An action potential
A. has no repolarization phase.
B. is not propagated.
C. is an example of negative feedback.
D. occurs when the local potential reaches threshold level.
E. can be of varying strengths depending on strength of the stimulus.
Answer: D
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Bile is produced in the ________ and stored in the ________.
Fill in the blank(s) with the appropriate word(s).
Which statement about adrenomedullary hormones is incorrect?
a. Epinephrine accounts for 80% of adrenomedullary catecholamine output. b. Epinephrine and norepinephrine are stored within chromaffin granules in the adrenomedullary cells. c. Epinephrine and norepinephrine have about equal affinities for all the adrenergic receptor types. d. Epinephrine is at least 10 times more potent than norepinephrine at beta 2 receptors. e. Epinephrine exerts metabolic effects, whereas norepinephrine has limited action in this regard.
Protein channels that are situated between cells and create small pores for the passage of small substances are known as:
A) occluding junctions. B) gap junctions. C) tight junctions. D) desmosomes.
Surfactant is:
A) produced by the mucous cells of the left and right mainstem bronchi. B) quickly destroyed in patients who have a severe upper airway obstruction. C) a phospholipid compound that decreases surface tension on the alveolar walls. D) a lubricating substance that increases alveolar surface tension during breathing.