Bio 167 Lecture Exam 1 Notes (Chapters 1, 3, 4, 5) PDF

The Human Body: An orientation Chapter 1 Tuesday Sep 3 Topics of Anatomy: STRUCTURE Anatomy ○ Study of the structure of body parts and their relationship to one another Structure relates to function, fu...

The Human Body: An orientation Chapter 1 Tuesday Sep 3 Topics of Anatomy: STRUCTURE Anatomy ○ Study of the structure of body parts and their relationship to one another Structure relates to function, function relates to structure Structure to any part of the body relates to the function it has ○ Subdivisions of anatomy: Gross or Macroscopic Anatomy is the study of large, visible structures What you can see with your naked eye Regional anatomy looks at all structures in a particular area of the body System anatomy looks at just one system Surface anatomy looks at internal structures as they relate to overlying skin ○ EX: flexing muscles or seeing blood vessels/ veins Subdivisions- ○ Microscopic Anatomy anatomy deals with structures too small to be seen by naked eye OLOGY: Study of _____ (fill in blank) Cytology: microscopic study of cells Cyto → cells Histology: microscopic study of tissues Histo → tissue Four types of tissues ○ Epithelial Tissue ○ Muscle Tissue ○ Connective Tissue ○ Neural Tissue ○ Developmental Anatomy anatomy studies anatomical and physiological development throughout life Embryology: study of developments before birth Topics of Physiology: FUNCTION Physiology ○ Study of the function of body parts; how they work to carry out life-sustaining activities ○ Subdivisions of physiology Based on organ systems (e.g., renal or cardiovascular physiology) Often focuses on cellular and molecular (DNA/ Cells) levels of the body body’s abilities are dependent on chemical reactions in individual cells ○ Complementarity of Structure and Function Principle of complementarity of structure and function ○ Anatomy and physiology are inseparable 2“­­Structure relates to function” “Function relates to structure” EX: sharp edges of incisors (structure) male them ideal for chopping (function) EX: flat surfaces of molars (structure) make them i deal for grinding (function) Levels of Structural Organization (FIGURE 1.2 in textbook) Human body is very organized, from the smallest chemical level to whole organism level: (from simple to more complex, each made up of the level before) ○ Chemical Level: atoms, molecules, and organelles ○ Cellular Level: single cell ○ Tissue Level: groups of similar cells ○ Organ Level: contains two or more types of tissues ○ Organ system Level (11 total) : organs that work closely together ○ Organismal Level all organ systems combined to make the whole organism Necessary Life Functions-Requirements for Life Maintaining boundaries ○ Separation between internal and external environments must exist Plasma membranes (intercellular vs intracellular separating the inside of the cell from its environment) Skin separates Movement (contractility) ○ Muscular system allows movement: YOU NEED TO MOVE  Of body parts (skeletal muscles) Muscles contracting to push on veins in body to push the blood around so that it can circulate (compression socks) Of substances via (cardiac muscle and smooth muscle) Smooth muscle: GUT Necessary Life Functions Responsiveness (excitability) ○ Ability to sense and respond to stimuli Withdrawal reflex Control of breathing rate Flight or fight Digestion ○ Breakdown of ingested foodstuffs, followed by absorption of simple molecules into blood ○ Absorption is key Everything we eat is carbs, fat, protein Come into body in long strings of molecules that need to be broken down to absorb Metabolism ○ All chemical reactions that occur in body cells Catabolism and Anabolism Catabolic: it's getting broken down (Catabolic Catastrophe: things are getting broken down) ○ Digesting carbs into simple sugars Anabolism: it's getting build ○ Building muscles ○ Insulin Excretion ○ Removal of wastes from metabolism and digestion Urea ,carbon dioxide, feces Waste build up → toxic waste built up Reproduction ○ cellular level, division of cells for growth or repair Liver: mitosis to rebuild itself Skin: mitosis, cellular reproduction, when its damages ○ organismal level, the production of offspring (not necessary for life function) Don’t need to reproduce offspring to live Growth ○ Increase in size of a body part or of organism Necessary Life Functions (FILL IN FROM TEXT BOOK) Humans are multicellular, so to function, individual cells must be kept alive ○ Organ systems are designed to service the cells, by working together ○ All cells depend on organ systems to meet their survival needs ○ There are 11 organ systems work together to maintain life Integumentary system: forms the external body covering and protects deeper tissues from injury. Synthesized vitamin D, and house cutaneous receptors and sweat oil glands Skin → protection/covering Getting near a hot surface, getting hit Skeletal system: protects and supports body organs and provides a framework the muscles use to cause movement, Blood cells are formed within bones. Bones store minerals Supports body framework Muscular System: allows manipulation of the environment, locomotion, and facial expression, maintains posture, and produces heat MOVEMENT ○ Shivering: produces heat Nervous System: acts as the fast acting control system of the body, respond to internal and external changes by activating appropriate muscles and glands Endocrine System: glands secrete hormones that regulate processes such as growth Cardiovascular System: Lymphatic System: Checks n balances of body Respiratory System: Digestive System: Urinary System: Reproductive System: Survival Needs Humans need several factors for survival; too much or too little can be harmful: ○ Stay within many setpoints for the body Nutrients ○ Chemicals for energy and cell building Carbohydrate: major source of energy (ATP) Protein: needed for cell building and cell chemistry Fats: long-term energy storage Mineral and Vitamins: involved in chemical reactions as well as for structural purposes  Oxygen ○ Essential for release of energy from foods The body can survive only a few minutes without oxygen Water ○ Most abundant chemical in body; provides the watery environment needed for chemical reactions Normal Body Temperature ○ If body temp falls below or goes above 37°C (98.6 F) rates of chemical reactions are affected Too hot → proteins get denatured → protein shape and function changes Appropriate atmospheric conditions ○ Specific pressure of air is needed for adequate breathing and gas exchange in lungs in order to breathe Homeostasis Maintenance of stable internal conditions despite continuous changes in environment Bodies fluctuate throughout the day to adapt to surroundings and happenings Running vs sitting vs standing ○ A state of equilibrium, always re-adjusting as needed ○ Maintained by contributions of all organ systems Internal Environment: Extracellular Fluid- Fluid surrounding body cells (not body) Within Blood vessels Between Cells in Tissue In Organ Cavities-(CSF, Synovial, Ocular) Intracellular Fluid- Fluid within body cells Homeostatic Controls Body must constantly be monitored and regulated to maintain homeostasis ○ Stresses change optimal conditions- disturbs homeostasis ○ We react in a way to maintain homeostasis to maintain equilibrium Stress-an event that creates an imbalance in the internal environment Exogenous Stress- temp, noise, lack of O2, pressure changes Endogenous Stress- BP, tumors ○ Variables are factors that can change EX: blood sugar, body temperature, blood volume, etc As we get older, our bodies attempt to maintain homeostasis happens more slowly (ex: takes more time to bring bp up) Thursday Sep 05 Homeostatic Control Mechanisms  Homeostatic control of variables involves three components: Receptor Sensor ○ Monitors environment ○ Receiving the stimuli/message, sends a message to the brain (control center) ○ Responds to stimuli (things that cause changes in controlled variables) Control Center ○ Determines set point at which variable is maintained ○ Receives input from receptor ○ Determines appropriate response ○ Sends out response (effector) Effector ○ Receives output from control center ○ Provides the means to respond ○ Response either reduces stimulus (negative feedback) or enhances stimulus (positive feedback) With control mechanism, you have to receive it sans sense it, it must go to the control center, and a response is then done Overall process: (receptor control center figure in book) ○ Stimulus: ○ Receptor: ○ Input: ○ Output: ○ Response: Feedback System Positive Feedback System → GIVE ME MORE ○ Response enhances or exaggerates the original stimulus ○ May exhibit a cascade or amplifying effect ○ Variable to continue in same direction as initial change ○ Usually controls infrequent events that do not require continuous adjustment, for example: Enhancements of labor contractions by oxytocin: oxytocin → contractions → oxytocin Lactation: figure 20.2 in textbook More suckling time, more milk produced, etc Blood Clotting: regulates the formation of platelet plug Negative Feedback System → GOES BACK N FORTH ○ Most-used feedback mechanism in body ○ Response reduces or shuts off original stimulus  Reverses direction of initial change ○ Imbalance—> Receptors → afferent pathway (a for away) —control center → efferent (e for exiting) pathways —--> effectors —> balance ○ Examples (textbook add to notes) Regulation of body temperature (nervous system mechanism) Like a thermostat: will go back and forth to maintain perfect temperature (set point) ○ Too hot: will sweat, evaporation of sweat makes us cooler ○ To cold: will shiver to raise body temperature Pancreas (control center) secretes insulin into the blood (an endocrine system mechanism) Anatomical Terms Anatomical Position and Directional Terms Standard anatomical position ○ Body erect ○ Feet slightly apart ○ Palms facing forward (anterior) with thumbs pointing away from body Directional terms describe one body structure in relation to another body structure ○ Direction is always based on standard anatomical position ○ Right and left refer to the body being viewed, not right and left of observer ○ Table 1.1 in textbook: superior, inferior, anterior, posterior, medial, lateral , intermediate, proximal (closest to point of attachment at shoulder and at hip of limbs), distal, superficial, deep Directional Terms Median- midline (left and right and basically equal) Parietal- outer wall of a cavity (like thoracic, abdominal, pelvic CAVITY) Visceral- covering an organ with in a body cavity (lining on ANY ORGAN) Ipsilateral- same side Contralateral- opposite side Prone- lying face down- on stomach Supine-lying face up - on back Regional Terms Two major divisions of body ○ Axial Skeleton (COLLARBONE Head, neck, and trunk ○ Appendicular Skeleton Appendages-Limbs (legs and arms) Associated girdles (pectoral (shoulder) and pelvic (hip)) Regional terms designate specific areas within body divisions a Lumbar: loin (lower back) Regions of body (terminology) (FIGURE Mammary: breast 1.8 A and B in textbook) Manus: hand Abdominal: abdomen Mental: chin Acromial: point of shoulder Metacarpal: between the wrist and Antebrachial: forearm fingers (long bones in back of hand) Antecubital: front of the elbow Metatarsal: between ankle and toes Appendicular: limbs Nasal: nose Axial: main body axis (head neck Occipital: base of skull and truck) Olecranal: back on elbow Axillary: armpit Oral: mouth Brachial: arm Orbital: eye Buccal (“buckle”): cheek Otic: ear Calcaneal: heel Palmar: palm Carpal: wrist Patellar: anterior knee (patella) Cephalic: head Pedal: foot Cervical: neck Pelvic: pelvis Coxal:hip Perineal: between anus and external Cranial: skull (houses brain) genitalia Crural: leg Peroneal or fibular: side of leg Digital: fingers or toes Phalangeal: fingers or toes Dorsal/posterior: back Plantar: sole of foot Facial: skull that forms face Pollex: thumb Femoral: thigh Popliteal: back of knee Frontal: forehead Pubic: genetial region Gluteal: buttocks Sacral: posterior area between hips Hallux: big toe Scapular: shoulder blade region Inguinal: groin Sternal: breastbone  Sural: calf region Umbilical: naval Tarsal: ankle Vertebral: spinal column Thoracic: chest Trunk: body excluding head, neck, and limbs Body Planes and Sections DRAW ON A PERSON/HAND/ETC Body planes ○ Surfaces along which body or structures may be cut for anatomical study ○ Three most common planes: Sagittal Plane Frontal (coronol) plane Transverse (horizontal) plane Sagittal plane ○ Divides body vertically into right and left parts ○ Produces a sagittal section if cut along this plane ○ Midsagittal (median) plane Cut was made perfectly on midline (perfect left and right size) ○ Parasagittal Plane Cut was off-centered, not on midline (disproportionate left and right sizes) Frontal (coronal) plane ○ Divides body vertically into anterior and posterior parts (front and back) ○ Produces a frontal or coronal section Transverse (horizontal) plane ○ Divides body horizontally (90° to vertical plane) into superior and inferior parts (top and bottom) ○ Produces a cross section: taking a piece and flipping it out (showing the cut) Cutting a leg into top and bottom, then looking at the superior piece from the tip to see the femur, muscles, etc Oblique section ○ Result of cuts at angles other than 90° to vertical plane( slanted) Body Cavities Internal cavities that are closed to environment Cavities provide different degrees of protection to organs within them Two sets of Cavities  · Houses the internal organs (collectively called viscera) ○ Protects fragile nervous system sms ○ Two subdivisions separated by the diaphragm → figure 1.9b dorsal body cavities Encases brain ventral body cavities body Encases spinal cord __________________ ○ Houses the internal organs (collectively called viscera) ○ Two subdivisions, which are separated by the diaphragm Thoracic cavity Abdominopelvic cavity Thoracic cavity ○ Two pleural cavities Each cavity houses one lung ○ Mediastinum Contains pericardial cavity Surrounds other thoracic organs, such as esophagus, trachea, arteries and veins of heart, thymus. ○ Pericardial Cavity Encloses heart Abdominopelvic cavity ○ Abdominal cavity Contains stomach, intestines, spleen, and liver ○ Pelvic cavity Contains urinary bladder, reproductive organs, and rectum · *Imaginary line from sacral promontory to pubic symphysis separates abdominal and pelvic cavities Dorsal and ventral body cavities and their subdivisions. Ventral Body Cavity Membranes Serous Membrane- aka (serosa) ○ Thin, double-layered membranes that cover surfaces in ventral body cavity Parietal serosa lines internal body cavity walls Visceral serosa covers viscera  ○ Layers separated by slit-like cavity filled with serous fluid ○ Fluid secreted by both layers of membrane The fluid allows for smooth,painless, movement of organs by lubricating them (from surface tension) ○ Named for specific cavity and organs that they are associated with Each has parietal and visceral layer Pericardium Heart Pleurae Lungs Peritoneum Abdominopelvic cavity Abdominopelvic quadrants and regions ○ Quadrants are divisions used primarily by medical personnel Abdominopelvic region is sectioned into quarters Right upper quadrant (RUQ) Left upper quadrant (LUQ) Right lower quadrant (RLQ) Left lower quadrant (LLQ) ○ Nine divisions called regions (IN TEXTBOOK) ○ used primarily by anatomists, usually not in medicine Other Body Cavities In addition to the two main body cavities, the body has several smaller cavities that are exposed to environment  ○ Oral and digestive cavities ○ Nasal cavity ○ Orbital cavities ○ Middle ear cavities Not exposed to environment ○ Synovial cavities: joint cavities \ \ Cellular Level of Organization Chapter 3 – Cells: The Living Units Cellular Basis of Life: Cell Theory – A cell is the structural and functional unit of life – Activity of an organism depends on individual and collective cell function – Structure and function are complementary Biochemical activities ( function) of cells are dictated by shape of cell and specific subcellular structures/organelles (structure) – Continuity of life has cellular basis Cells can arise only from other preexisting cells Cell diversity – Over 250 different types of human cells  – Types differ in size, shape, and subcellular components; these differences lead to differences in functions - Sperm cell is the only cell with a flagellum - Tuesday Sep 10 2024 Cells: The Smallest Living Units → get cell diagram Cytology: the study of cells and their function Generalized cell – All cells have some common structures and functions – Human cells have three basic parts: Plasma Membrane: divides intracellular and extracellular of the cell Cytoplasm: made up of cytosol (fluid gel components) and organelles- intracellularly Nucleus: contains the DNA of the cell, nucleus pore allow for information to be sent from in and within the nucleus Extracellular Materials Substances found outside cells Classes of extracellular materials include: 1. Body Fluids: Interstitial fluid: cells are submersed (bathed) in this fluid (Extracellular) Blood plasma: fluid of the blood, contains clotting factors - Blood serum does NOT contain clotting factors Cerebrospinal fluid: fluid surrounding nervous system organs 2. Cellular Secretions Gastric/Intestinal Fluids (aid in digestion) Mucus, Saliva, Serous Fluids (act as lubrication) 3. Extracellular matrix: (Cell Glue- makes up everything in connective tissue ) Hyaluronic acid: viscous, fluid like material, stabilizes collagen  Chondroitin sulfate: jelly like material, helps with joint lubrication Connective tissue fibers – Collagen Fibers: strength – Elastic Fibers: stretch – Reticular Fibers: forms meshwork to hold cells w/in an organ Function of Plasma Membrane Acts as an active barrier separating intracellular fluid from extracellular fluid Plays dynamic role in cellular activity by controlling what enters and what leaves cell- Selective Permeability: determines what enters and leaves the cell and for how long Also known as the “cell membrane” Facilitates contact Provides receptors-hormones, chemicals, nutrients, antibodies…. Structure of Plasma Membrane Consists of membrane lipids that form a flexible lipid bilayer (phospholipid bilayer) (picture of phospholipid bilayer from a section of the cell membrane - Create fluid mosaic model so that the cells aren’t rigid and stiff Membrane proteins float through this fluid membrane, changing mosaic patterns Membrane structures help to hold cells together through cell junctions (tight, loose, stretchy, depends on where those cells are at and what organ, and function of cell) The Plasma Membrane (NOTES): FIGURE 3.1 Glycoalyx (carbs) identify cell Cholesterol: stabilizes cell membrane Membrane Lipids: Structural and Chemical Components Lipids form the bilayer: 1. Phospholipid- 75%  Phosphate heads: – polar (charged) – hydrophilic (water loving, so that they can sit near water, most of body is made up water ) Fatty acid tails: – nonpolar (no charge) – hydrophobic (water hating, like fats) 2. glycolipids- 5% Lipids with attached sugar groups outer membrane surface Glycocalyx – “Sugar Coating” = glycolipid +glycoprotein – Specific markers for cell to cell recognition – Allows immune system to recognize “self” vs “non-self” – Ex: sperm cell recognizes ovum (right cell) by its unique glycocalyx - Cancer: glycocalyx mutates very quickly, and mutations are not always recognized, so mutated cells continue to grow 3.Cholesterol-20% Steroid Lipid Increases membrane stability- strength Decreases mobility of phospholipids and fluidity of membrane, so that the cells aren’t moving crazy and have some sort of structure Membrane Proteins: Structural and Chemical Components Proteins: -Allow cell communication with environment- intracellular and intercellular -Make up about half the mass of plasma membrane -Most have specialized membrane functions Two types: 1. Integral Proteins- embedded in lipid bilayer 2. Peripheral Proteins- loosely bound to surface of lipid bilayer Membrane Proteins: Structural and Chemical Components Integral proteins – Firmly inserted into the membrane – Most are transmembrane proteins (spans entire membrane ) – Have both hydrophobic and hydrophilic regions Hydrophobic areas interact with lipid tails Hydrophilic areas interact with water (heads) – Function as transport proteins (channels and carriers), enzymes (lock in key fix), or receptors( ex: for specific hormones or signal transduction) → specific in what they do Peripheral proteins – loosely attached to integral proteins – Include filaments on intracellular surface used for plasma membrane support – Function as: Enzymes Motor proteins for shape change during cell division and muscle contraction Cell-to-cell connections Figure 3.4 membrane proteins perform many tasks Membrane proteins perform many tasks (NOTES). Membrane-Cell Junctions Some cells are “free” (not bound to any other cells) – Examples: blood cells, sperm cells Most cells -bound together to form tissues and organs Three ways cells can be bound to each other: tight junctions, desmosomes, gap junctions  1.Tight Junctions – Integral proteins on adjacent cells fuse to form an impermeable junction that encircles whole cell – Prevent fluids and most molecules from moving in between cells: when we eat food → prevent food to leak into other organs or cavities, or blood brain barrier 2.Desmosomes – Anchoring Junctions “velcro” (like the heart beating) – Linker protein is anchored to its cell through thickened “button-like” areas on inside of plasma membrane called plaques – Desmosomes allow “give” between cells, reducing the possibility of tearing under tensions 3.Gap junctions – Transmembrane proteins (connexons) form tunnels that allow small molecules to pass from cell to cell – Used to spread ions, simple sugars, or other small molecules between cells – Allows electrical signals to be passed quickly from one cell to next cell ex: allowing the heart to beat in one rhythm Plasma Membrane- Selective Permeability Plasma membranes are selectively permeable – Some molecules pass through easily; some do not – If item can cross= “permeable” – Factors affecting permeability: size of molecule: effects permeability (tennis net vs golf ball, ping pong, football, etc) concentration: greater difference between areas, faster diffusion, concentration gradient: from high to low concentration Temperature- higher temperature = faster diffusion , molecules speed up and start to bump off one another encouraging diffusion Movement across Plasma Membrane Passive Transport- Move substances down the concentration gradient (high to low) – NO ENERGY: PASSIVE AND LAXXXXXX – Continues until no net movement (equilibrium) – Simple Diffusion, Facilitated Diffusion, Osmosis - Going down a hill (high top to low) → no energy Active Transport- substances move against the concentration gradient (low to high) – energy is required – Particles may be too large to use passive processes - Going up a hill (low to high) → requires effort Type of Passive Transport- Simple Diffusion – Substances move from area of area of higher concentration to lower concentration – Movement continues until equilibrium – Nonpolar lipid-soluble (hydrophobic) substances diffuse directly through phospholipid bilayer – Examples: oxygen, carbon dioxide, fat-soluble vitamins Facilitated diffusion – Down concentration gradient – Certain lipid-insoluble molecules (e.g., glucose, amino acids, and ions) – Integral Proteins Carrier-mediated-Substances bind to protein carriers changing the proteins shape Channel-mediated-Substances move through protein channels filled with water Transport- Facilitated Diffusion Carrier-mediated facilitated diffusion – Carriers are transmembrane integral proteins – Carriers transport specific polar molecules, ex: glucose carriers will carry only glucose molecules, nothing else – Binding of molecule causes carrier to change shape moving molecule in process – Binding is limited by number of carriers present Carriers are saturated when all are bound to molecules and are busy transporting Channels with aqueous-filled cores are formed by transmembrane proteins Channels transport molecules such as ions or water (osmosis) down their concentration gradient – Specificity based on pore size and/or charge – Water channels are called aquaporins : dehydrated —> make more aquaporins to absorb more water Two types: – Leakage Channels Always open – Gates Channels Controlled by chemical or electrical signals, something needs to be bound to open up these channels Major extracellular cellular ion sodium, major intracellular cellular ion is potassium → sodium potassium pumps ?? Type of Passive Transport- Osmosis Osmosis – Movement of water down a concentration gradient – Water diffuses through lipid bilayer via osmosis  Through lipid bilayer (even though water is polar, it is so small that some molecules can sneak past nonpolar phospholipid tails) Through specific water channels called aquaporins: water moves freely through these aquaporins Osmolarity : total concentration of solute particles Movement of water causes pressures: – hydrostatic pressure: pressure of water inside cell pushing on membrane (pushing out) – osmotic: tendency of water to move into cell by osmosis, by sucking water into the cell (sucking in) Increase [Solute]- Increase Osmotic Pressure Tonicity: water moves from high to low concentration (with the gradient) -Ability of a solution to change the shape or tone of cells by altering the cells’ internal water volume: where would i want water to go to dilute the solutes Isotonic solution has same osmolarity as inside the cell, so volume remains unchanged→ at equilibrium Hypertonic solution has higher osmolarity than inside cell, so water flows out of cell, resulting in cell shrinking (Crenation) Hypotonic solution has lower osmolarity than inside cell, so water flows into cell, resulting in cell swelling (lysing) Osmosis (NOTES): Active Processes Two major active membrane transport processes – active transport – vesicular transport (bulk transport) Both require ATP to move solutes across a plasma membrane for any of these reasons: – Solute is too large for channels – Solute is not liquid soluble – Solute is not able to move down concentration gradient Active Transport  Moves solutes against their concentration gradient Requires energy(ATP) Requires carrier proteins (solute pumps) – Bind specifically and reversibly with substance being moved – Some carriers transport more than one substance Antiports transport one substance into a cell while transporting a different substance out of the cell (E.g. Sodium-Potassium Pump) (moving in opposite directions: one in one out) Symporters transports two different substances in the same direction (multiple moving in the same direction) Uniports transport one substance in one direction (one in OR one out one at a time) · Primary active transport – Energy from hydrolysis of ATP causes change in shape of transport protein – Shape change causes solutes (ions) bound to protein to be pumped across membrane – sodium- potassium pump Most studied pump Basically is an enzyme, called Na+-K+ ATPase, that pumps Na+ out of cell and K+ back into cell Located in all plasma membranes, but especially active in excitable cells (nerves and muscles) leaky channels in cells → can’t leave Na and K in and out in the wrong spot, so the sodium potassium pump helps regulate that move sodium that leaked into cell, out of the cell, and move potassium that leaked out of the cell, into the cell by a 3 sodium: 2 potassium ratio · Secondary active transport · Depends on ion gradient that was created by primary active transport system  · Energy stored in gradients is used indirectly to drive transport of other solutes · Low Na+ concentration that is maintained inside cell by Na+−K+ pump strengthens sodium’s drive to want to enter cell · Na+ can drag other molecules with it as it flows into cell through carrier proteins (usually symporters) in membrane 1. Some sugars, amino acids, and ions are usually transported into cells via secondary active transport Figure 3.9 Vesicular Transport · Involves transport of large particles, macromolecules, and fluids across membrane in membranous sacs called vesicles · Requires cellular energy (usually ATP) · endocytosis: transport into cell: ENGULF · 3 different types of endocytosis: phagocytosis, pinocytosis, receptor-mediated endocytosis · exocytosis: transport out of cell: take a piece out · Primarily Hormones and Neurotransmitters · transcytosis: transport into, across, and then out of cell · Vesicular Transport-Endocytosis · Phagocytosis: “cell eating” · Pseudopods engulf solids bringing them into cell · Form vesicle called Phagosome · Non-Specific · Ex: Macrophages and certain other white blood cells 1. move by amoeboid motion where cytoplasm flows into temporary extensions that allow cell to creep · Pinocytosis: “cell drinking → brings in liquids” (pino → pina colada)  · Membrane invaginates engulfing fluids - Fuses with endosome · Forms pinocytic vacuole · Common in absorptive cells · Non-Specific – Used by some cells to “sample” environment – Main way in which nutrient absorption occurs in the small intestine · receptor-mediated endocytosis involves endocytosis and transcytosis of specific molecules · Specific receptors in pits Protein coated vesicle formed E.g.: lipoproteins, hormones, viruses (diphtheria, cholera) Vesicular Transport-Exocytosis. Material is ejected (vomits) from cell Substance being ejected is enclosed in secretory vesicle Protein on vesicle called v-SNARE finds and hooks up to target t-SNARE proteins on membrane ○ Docking process triggers exocytosis E.g: hormones, neurotransmitters, mucus, cellular wastes Thursday 10SEP24 → page 96 Cytoplasm Cellular material that is located between the plasma membrane & nucleus ○ Composed of: Cytosol : gel-like solution made up of water and soluble molecules such as proteins, salts, sugars, etc. Inclusions: insoluble molecules; vary with cell type (examples: glycogen granules, pigments, lipid droplets) Organelles: metabolic machinery structures of cell; each with specialized function; Cytoplasmic Organelles *Membranous *Nonmembranous -Mitochondria: -Ribosomes -Endoplasmic reticulum -Cytoskeleton -Golgi apparatus -Centrioles -Peroxisomes -Lysosomes Membranes allow compartmentalization (keeping things in one compartment) which is crucial to cell functioning Mitochondria- MEMBRANOUS: “Powerplant ” -produce most of cell’s energy molecules (ATP/cellular currency) via aerobic (oxygen-requiring) cellular respiration Double membranes; inner membrane has many folds, called cristae ○ Cristae are embedded with membrane proteins that play a role in cellular respiration Own DNA,RNA, and ribosomes (endosymbiotic theory) Self-replicate by fission (like bacteria) → need to make more so that you can continue making ATP NECESSARY Ribosomes Non-Membranous Organelle- Protein Synthesis Ribosomal RNA + Protein Two forms found in cell: ○ Free ribosomes: free floating; site of synthesis of soluble proteins that function in cytosol or other organelles ○ Membrane-bound ribosomes: attached to membrane of endoplasmic reticulum (rough ER); site of synthesis of proteins to be incorporated into membranes or lysosomes, or exported from cell Endoplasmic Reticulum (ER) Membranous tubes continuous with outer nuclear membrane Two Types of ER: ○ Rough ER (granular)- “gritty” uneven surface Contains Ribosomes (ROUGH has R, Ribosomes have R, R for R) Rough ER synthesizes proteins (the ribosomes on the surface) ○ Smooth ER-(agranular)- appears to have even surface Network of tubules that is continuous with Rough ER No Ribosomes The endoplasmic reticulum. Synthesis lipids Endoplasmic Reticulum (ER) Rough ER ○ External surface appears rough because it is studded with attached ribosomes Site of synthesis of proteins that will be secreted from cell Site of synthesis of many plasma membrane proteins and phospholipids ○ Assembled proteins enter cisterns as they are synthesized and are modified as they wind through fluid-filled tubes ○ Final protein is enclosed in vesicle and sent to Golgi apparatus for further processing Smooth ER ○ NO Ribosomes ○ No Protein Synthesis Lipid metabolism; cholesterol and steroid-based hormone synthesis; making lipids for lipoproteins Absorption, synthesis, and transport of fats Detoxification of certain chemicals (drugs, alcohol, pesticides, etc.) Converting of glycogen (storage form of glucose) to free glucose Storage and release of calcium – Sarcoplasmic reticulum is specialized smooth ER found in skeletal and cardiac muscle cells Golgi Apparatus→ UPS Layers (stacks) of flattened membranous cistern sacs package proteins and lipids in vesicles received from rough ER Three steps are involved: ○ Transport vesicles from ER fuse with cis (inner) face of Golgi ○ Proteins or lipids taken inside are further modified, tagged, sorted, and packaged ○ Golgi is “traffic director,” controlling which of three pathways final products will take as new transport vesicles pinch off trans (outer) face  The sequence of events from protein synthesis on the rough ER to the final distribution of those proteins. Peroxisomes Membranous sacs -detoxifying substances that neutralize toxins ○ Free Radical (unpaired electrons): toxic, highly reactive molecules that are natural by-products of cellular metabolism; can cause havoc to cell if not detoxified ○ Two main detoxifiers of the waste that happens in the cell Two step processes Oxidase uses oxygen to convert toxins to hydrogen peroxide (H2O2), which is itself toxic; Catalase which converts H2O2 to harmless water Peroxisomes use oxidase to convert toxins to hydrogen peroxide then use catalase to convert it to water Lysosomes Spherical membranous bags containing digestive enzymes Digest ingested bacteria, viruses, and toxins Degrade nonfunctional organelles (autophagy- eat itself (the organelle)) Metabolic functions: ○ break down and release glycogen ○ break down and release Ca2+ from bone (bone resorption) When you break a bone, it doesn’t repair perfectly, so the cells come and eat away at the extra bone that isn’t needed → why we need calcium Injured cells digest themselves (autolysis) APOPTOSIS: pre-programmed cell death ○ Cytoskeleton: three cytoskeleton elements: microfilaments, intermediate filaments, microtubules Cell’s “bones, ligaments, and muscle” by playing a role in movement of cell components Three types: · Microfilaments Thread like- THINNEST of all cytoskeletal elements Semi-flexible strands of protein actin Each cell has a unique arrangement of strands, although share common terminal web- no two cells are woven alike – attach to cytoplasmic side of plasma membrane – Strengthens cell surface and helps to resist compression Some are involved in cell motility, changes in cell shape, or endocytosis and exocytosis  · Intermediate filaments Tough, insoluble, ropelike protein fibers Most stable and permanent of cytoskeleton fiber due to Tetramer subunits Act as internal guy-wires-Help cell resist pulling forces Protein composition various between cells – Called neurofilaments in nerve cells and keratin filaments in epithelial cells · Microtubules Largest of cytoskeletal elements Hollow tubes of protein subunits called tubulins – constantly being assembled and disassembled- not membrane bound Determine overall shape of cell and distribution of organelles – Many organelles are tethered to microtubules to keep organelles in place – Many substances are moved throughout cell by motor proteins, which use microtubules as tracks Centrosome Centrioles Centrosome, dense area near nucleus, means “cell center” ○ microtubule organizing center, consisting a pair Centrioles- barrel-shaped organelles that lie at right angles to each other ○ Plays role in cell division → sit at right angles of each other ○ form the basis of cilia (hair lik and flagella (sperm) Cellular Extensions Certain cells have structures extending from the cell surface: ○ Cillia –short cytoplasmic extensions Move substances along cell surface Short, hair like, move is sweeping motion to move substances ○ Flagella- long cytoplasmic extensions Movement of the cell (e.g. sperm only in human) Microvilli. · Microvilli are fingerlike projections that extend from the surface of the cell to increase surface area  (e.g: intestinal and kidney tubule cells) · Used to increase surface area for absorption · Have a core of actin microfilaments that is used for stiffening of projections Nucleus Largest organelle; contains the genetic library (dna, rna) of blueprints for synthesis of nearly all cellular proteins ○ Responds to signals that dictate the kinds and amounts of proteins that need to be synthesized Most cells are uninucleate (one nucleus)(smooth muscle), but skeletal muscle, certain bone cells, and some liver cells are multinucleated (many nuclei) ○ Red blood cells are anucleate(no nucleus) → to carry more oxygen Structure of the Nucleus The nucleus has three main structures: 1. Nuclear Envelope Double-membrane barrier that encloses the jelly-like fluid, the ○ Outer layer is continuous with rough ER and, like the rough ER, is studded with ribosomes ○ Inner layer, called nuclear lamina, is a network mesh of proteins that maintains nuclear shape and acts as scaffolding for DNA Nuclear pores allow substances to pass into and out of nucleus ○ Communication between cytoplasm and nucleus 2. Nucleolus- one or two per cell Spherical structure in nucleus Site of rRNA synthesis and storage 3. Chromatin a. Chromosomes (46 in humans) are condensed Chromatin B. only cells that have 23 chromosomes are gametes Three main components of cells are cytoplasm, cell membrane, and nucleus  Tissues: The Living Fabric Chapter 4- Tissues Tissues–) figure 4.1 · Groups of cells similar in structure that perform common or related function histology=Study of tissues Four basic tissue types: 1. Epithelial Tissue 2. Connective Tissue 3. Muscle Tissue 4. Nervous Tissue Epithelial Tissue Epithelial tissue (epithelium)- everywhere covers body surfaces of cavities Two main forms: Covering and lining epithelia On external and internal surfaces (example: skin) Glandular epithelia Forms glands (example: salivary glands) Epithelial Tissue Main functions: Specific to the Structure ○ Protection: skin (1st line of defense nonspecific immunity) ○ Absorption: small intestine, absorbs nutrients ○ Filtration: filtration of kidneys ○ Excretion: excretion of kidneys  ○ Secretion: hormones ○ Sensory Reception: taste buds on tongue Special Characteristics of Epithelial Tissues Epithelial tissue has five distinguishing characteristics: 1. Polarity : always has both apical and basal(Apical (free, not attached to anything)), Basal (attached to surface) ace - Apical is the “top” - Basal is the “bottom” attached to the surf 2. Specialized Contacts (tightly packed together) 3. Supported by Connective Tissues 4. Avascular 5. Regeneration Classification of Epithelial Tissue All epithelial tissues have two names 1. First name indicates number of cell layers Simple epithelia are a single layer thick, - Diffusion, absorption, does not use a lot of energy (structure related to function and function relates to structure) Stratified epithelia are two or more layers thick 2. Second name indicates shape of cells Squamous: flattened and scale-like Cuboidal: box-like, cube Columnar: tall, column-like 3. Have the tissue name at the end Practice Drawing Epithelial Tissue:  Simple Squamous Simple Cuboidal Simple Columnar Epithelium: have to put Epithelium Epithelium tissue name at the end Stratified Squamous Stratified Cuboidal Stratified Columnar Epithelium Epithelium Epithelium Classification of Simple Epithelia Simple Squamous Epithelium 1. Involved in absorption, secretion, or filtration processes 2. Cells are flattened laterally 3. Cytoplasm is sparse 4. Function where rapid diffusion is priority Example: kidney, lungs Simple Cuboidal epithelium: had a lumen (hole of the house taken from a crosssection) 1. Single layer of cells 2. Function secretion and absorption 3. Forms walls of smallest ducts of glands and kidney tubules 4. Classification of Simple Epithelia  Simple Columnar epithelium 1. Single layer of tall, closely packed cells Some cells have microvilli, and some have cilia - Cillia gives it away in this class, cilia → smokers cough is from cilla dying in trachea Some layers contain mucus-secreting goblet cells 2. Function absorption and secretion mucus, enzymes, and other substances Ciliated cells move mucus 3. Found in digestive tract, gallbladder, ducts of some glands, bronchi, and uterine tubes Pseudostratified (ciliated) Columnar epithelium 1. Cells vary in height - Falsely stratestfied because it looks like there are multiple nucleus looks li 2. All cells in contact with basement membrane: close to basement membrane, more oxygen from the blood vessels in the connective tissue under the basement membrane, the farther away from basement membrane the less oxygen and more dead the cell sare 3. Nuclei positioned differently 4. Not all cells reach apical surface 5. Involved in secretion, particularly of mucus via ciliary sweeping action 6. Located mostly in upper respiratory tract, ducts of large glands, and tubules in testes Stratified epithelial tissues 1. Involve two or more layers of cells 2. New cells regenerate from below Basal cells divide and migrate toward surface  3. More durable than simple epithelia because protection is the major role 4. Function: Protection Stratified Squamous Epithelium 1. Allows for wear and tear 2. Keratinized: skin Cells lack nuclei apical surface, dead on free surface 3. Nonkeratinized: lines mouth, esophagus Cells have nuclei apical surface Stratified Cuboidal epithelium Quite rare Found in some sweat and mammary glands Typically only two cell layers thick stratified columnar epithelium Small amounts in pharynx, in male urethra, and lining some glandular ducts Occurs at transition areas between two other types of epithelia Only apical layer is columnar - You find it in transition areas: transitions between esophagus and stomach (between organs) Transitional epithelium Forms lining of hollow urinary organs that stretch Found in bladder, ureters, and urethra Basal layer cells are cuboidal or columnar, ROUND found in places that stretch Thursday 17 SEP 2024 Glandular Epithelium Gland 1. One or more cells that makes and secretes an aqueous fluid called a secretion 2 Types of Glands: endocrine internally secreting (example: hormones) Ductless exocrine: externally secreting (example: sweat) Ducts - Figure 4.5 Endocrine glands 1. Ductless glands Secretions are released into surrounding interstitial fluid 2. Secrete by exocytosis of Hormones into bloodstream 3. Target organs respond in some characteristic way Exocrine glands —> exocrine exit 1. Secretions are released onto body surfaces or into body cavities 2. More numerous than endocrine glands 3. Secretion into ducts 4. Examples include mucous, sweat, oil, and salivary glands 5. Can be: Unicellular Multicellular Unicellular exocrine glands 1. Mucous cells and Goblet cells epithelial linings of intestinal and respiratory tracts 2. All produce Mucin a sugar-protein that can dissolve in water to form mucus  a slimy protective, lubricating coating Multicellular exocrine glands Classified by: Structure Simple=unbranched ducts Compound=branched ducts Mode of secretion Tubular=tube shaped Alveolar (acinar)=sac shaped Tubuloalveolar glands =have both types Mode of secretion Merocrine: most exocrine glands-secrete products by exocytosis as secretions are produced (secrete) (sweat, pancreas) - M for Moves out and Merocrine Holocrine: accumulate products within- then rupture (zit) (sebaceous oil glands) - H for halt and holocrine Apocrine: accumulate products within, but only apex ruptures; - Also a sweat gland Connective Tissue Connective tissue is the most abundant and widely distributed of primary tissues Major functions: 1. Binding and support 2. Protection → bone 3. Insulating → adipose 4. Storing reserve fuel → storing salt water fat 5. Transporting substances → blood is the only circulating connective tissue Four main classes Connective Tissue Proper Cartilage Bone Blood Connective Tissue Characteristics Common embryonic origin: mesenchyme tissue Degrees of vascularity: Avascular-Vascular Extracellular matrix (ECM) - Non living substance (ground substance plus fibers) surrounding cells, doe not include the cells Main Structural Elements Ground Substance Fibers Cells Composition and arrangement of these three elements vary considerably in different types of connective tissues Ground substance Unstructured gel-like material that fills space between cells Components Interstitial fluid Cell adhesion proteins (“glue” for attachment) Proteoglycans =protein core + large polysaccharides Water also is trapped in varying amounts, affecting viscosity of ground substance Connective tissue fibers Three types of fibers provide support Collagen-Strongest and most abundant type  Tough; provides high tensile strength Elastic Fibers Elastin fibers that allow for stretch and recoil Reticular Short, fine, highly branched Branching forms networks that offer more “give” Connective Tissue Cells “Blast” cells (younger sibling) 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 Hematopoietic stem in bone marrow “Cyte” cells (older sibling) Mature form Chondrocyte → in lacunae Osteocyte Fibrocyte less active form of “blast” cell that now becomes part of and Helps maintain health of matrix Other cell types in connective tissues White blood cells-Leukocytes types of leukocyte: Neutrophils, eosinophils, basophils, monocyte (can leave blood and turn into macrophages that are phagocytes) , lymphocytes Tissue response to injury Macrophage Phagocytic cells that “eat” dead cells, microorganisms; function in immune system  Mast cells Initiate local inflammatory response against foreign microorganisms they detect Fat cells- Adipose Store nutrients Type of Connective Tissue Embryonic Connective Tissue mesenchyme Differentiates into all other connective tissue Wharton’s jelly or Mucous Connective Tissue Only in fetus-umbilical cord Four main classes of connective tissue: Connective Tissue Proper Cartilage Bone Blood Draw Diagram of Types of CT - figure 4.10 Connective tissue proper- Two subclasses: consists of all connective tissues except bone 1.CT proper: loose connective tissues ______________ ______________ ______________ 2.CT proper: dense connective tissues __________________ _________________ __________________ CT Proper-Loose CT Areolar connective tissue Most widely distributed CT Supports and binds- Strength and elasticity Hypodermis, around nerves and blood vessels Well vascularized Adipose Tissue White fat Similar to areolar tissue but greater nutrient storage Adipocytes Scanty matrix Richly vascularized Functions in shock absorption, insulation, and energy storage LocationL Sub Q, eyeballs, kidneys, breasts Women carry more than men → to feed young and deliver baby Brown fat Thermoregulation: use of lipid fuels to heat blood streak rather than produce ATP See more in infants → as they age it turns into white fat Reticular connective tissue Fibroblast cells are called reticular cells Secrete reticular fibers made up of thin collagen Reticular fibers form stroma acts as a support for blood cells in lymph nodes, spleen, and bone marrow In lymph nodes, bone marrow, and spleen CT proper: _dense connective tissues Dense Regular connective tissue Very high tensile strength; can withstand high tension and stretching Closely packed bundles of thick collagen fibers run parallel to direction of pull Fibroblasts manufacture collagen fibers and ground substance Poorly vascularized Example: tendons (muscle to bone) and ligaments (bone to bone) Dense Irregular connective tissue Same elements as dense regular, but no regular pattern to it bundles of collagen are thicker and irregularly arranged Resists tension from many directions Found in: Dermis, Fibrous joint capsules, Fibrous coverings of some organs Elastic connective tissue Elastic Fibers, fibroblasts, and ground substance, Collagen fibers Found where some degree of stretching Also found in walls of many large arteries, trachea, bronchial tubes CT Proper- Cartilage Chondroblasts –immature cartilage cell Chondrocytes- mature cartilage cell lacuna- space in matrix that houses chondrocytes 80% water Avascular: receives nutrients from membrane surrounding it (perichondrium what wraps and surrounds and supported cartilage )  Likes nerve fibers hyaline cartilage Most abundant “gristle” Appears as shiny bluish glass Found at tips of long bones, nose, trachea, larynx, and cartilage of the ribs elastic cartilage Similar to hyaline but with more elastic fibers Found in ears and epiglottis Fibrocartilage Properties between hyaline and dense regular tissue Strong-withstand stress and compression Found; intervertebral discs and knee Types of Connective Tissues-Other Bone Also called osseous tissue Supports and protects body structures Stores fat and synthesizes blood cells in cavities Has more collagen compared to cartilage Has inorganic calcium salts osteoblasts produce matrix osteocytes maintain the matrix Reside in cavities in matrix called lacunae osteons : individual structural units (tunnel like) Richly vascularized Blood  Atypical connective tissue because fluid matrix (plasma) Erythrocytes are most common cell type, no nucleus Leukocytes and platelets (thrombocytes) Fibers are soluble proteins precipitate during blood clotting Functions in transport Muscle Tissue Highly vascularized Responsible for most types of movement Muscle cells possess myofilaments up of actin and myosin proteins that bring about contraction Three types of muscle tissues: Questions to ask when identifying muscle tissue: - Is it involuntary or voluntary - Does it have striations that allow for quick hard contracts Make mind map for this starting with if there are striations, then interrelated discs then voluntary voluntary Muscle Types Involuntary or Striations, allow for Voluntary quick hard contracts Special (has lines through it Characteristics |\\\\\| Skeletal Muscle Voluntary Yes it does, to move from walking to running Cardiac Muscle Involuntary Yes (when it needs to pump harder and Has interrelated faster) discs → allows for simultaneous  contractions Smooth Muscle Involuntary (digestive system No, we want slow and gut) pace (peristaltic motions) 1. Skeletal muscle tissue Attached to and causes movement of bones Voluntary muscle Cells are called muscle fibers Contain multiple nuclei Appear striated or banded 2.Cardiac muscle tissue Found only in walls of heart Involuntary muscle Striations Cells have only one nucleus Cells can have many branches that join branches of other cardiac cells intercalated disks are special joints where cardiac cells are joined 3.Smooth muscle tissue Found mainly in walls of hollow organs Involuntary muscle No striations Spindle-shaped cells with one nucleus, fusi formed cells Nervous Tissue Main component of nervous system (brain, spinal cord, nerves) 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 at least two primary tissue types: an epithelium bound to underlying connective tissue proper layer Three types: 1.Cutaneous Membrane Skin Keratinized stratified squamous epithelium (epidermis) Connective tissue(dermis)- loose CT, Dense irregular CT skin is a dry membrane, no lubrication 2. Mucous Membrane Mucosa indicates location, not cell composition Also called mucosae Line body cavities that are open to the exterior (example: digestive (mouth to anus), respiratory, urogenital tracts) Moist membranes bathed by secretions (or urine) Epithelial sheet lies over layer of loose connective tissue called lamina propria May secrete mucus 3. Serous Membrane Also called serosae Found in closed ventral body cavities Constructed from simple squamous epithelium (called mesothelium) resting on thin areolar connective tissue parietal serosae line internal body cavity walls  visceral serosae cover internal organs Cavity between layers is filled with slippery serous fluid, so these are moist membranes Special names given to show location: pleurae (lungs), pericardium (heart), peritoneum (abdomen) Thursday 19SEP24 Tissue Repair When the body’s barriers are compromised, the inflammatory and immune responses are activated Repair starts very quickly Repair is the function of the inflammatory process Tissue Repair Repair 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 lost → scar tissues and Stage 1 Inflammation sets stage - Release of inflammatory chemicals causes - Dilation of blood vessels - Increase in blood vessel permeability - More blood → more chemicals → more healing - Clotting occurs - Removing injuring causing agent Stage 2  Organization restores blood supply - Proliferation - Organization begins as the blood clot is replaced with granulation tissue - Granulation tissue: new capillary-enriched tissue - Epithelium begins to regenerate - Fibroblasts produce collagen fibers to bridge the gap until regeneration is complete - Start to bridge the gap within the damaged tissue - Any debris in area is phagocytized - Filling wound space - Blood vessels get smaller because it isn’t needed before the final stage Stage 3 Regeneration and Fibrosis effect permanent repair - Maturation - The scab detaches - Fibrous tissue matures - Epithelium thickens and begins to resemble adjacent tissue - Results in a fully regenerated epithelium with underlying scar tissue, which may or may not be visible - Wound healing dania b on youtube Regenerative Capacity of Different Tissues Tissues that regenerate _________________ include: Epithelial tissues, bone, areolar connective tissue, dense irregular connective tissue, blood-forming tissue Tissue with ____________ regenerating capacity: Smooth muscle and dense regular connective tissue Tissues with virtually _____ functional regenerative capacity: Cardiac muscle and nervous tissue of brain and spinal cord  The Integumentary System Chapter 5 Integumentary system consists of: ◦ Skin- Largest Organ in Body ◦ Hair ◦ Nails ◦ Sweat glands ◦ Sebaceous (oil) glands Structure of skin Skin consists of two distinct regions: ◦ epidermis: superficial region ◦ Consists of epithelial tissue ◦ avascular - Receives oxygen from the dermis ◦ dermis: underlies epidermis ◦ Fibrous connective tissue ◦ Vascular ◦ diffusion of nutrients to epidermis - Has lots of capillaries and blood vessels ◦ hypodermis, subcutaneous ◦ Subcutaneous layer deep to skin ◦ Not part of skin ◦ Mostly adipose tissue that absorbs shock and insulates ◦ Anchors skin to underlying structures: mostly muscles Fascia-thin sheath of fibrous tissue enclosing a muscle or other organ Epidermis Cells of the Epidermis Four cell types found in epidermis: 1. keratinocytes-Major cell of epidermis ◦ Produce fibrous keratin (protein that gives skin its protective properties, strength) ◦ Tightly connected by desmosomes ◦ Millions slough off every day→ dust 2. Melanocytes ◦ located in deepest epidermis ◦ Produce pigment melanin, which is packaged into melanosomes - Gives you your color of skin, we all have similar melanosomes but how much much melanin we produce is different between everyone ◦ Melanosomes are transferred to keratinocytes, where they protect nucleus from UV damage, - Melanin production is stimulated from sunlight 3. Dendritic cells (langerhans cells) ◦ Macrophages that patrol deep epidermis ◦ Are key activators of immune system -> as they protocol dermal layers, they spot out any “suspicious” activity and lets t and b cell in immune system know of potential pathogens 4. Tactile cells (merkel cells) ◦ Sensory receptors that sense touch - Hot, cold, pressure, pain Layers of the Epidermis Epidermis is made up of four (where there is hair) or five (where you are hairless and have thick skin → using your hands and feet all the time for protection) distinct layers  Five layers of skin 1. Stratum basale (basal layer)- stratum germinativum ◦ Deepest of all epidermal layers (b for basement) ◦ Layer that is firmly attached to dermis ◦ Actively divide (miotic), ◦ 25–45 days to reach surface ◦ Cell dies as it moves toward surface, cells keep moving up, the closer they get to the surface, the less oxygen they get from blood vessels diffusing oxygen in the dermis layer, the more dead they are ◦ 10–25% of layer also composed of melanocytes 2. Stratum spinosum -(prickly layer) ◦ 8-10 cell layers thick. ◦ Weblike system-Allows them to resist tension and pulling ◦ Keratinocytes-appear spikey, so they are called prickle cells ◦ Melanosomes and Dendritic cells also abundant 3. Stratum granulosum (granular layer) ◦ Four to six cells thick ◦ Cell appearance changes ◦ Cells flatten ◦ Nuclei and organelles disintegrate ◦ keratinization begins ◦ Keratohyaline granules accumulate and form keratin fibers ◦ Cells also accumulate lamellar granules, a water-resistant glycolipid that slows water loss ◦ Cells above this layer die ◦ Too far from dermal capillaries to survive - Water resistance to slow the removal of it  4. Stratum lucidum (clear layer) ◦ Found only in thick skin with no hair ◦ Consists of thin, translucent band ◦ Two to three rows of clear, flat, dead keratinocytes ◦ Lies superficial to the stratum granulosum - Looks translucent 5. Stratum corneum - (horny layer) ◦ Thickest Layer (20–30) rows of flat, anucleated, keratinized dead cells ◦ Accounts for three-quarters of epidermal thickness ◦ Though dead, cells still function to: ◦ Protect deeper cells from the environment ◦ Prevent water loss ◦ Protect from abrasion and penetration ◦ Act as a barrier against biological, chemical, and physical assaults - Nonspecific immunity → creates a barrier of protection Layers of the Epidermis Cells change by going through apoptosis (controlled and organized cell death) ◦ Dead cells slough off as dandruff and dander ◦ Humans can shed ~50,000 cells every minute - Know they are going to move up to surface and die off→ controlled cell death Dermis Strong, flexible connective tissue Cells include fibroblasts, macrophages, and occasionally mast cells and white blood cells Fibers in matrix bind body together  Contains nerves, blood vessels, and lymphatic vessels, epidermal hair follicles, oil glands, and sweat glands Two layers 1. Papillary 20% of the layer Superficial layer Areolar connective tissue Loose fibers allow phagocytes to patrol for microorganisms Dermal papillae: superficial region of dermis that sends fingerlike projections up into epidermis →> locks into the epidermis very closely (knuckles) Capillary loops Free nerve endings- pain receptors (like fingers) Touch receptors - Meissner’s corpuscles In thick skin, dermal papillae lie on top of dermal ridges, which give rise to epidermal ridges, what gives you your fingerprint ◦ Collectively ridges are called friction ridges ◦ Enhance gripping ability ◦ Contribute to sense of touch ◦ Sweat pores in ridges leave unique fingerprint pattern 2.Reticular ~80% of dermal thickness Dense irregular connective tissue Many elastic fibers provide stretch-recoil properties Collagen fibers provide strength and resiliency Bind water, keeping skin hydrated cutaneous plexus: network of blood vessels between reticular layer and hypodermis, where a majority of the blood is being brought in Reticular Layer flexure lines of reticular layer are dermal folds at or near joints ◦ Dermis is tightly secured to deeper structures ◦ Skin’s inability to slide easily for joint movement causes deep creases ◦ Visible on hands, wrists, fingers, soles, toes - If you didn't have these you wouldn't be able to move your hands and fingers cleavage (tension) lines in reticular layer ◦ caused by many collagen fibers running parallel to skin surface ◦ Externally invisible ◦ Important to surgeons because incisions parallel to cleavage lines heal more readily - Stretch marks → ripping of dermal layers - Blisters → separation between dermal and epidermal layer and that serpation fills with fluid Skin Color Three pigments contribute to skin color 1. melanin ◦ Only pigment made in skin; made by melanocytes ◦ Packaged into melanosomes that are sent to keratinocytes to shield DNA from sunlight ◦ Sun exposure stimulates melanin production ◦ Two forms: reddish yellow to brownish black ◦ Skin color differences are due to amount and form of melanin ◦ Freckles and pigmented moles are local accumulations of melanin 2. carotene ◦ Yellow to orange pigment ◦ Most obvious in palms and soles ◦ Accumulates in stratum corneum and hypodermis  ◦ Can be converted to vitamin A for vision (works on rods in eye that see black and white, low vitamin A, bad night vision ) and epidermal health 3. hemoglobin ◦ Pinkish hue of fair skin is due to lower levels of melanin ◦ Skin of Caucasians is more transparent, so color of hemoglobin shows through Epidermal Derivatives 1.Hair Consists of dead keratinized cells None located on palms, soles, lips, nipples, and portions of external genitalia (penis tip) Functions: Warn of insects on skin Hair on head guards against physical trauma Protect from heat loss Shield skin from sunlight - Female and male have different hair → androgens testosterone Structure of a Hair Hairs (also called pili): flexible strands of dead, keratinized cells Produced by hair follicles Contains hard keratin, not like soft keratin found in skin Hard keratin is tougher and more durable, and cells do not flake off (like soft keratin in skin) Regions: shaft: area that extends above scalp, where keratinization is complete root: area within scalp, where keratinization is still going on Three parts of hair: ◦ medulla: central core of large cells and air spaces  ◦ cortex: several layers of flattened cells surrounding medulla ◦ cuticle: outer layer consisting of overlapping layers of single cells, prevents hair from sticking together Hair pigments are made by melanocytes in hair follicles ◦ Combinations of different melanins (yellow, rust, brown, black) create all the hair colors ◦ Red hair has additional pheomelanin pigments ◦ Gray/white hair results when melanin production decreases and air bubbles melanin in shaft Structure of a Hair Follicle Extends from epidermal surface to dermis Hair bulb: expanded area at deep end of follicle Hair follicle receptor (or root hair plexus): sensory nerve endings that wrap around bulb Hair is considered a sensory touch receptor Wall of follicle composed of: Peripheral connective tissue sheath Derived from dermis Glassy membrane: thickened basal lamina Epithelial root sheath Derived from epidermis Hair matrix: actively dividing area of bulb that produces hair cells As matrix makes new cells, it pushes older ones upward arrector pili: small band of smooth muscle attached to follicle Responsible for goose bumps Hair papilla Dermal tissue containing a knot of capillaries that supplies nutrients to growing hair  Types and Growth of Hair.vellus hair: pale, fine body hair of children and adult females → body warmth.Terminal hair: coarse, long hair ◦ Found on scalp and eyebrows ◦ At puberty ◦ Appear in axillary and pubic regions of both sexes ◦ Also on face and neck of males Nutrition and hormones affect hair growth → pcos increases testosterone production and they start getting hair on chest and neck Follicles cycle between active and regressive phases ◦ Average 2.25 mm growth per week ◦ Lose 90 scalp hairs daily 2.Nails Scale-like modifications of epidermis that contain hard keratin Act as a protective cover for distal, dorsal surface of fingers and toes Nail matrix: responsible for nail growth Nail folds: skin folds that overlap border of nail eponychium: nail fold that projects onto surface of nail body o Also called cuticle hyponychium: area under free edge of plate that accumulates dirt lunule: thickened nail matrix, appears white o Abnormal color or shape can be an indicator of disease - Yellow and thickened: fungus - Bows line: cancer, heart attack, diabetes - Spoon nails (endents): iron diffencacy - Yellow no thickened, respiratory and thyroid disease 3. Sweat Glands Sudoriferous glands All skin surfaces except nipples and parts of external genitalia contain sweat glands About 3 million per person Two main types Eccrine (merocrine) sweat glands → most apocrine sweat glands → nervous (armpit and groin) Contain myoepithelial cells (myo = muscles) Contract upon nervous system stimulation to force sweat into ducts, proteins (actin and myosin) Eccrine (Merocrine) Sweat Glands Most numerous Abundant on palms, soles, and forehead Ducts connect to pores Function in thermoregulation Their secretion is sweat 99% water, salts, vitamin C, antibodies, dermcidin (microbe-killing peptide), metabolic wastes Apocrine Sweat Glands → exocrine Confined to axillary and anogenital Secrete viscous milky or yellowish sweat that contains fatty substances and proteins bacteria break down sweat, leading to body odor Larger than eccrine sweat glands/ ducts empty into hair follicles Begin functioning at puberty Function unknown but may act as sexual scent gland → pheromone Sweat Glands Modified Apocrine glands ◦ ceruminous glands:  ◦ lining of external ear canal ◦ secrete cerumen (earwax) ◦ mammary glands: ◦ secrete milk 4.Sebaceous Oil glands Widely distributed Not in thick skin of palms and soles Most develop from hair follicles Secrete into hair follicles Relatively inactive until puberty Stimulated by hormones, especially androgens Secrete sebum Oily holocrine secretion Bactericidal (bacteria-killing) properties Softens hair and skin - Cradle cap: seborrhea Functions of Skin Skin is first and foremost a barrier → non specific immunity Its main functions include: ◦ Protection ◦ Body temperature regulation ◦ Cutaneous sensations ◦ Metabolic functions ◦ Blood reservoir ◦ Excretion of wastes Protection Skin is exposed to microorganisms, abrasions, temperature extremes, and harmful chemicals Constitutes three barriers: 1.Chemical Barrier ◦ Skin secretes many chemicals, such as: ◦ Sweat, which contains antimicrobial proteins ◦ Sebum and defensins, which kill bacteria ◦ Acid Mantle: low pH of skin retards bacterial multiplication ◦ Melanin provides a chemical barrier against UV radiation damage 2. Physical Barrier ◦ Flat, dead, keratinized cells of stratum corneum, surrounded by glycolipids, block most water and water-soluble substances ◦ Some chemicals have limited penetration of skin ◦ Lipid-soluble substances ◦ Plant oleoresins (e.g., poison ivy) ◦ Organic solvents (acetone, paint thinner) ◦ Salts of heavy metals (lead, mercury) ◦ Some drugs (nitroglycerin) ◦ Drug agents (enhancers that help carry other drugs across skin) 3. Biological Barriers ◦ Epidermis contains phagocytic cells ◦ Dendritic cells of epidermis engulf foreign antigens and present to white blood cells, activating the immune response ◦ Dermis contains macrophages ◦ Macrophages also activate immune system by presenting foreign antigens to white blood cells  ◦ DNA can absorb harmful UV radiation, converting it to harmless heat Body Temperature Regulation Normal body temp sweat glands produce about 500 ml/day of unnoticeable sweat Called insensible perspiration Increased Body Temp dilation of dermal vessels increase sweat gland activity to produce 12 L (3 gallons) of noticeable sweat Called sensible perspiration; designed to cool body → what you feel Cold external environment Dermal blood vessels constrict Skin temperature drops to slow passive heat loss Cutaneous Sensations Cutaneous sensory receptors - part of the nervous system exteroreceptors respond to stimuli outside body, such as temperature, touch, pain Meissner’s Corpuscles- detect light touch Pacinian Corpuscles (lamellar corpuscles)- detect deep pressure Free Nerve Endings-pain (not adaptable) arrector pili muscles Goosebumps- efferent motor information Other Skin Functions Metabolic Function Skin can synthesize vitamin d needed for calcium absorption in intestine  Chemicals from keratinocytes can disarm some carcinogens, activates hormones Blood Reservoir Skin can hold up t