oxytocin

Examples of oxytocin in the following topics:

• Labor and Birth

  • Toward the end of the third trimester, estrogen causes receptors on the uterine wall to develop and bind the hormone oxytocin.
  • The oxytocin causes the smooth muscle in the uterine wall to contract.
  • A positive feedback relay occurs between the uterus, hypothalamus, and the posterior pituitary to assure an adequate supply of oxytocin.
  • If labor should stop before stage two is reached, synthetic oxytocin, known as Pitocin, can be administered to restart and maintain labor.
  • Oxytocin is also released, promoting the release of the milk.

• Hormonal Regulation of the Reproductive System

  • The posterior pituitary releases the hormone oxytocin, which stimulates uterine contractions during childbirth.
  • The uterine smooth muscles are not very sensitive to oxytocin until late in pregnancy, when the number of oxytocin receptors in the uterus peaks.
  • Stretching of tissues in the uterus and cervix stimulates oxytocin release during childbirth.
  • Oxytocin also stimulates the contraction of myoepithelial cells around the milk-producing mammary glands.
  • Oxytocin release is stimulated by the suckling of an infant, which triggers the synthesis of oxytocin in the hypothalamus and its release into circulation at the posterior pituitary.

• Lipid-Derived, Amino Acid-Derived, and Peptide Hormones

  • The peptide hormones include molecules that are short polypeptide chains, such as antidiuretic hormone and oxytocin produced in the brain and released into the blood in the posterior pituitary gland.
  • The structures of peptide hormones (a) oxytocin, (b) growth hormone, and (c) follicle-stimulating hormone are shown.

• Control of Homeostasis

  • The hormone oxytocin, made by the endocrine system, stimulates the contraction of the uterus.
  • Instead of lowering the oxytocin and causing the pain to subside, more oxytocin is produced until the contractions are powerful enough to produce childbirth .

• Hypothalamic-Pituitary Axis

  • The antidiuretic hormone (ADH) (or vasopressin) and oxytocin are produced by neurons in the hypothalamus and transported within these axons along the infundibulum to the posterior pituitary.
  • Oxytocin, known as the bonding hormone, has roles in various behaviors, including orgasm, social recognition, pair bonding, anxiety, and maternal behaviors.