MENSTRUAL CYCLE

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Created by
lianne, RMT, MD

Cards (12)

  • The menstrual cycle is the process in which females ripen or release one mature egg
  • The average menstrual cycle repeats about every 28 days, but normal cycles can range from 21 to 40 days
  • During the first half of the cycle (Days 1 - 14), the pituitary produces FSH, which stimulates egg production and triggers the release of estrogen from the ovaries
  • On the 14th day, the pituitary begins releasing LH, causing ovulation
  • LH also directs the production of progesterone, which maintains the growth of the endometrium
  • If the egg is not fertilized, progesterone levels drop, causing estrogen levels to drop, leading to menstruation
  • Changes in the ovaries:
    • Stage 1: An egg begins to mature within a cluster of cells called a follicle
    • Stage 2: Rapid follicle and egg growth
    • Stage 3: Ovulation occurs; fully mature egg bursts out of the follicle
    • Stage 4: Egg travels through the fallopian tube; if not fertilized, the corpus luteum shrinks, triggering menstruation and ripening of a new egg
  • Estrogen gradually increases during days 1 - 14, signaling the body to thicken the lining of the uterus; levels drop sharply after ovulation
  • Progesterone levels remain low during the first half of the cycle and then increase sharply during the second half, maintaining the growth of the endometrium lining
  • Changes in the uterus:
    • Stage 1: Menstruation - endometrium breaks down and blood, mucus, tissue, and the egg are shed through the vagina
    • Stage 2: Menstrual flow stops and endometrium begins to thicken
    • Stage 3: Endometrium continues to thicken
    • Stage 4: The endometrium is at its thickest point
  • Days 1 - 14 triggers uterine lining thickening, produces estrogen and ovum, triggers the formation of the follicle within the ovary, and produces FSH (Follicle Stimulating Hormone) from the pituitary gland
  • Days 14 - 28 continues uterine lining thickening, produces progesterone, triggers ovulation and the formation of the corpus luteum within the ovary, and produces LH (Luteinizing Hormone) from the pituitary gland