The release of calcium ions from the sarcoplasmic reticulum in response to an action potential is known as ________
A) power stroke
B) sliding filament theory
C) tropomyosin
D) excitation-contraction coupling
D
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When the left ventricle contracts, the __________ valve closes and the __________ valve is pushed open.
A. mitral; pulmonary B. right AV; pulmonary C. right AV; aortic D. mitral; aortic E. aortic; pulmonary
Cyanide poisoning quickly leads to death because it blocks the final cytochrome molecule in the electron transport system. Why is this blockage lethal?
A) All hydrogen ion pumps deactivate. B) NADH molecules cannot give off their electrons. C) FADH2 molecules cannot give off their electrons. D) Electrons cannot transfer to oxygen. E) Coenzyme Q disassociates and becomes nonfunctional.
In most cells, insulin stimulates uptake of glucose by
a. penetrating the cellular membranes itself, and thereby providing a pathway for glucose to enter the cells. b. activating insulin receptors, which are themselves glucose transporters. c. stimulating the recruitment of glucose transporters to the membrane, which in turn facilitate the import of glucose. d. activating the transcription and translation of glucose transporter-genes, increasing their expression. e. altering the ratio of intracellular sodium concentrations to extracellular sodium concentrations in a way that favors co-transport of glucose and sodium.
Aldosterone causes kidney tubules to
A. reabsorb more sodium, water, and potassium. B. secrete more sodium, water, and potassium. C. reabsorb more sodium, and secret more water and potassium. D. reabsorb more sodium and water, and secrete more potassium. E. secrete more sodium and reabsorb more potassium.