BIOC32H3 Midterm: Human Phys Midterm Notes
1 Dec 2016
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Physiology involves the mechanisms the body takes to maintain homeostasis. 3 experimental designs: test tube, animal models, humans. Taking into considerations: variability of subjects, psychological bias (use placebos and double-blinded studies, ethics. Ber(cid:374)stei(cid:374)"s (cid:373)e(cid:373)(cid:271)ra(cid:374)e theory: cells have electrolytic interior with membrane selectively permeable to ions, electrical potential difference at rest, selectively permeable to k at rest, high intracellular [k, low extracellular [k] To measure membrane potential, voltmeter is set up with a recording electrode and a ground/reference electrode- 0mv. Muscle and neurons are excitable (dynamic potentials); rmp ~ -70mv. At rmp, only k efflux due to leak channels; na vg channels inactive. What affects rate of k efflux through leak channels: neg (cid:272)harged protei(cid:374)s (cid:862)pulli(cid:374)g the(cid:373) (cid:271)a(cid:272)k(cid:863, k efflux slows thus decreasing potential until eq reached. What generates the rmp: k leak channels, na/k atpase pump, properties of pm; impermeability and vg ion channels. Ek = -90mv; concentration gradient would cause k efflux while electrical gradient would cause k influx.
