BIOL 1F90 Lecture 28: LECTURE 28win
1 Apr 2017
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Document Summary
Plasma membranes tend to be highly permeable to water and. Swollen or shrunken cells do not operate well. Can happen when cells exposed to more dilute (hypoosmotic) or more concentrated (hyperosmotic) extracellular fluids. Passive diffusion: movement of a solute down its concentration gradient, no carrier or atp required, only lipid soluble molecules. Transport proteins used in: facilitated diffusion passive, active transport. All organs that mediate diffusion or absorption have an extensive surface area. Increased space requirements avoided by shape changes: folding for example. Process of adjusting to the external environment and maintaining a stable internal environment. Conformers maintain same fluid composition as environment cheap. Regulators internal composition of fluids different from environment more expensive. Animal can be both with respect to different variables. No physiological function is constant for very long, which is why we call them variables. Normally, blood sugar (glucose) remains at fairly steady and predictable levels in any healthy individual.
