Overview
This lecture describes the anatomy and function of the male reproductive system, tracing the path of sperm from production to ejaculation and linking the system to the urinary tract.
Male Reproductive Structures & Functions
- The testes are the primary male sex organs that produce sperm and testosterone.
- Spermatogenesis, the creation of sperm cells, occurs in the seminiferous tubules within the testes.
- Sperm cells have a head (nucleus with 23 chromosomes), a mitochondria-rich midpiece for energy, and a tail for movement.
- The scrotum is a skin sac that regulates the temperature of the testes for optimal sperm production.
- The epididymis sits atop each testis and is where sperm mature before ejaculation.
- During ejaculation, sperm travel from the epididymis into the vas deferens.
- The vas deferens carries sperm up and around the pelvic cavity, meeting fluid from the seminal vesicles.
Accessory Glands & Fluids
- Seminal vesicles secrete fluid that provides nutrients and forms part of the semen.
- The prostate gland adds additional fluid to semen and surrounds the urethra below the bladder.
- Bulbourethral (Cowper's) glands secrete fluid that also contributes to semen.
- Semen is the combination of sperm and fluids from these glands, aiding transport and survival of sperm.
Pathways of Sperm and Urine
- Sperm path: testes → epididymis → vas deferens → seminal vesicle → prostate → urethra → penis.
- Urine path: kidney → ureter → bladder → urethra → penis.
- The urethra serves as the exit for both urine and semen.
Disorders & Procedures
- An enlarged prostate can block urine flow, causing urination difficulties.
- Prostate exams are performed via the rectum to assess prostate size.
- A vasectomy cuts the vas deferens, preventing sperm from reaching the urethra, but does not affect testosterone or semen production.
External Anatomy
- The penis delivers sperm during ejaculation, with the glans penis as its tip.
- Foreskin covers the glans and may be removed in circumcision.
- The scrotum contains the testes and epididymis and contracts or relaxes for temperature control.
- Blood sinuses in the penis enable erection by filling with blood.
Key Terms & Definitions
- Testes — Primary male sex organs that produce sperm and testosterone.
- Spermatogenesis — The process of sperm cell production.
- Seminiferous Tubules — Coiled tubes inside the testes where spermatogenesis occurs.
- Epididymis — A structure where sperm mature and are stored.
- Vas Deferens — Tube transporting sperm from epididymis to urethra.
- Seminal Vesicle — Gland producing nutrient-rich fluid for semen.
- Prostate Gland — Gland adding fluid to semen and surrounding the urethra.
- Bulbourethral Glands — Glands producing fluid for semen.
- Urethra — Tube carrying urine and semen out of the body.
- Scrotum — Skin sac regulating testes temperature.
- Glans Penis — The tip of the penis.
- Foreskin — Skin covering the glans penis.
Action Items / Next Steps
- Review and identify all male reproductive structures and their functions.
- Prepare for quizzes on the path of sperm and the role of accessory glands.