Oxytocin
Oxytocin stimulates two large tissues during and after child birth;
Uterine smooth muscle and
Muscle cells of lactating breast.
Function
1. During childbirth increasing amount of oxytocin are release by posterior pituitary into blood stream response to increasing distension of sensory stretch receptor in utrine.
Sensory impulse are generated and travel to control center in hypothalamus, stimulation posterior pituitary to release more oxytocin. This is example of positive feedback mechanism.
2. Oxytocin also act as hormonal trigger for milk ejection in lactating women whose breast are producing milk in response to prolactin.
Suckling generate sensory impulses that are transmitted from breast to hypothalamus.
Impulse trigger release of oxytocin from posterior pituitary.
Oxytocin stimulate contraction of duct of lactating breast to contact, ejecting milk. (example of positive feedback mechanism).
3. Oxytocin may play a role in propulsion of semen through male reproductive track. In utrine contraction that help to transport sperm in female reproductive track.
In labour, uterins contraction force baby's head into cervix (connect vagina and Uterus)
Stretch receptors in uterine cervix (detector)
Nerve impulse
Hypothalamus and posterior pituitary control center
Release of oxytocin
Uterine, smooth muscle (effector)
Strong contraction force baby's head into cervix
Inhibition occurs after delivery when uterine contraction no longer stretch cervix.
(Regulation of Secretion of oxytocin through positive feedback mechanism).
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