Sinoatrial node cells:
A. reach threshold only when action potentials generated by the AV node arrive through gap junctions.
B. exhibit spontaneous depolarization that is speeded by activation of their cholinergic receptors.
C. exhibit spontaneous depolarization that is speeded by activation of their beta-adrenergic receptors.
D. exhibit a steep upstroke due to the presence of the same type of Na+ channels found in neuronal membranes.
E. are in-between atrial muscle cells and cells of the bundle of His.
C
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In a neuromuscular junction, the effect of acetylcholine (ACh) binding to receptors on the motor end plate lasts only briefly due to
a) rapid uptake of the ACh into the myofiber. b) endocytosis of the ACh receptor into the myofiber. c) rapid destruction of ACh in the synaptic cleft by acetylcholinesterase. d) rapid destruction of ACh in the synaptic cleft by monoamine oxidase. e) diffusion of the ACh out of the synaptic cleft.
Regarding Fragile-X syndrome,
A) the affected females have nonfunctional ovaries, and estrogen production occurs at negligible levels. B) the cause is trisomy, a mistake that occurs in meiosis, and affected individuals carry an extra chromosome. C) the phenotype is male, but the testes fail to mature so the individuals are sterile, and the breasts are slightly enlarged. D) the cause is a kind of chromosomal deletion known as monosomy where the phenotype is normal female. E) the affected individuals display mental retardation, abnormal facial development, and enlarged testes in affected males.
The hindlimb is innervated with nerves that arise from the lumbosacral____________
Fill in the blank(s) with correct word
On average, each FADH2 generates 1.5 ATP in oxidative phosphorylation.
Answer the following statement true (T) or false (F)