Chapter 11: Reproductive Hormones

Question 1

Hormones

Answer 1

Spermatogenesis, oogenesis, ovarian & menstrual cycle all regulated by hormones (chemical messengers) released by endocrine glands into extracellular fluid. Then goes to target organ by blood circulation.

Question 2

Pituitary gland

Answer 2

In the brain, important endocrine gland for regulating gonad activity by secreting Gonadotropins (stimulates activity of another organ both male & female).

Question 3

Follicle-stimulating hormone (FSH) males

Answer 3

Secreted by pituitary gland, stimulates seminiferous tubules in testes to produce sperm by spermatogenesis.

Question 4

Luteinising hormone (LH) males

Answer 4

Secreted by pituitary gland, stimulates cells in testes to secrete testosterone (maintains reproductive organs & sperm, develop sexual characteristics).

Question 5

Follicle-stimulating hormone (FSH) females

Answer 5

Secreted by pituitary gland, stimulates ovarian follicle development in females. FSH secretions lowers as oestrogen levels increases in blood.

Question 6

Oestrogen

Answer 6

Secreted by corpus luteum, placenta, ovary follicles. It develops reproductive system (develop uterus lining) and sexual characteristics.

Question 7

Luteinising hormone (LH) females

Answer 7

Secreted by pituitary gland. Supports final maturation of ovarian follicle, ovulation, corpus luteum formation. LH Production lowers as progesterone levels in blood increases.

Question 8

Progesterone

Answer 8

Secreted by corpus luteum, placenta, ovary. Develops, maintain uterus lining (endometrium) preparing it for implantation if fertilisation occurs. Also develops placenta & milk secreting glands. Hinders FSH, LH secretions preventing other follicles developing.

Question 9

Human Chorionic Gonadotropic (HCG) hormone

Answer 9

Made by placenta, maintains corpus luteum (maintains hormones production).

Question 10

Prolactin hormone

Answer 10

Secreted by pituitary gland. Important in preparation and maintenance of milk production.

Question 11

Oxytocin hormone

Answer 11

Secreted by pituitary gland. Allows uterine contractions for childbirth and milk let-down reflex for breastfeeding.

Question 12

Ovulation

Answer 12

Female menstrual cycle phase involves release of

egg from 1 ovary usually occurs 2 weeks before menstrual period starts.

Question 13

Menarche

Answer 13

1st menstruation (menopause, stop menstruation).

Question 14

Ovarian cycle

Answer 14

28 day cycle in ovaries and regulated by hormones. Involves:
-Egg maturation and release from ovary into uterine tubes (ovulation, occurs day 14/halfway).

-Follicle maturation and corpus luteum formation.

Question 15

1.

Answer 15

Cells of primary follicle begin to enlarge and divide, creating cells layer around developing oocyte. Cells produce fluid that pushes egg to edge, forming secondary follicle.

Question 16

2.

Answer 16

When egg reaches the edge, it pushes against surface producing bulge on ovary now referred as mature follicle (Graafian follicle).

Question 17

3.

Answer 17

As follicle grows (follicular phase), it releases oestrogen and low progesterone levels. At day 14 oestrogen levels is high enough to stimulate spike in LH and FSH hormones. Surging LH levels causes ovulation of mature follicles while others degenerate.

Question 18

4.

Answer 18

Ovulation, mature follicle ruptures and expels oocyte down uterine tube towards uterus by cilia lining in uterine tube.

Question 19

5.

Answer 19

Ruptured follicle collapses and forms clot absorbed by remaining follicle cells that enlarge and change colour (yellow), forming corpus luteum secreting oestrogen and progesterone.

Question 20

Fertilisation occured

Answer 20

Pregnancy follows, placenta produces human chorionic gonadotropin (HCG) maintaining corpus luteum (maintains hormone production) till placenta is able to secrete oestrogen and progesterone. Then corpus luteum degenerates.

Question 21

Fertilisation hasn’t occured

Answer 21

Corpus luteum reaches max. development 8-10 days after ovulation, then degenerates to fibrous tissue (corpus albicans) disappearing.

Question 22

Menstrual cycle

Answer 22

Occurs in uterus lining (endometrium) regulated by hormones. Prepares for developing embryo if egg released in ovulation is fertilised.

Question 23

1.

Answer 23

Endometrium proliferates (multiplies), becoming softer, thicker filled with capillaries and glands by progesterone.

Question 24

2.

Answer 24

After ovulation, endometrium continues to thicken and glands produce watery mucus rich with glycogen (luteal phase).

Question 25

3.

Answer 25

If egg isn’t fertilised by sperm, corpus luteum breaks down (because no HCG from placenta to maintain it), reducing progesterone leading to menstruation (blood, cell debris loss through vagina).

Question 26

When menstrual cycle occurs?

Answer 26

Appears 14 days after ovulation. Menstruation is day 1 of cycle.