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Homeostasis: Positive Hormonal Feedback during Childbirth

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Nia Rowe

on 17 January 2013

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Transcript of Homeostasis: Positive Hormonal Feedback during Childbirth

Homeostasis: Positive Hormonal Feedback during Childbirth By: Nia Rowe Positive Feedback : process by which a small effect is amplified Unlike negative feedback, positive feedback's are less common in the human body system.

During the childbirth process, women will experience a decrease in the hormone named PROGESTERONE.

This hormone is believed to initiate a small contractions of the uterus or womb.

Oxytocin causes much stronger contractions of the uterus.

As the contraction increase in seize and length the baby moves towards the opening of the uterus.

The descend of the baby causes stronger contractions, which release more oxytocin, which causes stronger contractions until the baby expels the womb. Once the baby is expelled from the womb the uterine contractions stop.

The uterine contractions stop, stops the release of oxytocin, which stops the contracts as well. The hypothalamus stimulates the release of hormones by the pituitary gland.

The pituitary gland is composed of two separate lobes
a) the posterior lobe
b) anterior lobe

Alongside many different hormones the posterior lobe release the hormone OXYTOCIN.

Oxytocin is produced by the hypothalamus and released initiates strong uterine contractions during child birth. The ovaries produce the hormone progesterone The End Work Cited http://www.omnimedicalsearch.com/conditions-diseases/images/Female_reproductive_system_lateral.jpg http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/S/SexHormones.html



http://www.marchofdimes.com/pregnancy/pretermlabor_progesterone.html Cesarean Birth (C-section) Oxytocin Progesterone Cervical Nerves
Before Oxytocin can be release the hypothalamus must first be made aware of the hormonal changes made in the uterus.

Cervical nerves (C1-C8) branch off of the spinal cord and control different types of bodily and sensory activities.

Naming: Each cervical nerve is named based on the lower cervical vertebra that it runs between. As an example, the nerve root that runs between the second cervical vertebra and the third cervical vertebra in the neck is described as the C3 nerve.

•The bones and muscles of the pelvis provide support for the growing uterus and baby, and provide a passage through which the baby emerges during birth.

The cervical nerves will detect and send a message up your spine to your hypothalamus.

•C1 and C2 control the head.
•C3 and C4 help control the diaphragm (the sheet of muscle that stretches to the bottom of the rib cage and plays an important role in breathing and respiration).
•C5 controls upper body muscles and the Biceps (which allow flexion of the elbow and rotation of the forearm).
•C6 controls the wrist extensors (muscles that control wrist extension)
•C7 controls the Triceps (the large muscle on the back of the arm that allows for straightening of the elbow).
•C8 controls the hands Progesterone is a hormone. It plays a key role during pregnancy.

In early pregnancy, the hormone helps your uterus grow and keeps it from contracting. (If your uterus contracts in early pregnancy, this may lead to miscarriage.) In later pregnancy, progesterone helps your breasts get ready to make breast milk. It also helps your lungs work harder to give oxygen to your growing baby.

Recent studies show that for some women, especially if they have a short cervix or if they already had a preterm birth, being given progesterone during pregnancy may help reduce the risk of having a premature baby.

There are two kinds of progesterone treatment: vaginal gel and shots. Studies to date show that gel may help reduce preterm birth for pregnant women with a short cervix. Shots are recommended for pregnant women who already had a preterm birth.

The release of Progesterone is believed to begin the release of another hormone called oxytocin. Hypothalamus •Hormones work to soften the ligaments between the bones in your pelvis, which gives your pelvis additional room for birth. During this time, you might feel a shift in your sense of balance, your joints might feel looser, and you might feel sore and achy.

•Other hormones begin to soften your cervix, which is the neck of the uterus. Throughout most of pregnancy, your cervix is closed, holding the baby inside your uterus. Much of the work of labor is in opening the cervix to the passage of your baby. However, your cervix may begin to both soften and open even before labor begins. This varies from woman to woman, and from pregnancy to pregnancy. Some women may have closed cervixes until labor starts. Others may have pre-labor contractions that dilate their cervix to three or four centimeters (or even more) before labor begins.
The Effects of Hormones At the end of gestation, the uterus must contract vigorously and for a prolonged period of time in order to deliver the fetus. During the later stages of gestation, there is an increase in abundance of oxytocin receptors on uterine smooth muscle cells, which is associated with increased "irritability" of the uterus (and sometimes the mother as well). Oxytocin is released during labor when the fetus stimulates the cervix and vagina, and it enhances contraction of uterine smooth muscle to facilitate parturition or birth.

In cases where uterine contractions are not sufficient to complete delivery, physicians and veterinarians sometimes administer oxytocin ("pitocin") to further stimulate uterine contractions - great care must be exercised in such situations to assure that the fetus can indeed be delivered and to avoid rupture of the uterus.

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