What is the main action of oxytocin?

• A. Smooth muscle contraction
• B. Digestion stimulation
• C. Glucose uptake
• D. Cardiac contraction

Answer: (A)

Oxytocin's main action is to promote smooth muscle contraction. It binds to receptors on uterine smooth muscle, triggering contractions that help drive labor. It also stimulates milk ejection by causing the myoepithelial cells around the mammary alveoli to contract, pushing milk toward the ducts. Digestion stimulation is governed by other hormones and neural signals, not oxytocin. Glucose uptake is primarily controlled by insulin, not oxytocin. Cardiac contraction is driven by cardiac muscle physiology and autonomic regulation, and is not a primary action of oxytocin.