Chapter 16: The Reproductive System

1. Chapter 16: The Reproductive System Page 544

2. Female reproductive system • Primary sex organ: ovaries • Exocrine function (produce eggs or ova) and endocrine function (estrogens and progesterone production) • Oogenesis- the formation of gametes in the ovaries; begins in females before birth. • A woman has ~40,000 primary oocytes at puberty, but only 400 will mature and ovulate during a woman’s reproductive life.

3. Ovaries • Paired organs that produce secondary oocytes (cells that develop into eggs after fertilization). • Also produces the hormones progesterone, estrogen, inhibin, and relaxin. • Same size and shape as unshelled almonds.

4. Ovulation • A secondary oocyte is expelled into the pelvic cavity and swept into the uterine tube. It is here that fertilization by a sperm can occur. The united nuclei of sperm and ovum forms a diploid zygote. • Generally occurs every 28 days

5. Accessory reproductive structures • The uterine (fallopian) tubes, uterus, and vagina form the duct system of the female reproductive tract

6. Uterine (Fallopian) tubes • Receive the ovulated oocyte and provide a site where fertilization can occur • Fingerlike projections called fimbriae create a current to guide the oocyte toward the uterus • The oocyte is viable for up to 24 hours after ovulation, the usual site of fertilization is the uterine tube • Sperm must swim up through the vagina and uterus to reach the uterine tubes • Fertilized zygotes descend into uterus within 7 days. • Unfertilized disintergrate.

7. Uterus • Located in the pelvis between the urinary bladder and rectum • Site of implantation of a fertilized ovum, development of the fetus during pregnancy and labor. • About the size of a pear in never been pregnant women • The wall of the uterus is thick and composed of 3 layers: • Myometrium- smooth muscle, bulk of uterine wall • Contracts to force the baby out during childbirth • Endometrium- innermost, mucous membrane, place where the fertilized egg resides • Layer is shed during menstruation if fertilization does not occur.

8. Vagina • Receives the penis during sexual intercourse; passageway for childbirth; passageway for the menstrual flow to leave the body • The thin fold of mucosa called the hymen partially closes the distal end of the vagina • Very vascular and bleeds when first ruptured

9. Vulva • Aka external genitalia • Includes mons pubis, labia, clitoris, urethral and vaginal orifices, greater vestibular glands

10. Mammary Glands • Present in both sexes but function only in women • Female sex hormones cause them to increase in size during puberty • Modified sudoriferous (sweat) glands; synthesize, secrete, and eject milk for nourishment of a newborn.Alveolarglands produce the milk when a woman is lactating

11. Oogenesis • All the eggs a female can release is already determined at birth • Approximately 2 million oocytes are in the ovarian follicles • Reproductive ability starts at puberty and ends at menopause • Fewer than 500 ova out of her potential of 250,000 are released during a woman’s lifetime • An egg cell is larger than a sperm cell and is nonmotile

12. Hormone production by the ovaries • Estrogen maintains low total blood cholesterol levels and facilitates calcium uptake to sustain bone density • Mature follicles produce estrogens which causes the appearance of secondary sex characteristics: • Enlargement of the accessory organs of the female reproductive system • Development of the breasts • Appearance of axillary and pubic hair • Increased deposits of fat beneath the skin in the general (particularly in the hips and breasts) • Widening and lightening of the pelvis • Onset of menses or the menstrual cycle

13. Progesterone • Produced by the glandular corpus luteum • Does not contribute to the secondary sex characteristics • Inhibits contraction of the myometrium of the uterus and prepare the breast for milk production