membranes** - **Mucous Membranes** - **Serous Membranes** CUTANEOUS MEMBRANE: - Another name for **skin**. - Keratinized stratified squamous epithelium (epidermis) attached to a thick layer of connective tissue (dermis) - Unlike other membranes, skin is a dry membrane MUCOUS MEMBRANE: - Mucosa indicates location, not cell composition - Line body cavities that are open to exterior. (ex. Digestive, respiratory, urogenital tracks). - Moist membranes bathed by secretions (urine). - Epithelial sheet lies over layer of loose connective tissue called **lamina propria.** SEROUS MEMBRANE: - Also called serosae - Found in closed ventral body cavities. - **Parietal** serosae line internal body cavity **walls** - **Visceral** serosae cover internal **organs**. TISSUE REPAIR: - Repair is the function of the inflammatory process. - Can occur in two major ways: - Regeneration: same kind of tissue replaces destroyed tissue, so original function is restored. - Fibrosis: connective tissue replaces destroyed tissue, and original function is lost. - Three steps: - 1\. Inflammation: inflammatory chemicals are released; clotting of blood occurs and seals off injured area - 2\. Organization restores blood supply: blood clot is replaced w/ granulation tissue; epithelium begins to regenerate - 3\. Regeneration & fibrosis permanent repair: scab detaches; fibrous tissue matures; epithelium thickens - Tissues that generate **extremely well**: - Epithelial tissues, bone, areolar connective tissue, dense irregular connective tissue - Tissues w/ **moderate** regenerating capacity: - Smooth muscle and dense regular connective tissue - Tissues w/ **no functional regenerative** capacity: - Cardiac muscle and nervous tissue of brain and spinal cord - Primary Germ Layers: - Superficial to deep: **Ectoderm, Mesoderm, and Endoderm** - Formed early in embryonic development. - Specialize to form the four primary tissues - **Nerve tissue** arises from **ectoderm** - **Muscle** and **connective tissues** arise from **mesoderm** - **Epithelial tissues** arise from **all three** germ layers