Oxytocin stimulates vigorous contraction of smooth muscles for  

Oxytocin stimulates vigorous contraction of smooth muscles during various physiological processes, particularly during childbirth and lactation.

• Childbirth: During labor and delivery, oxytocin is released in large amounts from the pituitary gland. This hormone plays a critical role in initiating and strengthening uterine contractions, helping to push the baby through the birth canal.
• Lactation: After childbirth, oxytocin continues to be involved in lactation. It stimulates the contraction of myoepithelial cells surrounding the milk-producing mammary glands. This contraction helps to eject milk from the alveoli into the ducts, making it available for the baby to nurse.

Oxytocin acts on smooth muscle cells, which are found in the uterus and the mammary glands. Its ability to promote strong and coordinated contractions in these smooth muscles is essential for the progression of childbirth and the proper functioning of lactation.