The urethra. This is the tube which passes from the bladder down the penis to the outside. It carries both urine and semen. The main function is to give men the ability to fertilise a woman's egg ovum by producing and delivering semen. The testicles testes also make hormones which help men develop the characteristics associated with being male. This includes:. Find a range of men's health services, delivered by local professionals today. During puberty, the level of a hormone called gonadotrophin-releasing hormone GnRH increases.
GnRH is produced in a part of the brain called the hypothalamus. In turn this causes an increase in the production of two hormones from another part of the brain, called the pituitary gland. LH in the bloodstream causes cells in the testicles testes to make and release testosterone, the main male hormone. FSH and testosterone work together to stimulate the testes to produce sperm. Each sperm cell takes between days to form and around million are produced every day. Inside the testes sperm is made in structures called the seminiferous tubules.
At the top and to the back of each testicle testis is the epididymis, which stores sperm. Leading from the epididymis is the vas deferens. The vas deferens carries sperm towards the penis. Along the way it joins other tubes and during ejaculation collects fluids from the accessory sex glands.
The mixture of sperm and fluids from the accessory sex glands is called semen. About two thirds of the volume of semen come from the seminal vesicles.
The semen is then passed into the urethra. When sexually aroused, a number of changes occur inside the penis. The arteries supplying the penis get bigger, allowing more blood to enter its tissues.
The extra blood flow causes the penis to enlarge and to become more rigid. The extra blood flow plus signals from the nervous system and chemical changes cause an erection. Ejaculation is the term for the contractions that release semen.
Testosterone is an important hormone during male development and maturation for developing muscles, deepening the voice, and growing body hair. A long tube that is located near each testicle. The epididymis is the tube which moves the sperm from the testicles. Vas deferens. This is a tube in which the sperm is stored and it carries the sperm out of the scrotal sac.
The vas deferens is between the epididymis and the urethra and connects these together. Seminal vesicles. The sac-like glands that lie behind the bladder and release a fluid that forms part of semen. Prostate gland. It is about the size of a walnut, and surrounds the neck of the bladder and urethra—the tube that carries urine from the bladder.
It is partly muscular and partly glandular with ducts opening into the prostatic portion of the urethra. They are cm long, 2. The testes generate sperm, the male sex cells, as well as testosterone and other sex hormones. The production of sperm is constant and occurs within numerous lobules in each testis.
First, structures called seminiferous tubules generate stem cells. These cells, the spermatogonia, divide into spermatocytes, and then divide further to become spermatids. The process is called spermatogenesis. Spermatids move from the testis to the epididymis and mature into sperm. The epididymis, vas deferens, ejaculatory ducts, and urethra form a four-part transportation system. The epididymis sits directly on top of each testis.
Sperm from the testis mature as they move through the coiled duct of the epididymis. During sexual intercourse and ejaculation, they are expelled into the vas deferens. The vas deferens pushes the sperm up over the bladder and down toward the prostate gland. There, the vas deferens joins the ends of the seminal vesicles accessory reproductive glands to form the ejaculatory ducts. The ejaculatory ducts receive seminal fluid from the vesicles, pass through the prostate, and move semen into the urethra.
The male urethra extends from the bladder, through the prostate, to the external orifice at the end of the penis. It receives additional seminal fluids from the prostate before it expels semen out of the body.
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