MCAT Question A Day - 5/24/13 - Answer!
The smooth muscle wall of the uterus (myometrium) is regulated by
A. somatic nervous system circuits.
B. autonomic nervous system circuits.
C. somatic nervous system circuits and hormones.
D. autonomic nervous system circuits and hormones.
The correct answer is (D). Since the myometrium is primarily smooth, involuntary muscle, autonomic motor neurons are responsible for its contraction. In addition, oxytocin (made in the hypothalamus and released from the posterior pituitary gland) stimulates uterine contractions as well. Somatic motor neurons (choices A and C) only stimulate voluntary (skeletal) muscles.
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