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what are the structures of the male reproductive system

what are the structures of the male reproductive system插图

Key PointsThe functions of the male reproductive system include producing and transporting sperm,ejaculating sperm into the female reproductive tract,and producing and secreting male hormones.Most of the male reproductive system is located outside of the body. ...The internal organs of the male reproductive system are called accessory organs. ...

What are the five major parts of the male reproductive system?

The male reproductive system includes the scrotum,testes,spermatic ducts,sex glands,and penis. These organs work together to produce sperm,the male gamete,and the other components of semen. These organs also work together to deliver semen out of the body and into the vagina where it can fertilize egg cells to produce offspring.

What are the four ducts of male reproductive system?

male reproductive duct systemEpididymis. Sperm leave the testes through a series of efferent ducts that enter the epididymis. ...Ductus deferens. The ductus deferens,also called vas deferens,is a fibromuscular tube that is continuous ( or contiguous) with the epididymis.Ejaculatory duct. ...Urethra. ...

Which structure produces sperm in a male?

They include:the testes ( testicles)the duct system: epididymis and vas deferens (sperm duct)the accessory glands: seminal vesicles and prostate glandthe penis

What systems work with the male reproductive system?

The reproductive system is usually comprised of either male or female reproductive organs and structures. The growth and activity of these parts are regulated by hormones. The reproductive system is closely associated with other organ systems, particularly the endocrine systemand urinary system.

What are the internal organs of the male reproductive system?

These external organs include the penis, scrotum and testicles. Internal organs include the vas deferens, prostate and urethra. The male reproductive system is responsible for sexual function, as well as urination. Urology 216.444.5600.

How many testes do men have?

Most men have two testes. The testes are responsible for making testosterone, the primary male sex hormone, and for producing 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.

Where are the cowper glands located?

Bulbourethral glands: The bulbourethral glands, or Cowper’s glands, are pea-sized structures located on the sides of the urethra , just below the prostate gland. These glands produce a clear, slippery fluid that empties directly into the urethra. This fluid serves to lubricate the urethra and to neutralize any acidity that may be present due to residual drops of urine in the urethra.

What is LH in a male?

LH stimulates the production of testosterone, which is necessary to continue the process of spermatogenesis. Testosterone is also important in the development of male characteristics, including muscle mass and strength, fat distribution, bone mass and sex drive.

Why is testosterone decreasing in men?

This can sometimes be a result of an illness, such as diabetes. It’s unclear whether decreasing testicular function contributes to symptoms like fatigue, weakness, depression or impotence.

Which gland is responsible for ejaculation?

The fluid of the seminal vesicles makes up most of the volume of your ejaculatory fluid, or ejaculate. Prostate gland: The prostate gland is a walnut-sized structure that’s located below the urinary bladder in front of the rectum. The prostate g land contributes additional fluid to the ejaculate.

What is the glans?

The glans: This is the cone-shaped end of the penis. The glans, which is also called the head of the penis, is covered with a loose layer of skin called foreskin. This skin is sometimes removed in a procedure called circumcision.

What are the reproductive systems of men?

The male reproductive system includes the penis, scrotum, testes, epididymis, vas deferens, prostate, and seminal vesicles. The penis and the urethra are part of the urinary and reproductive systems. The scrotum, testes (testicles), epididymis, vas deferens, seminal vesicles, and prostate comprise the rest of the reproductive system.

What is the epididymis?

Producing sperm (which carry the man's genes) Producing testosterone (the primary male sex hormone) The epididymis consists of a single coiled microscopic tube that measures almost 20 feet (6 meters) in length. The epididymis collects sperm from the testis and provides the environment for sperm to mature and acquire ...

Where does the semen come from?

Other fluid that makes up a very small amount of the semen comes from the vas deferens and from Cowper glands in the urethra.

Where does the spermatic cord travel?

In the scrotum, other structures, such as muscle fibers, blood vessels, and nerves, also travel along with each vas deferens and together form an intertwined structure, the spermatic cord.

What is the function of the urethra?

This channel is the part of the urinary tract that transports urine from the bladder and the part of the reproductive system through which semen is ejaculated. The prostate lies just under the bladder and surrounds the urethra. Walnut-sized in young men, the prostate enlarges with age.

What is the prostate?

The prostate lies just under the bladder and surrounds the urethra. Walnut-sized in young men, the prostate enlarges with age. When the prostate enlarges too much, it can block urine flow through the urethra and cause bothersome urinary symptoms.

How big are testes?

The testes are oval bodies that average about 1.5 to 3 inches (4 to 7 centimeters) in length and 2 to 3 teaspoons (20 to 25 milliliters) in volume. Usually the left testis hangs slightly lower than the right one. The testes have two primary functions:

What is the ejaculatory duct?

Ejaculatory ducts: These are formed by the fusion of the vas deferens and the seminal vesicles (see below). The ejaculatory ducts empty into the urethra. Urethra: The urethra is the tube that carries urine from the bladder to outside of the body.

What is the job of the epididymis?

It transports and stores 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.

How many testes do men have?

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 tubes are responsible for producing sperm cells. The internal organs of the male reproductive system, also called accessory organs, ...

Where does the vas deferens go?

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, the tube that carries urine or sperm to outside of the body, in preparation for ejaculation.

What are the internal organs of the male reproductive system?

The internal organs of the male reproductive system, also called accessory organs, include the following: Epididymis: The epididymis is a long, coiled tube that rests on the backside of each testicle. It transports and stores sperm cells that are produced in the testes. It also is the job of the epididymis to bring the sperm to maturity, ...

What is testosterone responsible for?

Testosterone is responsible for the development of male characteristics, including muscle mass and strength, fat distribution, bone mass, facial hair growth, voice change, and sex drive. Share on Facebook Share on Twitter Share on Pinterest Email Print.

What is the sac of skin that hangs behind and below the penis?

Scrotum: This is the loose pouch-like sac of skin that hangs behind and below the penis. It contains the testicles (also called testes), as well as many nerves and blood vessels. The scrotum acts as a "climate control system" for the testes.

How many rounds of cell division are there in meiosis?

Meiosis has two rounds of cell division: primary spermatocyte to secondary spermatocyte, and then secondary spermatocyte to spermatid. This produces four haploid daughter cells (spermatids). (b) In this electron micrograph of a cross-section of a seminiferous tubule from a rat, the lumen is the light-shaded area in the center of the image. The location of the primary spermatocytes is near the basement membrane, and the early spermatids are approaching the lumen (tissue source: rat). EM × 900. (Micrograph provided by the Regents of University of Michigan Medical School © 2012)

What are the male reproductive organs?

The testes (singular = testis) are the male gonads —that is, the male reproductive organs. They produce both sperm and androgens, such as testosterone, and are active throughout the reproductive lifespan of the male.

Where does immotile sperm mature?

From the lumen of the seminiferous tubules, the immotile sperm are surrounded by testicular fluid and moved to the epididymis (plural = epididymides), a coiled tube attached to the testis where newly formed sperm continue to mature (see Figure 27.4 ).

How many chromosomes are in a mature gamete?

However, mature gametes are haploid (1 n ), containing 23 chromosomes—meaning that daughter cells of spermatogonia must undergo a second cellular division through the process of meiosis.

What is the function of a male gamete?

The function of the male reproductive system ( Figure 27.2) is to produce sperm and transfer them to the female reproductive tract.

Where does the ductus deferens end?

From here, the ductus deferens continues posteriorly to the pelvic cavity, ending posterior to the bladder where it dilates in a region called the ampulla (meaning “flask”).

Where does sperm go in the testis?

Specifically, from the lumens of the seminiferous tubules, sperm move into the straight tubules (or tubuli recti), and from there into a fine meshwork of tubules called the rete testes. Sperm leave the rete testes, and the testis itself, through the 15 to 20 efferent ductules that cross the tunica albuginea.

How much sperm is in an ejaculate?

An ejaculate (a single emission of sperm) will contain from two to five milliliters of fluid with from 50–120 million sperm per milliliter. Figure 2.

Where do oviducts go?

The oviducts, or fallopian tubes, extend from the uterus in the lower abdominal cavity to the ovaries, but they are not in contact with the ovaries. The lateral ends of the oviducts flare out into a trumpet-like structure and have a fringe of finger-like projections called fimbriae, illustrated in Figure 4b. When an egg is released at ovulation, the fimbrae help the non-motile egg enter into the tube and passage to the uterus. The walls of the oviducts are ciliated and are made up mostly of smooth muscle. The cilia beat toward the middle, and the smooth muscle contracts in the same direction, moving the egg toward the uterus. Fertilization usually takes place within the oviducts and the developing embryo is moved toward the uterus for development. It usually takes the egg or embryo a week to travel through the oviduct. Sterilization in females is called a tubal ligation; it is analogous to a vasectomy in males in that the oviducts are severed and sealed.

What is the male reproductive system?

Male Reproductive Anatomy. In the male reproductive system, the scrotum houses the testicles or testes (singular: testis), including providing passage for blood vessels, nerves, and muscles related to testicular function. The testes are gonads, and they produce sperm (the male gametes) and some reproductive hormones.

How big is a testis?

The testes are gonads, and they produce sperm (the male gametes) and some reproductive hormones. Each testis is approximately 2.5 by 3.8 cm (1.5 by 1 in) in size and divided into wedge-shaped lobules by connective tissue called septa.

What is the haploid cell of sperm?

Sperm are haploid cells, consisting of a flagellum as a tail, a neck that contains the cell’s energy-producing mitochondria, and a head that contains the genetic material. Figure 2 shows a micrograph of human sperm as well as a diagram of the parts of the sperm. An acrosome is found at the top of the head of the sperm.

What are the cells that protect germ cells called?

The sperm cells are mixed with “nursemaid” cells called Sertoli cells which protect the germ cells and promote their development. Other cells mixed in the wall of the tubules are the interstitial cells of Leydig. These cells produce high levels of testosterone once the male reaches adolescence.

Why is pH important for sperm?

As sperm are only motile in an alkaline environment, a basic pH is important to reverse the acidity of the vaginal environment. The solution also contains mucus, fructose (a sperm mitochondrial nutrient), a coagulating enzyme, ascorbic acid, and local-acting hormones called prostaglandins.

What causes hypogonadism in men?

Primary hypogonadism (also referred to as hypergonadotropic hypogonadism) results from a gonadal failure to produce adequate testosterone or spermatogenesis despite high LH and FSH levels. Congenital causes of primary hypogonadism include Klinefelter syndrome, androgen synthesis disorder, or cryptorchidism. Acquired causes include hepatic cirrhosis, renal failure, drugs, autoimmune disease, irradiation, infections, trauma or commonly, age. These result in failure of the testes to develop properly, injury to the testes or impaired function. Hence, loss of testicular function results in damaged or underdeveloped Leydig or Sertoli cells that cannot respond to stimuli to maintain reproductive function.

What hormones are secreted by the pituitary?

In response, the anterior pituitary secretes LH and FSH into the blood. These gonadotropic hormones act on membrane receptors in the Leydig and Sertoli cells of the testes respectively. Both hormones come from the same glycoprotein family and consist of identical alpha subunits, but their different beta-subunit differentiates their functions. Both exert their physiologic effects by binding and activating a G protein receptor, which activates adenylyl cyclase and increases cellular cAMP levels, to stimulate Sertoli and Leydig cells. LH stimulates Leydig cells in the interstitium of the testes to produce testosterone from cholesterol. LH promotes desmolase, which is the initial rate-limiting enzyme that converts cholesterol into pregnenolone. This goes on to produce two key weak androgen intermediates: dehydroepiandrosterone (DHEA) and androstenedione. The enzyme 17-beta-hydroxysteroid dehydrogenase completes the conversion of androstenedione to testosterone. Testosterone acts on the hypothalamus and anterior pituitary via negative feedback to decrease the secretion of LH and FSH. Testosterone can also exert some effect on Sertoli cells, found in the periphery of the seminiferous tubules of testes. FSH and testosterone can stimulate Sertoli cells to release androgen-binding protein (ABP), which provides testosterone to germ cells during spermatogenesis. FSH stimulates Sertoli cells to promote sperm production and release inhibin B and MIS.  Inhibin serves as the negative feedback control that Sertoli cells exert on the hypothalamic-pituitary system to decrease FSH release. [6]

What is the function of the male reproductive system?

The function of the male reproductive system is to produce androgens such as testosterone that maintain male reproductive function and to promote spermatogenesis and transport into the female reproductive system for fertilization. The testes act as both endocrine and exocrine organs in that they are responsible for androgen production and sperm production and transport.

Where does testosterone come from?

Although a majority of testosterone production in men come from the Leydig cells in testes, the adrenal cortex contributes some androgen production. Similar to the hypothalamic-pituitary-gonadal axis, the adrenal glands are also controlled by the hypothalamus and anterior pituitary to form the hypothalamic-pituitary-adrenal axis. The hypothalamus release corticotrophin-releasing hormone (CRH), which stimulates the release of adrenocorticotropic hormone (ACTH) from the anterior pituitary. ACTH stimulates the enzyme desmolase to convert cholesterol into pregnenolone in the adrenals, similar to testosterone synthesis in the testes. Specifically, the zona reticularis of the adrenal medulla is responsible for generating the weak androgens DHEA and androstenedione, which go on to be converted to testosterone or estradiol peripherally. [2]

Where are the Leydig and Sertoli cells located?

Leydig cells are found in the interstitium of the testes adjacent to the seminiferous tubules. On histology, they have pink cytoplasm and can be identified by pink crystals of Reinke. They produce testosterone, a steroid hormone that exerts its effects by binding intracellular receptors of different tissues and regulating protein expression.[3]  Sertoli cells are found in the periphery of the seminiferous tubules. They promote spermatogenesis, which begins at the periphery of the tubules. They bind together to form a blood-testis barrier to keep germ cells contained in the seminiferous tubules and connect with each other through tight junctions. These cells are characterized by their relation to germ cells or primitive spermatogonia. Sertoli cells are much larger than germ cells, which are found nearby, and have less prominent nuclei. Germ cells line the interior of the seminiferous tubules and progress toward the lumen as they mature. These cells feature prominent, dark and dense nuclei. [4]

How often does the hypothalamus release GnRH?

Once puberty occurs, the hypothalamus releases GnRH in a pulsatile fashion every one to two hours to maintain amounts of FSH, LH and plasma testosterone, all of which regulate each other to maintain hormonal balance. In the third decade of life, testosterone levels are found to decline. [2][5][7]

Why do men have infertility?

Other causes of infertility in men include defects in androgen action, hyper/hypothyroidism, adrenal insufficiency, congenital adrenal hyperplasia, disordered sperm transport (i.e., ductal obstruction), and systemic disease. Defects in androgen action, such as androgen insensitivity syndrome, result in a female phenotype despite male genotype due to an inability of the body's tissues to respond to testosterone. Hence, despite high testosterone levels in circulation, the clinical presentation is that of a patient with low testosterone and typically female as the disorder arises from birth.

what are the structures of the male reproductive system
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