MALE REPRODUCTIVE SYSTEM
MALE REPRODUCTIVE SYSTEM
GONADS: Early in prenatal life specialized cells organize into groups of cells know as gonads. Gonads develop into testes in the male and ovaries in the female.
TESTES: The testes develop about the 7th -8th week of prenatal life just below the hip bone. During the 8th and 9th months of fetal life, they start to move downward through a tunnel called the INGUINAL CANAL into a sac called the SCROTUM. After the testes pass through the inguinal canal, this tunnel closes to prevent other tissue from descending into the scrotum.
• HERNIA - A protrusion of tissue through an opening in its surrounding wall
• Hernia may occur anywhere in the body, but in males hernias are common through the inguinal canal, thus called an INGUINAL HERNIA.
SCROTUM: 2 FUNCTIONS
1. Contain the testes
2. Regulate temperature
o The testes are located outside the body in the scrotum because sperm cannot be effectively produced at body temperature. Sperm are most effectively produced at 1.5-3 degrees C. below body temperature.
2 MECHANISMS FOR REGULATING TEMPERATURE:
1. Sweat glands
2. Muscles that contract and bring the testes close to the body to increase temperature and relax to lower the testes away from the body and thus reduce temperature.
• If the testes do not descend into the scrotum, sperm cannot be produced and the male is sterile.
• After prolonged fever, sperm production may be reduced for as long as 2 months.
• Occupations that cause the scrotum to be bound up close to the body for many continuous hours may impair sperm production i.e., continual compression of the testes by tight underwear or athletic supporters.
TESTES – 2 FUNCTIONS:
1. Produce male sex hormone Testosterone
2. Produce sperm
HORMONES: Hormones play a very important role in human sexuality. Hormones are the direct cause of anatomical differences between males and females. The pituitary gland sends “gonad stimulating hormones” called gonadotropic hormones into the blood to the testes in males or ovaries in females. These 2 hormones are Follicle Stimulating Hormone (FSH) and Leutenizing Hormone (LH)
• FSH (FOLLICLE STIMULATING HORMONE): this is the first hormone secreted by the pituitary. It stimulates sperm production in males and maturation of ova (egg) in the females.
• LH (LEUTENIZING HORMONE): This is the second hormone released from the pituitary gland. In males it instructs the testes to produce the sex hormone testosterone and in females it triggers ovulation.
TESTERONE: Is responsible for the changes that occur during puberty in males (primary sex characteristics).
PRIMARY SEX CHARACTERISTICS: due to the production of testosterone
• Longer and heavier bones
• Larger muscles & increased metabolism
• Thicker and tougher skin
• Deep voice
• Distribution of body hair
• Development of pubic hair with a triangular border
• Baldness in later life
SPERM PRODUCTION : occurs in the microscopic tubes located in the testes know at the SEMINIFEROUS TUBULES . If uncoiled these tubules would extend over a mile. These Seminiferous Tubules are stimulated to produce sperm by FSH (Follicle Stimulating Hormone) and Testosterone. Sperm production begins about 12 years of age but the first ejaculation of sperm usually occurs at about 13 years and 10 months. Sperm formation requires about 74 days and is not affected by sexual activity.
• Teenage males may experience NOCTURNAL EMMISSION or “wet dream” which is and erection and ejaculation during sleep.
• Factors that affect Sperm Production include stress, high temperatures in the testes, radiation etc.
EJACULATION: After sperm is produced in the testes, it must pass through the penis and into the female vagina in order to fertilize the ovum(egg). The mechanism by which this is accomplished is termed ejaculation. During ejaculation sperm pass through 4 structures.
1. Epididymis
2. Vas Deferens
3. Ejaculatory duct
4. Urethra
Along the way sperm are joined by chemicals/fluids from 3 glands;
1. Seminal Vesicles
2. Prostate gland
3. Bulbourethral gland (Cowper’s gland)
EPIDIDYMIS: a J shaped tube located on the back of each testes, where a small quantity of sperm is stored. Sperm mature and gain ability to move in this structure.
VAS DEFERENS: Two 18 inch tubes that receives sperm from the epididymis. The two vas deferens loop over the bladder and join the urethra.
SEMINAL VESICLES: During ejaculation the seminal vesicle add a fluid secretion, fructose, a simple sugar that provides nutrition for the sperm. The fluid from the seminal vesicles makes up about 60% of semen and is a thick yellow color.
EJACULATORY DUCT: the duct that leaves the seminal vesicles joins the vas deferentia to one common duct know as the ejaculatory duct. It is a short straight tube that passes into the prostate gland to open into the urethra.
PROSTATE GLAND: The role of the prostate fluid is to neutralize the acid in the vagina in order to aid sperm in their attempt to fertilize an ovum (egg). The fluid is milky white and accounts for about 35% of semen.
COWPER’S GLAND or BULBOURETHRAL GLANDS - two small glands that secretion a fluid that neutralizes the urethra before ejaculation. It is often referred to precocial fluid (before ejaculation) and is clear and accounts for 5% of the semen.
PENIS: a soft tubular organ that hangs from the front of the body. It is composed of 3 cylinders, each containing erectile sponge like tissue that can fill with blood to cause an erection.
▪ FORESKIN – is a circular fold of skin over the end of the penis.
▪ CIRCUMCISION - removal of the foreskin over the tip of the penis
URETHRA: The urethra is a tube-like passageway extending from the bladder through the prostate gland where it is joined by the ejaculatory duct. From the prostate gland the urethra passes through the penis to the outside. It serves as a passageway for both sperm and urine but not at the same time. Prior to the passage of sperm, the acid urethra is neutralized by fluids from the Cowper’s Gland (Bulbourethral Glands). During ejaculation the opening form the bladder is normally closed off by a nervous reflex.
MALE REPRODUCTIVE ROLE: - to produce sperm and transfer sperm to the female reproductive tract.
To accomplish this the penis becomes erect, is inserted into the vagina and sperm are ejaculated. Erections occur when the erectile tissue of the penis becomes engorged with blood.
EJACULATION: the male ejaculate is called SEMEN. Semen contains sperm, secretions from the Seminal Vesicles (fructose sugar nutrition for the sperm), secretions from the Prostate Gland (neutralize the acid in the vagina) and fluid from the Cowper’s Gland (Bulbourethral Glands) which neutralizes the urethra.
▪ Semen is 1% sperm and 99% fluid. Mature sperm are very small.
▪ The average male ejaculate is about ½ teaspoon and contains approximately 360-400 million sperm. A sperm count of at least 60 million equals normal fertilization, 40 to 60 million sperm equals fair fertilization, 20-40 million sperm equals fertilization possible and a sperm count of 10-20 million conception is barely possible.
▪ Each sperm carries a small enzyme bomb in its head called an ACROSOME. When the acrosome comes near the ovum (egg) it is thought to explode.
▪ Sperm live in storage for 30-60 days. If ejaculation does no occur during this time, sperm degenerate (die) and are replaced by new ones.
SPERM AND AN ACID ENVIRONMENT: sperm do not move well in the acid environment of the vagina. They can only live about 72 hours after ejaculation. However, sperm have been found alive in the vagina 7 days after ejaculation.
VASECTOMY: A popular form of birth control for men. It is a surgical procedure in which the vas deference is cut and tied off.
CASTRATION: surgical removal of the testes.
SEX LIFE OF THE MALE: The average age of first ejaculation is 13 years and 10 months. Only 25% of the male population has experienced ejaculation by age 12. Men are able to reproduce their entire life span.
ORGASM is the highest point of sexual excitement, marked by strong feelings of pleasure and also normally by ejaculation of semen by the male and by vaginal contractions within the female. Orgasm is highest between the ages of 15-30 years. After 30 there is a gradual decline into old age but 70% of the population continues to be sexually active past the age of 70 years.
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