Male Reproductive System Quiz

Male Reproductive System

• The male reproductive system produces and transports sperm, and produces male hormones like testosterone.
• The gonads in males are the testes.
• The testes are located within the scrotum.
• The scrotum is a sac containing the testes and regulates testicular temperature.
• Spermatogenesis (sperm production) requires 2-3°C lower than body temperature. Testicular temperature is regulated by the dartos muscle.

Penis

• The penis is composed of three erectile tissues: corpora cavernosa (2, dorsolateral, vascular spaces) and corpus spongiosum.
• The corpus spongiosum contains the spongy urethra.
• The penis's root has a bulb-expanded proximal portion of the corpus spongiosum, covered by bulbospongiosum. The crura are proximal tapered parts of corpora cavernosa, covered by ischiocavernosum.
• The glans penis is the expanded distal end of the corpus spongiosum. The distal terminal urethra expands to form the fossa navicularis. The glans is covered by prepuce and frenulum.

Internal Genitalia

• Testes: Intra-abdominal during fetal development, descend and are covered by the tunica vaginalis from the peritoneum. They have a deeper covering called the tunica albuginea. This divides the testes into lobules, each containing seminiferous tubules.
• Cells in the Testes: Spermatogenic cells produce sperm; Sertoli cells support and protect sperm; Interstitial cells of Leydig secrete testosterone located between seminiferous tubules.
• Epididymis: Comma-shaped, 4cm long, located posterior to the testes. It has head, body, and tail parts. The tail is continuous with vas deferens and is the site of sperm maturation-mobility and capability to fertilize an ovum (10-14 days). It also stores sperm cells and propels sperm cells to vas deferens.
• Ductus Deferens (Vas Deferens): Continuation of the epididymis, 45cm long, passes through the inguinal canal and enters the pelvic cavity, joins the duct of the seminal vesicle to form the ejaculatory duct.
• Functions: Storage of sperm cells, conveys sperm cells from epididymis to ejaculatory duct and urethra, reabsorbs not ejaculated sperm cells.
• Ejaculatory Duct: Formed by the joining of the duct from the seminal vesicle and the ductus deferens.
• Urethra: 20cm long, has three parts: prostatic, membranous, and penile.
• Prostatic urethra (2-3cm) is the widest and most dilatable.
• Membranous urethra (1cm) is the shortest and least dilatable, passing through the urogenital diaphragm.
• Penile urethra (15-20cm) is the longest and traverses corpus spongiosum.

Accessory Reproductive Organs

• Prostate Gland: Located beneath the urinary bladder with 5 lobes. Surrounds the prostatic urethra and secretes a milky, slightly acidic (pH 6.5) seminal fluid. Secretions include citric acid for ATP energy of sperm, acid phosphatase, proteolytic enzyme to break down clotting protein.
• Seminal Vesicles: Located postero-inferior to the urinary bladder. 5cm long, convoluted pouch, secretes fructose, contributing about 60% of semen volume. Secretions include alkaline viscous fluid which neutralizes acidic vaginal and male urethral environments, contains fructose, mobility and sperm viability, stimulate smooth muscle contraction of female, and clotting protein to coagulate sperm after ejaculation.
• Cowper's (Bulbourethral) Glands: Located within the urogenital diaphragm on either side of the membranous urethra. They secrete alkaline fluid and mucus to lubricate the penis and urethra lining.

Semen

• Volume: 2.5-5ml with 50-150 million sperm cells/ml (approx. 300-500 million).
• Slightly alkaline (pH 7.2-7.7).
• Contains seminal plasmin which destroys certain bacteria.
• Once ejaculated, sperm become coagulated due to clotting protein from seminal vesicles.
• After 10-20 minutes, prostate specific antigen (PSA) and other enzymes cause liquefaction.

Sperm Cells

• Head: Acrosome with lysosomal enzymes for zona pellucida penetration, and a nucleus with a 23 chromosome haploid number.
• Midpiece: Contains mitochondria for energy.
• Tail: Flagella for motility.

Erection

• Enlargement and stiffening of the penis (due to tactile, visual, auditory, olfactory, and imagination).
• Hypothalamus sends parasympathetic nerve impulses, leading to vasodilatation of helicine arteries in the penis.

Ejaculation

• Powerful expulsion of semen from the urethra to the exterior (sympathetic reflex).
• Closure of smooth muscle sphincter at the base of the urinary bladder.
• Peristaltic contraction of the male reproductive tract.

Emission

• Discharge of a small volume of semen before ejaculation.
• May occur during sleep (nocturnal emission).
• Due to peristaltic contraction in male reproductive tracts.

Cryptorchidism

• Undescended testes.
• 80% will spontaneously descend during the first year of life.
• May lead to sterility and testicular cancer.

Test your knowledge on the male reproductive system, including its anatomy and functions. This quiz covers key components such as the testes, penis, and the process of spermatogenesis. Dive deep into the intricate details to enhance your understanding.