Which of the following does oxytocin stimulate?

• A. Uterine contractions and milk ducts
• B. Pancreatic enzyme release
• C. Kidney filtration
• D. Liver glucose production

Answer: (A)

Oxytocin’s main role is to drive actions in the reproductive system: it binds to receptors on uterine smooth muscle to increase intracellular calcium, prompting strong uterine contractions, especially during labor. It also acts on myoepithelial cells surrounding the mammary ducts, causing milk ejection (the let-down reflex) when a nursing infant stimulates the nipple. These are the effects that define oxytocin’s physiologic actions.

Pancreatic enzyme release is regulated mainly by hormones like cholecystokinin and secretin, not oxytocin. Kidney filtration is governed by factors such as renal blood flow, autonomic tone, and hormones like angiotensin II and vasopressin to some extent, but oxytocin isn’t the primary driver there. Liver glucose production is controlled by glucagon and cortisol (and catecholamines in stress), not oxytocin.