BIOL 230 Lecture Notes - Lecture 3: Follicular Cell, Morula, Arteriole
29 Jul 2018
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Document Summary
An erect penis is engorged with blood, which facilitates its penetration into the vagina. Touch receptors in the glans penis signal the parasympathetic nervous system to increase vasodilation of the penile arterioles and signal the sympathetic nervous system to inactivate vasoconstriction. A spinal reflex brings about ejaculation from a sympathetically-derived series of smooth muscle contractions in the prostate, reproductive ducts, and seminal vesicles that deliver all of the seminal fluids to the urethra. The expulsion of semen is finalized by skeletal muscles at the base of the penis. Immediately following orgasm, the sympathetic system slows the flow of blood into the penis, causing the erection to subside. Sexual excitement in the female, as in the male, can be initiated physically or psychologically. Touch receptors in the clitoris or perineum are particularly sensitive. As in the male, spinal reflexes through the parasympathetic nervous system induce arteriolar vasodilation in the vaginal tract and the external genitalia.
