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BIO169-Week 1
Week 1 Physiology Notes
| Question | Answer |
|---|---|
| What is physiology? | The study of the normal functioning of the body |
| What are some of the parameters inside the body that cells live in? | pH, temperature, osmotic concentration |
| What is homeostatsis? | the abilitiy of the body to maintain a consistent internal environment while being exposed to continuously changing conditions |
| What are the mechanisms of homeostaic regulation? What is the most common? | negative feedback and positive feedback; negative feedback most common because it promotes stability |
| What is negative feedback regulation? | a type of control mechanism in which a change in a variable in one direction initiates response which will promote changes in that variable back to normal |
| What is an example of negative feedback? | an increase in blood glucose after a meal triggers the release of insulin from the pancreas; the insulin triggers the uptake of glucose from the blood into cells, bringing the glucose level back down |
| What is normal body temperature? What type of feedback maintains normal temperature? How? | Normal temp is 37 deg Celsius; negative feedback helps to regulate temp; sweating occurs when body temp is too high (acts to cool the body); shivering occurs when body temp is too low (acts to raise temp) |
| What is positive feedback? | The initiating change in a variable triggers responses which promote further change in the variable |
| What is an example of positive feedback? | Labor & delivery; pressure, iritation, and stretch of the uterine wall & cervix --> oxytocin; oxytocin --> uterine contractions --> push baby into the cervix --> irritation, pressure, and distension --> more oxytocin --> ... |
| What are the physiological functions of the cell membrane? | 1) serves as a boundary between the cell's internal & external environments 2) regulates transport of substances in & out of cell 3) contains receptors for environmental stiumuli 4) contains antigens |
| What role do antigens play? | recognition of self vs nonself & the immune response |
| What is the most accepted theory of cell membrane structure? | the Nicholson Fluid Mosaic Model |
| How is the cell membrane constructed? | a double layer of lipids w/various proteins embedded in it |
| What are the components of the membrane? | 35% lipid; 62% protein; 3% carbohydrate |
| Describe the lipid molecules of the cell membrane: | they are phospholipids w/polar heads & nonpolar tails; polar heads (hydrophilic) and face the inner and outer membrane surfaces (surfaces freely interact with H2O); nonpolar tails (hydrophobic) face inward (waterproof barrier) |
| What are the functions of the membrane proteins? | 1) peripheral proteins (associated w/membrane surface) act as receptors (antigens & enzymes) 2) integral (transmembranal proteins) extend thru the membrane and allow water soluble substance to pass thru membrane |
| What are the types of carbohydrate "tails" of the membrane? | 1) glycolipid consist of a phospholibpi & a carbohydrate group 2) glycoprotein consist of a protein & a carbohydrate group |
| What is the function of carbohydrates in the membrane? | cell adherence and antigens |
| What are the 2 main types of membrane transport? | passive and active mechanisms |
| Describe passive membrane transport: | requires no cellular energy; utilizes random kinetic energy of the molecules themselves; can only transport substances down a concentration gradient |
| Describe active membrane transport: | require the expenditure of cellular energy in the form of ATP; can be used to transport large substances and other substances which can't pass by passive means |
| What are the types of passive membrane transport? | simple diffusion & osmosis, |
| Describe simple diffusion: | the net movement of molecules from an area of high concentration to low concentration, driven by random kinetic energy |
| What are the factors that determine the diffusability of a substance? | 1) solubility (lipid vs water) 2) molecular size, 3) molecular charge |
| How does solubility affect diffusion? | lipid soluble substances can freely diffuse thru cell membranes by dissolving in the phospholipid bilayer; water soluble substances may be able to diffuse depending on size & molecular charge |
| How does molecular size affect diffusion? | if small enough, a water soluble substance may be able to diffuse thru the pores or channels in transmembranal proteins; if too large, they can't pass by simple diffusion |
| How does molecular charge affect diffusion? | the pores of the membrane are lined w/positive charges; netural substances should pass freely; positively & negatively charged substances will diffuse w/difficulty |
| Which factors affect diffusion rate in a directly proportional manner? | concentration gradient, surface area, temperature, degree of lipid solubility |
| Which factors affect diffusion rate in an indirectly proportional manner? | molecular wweight & distance |
Created by:
debmurph