In females, vigorous contraction of uterus at the time of child birth and milk ejection from the mammary gland is due to

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the physiological processes in females during childbirth and breastfeeding, specifically what causes vigorous contractions of the uterus and milk ejection.

2. **Identifying the Key Hormones**: The two key processes mentioned are uterine contractions during childbirth and milk ejection during breastfeeding.

3. **Role of the Hypothalamus**: The hypothalamus is a crucial part of the brain that regulates various bodily functions, including hormone release.

4. **Connection to the Pituitary Gland**: The hypothalamus is connected to the pituitary gland, which has two lobes: the anterior and the posterior.

5. **Focus on the Posterior Pituitary**: The posterior lobe of the pituitary gland releases specific hormones that are important for childbirth and lactation.

6. **Oxytocin's Function**: The hormone oxytocin is released from the posterior pituitary gland. It is responsible for causing the strong contractions of the uterus during childbirth, facilitating the expulsion of the baby.

7. **Milk Ejection Mechanism**: Oxytocin also plays a crucial role in lactation. When a baby suckles at the breast, oxytocin is released, leading to the ejection of milk from the mammary glands.

8. **Conclusion**: Therefore, the hormone responsible for both the vigorous contraction of the uterus during childbirth and the milk ejection from the mammary glands is oxytocin.

**Final Answer**: The vigorous contraction of the uterus at the time of childbirth and milk ejection from the mammary gland is due to the hormone **oxytocin**.

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