Male Reproductive System: Hormones, Structures, and Functions

Effects of testosterone

Growth and development, maintenance of sex organs, influences sexual behavior, influences final maturation of sperm cells, stimulates development of secondary male sexual characteristics.

Ejaculatory ducts

Ducts that are just posterior to the urinary bladder formed by the union of the ducts from seminal vesicles and vas deferens.

Testosterone

Main male hormone.

Male secondary sex characteristics

Muscular and skeletal development, development of pubic, axillary, and chest hair, facial hair growth, temporal hairline recession, deepening voice.

Male puberty

Characteristics start to appear, begins at 10-11 years, completed at 15-17 years.

Prostate gland

Single doughnut-shaped gland about the size of a chestnut located inferior to the urinary bladder, surrounds urethra.

Prostate gland secretion

Secretes fluid rich in citric acid, prostatic acid phosphatase, and prostaglandins.

Semen

Mixture of sperm and secretions of the seminal vesicles, prostate gland, and bulbourethral glands.

Sperm count

150 million sperm per ejaculation; less than 20 million sperm is considered infertile.

Penis

Male anatomical structure used to introduce sperm into vagina.

Gonads

Organs in the body that produce sex cells; male testes produce sperm, female ovaries produce eggs.

Testicles (testes)

Responsible for production of sperm cells and male hormones.

Epididymis

Comma-shaped organ lying posterior to the testes, site of sperm final maturation.

Ductus (Vas) deferens

A long duct (18 inches) that is the passageway for sperm from epididymis to urethra.

Seminal vesicles

Convoluted pouch-like structures that secrete an alkaline fluid rich in fructose, making up 60% of the volume of sperm.

Corpora cavernosa penis

Two most dorsal lateral masses of penis.

Corpus spongiosum penis

Smaller mid-ventral mass of penis through which the urethra passes.

Glans penis

Slightly enlarged distal end of the penis, shaped like an acorn.

Urethra

Terminal duct for both reproductive and urinary systems, passageway for semen and sperm.

Bulbourethral (Cowper's) glands

Pea-sized glands located inferior to prostate gland that secrete alkaline substance to neutralize acidic environments.

Seminiferous tubules

Tightly coiled tubules in testes where spermatogenesis occurs.

Spermatozoa

Mature sperm, produced at a rate of 300 million a day, live for 48 hours after ejaculation.

Components of sperm

Head (genetic material), midpiece (mitochondria), tail (propeller).

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