Chapter 16 outline
* The Reproductive system
The gonads or primary sex organs: testes in men, and ovaries in women. a. Produce sex cells or gametes, and secrete sex hormones Male and female reproductive systems are different.
Sex hormones play vital roles both in the development and function of the reproductive organs. Anatomy of the male reproductive system
Plum-sized and approx. 4cm long and 2.5cm wide
Fibrous connective tissue capsules, te tunica albuginea surrounds each testis. Each lobule contains one to four tightly coiled seminiferous tubules. a. The seminiferous tubules of each lobe empty sperm into another set of tubules, the rete testis, located at one side of the testis. Sperm travel through the rete testis to enter the first part of the duct system, the epididymis, which hugs the external surface of the testis. The interstitial cells produce androgens-the most important of which testosterone. Thus sperm-producing and hormone producing functions of the testes are carried out by completely different cell populations. B. Duct System
1. The cup shaped epididymis is a highly coiled tube about 6m long that caps the superior part of the testis and then runs down its posterolateral side. 2. It’s the first part of the male duct system and provides a temporary home for immature sperm. 3. The sperm travel this long tube that takes about 20 days to mature, gaining the ablility to swim. 4. When the male is sexually stimulated, he ejaculates, the walls of the epididymis contract to expel the sperm into the next part of the duct system, the ductus deferens. b. Ductus Deferens
1. This is also often referred to as the vas deferens.
2. It runs upward from the epididymis through the inguinal canal to the pelvic cavity and arches over the superior aspect of the urinary bladder. It then loops medially over the ureter and descends along the posterior bladder wall. 3. This tube is enclosed, along with blood vessels and nerves, in a connective tissue sheath called the spermatic cord. a. This travels upward through the inguinal canal.
4. The end of the ductus deferens expands at the apulla and then empties into the ejaculatory duct. b. The ejaculatory duct passes through the prostate gland to merge with the urethra. 5. The main function is to propel live sperm from their storage sites, epididymis and distal part of the ductus deferens into the urethra. 6. When ejaculation occurs, the thick layers of smooth muscle in its walls create peristaltic waves that rapidly squeeze sperm forward. 7. Part of the ductus deferens lies in the scrotum, which hangs outside the body. c. Urethra
1. It extends from the base of the urinary bladder to the tip of the penis, is the terminal part of the male duct system. 2. 3 named regions: prostatic urethra, membranous, spongy (penile) urethra. 3. The male urethra carries both sperm and urine to the body exterior. * ꜜ Urine and sperm never pass at the same time.
C. Accessory Glands and Semen
d. Seminal Vesicles
1. Located at the base of the bladder, produce about 60% of seminal fluid, the fluid volume of semen. 2. Their thick, yellowish secretion is rich in sugar, vitamin C, prostaglandins, and other substances, which nourish and activate the sperm passing through the tract. 3. Sperm and seminal fluid enter the urethra together during ejaculation. * b. Prostate
1. A single doughnut shaped gland about the size of a peach pit. 2. Prostate gland secretion is a milky fluid that plays a role in activating sperm. 3. During ejaculation, the fluid enters the urethra though several small ducts. * c. Bulbourethral Glands
1. Tiny pea-sized glands inferior to the prostate gland
2. They produce a thick, clear mucous that drains into the penile urethra. a. This secretion is the first to pass down the urethra when a man...
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