Reproductive Organ Control

Question 1

What are the levels of control of reproductive functions?

Answer 1

The brain and spinal cord integrally control reproductive functions. Within the brain, diencephalic and limbic centers mediate basic instinctive responses. The cerebral cortex, as the seat of consciousness, also contributes significantly to the appreciation of sexual arousal and control of complex sexual behaviors.

Feedback from visual, olfactory and somatosensory systems is also vital to sexual arousal and hence sexual behavior. All of these components contribute to coordination of somatic and autonomic responses, many of which are mediated spinally

Question 2

Summarize male reproductive organ innervation

Answer 2

Sympathetic
Adrenergic receptors →Ejaculation (α1)

Parasympathetic
Muscarinic receptors →Erection (NO)

Somatic - sensory

Question 3

Summarize female reproductive organ innervation

Answer 3

Sympathetic
Adrenergic receptors → Uterine smooth muscle contraction (α1)

Parasympathetic
Muscarinic receptors →Erection of clitoris (NO)

Somatic- sensory

Question 4

Explain innervation of reproductive organs

Answer 4

First order sensory fibers originating in the female and male genitalia enter the spinal cord at the lumbar and sacral levels, where they either synapse on the sympathetic or parasympathetic preganglionic neurons (either directly or via interneurons) or ascend to the brain.

The sympathetic fibers innervating male and female reproductive organs originate in the lower thoracic and upper lumbar segments of the spinal cord. Their preganglionic fibers pass through the sympathetic chain and synapse in the inferior mesenteric ganglion. From there, postganglionic fibers reach their target after passing through the hypogastric plexus. Sympathetic activation causes ejaculation in males and uterine contraction in females.

Parasympathetic innervation of male and female reproductive organs originates in the sacral cord. Their preganglionic fibers run in the pelvic nerves, pass through the hypogastric plexus and synapse on postganglionic neurons located in the organ walls. Activity of parasympathetic efferents contributes to the erection of clitoris and penis.