Which of the following correctly describes oxytocin's actions? 1. Stimulates uterine smooth muscle contraction during parturition. 2. It inhibits milk ejection. 3. It primarily contracts smooth muscles. Select the correct answer using the code below:

The correct option is 1 and 3 only. Explanation Oxytocin is a peptide hormone synthesized by the hypothalamus and released by the posterior pituitary gland (neurohypophysis). It acts primarily on smooth muscles within the body and stimulates their contraction. It plays a critical role in female reproductive physiology, specifically during childbirth and lactation. Statement-wise Analysis - Statement 1 is Correct: Oxytocin acts on the smooth muscles of the uterus. During the later stages of pregnancy, it stimulates vigorous contractions of the uterine smooth muscles, which is essential for the expulsion of the foetus. This process is known as parturition (childbirth). - Statement 2 is Incorrect: Oxytocin does not inhibit milk ejection; rather, it stimulates it. While Prolactin is responsible for the synthesis and production of milk, Oxytocin acts on the myoepithelial cells of the mammary glands to cause contraction. This contraction forces milk from the alveoli into the ducts, a process known as the "milk let-down" or milk ejection reflex. - Statement 3 is Correct: The primary physiological mechanism of oxytocin is the stimulation of smooth muscle contraction. This applies to both the uterine muscles during labor and the smooth muscle-like myoepithelial cells in the mammary glands during lactation. Key Takeaway: Oxytocin is known as the "birth hormone" and the "milk-ejecting hormone." It stimulates smooth muscle contraction to facilitate parturition and the milk let-down reflex, whereas Prolactin is responsible for milk synthesis.

NCERT Class 11 Science — Chapter 9: Chemical Coordination and Integration

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Which of the following correctly describes oxytocin's actions?

Stimulates uterine smooth muscle contraction during parturition.
It inhibits milk ejection.
It primarily contracts smooth muscles.

Select the correct answer using the code below:

Official previous-year question

Verified 1 Aug 2026.

Options

A1 and 3 only
B1, 2 and 3
C2 only
D1 and 2 only

Did you get this right?

Solution

The correct option is 1 and 3 only.

Explanation

Oxytocin is a peptide hormone synthesized by the hypothalamus and released by the posterior pituitary gland (neurohypophysis). It acts primarily on smooth muscles within the body and stimulates their contraction. It plays a critical role in female reproductive physiology, specifically during childbirth and lactation.

Statement-wise Analysis

Statement 1 is Correct: Oxytocin acts on the smooth muscles of the uterus. During the later stages of pregnancy, it stimulates vigorous contractions of the uterine smooth muscles, which is essential for the expulsion of the foetus. This process is known as parturition (childbirth).
Statement 2 is Incorrect: Oxytocin does not inhibit milk ejection; rather, it stimulates it. While Prolactin is responsible for the synthesis and production of milk, Oxytocin acts on the myoepithelial cells of the mammary glands to cause contraction. This contraction forces milk from the alveoli into the ducts, a process known as the "milk let-down" or milk ejection reflex.
Statement 3 is Correct: The primary physiological mechanism of oxytocin is the stimulation of smooth muscle contraction. This applies to both the uterine muscles during labor and the smooth muscle-like myoepithelial cells in the mammary glands during lactation.

Key Takeaway: Oxytocin is known as the "birth hormone" and the "milk-ejecting hormone." It stimulates smooth muscle contraction to facilitate parturition and the milk let-down reflex, whereas Prolactin is responsible for milk synthesis.

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The correct option is 1 and 3 only.

Explanation

Statement-wise Analysis

Statement 1 is Correct: Oxytocin acts on the smooth muscles of the uterus. During the later stages of pregnancy, it stimulates vigorous contractions of the uterine smooth muscles, which is essential for the expulsion of the foetus. This process is known as parturition (childbirth).
Statement 2 is Incorrect: Oxytocin does not inhibit milk ejection; rather, it stimulates it. While Prolactin is responsible for the synthesis and production of milk, Oxytocin acts on the myoepithelial cells of the mammary glands to cause contraction. This contraction forces milk from the alveoli into the ducts, a process known as the "milk let-down" or milk ejection reflex.
Statement 3 is Correct: The primary physiological mechanism of oxytocin is the stimulation of smooth muscle contraction. This applies to both the uterine muscles during labor and the smooth muscle-like myoepithelial cells in the mammary glands during lactation.