Anatomy of Male Reproductive System

Transcription

1 Anatomy of Male Reproductive System A. Reproductive Systems 1. Gonads: primary sex organs a. Produce gametes b. Produce hormones c. Male Gonads: testes d. Female Gonads: ovaries 2. Gametes: sex cells a. Male: sperm i. Produced by testes b. Female: ova i. Produced by ovaries 3. Accessory Reproductive Organs: sexual structures that do not produce gametes B. Testes 1. Testes: male gonads a. Exocrine function: producing sperm b. Endocrine function: producing testosterone 2. Olive-sized (about 4 cm long and 2.5 cm wide) 3. Tunica Albuginea: fibrous connective tissue capsule that surrounds a testis a. Septa: extensions of the capsule that divide the testis into lobules i. Each lobule contains one to four tightly coiled seminiferous tubules 4. Seminiferous Tubules: form immature sperm a. Empty into the rete testis

2 i. Rete testis: a set of tubules located at one side of the testis --Sperm empties from rete testis to epididymis 5. Interstitial Cells: soft connective tissue surrounding the seminiferous tubules a. Produces androgens Example: testosterone C. Duct System 1. Duct System: accessory organs for transport of sperm from body a. Epididymis b. Ductus Deferens (Vas deferens) c. Urethra 2. Epididymis: comma-shaped, highly coiled tube that caps the superior part of the testis a. About 6 meters long (20 feet) b. Runs down posterolateral side c. Provides temporary storage of immature sperm i. Sperm mature as they travel through epididymis --Takes about 20 days to complete trip --Gain ability to swim d. When sexually excited, walls of epididymis contract to expel sperm i. Sends sperm to Ductus Deferens 3. Ductus Deferens AKA: Vas Deferens a. Runs upward from epididymis through inguinal canal into pelvic cavity

3 i. Then arches over superior aspect of urinary bladder b. Spermatic Cord: a connective tissue sheath that encloses the ductus deferens, blood vessels, and nerves c. Empties into ejaculatory duct i. Which passes through prostate gland to merge with urethra d. Functions to propel live sperm from storage to urethra e. Vasectomy: cutting or cauterizing the vas deferens (ductus deferens) i. Prevents sperm from leaving body ii. Testosterone still produced --So sex drive still exists 4. Urethra: tube that extends from base of urinary bladder to tip of penis a. Regions of Urethra i. Prostatic urethra: part of urethra surrounded by prostate gland ii. Membranous urethra: part of urethra spanning distance from prostatic urethra to penis iii. Spongy urethra: part of urethra running within the length of the penis AKA: Penile urethra b. Carries both semen and urine to body exterior c. When ejaculation occurs, bladder sphincter (internal urethral sphincter) constricts i. Prevents urine from entering urethra ii. Prevents sperm from entering the urinary bladder D. Accessory Glands 1. Accessory glands produce the bulk of semen a. These glands are: seminal vesicles (paired), prostate gland, and bulbourethral glands

4 b. Semen: sperm-containing fluid i. Propelled from body by ejaculation 2. Seminal Vesicles: located at base of bladder a. Produce 60 % of fluid volume of semen b. Thick, yellowish secretion i. Contains: Sugar (fructose), vitamin C, and prostaglandins ii. Nourishes active sperm c. Duct of seminal vesicle joints ductus deferens on same side to form ejaculatory duct i. Sperm and seminal fluid enter urethra together 3. Prostate Gland: a single gland that encircles the upper part of the urethra a. About the size of a chestnut b. Produces a milky fluid i. Plays a role in activating sperm c. Enters urethra through several small ducts i. During ejaculation 4. Bulbourethral Glands: tiny, pea-sized glands inferior to prostate gland AKA: Cowpers Glands (formerly called) a. Produce thick, clear mucus i. Drains into the penile urethra b. First secretion to pass down urethra when sexually excited i. Cleanses the urethra of acidic urine ii. Serves as lubricant during intercourse

5 5. Semen: a milky white, somewhat sticky mixture of sperm and accessory gland secretions a. Liquid provides transport medium, nutrients, and chemicals for sperm b. Fluid from seminal vesicle provides fructose needed for sperm s energy c. Semen s alkalinity (ph ) neutralizes acid environment of vagina (ph ) i. Protects delicate sperm d. Contains seminalplasmin i. An antibiotic that inhibits bacterial growth e. Contains the hormone relaxin f. Contains enzymes i. Enhance sperm mobility g. Dilutes sperm i. Allows them to swim much better h. Produce about 2-5 ml (about a teaspoon) during ejaculation i. 1 ml contains between 50 and 130 million sperm E. External Genitalia 1. External Genitalia: include the scrotum and penis 2. Scrotum: a divided sac of skin that hangs outside the abdominal cavity, between the legs, and at root of penis a. Provides a temperature about 3 0 C (5.4 0 F) lower than body temperature i. Necessary for healthy sperm production b. When temperature is cold, pulls closer to body for warmth and becomes wrinkled 3. Penis: delivers the sperm into the female reproductive tract a. Shaft: length of the penis

6 b. Glans Penis: enlarged tip at the end of the shaft c. Prepuce: loose folds of skin that form a cuff around proximal end of the glans AKA: Foreskin i. Circumcision: surgical removal of the prepuce (foreskin) d. Internally, Spongy Urethra is surrounded by three layers of erectile tissue i. Erectile Tissue: spongy tissue that fills with blood during sexual arousal --Causes erection --Erection: penis enlarges and becomes rigid --Helps penetrate to deliver semen to female