Function • What is the main function of the male reproductive system? • When do males begin producing sperm? • What gland secretes a hormone that causes testes to begin producing testosterone?
Function • Male reproductive system functions to producesperm-the male reproductive cell • A sperm cell unites with a female egg cell (ovum) to form a fertilized ovum. • Males do not begin producing sperm until puberty • The pituitary gland secretes a hormone that causes the testes to begin producing sperm • Once a male reaches puberty and begins producing sperm, he is capable of producing sperm for the rest of his life. (Spermatogenesis)
External Male Reproductive Organs • External male reproductive organs include the scrotum,testes,and penis. • Testes-male sex glands-serve 2 functions • Manufacture the male sex hormone-testosterone • Produce male reproductive cells-sperm • Scrotum-sac that hangs outside the body that holds the testes • Penis- tube like organ that functions in sexual reproduction, sexual pleasure, and elimination of body wastes.
Scrotum • Loose pouch of skin that becomes darker as males grow and develop. • As puberty progresses, hair will appear • As testes grow skin of scrotum becomes wrinkled. • Main function is to keep testes at the right temperature so they can produce sperm (3-4 degrees lower then normal body temp of 98.6) • If body temp rises, muscles in scrotum relax to lower the testes away from the body. If body temp lowers, muscles of scrotum contract to pull the testes close to the body.
Testes • Sperm is actually produced in a section of the testes called seminiferous tubules. • Seminiferous tubules-long series of threadlike tubes packed in testes. (about 1000 each about 1-3 ft long-combined length of all tubules can extend almost ½ mile capable of producing billions and billions of sperm.) • The testes produce 500million or more sperm each day • Once sperm are produced they move to epididymis.
Epididymis • *Highly coiled structure located on the backside of each of the testes. • Stores newly produced sperm • 20 ft in length. • The maturation of sperm which began in the seminiferous tubules, continues to the epididymis • It takes about 72 days from the time sperm are produced until they become fully mature.
Sperm Cell • Very tiny- consists of head,neck,middle piece and tail • Carries 23 chromosomes in the head-1/2 the number of chromosomes in all other cells of body • When sperm unites with ovum,which carries 23 chromosomes-the results is one cell of 46 chromosomes and the production of a human offspring
Penis • Tubelike organ that functions in sexual reproduction, sexual pleasure and elimination of body wastes. • Made up of three long cylinders of spongy tissue • Tissue is filled w/spaces much like a sponge that contain a very rick supply of blood vessels and nerves • When penis is soft these cylinders contain little blood • When blood from circulatory system fills these spaces the penis becomes enlarged and hard-erection • Contrary to what some people think, the penis is neither a muscle nor a bone. • Erections result entirely from blood flow.
Erections and Ejaculation • Erection-increased blood flow to the penis • Males of all ages experience erections and can occur for no reason at all • At puberty the penis becomes more sensitive and erections are more often • Ejaculation-is a series of muscular contractions releasing semen • Semen-is thick fluid containing sperm and other fluid • In less than a teaspoon of semen there are about 300-400 million sperm. • When males begin to produce sperm nocturnalemission can occur which is ejaculation during sleep
Circumcision • All male babies are born with a fold of skin covering end of penis-foreskin • Circumcision is the removal of the foreskin • Some circumcision is performed as a religious custom • Doctors thought it was necessary for health reasons to remove, but not necessary. • In recent years about ½ of parents chose not to.
Internal Male Reproductive Organs • Vas Deferens • Seminal Vesicles • Prostate Gland • Cowper’s Gland • Urethra
Vas Deferens • Vas Deferens-2 long tubes that connect the epididymis with the urethra • Lined w/ cilia(fingerlike projections)which help move sperm through tube • Vas deferens loop over pubic bone, around bladder , and through prostate gland. • As it passes through prostate gland it narrows and becomes the ejaculatory duct into urethra
Seminal Vesicles • Two little pouches above and on either side of prostate gland. • SVs' secrete a fluid that mixes w/sperm • This fluid helps make sperm mobile and provides nourishment to the sperm.
Prostate Gland • Lies just below the bladder and surrounds the urethra • Made up of both muscular and glandular tissue • Secretes a milky,alkaline fluid that mixes w/sperm and makes up major portion of semen. • It is this solution that helps protect sperm by neutralizing the acidity of the urethra and vagina in the female
Cowper’s Gland • Two pea-sized glands below the prostate that open into urethra • Secrete clear, sticky fluid that is thought to cleanse urethra of acid from urine allowing the safe passage of sperm • Semen-mixture of sperm and fluids from the seminal vesicles,prostate gland,and Cowper’s Gland • Some of the clear fluid from the Cowper’s gland is released before the semen is released-this secretion causes droplets of fluid to form on the end of penis before ejaculation • These droplets of fluid can contain sperm-pregnancy can occur.
Urethra • Tubelike organ that travels through the penis. • Serves as a passageway for sperm and urine, however both can not leave the body at same time. • Special muscles surround the urethra at the base of the bladder that contact and close off bladder preventing urine to be released when semen is leaving body
Concerns About Male Reproductive System • Hernia • Sterility • Cancer of Testes or Prostate
Hernia • Pushing of a part of the body through the muscle wall normally keeping it in (several types) • Inguinal hernia-common hernia of reproductive system where part of the intestine can push through abdominal wall into the scrotum. • Surgery can correct this and males can help avoid this by using care when lifting or pushing heavy objects- lift w/legs not back.
Sterility • Condition wherein sperm of male is weak,malformed,sparse or nonexistent, or unable to join an ovum. • Fertilization can not take place • Causes of sterility: temperature changes, exposure to certain chemicles,smoking,contracting mumps as an adult,untreated STD,faulty operation of epididymis,vas deferens,or urethra
Testicular Cancer • Most common cancer in men ages 15-34 yrs • If discovered in early stages, testicular cancer can be treated properly and effectively. • 1st sign-usually slight enlargement of one of the testes and change in its consistency. • May be small, hard lump in testicle or a collection of fluid or blood in scrotum. • There might be no pain-but often there is a dull ache in lower abdomen and groin • Men who have an undescended or partial descended testicle are at high risk