QS Study

Progesterone is a hormone that occurs naturally in the body. It is produced by the ovaries, placenta, and adrenal glands. It plays a function in maintaining pregnancy. The hormone is produced in the ovaries, the placenta (when a woman gets pregnant), and the adrenal glands. It helps organize your body regulates the monthly menstrual cycle. It also plays a role in sexual desire.

Functions of Progesterone

On the uterus:

  1. Myometrial cells become less excitable and active and decrease the sensitivity to oxytocin.
  2. By decreasing the frequency and intensity of uterine contractions, it helps to prevent the expulsion of an implanted ovum.
  3. Decreases the number of estrogen receptors in the endometrium.
  4. Causes secretory phase of the endometrium and preparing the uterus for implantation.
  5. Makes the cervical mucosa thick, tenacious, and cellular. Thus, prevents sperm passage.

On uterine tubes:

  1. Promotes increased secretion by the mucosal lining of the tube.
  2. Causes relaxation of the isthmus of fallopian tube after fertilization and allows entry of testicle ovum into the uterus.

On vagina: Induces cellular proliferation, increased secretion, and infiltration with leukocytes.

On breasts:

  1. Promotes the development of the lobules and alveoli.
  2. Causes the alveolar cells to proliferate, enlarge, and become secretory in nature.
  3. Also causes the breast to swell.

On endocrine gland:

  1. Exerts feedback effects at both the hypothalamic and pituitary levels.
  2. Inhibits LH secretion and prevents ovulation.

Thermogenic: Probably responsible for the rise in basal body temperature during ovulation.

On respiration: Stimulates respiration and barns alveolar PCO2.

On Kidney: Large dose of progesterone produces natriuresis probably by blocking the action of aldosterone on the kidney.

During pregnancy: Once pregnancy occurs progesterone levels remain high throughout the entire pregnancy.

  1. Cause development of decidual cells in endometrium which provides nutrition to early embryo.
  2. Helps die estrogen prepare the mother’s breast for lactation.
  3. Decreases the contractility of the pregnant uterus.
  4. Increase secretions of the fallopian tubes and uterus provide nutrition for developing morula and blastocyst.