Male Reproductive System: Organs and Functions

• Lesson 2 covers the male reproductive system's organs, functions, and sperm cell pathways.
• The objectives are to identify the structures and major organs of the male reproductive system and describe their functions, and to trace the pathway of the sperm cells in the organ system.
• The male reproductive system consists of sex organs that participate in the human reproductive process.
• The role of the reproductive system is to produce, store, and release male gametes or sperm.
• Gametes are sex cells.

Male Reproductive Organs

• External genital organs include the penis and scrotum.
• Internal genital organs include the testis, epididymis, vas deferens, and accessory glands.
• Accessory glands consist of seminal vesicles, the prostate gland, and bulbourethral glands.
• Sperm route: Urinary bladder, ureter, seminal vesicle, prostate gland, ductus deferens, bulb, epididymis, testis, urethra, glans penis.
• Sperm pathway also includes: Bladder, pubic bone, vas deferens, urethra, prostate, testicle, epididymis, scrotum, seminal vesicles, and the rectum.

Testis

• Testes are the two oval-shaped male organs that produce sperm and the hormone testosterone.
• Testosterone is the primary male sex hormone.
• Each testis is made of tightly coiled structures called seminiferous tubules.

Epididymis

• The epididymis consists of tightly coiled tubes attached alongside the testicles.
• The epididymis functions in sperm maturation and storage.

Vas Deferens

• The vas deferens is a narrow tube extending from the epididymis up to the urethra in the penis.
• The vas deferens transports sperm from the epididymis in anticipation of ejaculation.

Accessory Glands

• Accessory glands--seminal vesicles, prostate gland, and bulbourethral glands--produce nourishing fluids for sperm entering the urethra .
• The seminal vesicles are sac-like structures attached to the vas deferens on one side of the bladder.
• The seminal vesicles produce a sticky, yellowish fluid containing fructose.
• The prostate gland surrounds the ejaculatory ducts at the base of the urethra, just below the bladder.
• The prostate gland's function is to produce semen, a liquid mixture of sperm cells, plus seminal and prostate fluid.
• The bulbourethral glands (Cowper's gland) are two small glands on the sides of the urethra just below the prostate gland.
• These glands produce a clear, slippery fluid that empties directly into the urethra.

External Genital Organs

• The external genital organs are the penis and scrotum.
• The urethra is a tube within the penis conveying semen out of the body during ejaculation.
• The glans is the rounded, highly sensitive head of the penis.
• The prepuce, or foreskin, is a fold of skin covering the glans.
• The corpus spongiosum is a spongy tissue mass surrounding the urethra, assisting in erection by permitting blood rush.
• Corpus cavernosa is one of a pair of sponge-like regions of erectile tissue, which contains the majority of blood in the penis during penile erection.

Ejaculation

• Ejaculation refers to semen discharge from the penis.
• During orgasm, semen is forcefully expelled via strong muscular sperm duct contractions.
• Muscular contractions in the epididymis, seminal vesicles, prostate gland, plus the vas deferens occur at the peak of sexual arousal.
• Simultaneously, a sphincter muscle at the base of the bladder contracts to prevent urine leakage into the urethra.
• Another sphincter closes off the urethra entrance into the penis.
• During the second stage of ejaculation, the expulsion stage, the sphincter at the base of the penis relaxes, allowing semen into the penis.
• Simultaneously, strong muscular contractions around the base of the penis and along the urethra expel the semen.
• A vasectomy involves the vas deferens being cut and sealed so sperm cannot enter the urethra and fertilize a female egg during sexual intercourse.

Scrotum

• The scrotum consists of a skin pouch formed from the lower part of the abdominal wall.
• The function of the scrotum is to maintain the testes at a slightly cooler temperature than body temperature.

Sperm

• Sperm function is to move and carry genetic information to the egg.
• Sperm structure includes: A head, midpiece, and tail.
• Head: Contains DNA
• Midpiece: The narrow, middle portion of the cell which contains mitochondria.
• Tail: The wavelike flagellum propels the sperm forward.

Spermatogenesis

• Spermatogenesis refers to the creation of sperm cells; this process occurs in the seminiferous tubules.
• Diploid cells starting spermatogenesis live near the tubules' outer walls.
• Around 3 million of these cells, multiplying constantly by mitosis, differentiate daily into primary spermatocytes, the cells undergoing meiosis.
• Meiosis I of a primary spermatocyte forms secondary spermatocytes, each containing a haploid number of chromosomes (n=23).
• These cells remain in their duplicated state, consisting of two identical chromatids apiece.
• Meiosis II then makes four cells, each containing the haploid number of single-chromatid chromosomes.
• A sperm cell grows through these cells differentiating and gradually getting pushed towards the center of the seminiferous tubule.
• From there, it proceeds to the epididymis, where sperm is stored until ejaculation because it is now mobile and can mature.

Explore the organs and functions of the male reproductive system. Learn about the roles of the penis, scrotum, testis, and accessory glands. Trace the pathway of sperm cells through the reproductive system.