Human+Reproduction

Human Reproduction Male Reproductive Organs Penis — The penis is the male organ for sexual intercourse. It has three parts: the root, which attaches to the wall of the abdomen. Semen, which contains sperm, is expelled (ejaculated) through the end of the Scrotum — The scrotum is the loose pouch-like sac of skin that hangs behind the penis. It contains the testicles (also called testes), as well as many nerves and blood vessels. The scrotum has a protective function and acts as a climate control system for the testes. For normal sperm development, the testes must be at a temperature slightly cooler than the body temperature. Special muscles in the wall of the scrotum allow it to contract and relax, moving the testicles closer to the body for warmth and protection or farther away from the body to cool the temperature. Testicles (testes) — The testes are oval organs about the size of large olives that lie in the scrotum, secured at either end by a structure called the spermatic cord. Most men have two testes. The testes are responsible for making testosterone, the primary male sex hormone, and for generating sperm. Within the testes are coiled masses of tubes called seminiferous tubules. These tubules are responsible for producing the sperm cells through a process called spermatogenesis. Epididymis — The epididymis is a long, coiled tube that rests on the backside of each testicle. It functions in the transport and storage of the sperm cells that are produced in the testes. It also is the job of the epididymis to bring the sperm to maturity, since the sperm that emerge from the testes are immature and incapable of fertilization. During sexual arousal, contractions force the sperm into the vas deferens. Female Reproductive Organs The vagina is a muscular tunnel that connects the uterus to the outside of the body. It provides an exit for the menstrual fluid; and an entrance for the semen. The uterus, or the womb, is the place where the fertilized egg grows and develops into a baby during pregnancy. The neck of the uterus is called the cervix. It connects the uterus to the vagina and contains special glands called crypts that make mucus which helps to keep bacteria out of the uterus. The two fallopian tubes are attached to the upper part of the uterus on either side and are about 10 cm long. They are about as big as a piece of spaghetti. Each tube forms a narrow passageway that opens like a funnel into the abdominal cavity, near the ovaries. The ends of the fallopian tubes are draped over the two ovaries and they serve as a passageway for the egg to travel from the ovary into the uterus The two almond-sized ovaries are perched in the pelvis, one on each side, just within the fallopian tubes' grasp. The ovary serves two functions: the production of eggs and the secretion of hormones. Each month, at the time of ovulation, a mature egg is released by an ovary
 * Vas deferens — The vas deferens is a long, muscular tube that travels from the epididymis into the pelvic cavity, to just behind the bladder. The vas deferens transports mature sperm to the urethra in preparation for ejaculation.
 * Urethra — The urethra is the tube that carries urine from the bladder to outside of the body. In males, it has the additional function of expelling (ejaculating) semen when the man reaches orgasm. When the penis is erect during sex, the flow of urine is blocked from the urethra, allowing only semen to be ejaculated at orgasm.
 * Seminal vesicles — The seminal vesicles are sac-like pouches that attach to the vas deferens near the base of the bladder. The seminal vesicles produce a sugar-rich fluid (fructose) that provides sperm with a source of energy and helps with the sperms’ motility (ability to move). The fluid of the seminal vesicles makes up most of the volume of a man’s ejaculatory fluid, or ejaculate.
 * Prostate gland — The prostate gland is a walnut-sized structure that is located below the urinary bladder in front of the rectum. The prostate gland contributes additional fluid to the ejaculate. Prostate fluids also help to nourish the sperm. The urethra, which carries the ejaculate to be expelled during orgasm, runs through the center of the prostate gland.



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