The Menstrual Cycle Flashcards
Discuss the onset of menarche.
The onset of menarche refers to a girl’s first menstrual period.
Usually between 12 and 14 years old
Body goes through changes which are part of a process called puberty.
Hormones in the girl’s body begin to increase, causing physical changes like breast development and the growth of pubic hair.
The menstrual cycle is the body’s way of preparing for the possibility of pregnancy - each month, the lining of the uterus thickens to create a suitable environment for a fertilized egg - if the girl doesn’t become pregnant, the lining is shed through the vagina, resulting in menstrual bleeding.
Discuss the effects of hormones on the female reproductive system and the menstrual cycle.
FSH - produced and released by the pituitary gland - during menstrual cycle, FSH stimulates growth and development of ovarian follicles, which contain the immature eggs - also stimulates the follicles to produce estrogen.
Oestrogen - promotes the growth and thickening of the uterine lining (endometrium) in preparation for potential implantation of a fertilized egg - also promotes the development of secondary sexual characteristics for ex breast development, widening of hips.
LH - also produced by the pituitary gland - as levels of oestrogen rise, a surge of LH is triggered, leading to ovulation - LH causes the dominant follicle to release a mature egg from the ovary, ready for fertilization.
Progesterone - After ovulation, the empty follicle transforms into a structure called the corpus luteum, which produces progesterone - prepares the uterus for potential implantation - promotes thickening of the endometrium, secretion of nutrients into the uterine lining - if fertilization does not occur, corpus luteum degenerates, leading to drop in progesterone levels, triggering menstruation.
Gonadotropin-Releasing Hormone (GnRH) - released by the hypothalamus - stimulates the pituitary gland to release FSH and LH.
