Lecture 15: Regulation of the Reproductive System Flashcards
Describe what happens when testosterone levels in the blood are low.
- Gonadotropin releasing hormone travels to anterior pituitary via portal vein.
- Releases luteinizing hormone and follicle stimulating hormone.
- LH activates Leydig cells to release testosterone.
- Stimulates spermatogenesis
- Acts as an inhibitor when levels rise.
How is sperm produced?
FSH and testosterone work together in seminiferous tubules. FSH acts on Sertoli cells to secrete Androgen Binding Protein which binds to testosterone making it less hydrophobic and stimulate sperm production.
How is sperm production stopped?
The seminiferous tubules release a hormone called inhibin into the blood which inhibits release of GnRH and FSH.
Describe follicular phase of the ovarian cycle.
Stimulated by follicle stimulating hormone. Involves the maturation of primary follicle (egg with surrounding follicle cells) into a mature vesicular follicle (egg surrounded by a fluid space and follicle cells).
Note: Increasing amount of estrogen released.
Describe ovulation phase of the ovarian cycle.
Threshold high level of estrogen causes release of FSH and LH from anterior pituitary.
LH triggers:
1. Meiosis I (primary oocyte divides into secondary oocyte)
2. Ovulation of the secondary oocyte.
Describe luteal phase of the ovarian cycle.
Empty follicle collapses becoming corpus luteum which secretes progesterone and estrogen.
Increased levels of progesterone enrich and maintain the endometrial lining of the uterus.
Describe the menstruation phase of the uterine cycle.
Shedding of the outer endometrial layer of the uterus. Triggered by the drop in levels of estrogen and progesterone.
Describe proliferation phase of the uterine cycle.
Endometrium rebuilds itself due to increasing levels of estrogen due to new developing follicle in the ovary.
Describe secretory phase of the uterine cycle.
Endometrium prepares for implantation and at it’s thickest. This is triggered by increased levels of progesterone and estrogen being secreted by corpus luteum after ovulation.
What is the function of estrogen?
- Helps regulate body temperature
- Regulates cholesterol production
- Inhibits osteoclast activity and helps maintain bone density.
- Affects our mood.
What is osteoporosis?
Bones become weaker and become more prone to break. (Mostly after menopause due to low estrogen levels)
What is estrogen dose effect?
Low estrogen level: Stimulates
Moderate estrogen levels: Inhibits
Peak estrogen levels: Stimulates
What is the function of progesterone?
- Inhibits the release of FSH and LH.
- Causes cervical mucus to thicken
- Reduces contraction of the uterine myometrium.
How do oral contraceptives and birth control pills work?
Tricks your brain into thinking you are pregnant. This inhibits egg development and ovulation by blocking the release of GnRH from the hypothalamus.
What is human chorionic gonadotropin (HCG)?
prevents the normal degeneration of the corpus luteum.
Prevents menstruation from occurring. Inhibits the development of a new follicle and ovulation.
