Male Reproductive Anatomy

• The male internal reproductive organs are: testes, vas deferens, seminal vesicles, ejaculatory ducts, prostate, and urethra.

Penis

• Consists of the glans (head), shaft, and root.
• The glans is particularly sensitive to stimulation.
• The urethra runs the length of the penis, surrounded by the spongy body and two cylindrical chambers known as the cavernous bodies.
• During arousal, the cavernous bodies become engorged with blood, resulting in erection.
• The corona is the rim of the glans where it arises from the shaft.
• The frenulum is a thin strip of skin connecting the glans and shaft on the underside of the penis.
• The urethral opening is on the head of the penis and connects to the bladder for urination.
• Internal structures use it to deliver semen during ejaculation.

Scrotum

• A sac that encloses the two compartments housing the testes.

Perineum

• The area of skin separating the genitalia from the anus; this distance is greater in males than in females.

Testes

• -produce androgen, particularly large quantities of testosterone, which greatly influence male development and drive sexual motivation.
• Also produce sperm cells in virtually unlimited quantity over the entire course of the lifespan.

Vas Deferens

• Travels from the testicle toward the urethra, carrying sperm.

Seminal Vesicles

• Two glands producing an alkaline fluid rich in fructose sugar, comprising about 70% of semen volume.
• The alkaline nature may stimulate sperm for self-propulsion and sugar may provide sperm nutrients.
• Ducts carry fluid and connect with the vas deferens, forming ejaculatory ducts.

Ejaculatory Ducts

• Connect the vas deferens to the urethra.

Prostate

• A gland producing alkaline secretions that account for about 10% of semen volume.
• The alkaline nature may help counteract the acidic environment of the urethra and vagina, making them more hospitable for sperm.
• Fluid passes through a series of ducts along the wall of the urethra.

Urethra

• A tube within the penis that carries sperm and semen

Male Characteristics

• Generally taller and have a greater proportion of body weight composed of water.
• Proportionately larger heart and lungs to handle greater blood volume.
• Increased exposure to greater levels of testosterone leads to heavier body and facial hair, increased frequency, and degree of baldness.
• Single X chromosome results in sex-linked conditions such as colorblindness and hemophilia.

Male Hormones

• Testosterone is the major male hormone produced mainly by the testes, but also by the adrenal glands.
• If a man loses his testes, the adrenal glands would continue to produce testosterone, supporting male physical appearance.
• Testosterone is responsible for the growth and development of a boy during adolescence and for the development of sperm and secondary sexual characteristics.

Physical changes during male puberty

• Growth of facial and body hair
• Deepening of the voice
• Growth of the genitals
• Increase in height and muscle mass
• Development of acne