S EXUAL A NATOMY o Female-External o Female-Internal o Male-External o Male-Internal

M ALE I NTERNAL S EX O RGANS Increased knowledge of the structure and function of your reproductive organs can: Improve sexual health Increase sexual pleasure Increase responsibility in sexual behavior Female and male sexual organs develop from similar tissue before birth. Genitals : External sexual organs

M ALE I NTERNAL S EX O RGANS The primary function of the internal sexual organs of the human male is the production of semen. Defined : Fluid containing sperm and secretions from the testicles, prostate, and seminal vesicles that is expelled from the penis during ejaculation. Also known as Ejaculate Contains Sperm : Male reproductive cell Only one is needed to fertilize an egg 1% of semen

M ALE I NTERNAL S EX O RGANS Seminal Fluid: Fluid from the prostate and other sex glands that helps transport semen out of a man’s body during ejaculation. Teaspoon of semen contains between 200 and 500 million sperm 99% of semen is composed: Ascorbic and Citric Acids, Enzymes, Fructose, Water, Substances Amount of semen ejaculated by a male is a teaspoonful Volume is influenced by Amount of time since the last ejaculation Duration of arousal prior to ejaculation Age ( men tend to produce less ejaculate as they age )

S EMINIFEROUS T UBULES Defined : Thin coiled tubes located in the testicles in which sperm are produced. Located within the testes Inside approximately 250 cone-shaped lobes of the interior of each testicle Placed end to end they would span the length of two football fields Thin, densely coiled sperm-bearing tubes Site of Spermatogenesis: Sperm production

S EMINIFEROUS T UBULES Leydig’s Cells : ( Interstitial Cells ) Produce Androgens Close proximity to blood vessels allows direct secretion of androgens into the bloodstream Androgens : Hormones that promote the development of male genitals and secondary sex characteristics. Testosterone is the most important androgen

E PIDIDYMIS Defined : Tightly coiled thin walled tube where sperm maturation is completed. C-Shaped Attached to the back and top surface of each testis Sperm may be stored for a period of several weeks. During this time sperm cells continue to mature but are completely inactive

V AS D EFERENS Defined : Tubes that convey sperm from the testes to the ejaculatory duct of the penis. Eventually the sperm stored in the epididymis move into the vas deferens: Carries sperm up into the body cavity, where at the base of the bladder they form the ejaculatory ducts The two ejaculatory ducts run through the prostate gland and connect to the urethra. Common duct that carries urine from the bladder to the opening of the penis where it is expelled from the body.

S EMINAL V ESICLES Defined: Two small glands that lie behind the bladder and secrete fluid that combines with sperm in the ejaculatory ducts. Excretory ducts of the seminal vesicles join the vas deferens to form the ejaculatory ducts. Seminal vesicles contribute to the production of seminal fluid, the viscous fluid ejaculated through the penis Secretion of the seminal vesicles is high in fructose ( form of sugar ) Sugar serves as a nutrient for the sperm, which require energy to make it to their destination Once enriched by the secretions of the seminal vesicles, the sperm begin to propel themselves by the whiplike action of their tails

P ROSTATE G LAND Defined : Gland which lies just below the bladder and surrounds the urethra, that produces about 30% of the seminal fluid released during ejaculation. The other 70% is produced by the seminal vesicles Composed of muscle as well as glandular tissue

P ROSTATE GLAND Both the ejaculatory ducts and the urethra pass through this gland, located at the base of the bladder and normally about the size and shape of a walnut. During arousal the muscular tissue of the prostate gland squeezes shut and the urethral duct to the bladder Thus preventing urine from mixing with the semen and disturbing the chemical balance required by sperm. If the prostate gland becomes enlarged, as it often does as men age, the swelling can close off the ejaculatory ducts and urethra, making urination difficult and painful.

C OWPER ’ S G LANDS Defined : ( bulbourethral glands ) Glands located beneath the prostate that produce a clear, colorless liquid before ejaculation that neutralizes acid to prevent damage to the sperm. Two small structures about the size of a pea located one on each side of the urethra just below the prostate gland When a man is sexually aroused these glands may produce a fluid secretion called pre-ejaculate Tiny ducts carry this secretion from the Cowper’s glands to the urethra. It neutralizes the acidity of the urethra and also may help to lubricate the urethra and thus increase the flow of seminal fluid

C OWPER ’ S G LANDS Some men notice the secretion of the Cowper’s Glands as soon as they get an erection Others rarely or never produce these droplets For many men this secretion appears just prior to ejaculation While this fluid is not semen, it may contain healthy sperm if the man has not urinated since the last ejaculation This is one reason why the withdrawal method of birth control is not highly effective ( withdrawal of the penis from the vagina prior to ejaculation )