Male Reproductive System - PPT/PDF
Download notes (PPT/PDF) on the Male Reproductive System, covering both internal and external structures. These notes provide detailed anatomical descriptions of the epididymis, vas deferens, seminal vesicles, ejaculatory ducts, prostate gland, bulbourethral glands, urethra, scrotum, testes, and penis. Suitable for B.Pharm and related health science programs.
Keywords: Male Reproductive System, Internal Structures, External Structures, Epididymis, Vas Deferens, Seminal Vesicles, Ejaculatory Ducts, Prostate Gland, Bulbourethral Glands, Urethra, Scrotum, Testes, Penis, Human Anatomy and Physiology, B.Pharm, PPT, PDF, Download.
Male Reproductive System - Anatomical Description
1. Internal Structures
- Epididymis:
- A highly coiled tube located on the posterior border of each testis.
- About 6 meters (20 feet) long if uncoiled.
- Regions: head, body, and tail.
- Functions:
- Sperm Maturation: Sperm spend several weeks in the epididymis, during which they gain motility and the ability to fertilize an egg.
- Sperm Storage: Stores sperm for several months.
- Propulsion: During ejaculation, smooth muscle in the wall of the epididymis contracts, propelling sperm into the vas deferens.
- Vas Deferens (Ductus Deferens):
- A muscular tube, about 45 cm (18 inches) long, that transports sperm from the epididymis to the ejaculatory duct.
- Ascends along the posterior border of the testis, passes through the inguinal canal (a passageway in the anterior abdominal wall), and enters the pelvic cavity.
- Joins with the duct of the seminal vesicle to form the ejaculatory duct.
- Uses peristaltic contractions to propel sperm.
- Can also store sperm for several months.
- Seminal Vesicles:
- Paired, convoluted, pouch-like structures located posterior to the urinary bladder and lateral to the ampulla of the vas deferens.
- Secrete an alkaline, viscous fluid that makes up about 60% of the volume of semen. This fluid contains:
- Fructose: A sugar that provides energy for sperm.
- Prostaglandins: Contribute to sperm motility and viability, and may stimulate smooth muscle contractions in the female reproductive tract.
- Clotting Proteins: Help semen coagulate after ejaculation.
- Ejaculatory Ducts:
- Short ducts (about 2 cm long) formed by the union of the duct from the seminal vesicle and the ampulla of the vas deferens.
- Pass through the prostate gland and empty into the prostatic urethra.
- Eject sperm and seminal vesicle secretions into the urethra just before ejaculation.
- Prostate Gland:
- A single, donut-shaped gland about the size of a walnut, located inferior to the urinary bladder and surrounding the prostatic urethra.
- Secretes a milky, slightly acidic fluid that makes up about 25% of the volume of semen. This fluid contains:
- Citric Acid: Used by sperm for ATP production.
- Proteolytic Enzymes (e.g., PSA - prostate-specific antigen): Help liquefy coagulated semen.
- Seminalplasmin: An antibiotic that may help prevent urinary tract infections in males.
- Acid phosphatase
- Bulbourethral Glands (Cowper's Glands):
- Paired, pea-sized glands located inferior to the prostate gland, on either side of the membranous urethra.
- Secrete an alkaline fluid that neutralizes the acidity of the urethra and mucus that lubricates the tip of the penis during sexual arousal. This secretion occurs *before* ejaculation.
- Urethra:
- The terminal portion of the male duct system. Serves as a passageway for both urine and semen.
- Divided into three regions:
- Prostatic Urethra: Passes through the prostate gland.
- Membranous Urethra: The shortest portion, passing through the urogenital diaphragm.
- Spongy (Penile) Urethra: The longest portion, passing through the penis.
2. External Structures
- Scrotum:
- A sac of skin and superficial fascia that hangs from the root of the penis.
- Supports and protects the testes.
- Divided into two compartments by a septum, each containing one testis.
- The location of the scrotum and the contraction of its muscle fibers help regulate the temperature of the testes. Sperm production requires a temperature slightly lower than core body temperature.
- Dartos Muscle: Smooth muscle in the subcutaneous tissue of the scrotum. Wrinkles the scrotal skin when contracted.
- Cremaster Muscle: Bands of skeletal muscle that arise from the internal oblique muscle of the trunk. Elevate the testes closer to the body when cold, and lower them away from the body when warm.
- Testes (Testicles):
- Paired, oval-shaped glands located within the scrotum.
- The primary male reproductive organs. Responsible for:
- Spermatogenesis: The production of sperm.
- Hormone Production: Secretion of testosterone.
- Covered by a dense, white fibrous capsule called the *tunica albuginea*. Extensions of the tunica albuginea divide the testis into lobules.
- Each lobule contains *seminiferous tubules*, where sperm are produced.
- Spermatogenic Cells: Various stages of developing sperm cells.
- Sertoli Cells (Sustentacular Cells): Support and nourish developing sperm cells, form the blood-testis barrier, and secrete inhibin.
- Leydig Cells (Interstitial Cells): Located in the spaces between seminiferous tubules. Produce testosterone.
- Sperm move from the seminiferous tubules → straight tubules → rete testis → efferent ducts → epididymis.
- Penis:
- The male organ of copulation. Delivers sperm into the female reproductive tract.
- Consists of a root, body, and glans penis.
- Root: The attached portion.
- Body: The main, elongated portion. Contains three cylindrical columns of erectile tissue:
- Corpora Cavernosa (2): The two dorsolateral masses.
- Corpus Spongiosum: The smaller, midventral mass. Contains the spongy urethra.
- Glans Penis: The enlarged, distal end of the penis. Covered by the prepuce (foreskin) in uncircumcised males. The external urethral orifice is located at the tip of the glans penis.
- During sexual arousal, the erectile tissues fill with blood, causing the penis to become erect.
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