Male Reproductive System Anatomy

• The male reproductive system is responsible for producing sperm and delivering it to the female reproductive system for fertilization.

Anatomy of the Male Reproductive System:

• Testes are the primary male reproductive organs and produce sperm and testosterone.
• The scrotum is a pouch of skin housing the testes, regulating their temperature for optimal sperm production.
• The epididymis is a coiled tube on the posterior side of the testis where sperm mature and are stored.
• The vas deferens is a duct that transports sperm from the epididymis to the ejaculatory duct.
• Seminal vesicles are glands that secrete nutrient-rich fluid, a significant component of semen.
• The prostate gland secretes a fluid with enzymes and nutrients, contributing to semen volume and sperm viability.
• Bulbourethral (Cowper's) glands secrete clear, alkaline mucus, lubricating the urethra and neutralizing acidity during arousal.
• The urethra is a tube that carries both urine and semen out of the body through the penis.
• The penis, the male organ for sexual intercourse, has erectile tissue that engorges with blood during sexual stimulation, facilitating penetration.

Hormones and Regulation:

• Gonadotropin-Releasing Hormone (GnRH) from the hypothalamus stimulates the anterior pituitary to secrete LH and FSH.
• Luteinizing Hormone (LH) stimulates Leydig cells in the testes to produce testosterone.
• Follicle-Stimulating Hormone (FSH) stimulates Sertoli cells in the testes to support spermatogenesis.
• Testosterone is the primary male sex hormone for developing male secondary sexual characteristics, maintaining libido, and supporting spermatogenesis.
• Inhibin, secreted by Sertoli cells, inhibits FSH secretion by the anterior pituitary, providing negative feedback control of spermatogenesis.

Spermatogenesis:

• Spermatogenesis occurs in the seminiferous tubules of the testes
• It involves mitotic divisions of spermatogonia, followed by meiotic divisions to produce haploid spermatids.
• Spermatids undergo spermiogenesis to differentiate into mature spermatozoa (sperm).
• Sertoli cells provide support and nourishment to developing sperm cells.

Erection and Ejaculation:

• Erection occurs when the penis becomes rigid due to vasodilation of blood vessels in the erectile tissue.
• Parasympathetic nervous system activity releases nitric oxide (NO), causing vasodilation.
• Ejaculation occurs as semen is expelled from the penis.
• Sympathetic nervous system activity triggers smooth muscle contraction in the vas deferens, seminal vesicles, and prostate gland, propelling semen through the urethra.
• Contraction of the bulbospongiosus muscle surrounding the base of the penis further aids ejaculation.

Semen Composition:

• Semen is composed of sperm and seminal fluid.
• Seminal fluid is a mixture of secretions from the seminal vesicles, prostate gland, and bulbourethral glands.
• Seminal fluid provides nutrients, buffers, and enzymes supporting sperm viability and motility.

Male Reproductive Health

• Prostate cancer is cancer of the prostate gland, typically affecting older men.
• Testicular cancer develops in the testicles and is more common in younger men.
• Erectile dysfunction is the inability to achieve or maintain an erection firm enough for satisfactory sexual intercourse.
• Infertility is the inability to conceive after one year of unprotected intercourse and may be due to low sperm count, poor sperm motility, or other factors.
• Sexually transmitted infections (STIs) are infections transmitted through sexual contact and include chlamydia, gonorrhea, syphilis, and HIV/AIDS.