The text states "all action potentials are identical to one another." There is an exception, however, where an action potential can have a smaller than normal amplitude. When does this occur and how?
What will be an ideal response?
During the relative refractory period, a smaller than normal action potential can occur. During this period potassium channels are still open causing repolarization. If a wave of depolarization occurs, Na+ can enter the cells through the newly reopened Na+ channels, but this depolarization is offset by the K+ efflux.
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Which of the following is TRUE regarding pituitary growth hormone (GH)?
A. GH exerts negative feedback on its own production by inhibiting the hypothalamic secretion of somatostatin. B. GH increases the sensitivity of tissues to the action of insulin. C. The liver produces a factor that mediates the metabolic actions of GH. D. GH stimulates insulin-like growth factor-1 (IGF-1) production by the liver and by many other cells. E. IGF-1 stimulates the secretion of GH by anterior pituitary gland cells.
Select which reactions will usually be irreversible regarding chemical equilibrium in living systems.
A) glucose to CO2 and H2O B) ADP + Pi to make ATP C) H2O + CO2 to make H2CO3 D) glucose molecules joined to make glycogen
The function of transverse tubules is to
A) conduct ATP molecules out of the mitochondria throughout the sarcoplasm. B) ensure a supply of glycogen throughout the muscle sarcoplasm. C) rapidly conduct action potentials to the interior of the muscle fiber. D) store Ca2+ ions inside the muscle fiber.
) Which of the following is an accurate description of the cellular level of organization?
A) Cells consist of two or more different tissues working together to perform specific functions. B) Cells are considered to be the largest living units in the body. C) Cells are comprised of different molecules that interact to form larger structures, each type of which has a specific function. D) Cells combine to form molecules with complex shapes, which determine their function(s). E) Cardiac muscle is an example of the cellular level of organization.