Reproductive System

• Section 1 Reproductive and Hormonal Functions of the Male

• Section 2. Reproductive and Hormonal Functions of the Female

• Section 3. Hormonal control of the menstrual cycle

• Section 4 Pregnancy

• Section 5 Oxytocin

Section 1 Reproductive and Hormonal Functions of the Male

Functions of testes

• spermatogenesis – seminiferous tubules

• secrete hormones– testosterone - by the instestitial cels of

Leydig,– inhibin - by Sertoil cells

I. Endocrine Function of Testes

• Androgens: testosterone, dihydrotesterone (双氢睾酮） and androstenodione （雄烯二酮）

• Function of testosterone– Maintenance of spermatogenesis– Stimulation of development of genitalia.– Development and maintenance of the male secondary sexual

characteristics. – Maintenance of libido.– Effect on metabolism.

• increases anabolism of protein, • causes growth of the bones • deposition of calcium salts • enhancement of production of red cells.

Endocrine Function of Testes (cont.)

• Inhibin– a glycoprotein with a molecular weight of

31,000-32,000– Secreted by by Sertoil cells in testis– potent inhibitory effect on FSH secretion by

pituitary gland. – slightly inhibitory in GnRH secretion.

II. Regulation of Testis Function

• Hypothalamic-Pituitary-Testis Axis– GnRH– FSH, LH– Testerone

• Negative Feedback Mechanism– Testosterone– Inhibin

• Local regulation in testes

Section 2 Reproductive and Hormonal Functions of the

Female

I. Menstruation, Ovulation and Hormonal Regulation

• Menstruation cycle or female sexual cycle

– Uterine cycle• Proliferative phase (estrogen phase)• Secretary phase (progesterone phase)• Menstruation

– Ovarian Cycle• Follicular phase• Ovulation• Luteal phase

Uterine Cycle

• Proliferative phase (estrogen phase)

• Secretary phase (progesterone phase)

• Menstruation

Ovarian Cycle

• Follicular phase

• Ovulation

• Luteal phase

Endocrine Functions of Ovaries

• Physiological function of estrogen– On sexual organs– On secondary female sexual characteristics– On metabolism– others

• Physiological function of progesterone– on uterus– on breasts– thermogenic effect– others

Section 3. Hormonal control of the menstrual cycle

Section 4 Pregnancy

I. Fertilization and Implantation

II. Hormones of Placenta

• Human Chorionic Gonadotropin (HCG)

• Progesterone and Estrogen

• Human Chorionic Somatommotropin (HCS)

Human Chorionic Gonadotropin (HCG)

• glycoprotein with a molecular weight of 39,000

• secreted by the syncytial trophoblast cells

• can be measured in the blood 8 to 9 days after ovulation

• Function:• identical to LH in its effect • maintain the corpus letum

Progesterone and Estrogen

• Secreted by corpus luteum before 5-6 weeks of pregancy and by placenta later

• maintain the endometrium and prevent menstruation

• Estrogen: cause enlargement of uterus, breasts and mother’s female external genitalia

• Progesterone: decrease the contractility of pregnant uterus

Human Chorionic Somatommotropin (HCS)

• protein with molecular weight of 38,000• begins to be secreted by the placenta at

the 5th week of pregnancy• Secretion in direct proportion to the weight

of placenta.• Function

– stimulates growth of fetus – regulates metabolism of carbohydrate, fat and

protein in both the fetus and the mother