PY 105 Chapter Notes - Chapter 14: Seminiferous Tubule, Vas Deferens, Erectile Tissue
Male Reproductive System
Anatomy
• Scrotum - a bag of skin containing the male gonads known as the testes
• Testes have two roles:
o Synthesis of sperm (spermatogenesis)
o Secretion of male sex hormones (androgens)
• Site of spermatogenesis within the testes are the seminiferous tubules
• The tubules are formed by cells called sustenacular cells (sertoli cells)
o Protect and nurture the developing sperm
• Tissue between seminiferous tubules is known as testicular interstitium
o Cells found here are interstitial cells (Leydig cells)
• Responsible for androgen (testosterone) synthesis
• Seminiferous tubules empty into epididymis
• Epididymis empties into a ductus deferens (vas deferens)
• Then goes to urethra
• Seminal vesicles secrete about 60 percent of the total volume of the semen
• Semen is a highly nourishing fluid for sperm produced by seminal vesicles, prostate and
bulbourethral glands
o Referred to as accessory glands
• The ejaculatory duct empties into the urethra as it passes through the prostate gland
• The urethra exits the body via the penis
• Specialized erectile tissue in the penis allows erection
• Erection occurs when blood accumulates at high pressure in the erectile tissue
• Three compartments contain erectile tissue: the corpora cavernosa (two) and the corpus
spongiosum (one)
The Male Sexual Act
• Three stages:
o Arousal
• Dependent upon parasympathetic nervous input
• Erection and lubrication
▪ Erection - involves dilation of arteries supplying the erectile tissue. Causes
swelling, which obstructs venous outflow. This causes erectile tissue to become
pressurized with blood
▪ Lubrication - function of parasympathetic system. Bulbourethral glands secrete
viscous mucous
o Orgasm
• Emission and ejaculation
▪ Emission - propulsion of sperm and semen into the urethra by contractions of
the smooth muscle surrounding these organs
▪ Ejaculation - semen is propelled out of the urethra by rhythmic contractions of
muscles surrounding the base of the penis
o Resolution
• Return to a normal, unstimulated state and is controlled by the sympathetic nervous
system
• Caused by a constriction of erectile arteries
• Decreased blood flow to erectile tissue and allows the veins to carry away trapped
blood
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Scrotum - a bag of skin containing the male gonads known as the testes: testes have two roles, synthesis of sperm (spermatogenesis, secretion of male sex hormones (androgens) Seminiferous tubules empty into epididymis: epididymis empties into a ductus deferens (vas deferens, then goes to urethra. Seminal vesicles secrete about 60 percent of the total volume of the semen. Specialized erectile tissue in the penis allows erection spongiosum (one) The male sexual act: three stages, arousal, dependent upon parasympathetic nervous input, erection and lubrication, erection - involves dilation of arteries supplying the erectile tissue. This causes erectile tissue to become pressurized with blood. Sperm synthesis is called spermatogenesis: begins at puberty and occurs in the testes, the seminiferous tubule is the site of spermatogenesis, the cells that give rise to spermatogonia are known as germ cells. Hormonal control of spermatogenesis: testosterone stimulates division of spermatogonia. Luteinizing hormone (lh) - stimulate interstitial cells to secrete testosterone.
