Male Reproductive System (pg 6)

Male Reproductive System (pg 6)

• Functions: Produce and transport sperm, introduce sperm into female vagina, and produce hormones responsible for development of secondary male sex characteristics

Testes

• Produce sperm

Testes

• Produce sperm• Begin development high in abdominal cavity.

Around 2 months before birth, they descend into the scrotum

Testes

• Produce sperm• Begin development high in abdominal cavity.

Around 2 months before birth, they descend into the scrotum

• Testes are around 3 degrees cooler than body temperature. Necessary for production of viable sperm.

Testes

• Produce sperm• Begin development high in abdominal cavity.

Around 2 months before birth, they descend into the scrotum

• Testes are around 3 degrees cooler than body temperature. Necessary for production of viable sperm.

• Cremaster muscle contracts when cold to bring the testes closer to the body for warmth

Duct system

• Once produced in the testes, sperm move through a series of ducts to reach the outside of the body. The ducts are the epididymis, ductus deferens, ejaculatory duct, and urethra

Epididymis

• Long tube (6 meters). Tightly coiled to form comma-shaped organ that sits on top of testes

Epididymis

• Long tube (6 meters). Tightly coiled to form comma-shaped organ that sits on top of testes

• When sperm leaves testes, they are unable to “swim” and incapable of fertilizing an egg

Epididymis

• Long tube (6 meters). Tightly coiled to form comma-shaped organ that sits on top of testes

• When sperm leaves testes, they are unable to “swim” and incapable of fertilizing an egg

• As sperm slowly move through the epididymis, they mature and become fertile

Ductus deferens (vas deferens)

• Tube that carries sperm from the epididymis to the ejaculatory duct

Ductus deferens (vas deferens)

• Tube that carries sperm from the epididymis to the ejaculatory duct

• Vasectomy: surgical procedure that severs the ductus deferens for birth control

Ejaculatory duct

• Ductus deferens joins duct from the seminal vesicle to form a short ejaculatory duct

Ejaculatory duct

• Ductus deferens joins duct from the seminal vesicle to form a short ejaculatory duct

• Passes through the prostate gland and into the urethra

Urethra

• Passageway for urine and semen

Urethra

• Passageway for urine and semen• 3 regions

1. Prostatic urethra: passes through prostate gland. Receives fluids from ejaculatory duct and prostate

Urethra

• Passageway for urine and semen• 3 regions

1. Prostatic urethra: passes through prostate gland. Receives fluids from ejaculatory duct and prostate2. Membranous urethra: short region that passes through the pelvic floor

Urethra• Passageway for urine and semen• 3 regions

1. Prostatic urethra: passes through prostate gland. Receives fluids from ejaculatory duct and prostate2. Membranous urethra: short region that passes through the pelvic floor3. Spongy (penile) urethra: extends the length of penis and opens to outside

Penis

• Male copulatory organ. Transfers sperm to the vagina

Penis

• Male copulatory organ. Transfers sperm to the vagina

• Parts: Root, shaft, glans (head)

Penis

• Male copulatory organ. Transfers sperm to the vagina

• Parts: Root, shaft, glans (head)• Contains erectile tissue that can become

engorged with blood and become rigid

Accessory Glands: secrete fluids that enter the urethra

Accessory Glands: secrete fluids that enter the urethra

• Seminal vesicles: glands posterior to urinary bladder. Produce viscous fluid that contains fructose, which serves as an energy source for sperm

Accessory Glands: secrete fluids that enter the urethra

• Seminal vesicles: glands posterior to urinary bladder. Produce viscous fluid that contains fructose, which serves as an energy source for sperm

• Prostate: Walnut sized. Encircles the urethra. Produces thin, milky, alkaline fluid that enhances the motility of sperm

Accessory Glands:• Seminal vesicles: glands posterior to urinary

bladder. Produce viscous fluid that contains fructose, which serves as an energy source for sperm

• Prostate: Walnut sized. Encircles the urethra. Produces thin, milky, alkaline fluid that enhances the motility of sperm

• Bulbourethral gland: pea sized. Produces pre-ejaculatory fluid, which provides lubrication and works as a buffer to prevent chemical reaction between acidic urine and basic semen

Semen

• Slightly alkaline (pH = 7.5)

Semen

• Slightly alkaline (pH = 7.5)• 60% of volume comes from seminal vesicles,

40% from prostate, <1% from sperm and bulbourethral glands

Semen

• Slightly alkaline (pH = 7.5)• 60% of volume comes from seminal vesicles,

40% from prostate, <1% from sperm and bulbourethral glands

• Contains 50 – 150 million sperm per mililiter