Male anatomy parts: Male Reproductive System | SEER Training

23.09.202108.06.2023 by alexxlab

The function and anatomy of the male reproductive system

The male reproductive system refers to the bodily systems responsible for sexual function in males. It consists of external and internal structures responsible for the formation, storage, and ejaculation of sperm, as well as the production of vital hormones for male development.

Similar to the female reproductive system, the male counterpart consists of various organs whose primary function is to accomplish reproduction.

In this article, we will explore the various components of the male reproductive system, including their individual functions.

Sex and gender exist on spectrums. For the purposes of this article, we use “male” and “female” to refer to a person’s sex assigned at birth. Learn more.

The male reproductive system consists of organs that are necessary for reproduction. Namely, this system consists of external and internal organs that play an essential role in the formation of sperm and the production of vital hormones that drive puberty. Additionally, these organs are also involved in other functions such as sexual function and urination.

The organs that comprise the male reproductive system all have individual roles that in combination aid in reproduction. To facilitate reproduction, the male reproductive system has several functions within the body. These include:

the production and secretion of male sex hormones
the production of sperm and semen
the transportation of semen into the female reproductive tract

Click on the BodyMap above to interact with a 3D model of the male reproductive system.

The male reproductive system comprises external and internal organs. The external organs include:

penis
testes
scrotum
epididymis

The penis

The penis is the cylindrical-shaped organ located in front of the scrotum. It consists of three columns of erectile tissue wrapped in connective tissue and skin. The penis becomes erect when blood fills the erectile tissue.

The erectile tissue includes two columns known as the corpora cavernosa and a single column in the front known as the corpus spongiosum. The corpus spongiosum also surrounds the urethra. The urethra is a muscular tube that allows the passage of urine from the bladder as well as semen, which contains sperm, from the seminal vesicles.

The penis has a root, a body, and a glans penis. The body is the visible cylindrical portion, while the root attaches to the pubic arch of the pelvis.

The glans penis is the top portion of the penis through which the urethra opens. Loose skin covers the glans penis. This is known as the prepuce (more commonly known as the foreskin). Some men may have their foreskin removed via a surgical process called circumcision. This may be for religious, medical, or aesthetic reasons.

The function of the penis, in addition to aiding in urination, is to assist with reproduction by transporting sperm to the female reproductive system.

During sexual intercourse, the penis becomes erect and stiffens, allowing a person to insert it into an orifice, such as the vagina. Following intercourse, a person will be able to ejaculate their semen into the vagina. Sperm cells within semen may then fertilize an egg.

The testes

The testes, also known as the testicles, are present behind the penis within the scrotum. The testes are about 2 inches long and 1.2 inches in diameter. They feel firm and slightly spongy. The testes typically begin growing between the ages of 11–13.

The testes are responsible for producing important hormones for sexual development, including:

testosterone
inhibin B
Mullerian inhibiting substance hormone (MIS)
estrogen

Testosterone increases sex drive (libido) in males and is also responsible for primary sexual development such as:

the descent of the testes
spermatogenesis
enlargement of the penis and testes

Testosterone is also responsible for the development of secondary sex characteristics, such as:

facial hair
vocal changes such as voice deepening
growth spurts
skeletal muscle growth

The testes are also where a person produces sperm through a process known as spermatogenesis. Sperm production begins during puberty and continues throughout life. Evidence notes that the testicles produce several million sperm per day and the full process of making sperm takes about 64 days.

The scrotum

The scrotum is the pouch of skin that houses and protects the testes, the epididymis, and part of the spermatic cord. It is present behind the penis.

The scrotum is outside of the body as sperm production requires a temperature that is lower than that of body temperature. The scrotum includes the cremaster muscle, which contracts and relaxes to regulate the temperature of the testes.

The epididymis

The epididymis is a coiled tube-like structure that is present on the top, outside edge of each testicle. Each epididymis is about 6 meters. The epididymis comprises a head, body, and tail. Sperm leave the testes and enter the epididymis. When sperm enter the epididymis, they are not yet mature and are unable to fertilize an egg.

Sperm complete their maturation within the epididymis which takes about 12 days. The body stores mature sperm in the tail portion of the epididymis. The epididymis tail joins with another tube known as the ductus deferens or vas deferens, which is a coiled tube that carries sperm out of the testes. Epididymis smooth muscles contract during ejaculation and push sperm into the vas deferens.

The internal organs include the spermatic cord, the prostate, the bulbourethral gland, and the seminal vesicles.

The spermatic cord

The spermatic cord is a cable-like structure that suspends and supports the testes and epididymis. The spermatic cord is composed of the vas deferens, arteries, and nerves. It provides blood and nerve supply to the testes, epididymis, and vas deferens.

The prostate

The prostate is a walnut-sized gland. It is dense and firm and is located below the urinary bladder. The prostate surrounds the urethra as it exits the urinary bladder. Short ducts are present that empty from the prostate into the urethra.

The prostate secretes an alkaline fluid that thickens the semen so that sperm can remain for longer in the female reproductive tract and enhances sperm motility.

The prostate is also where the body converts testosterone into its active form, dihydrotestosterone (DHT), which is essential for the normal development and function of the prostate.

The bulbourethral glands

The bulbourethral glands, also known as Cowper’s glands, are pea-sized glands that are located at the base of the penis and beneath the prostate.

The bulbourethral glands release a thick, alkaline, mucus-like fluid that lubricates the opening of the urethra and clears any residual urine. The fluid neutralizes the acidity of the urine and the acidity of the vagina.

The seminal vesicles

The seminal vesicles are glands that are present behind the urinary bladder. The seminal vesicles have ducts that connect with the vas deferens and form a structure known as the ejaculatory duct. The ejaculatory duct passes through the prostate and drains into the urethra.

The seminal vesicles release thick fluid which contains fructose (a type of sugar), proteins, and other enzymes. These act as a source of energy and nutrition for sperm.

The male reproductive system comprises various external and internal organs. The external organs include the testes, the penis, the scrotum and epididymis. The internal organs include the spermatic cord, the prostate, the bulbourethral gland, and the seminal vesicles.

These organs work together to facilitate reproduction and sexual function. Namely, this system assists in producing sex hormones to initiate puberty and enables a person to produce and transport sperm.

Male sex organs and reproductive system

Diagram of the male reproductive system

The testicles are 2 organs that are covered by a sac of skin
called the scrotum. They produce hormones (mostly testosterone) and sperm.

The male reproductive system is controlled by the pituitary
gland in the brain. When puberty begins, the pituitary gland signals the
testicles by releasing the follicle-stimulating hormone (FSH) and the luteinizing
hormone (LH). The testicles then start to make testosterone and sperm.
Testosterone is responsible for male sexual development, including deepening of
the voice, enlargement of the penis and testicles, growth of facial and body
hair and muscle development.

The epididymis sits on the back of each testicle. It stores sperm cells so they can mature.

The vas deferens carries mature sperm to the urethra for
ejaculation.

The prostate is deep in the pelvis in front of the rectum and
below the bladder. It makes prostatic fluid. Prostatic fluid is rich in enzymes, proteins and
minerals that help protect and nourish sperm. During sex, the prostate pushes
prostatic fluid through the ducts and into the urethra. Prostatic fluid mixes
with sperm and other fluids in the urethra and is ejaculated as semen.

The seminal vesicles are glands found on each side of the
prostate. They make most of the fluid in semen. The seminal vesicles fuse with
the vas deferens to empty into the urethra.

The urethra carries urine (pee) from the bladder to the outside
of the body. It also carries sperm out of the body through the meatus (opening
of the urethra out of the body) during ejaculation.

Diagram of the penis

The penis has 3 parts. The shaft is the main part of the penis. The head of the penis is called the glans. The glans is covered by a loose fold of moveable skin called the foreskin (prepuce). Sometimes the foreskin is surgically removed in an operation called a circumcision. The base of the penis within the pelvis is called the root.

For the penis to penetrate a vagina or an anus during sex, it needs to be erect, or stiff. An erection begins when the brain sends a signal down the spinal cord through the nerves that run to the pelvis. Nerves signal the blood vessels inside of each corpus cavernosum of the penis to fill with blood. When the blood flow increases, the spongy tissue expands and causes the penis to stiffen and enlarge.

During an orgasm, the prostate, seminal vesicles and vas deferens contract to move semen near the top of the urethra and then out during ejaculation. Each ejaculation can release up to 500 million sperm. After ejaculation, the extra blood flows out of the penis and the penis becomes soft again.

For pregnancy, semen ejaculated into a vagina (in the female reproductive system) allows for sperm to swim up through the cervix and uterus into the fallopian tube to meet an egg (if one is there). It only takes one sperm to fertilize the egg. Once fertilized, the egg grows in the uterus becoming an embryo and then a fetus.

Tim Rowe, MB BS, FRCSC, FRCOG
John Robinson, PhD, R Psych

Martini FH, Timmons MJ, Tallitsch RB. Human Anatomy. 7th ed. San Francisco: Pearson Benjamin Cummings; 2012.
Cancer Research UK. Men’s Sexual Organs. 2018: https://www.cancerresearchuk.org/about-cancer/coping/physically/sex/mens-organs.
American Cancer Society
. Sex and the Adult Male with Cancer
. 2021
: https://www.cancer.org/treatment/treatments-and-side-effects/physical-side-effects/fertility-and-sexual-side-effects/sexuality-for-men-with-cancer/treatment-and-desire-and-response.html.
American Society of Clinical Oncology. Sexual Health and Cancer Treatment: Men. 2019: https://www.cancer.net/navigating-cancer-care/dating-sex-and-reproduction/sexual-health-and-cancer-treatment-men.
National Cancer Institute. Sexual Health Issues in Men with Cancer. 2018: https://www.cancer.gov/about-cancer/treatment/side-effects/sexuality-men.
Cancer Research UK. About Sexuality and Sex Life. 2021: https://www.cancerresearchuk.org/about-cancer/coping/physically/sex/about-sexuality.
Cancer Research UK. How Cancer Can Affect Your Sexuality and Sex Life. 2018: https://www.cancerresearchuk.org/about-cancer/coping/physically/sex/effects#.

Anatomical structure of the male reproductive organs

Organs of the genitourinary system

The term “genitourinary” explains that this system consists of two components: urinary and genital. The combination of these two subsystems into one indicates a close relationship between the organs of this system, and in the male body this relationship is more closely manifested than in the female, since the male urethra (urethra) performs a dual function: urine excretion and ejaculation. Therefore, the urologist deals with the pathology of the male genitourinary system and the female urinary system.

The urinary system includes: kidneys, ureters, bladder, urethra. Kidneys In their shape, the kidneys resemble beans (or beans). The average size of the kidneys in an adult is 10 x 6 cm. The right kidney is usually located slightly lower than the left, since it is located under the liver. The kidneys are surrounded by fatty tissue, which, along with the surrounding muscles and ligaments, hold them in place. This explains why in thin people, as well as due to sudden weight loss, a disease such as nephroptosis can occur – omission of the kidney.

Kidneys consist of two layers. Superficial – cortical, and deeper – cerebral. On the section of the kidney, you can see the medulla is a system of tubules (tubules). The function of the tubules is to collect and divert urine into the pelvis. The pelvis is a combined collector of all tubules of the kidney. It opens into the gate of the kidney, in which, in addition to the pelvis, there is also an artery and a vein.

The basic unit of the kidney is the nephron. This is such a glomerulus, it consists of the very initial “cup-shaped” end of the tubule, which is entangled with capillaries, through which blood continuously circulates. Due to blood pressure and the membrane properties of the capillary walls, plasma is filtered from the blood into the glomerulus – that is, the liquid part of the blood without erythrocytes, leukocytes and other blood cells, which, normally, do not pass through the membrane, as well as some substances (sugar, protein, etc.) But in certain diseases, these blood components are filtered through the glomerular membrane and are found in the urine.

So, the main function of the kidneys is to “filter” the blood. The kidneys are the main organ that cleanses the blood of all toxins and metabolic products. When they become ill, this filtering function is disturbed, which leads to accumulation in the blood and poisoning of the body with its own metabolic products. It is worth noting that some drugs and their metabolic products are excreted from the body through the kidneys.

Ureters

The ureters are a downward extension of the pelvis and are a tube about 30 cm long. The lumen of the ureter is 5-6 mm. But this width is not constant and the lumen of the ureter narrows in three places – the so-called physiological narrowing. The significance of these narrowings lies in the fact that small kidney stones can get stuck in them. The ureters empty into the bladder.

Bladder

The bladder is an extensible reservoir, the wall of which contains a muscular layer and is lined with a mucous membrane from the inside. The ureters flow into the bladder. The average bladder capacity is 300 to 600 ml.

Urethra (urethra)

The urethra is a hollow tube that carries urine out of the bladder. The urethra in men and women is different: in men it is long and narrow (30 cm long, about 8 mm wide), while in women it is short and wide (3-4 cm long, 1-1.5 cm wide). These structural features of the urethra in women are the main reason that they often develop inflammatory diseases of the bladder – cystitis, since the infection easily enters the bladder through the short female urethra. The lumen of the urethra is covered with a mucous membrane. Inflammation of this membrane – urethritis – occurs as a result of infection, both non-specific (conditionally pathogenic) and specific (gonorrhea, chlamydia, trichomoniasis, etc.).

Reproductive system. Male reproductive organs

Male internal genital organs

Deferent ducts
spermatic cords
Seminal vesicles
Prostate
Bulbourethral gland

Male external genitalia

Male urethra
Scrotum
Testicles
Peritoneum of the pelvic cavity

Prostate (prostate)

The prostate is located directly under the bladder at its neck and covers the urethra with its thickness, i.e. the urethra passes through it. This is the so-called prostatic urethra. Both the ducts of the prostate and the ducts of the seminal vesicles open into it. The prostate is a glandular organ, meaning most of its tissue is glandular. In shape and size, the prostate resembles a chestnut.

The main function of the prostate is the production of a special transparent liquid – prostatic secretion (prostate juice), which is part of the semen. The composition of sperm is quite complex. Sperm is a mixture of secretions from a number of glands. In particular, in addition to spermatozoa, semen contains secretions of the prostate gland, seminal vesicles and glands of Littre and Cooper.

The secretions of the prostate gland attached to the seed have an alkaline reaction and an opalescent appearance, contain licitous grains, prostatic bodies, epithelial, granular cells and spermine, which gives the seed a translucent milky appearance and a specific smell. The discharge of the seminal vesicles is odorless, sticky, colorless, consists of epithelial cells, single leukocytes and formations similar to sago grains.

Secrets of the prostate and seminal vesicles liquefy thick semen, ensure the viability of spermatozoa and give them the necessary mobility.

Sperm has the appearance of a cloudy, gelatinous, stretchy liquid, and the white color is due to the presence of spermatozoa in it. The secretion of the testicles consists of spermatozoa and phosphate crystals.

Seminal vesicles

Seminal vesicles are peculiar convoluted sacs along the posterolateral surface of the bladder. The main function of the seminal vesicles is a reservoir of seminal fluid. In the seminal vesicles, the seminal fluid also undergoes some changes in order to become a full-fledged sperm. During sexual intercourse, during ejaculation, seminal fluid is ejected from the seminal vesicles through the ducts into the urethra, and, mixing with the juice of the prostate and the secret of other glands, is ejected through the external opening of the urethra.

The vas deferens

The vas deferens are thin tubes that lead from the testicles and empty into the seminal vesicles. Through them, the seminal fluid from the testicles enters the seminal vesicles.

Testicles

The testicles are a paired organ. They are located in the scrotum. In them, the formation and maturation of spermatozoa occurs. In addition, the testicles are the main organ in which the main male sex hormone, testosterone, is produced. It should be noted such an interesting fact that usually the left testicle is located slightly lower than the right one.

As already noted, the main function of the testicles is the production of spermatozoa. Spermatozoa are produced in them by special cells – Sertolli cells. In addition to these cells, there are also Leydig cells in the testicles, these are hormone-active cells that produce testosterone.

Each testicle consists of lobules filled with convoluted seminiferous tubules. On top of each testicle is an appendage that passes into the vas deferens. The functions of the testis are under the control of the anterior pituitary gland. It is worth noting the fact that such an arrangement of the testicles – the main, from the point of view of reproduction, genital organs – is associated with a special temperature regime, which is necessary for the maturation of spermatozoa in them. Those. for normal maturation of spermatozoa, a temperature of several degrees below body temperature is required. Therefore, such an important organ, from the point of view of storing and transmitting the genetic information of a species, is located in a not very reliable place – outside. However, many animals have a muscle that, in case of danger, raises the testicle and draws it into the abdominal cavity. In humans, it is underdeveloped.

Each testicle is covered with membranes in its half of the scrotum. There are seven in total. Sometimes, in case of accumulation between the layers of the testicles, dropsy (hydrocele) occurs.

Penis

The male penis is used for sexual intercourse and makes fertilization possible, as well as in the thickness of his spongy body passes the urethra, through which urine or semen is excreted. Those. the penis has a dual function: urination and procreation. The penis has a complex structure. In the upper part of it there are two cavernous bodies, and under them – a spongy body. The cavernous bodies are covered with a connective tissue protein membrane.

Cavernous bodies got their name for their special cellular structure, which looks like a cave. Such a structure is necessary to ensure an erection and sexual intercourse. Studies show that an erection occurs as a result of the expansion of the arteries that bring blood to the penis, the spasm of the veins through which this blood departs from the penis, and the relaxation of the cells of the cavernous bodies of the penis. Arteries, veins and cells of the corpora cavernosa are composed of smooth muscles. These muscles are affected by the so-called neurotransmitters – substances that are released during stimulation of the nerves that control the erection process.

After appropriate sexual stimulation, these substances lead to relaxation (relaxation) of the smooth muscles of the cavernous bodies of the penis, expansion of their arterial cells, which is manifested by a powerful increase in blood flow to the penis. Then the cells fill with blood, expand and compress the veins through which the blood drains, which leads to a further increase in intracavernous pressure, thereby causing an erection.

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Anatomy and physiology of the male genitourinary system

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Anatomy and function of the male reproductive system

In men and women, the genital organs are located both inside the pelvic cavity and outside it. Most of the male reproductive system is located outside. Such a device in wildlife is a demonstration of its strength and superiority. Perhaps this is why many, if not most, men are embarrassed to see a doctor if they have problems in their intimate life.

Article updated

Sep 22, 2022
Reading time: 6 minutes

Contents

Structure and functions of the external male genital organs

Internal male genital organs

Hormones regulating the function of the male reproductive system

Sperm formation

Menopause in men: myth or reality

9 0162

Promotion until June 22 Men’s check “Basic” with a 30% discount Tick-tock Men also have a biological clock Bad habits Smoking is bad for seminal fluid Spermogram Primary sperm fertility indicator

This article is not to be used for diagnosis, treatment, and is not a substitute for seeing a doctor.

The reproductive system of a man is extremely important, like the rest of the body’s systems that ensure normal life. Therefore, an untimely appeal to a specialist or, even worse, ignoring the warning signs, creates much bigger problems than they were originally.

The male reproductive system has three main tasks:

Formation of spermatozoa in the testes (seniferous tubules). In the process of one ejaculation, 30-500 million spermatozoa come out.
Evacuation of seminal fluid from the male genital organs and its delivery to the female.
Synthesis of the main androgen (a group of steroid sex hormones in men) – testosterone.

Penis (penis) – an organ involved in sexual contact, spewing seminal fluid. The place of attachment of the phallus to the pubis is the root. The body of the penis and the head are covered by the foreskin (skin fold), which normally should easily and painlessly move away, exposing the head. In the foreskin there are multiple glands that produce smegma (sebaceous lubricant). Internally, the penis consists of two cavernous (cavernous) and one spongy (spongiform) bodies. It is to the cavernous bodies that a man owes the appearance of an erection, in which the bodies are filled with blood and “swell”, increasing the size of the penis. In the spongy body is the urethra (urethra), which blocks the path for the passage of urine during intercourse and ejaculation.
Testicles (testicles) – olive-shaped paired organs of different sizes produce testosterone and spermatozoa. They are located in the sac (scrotum), which acts as a “climate control”. For healthy spermatogenesis (sperm production), the testicles must be maintained at a constant temperature below general body temperature. This provides the scrotum and the external location of the testicles. Otherwise, spermatogenesis will be impaired, which will negatively affect fertility (the ability to conceive).

The secretory and barrier function of the prostate is distinguished. The gland produces its own secret, which enters the sperm during ejaculation. The secret contains enzymes, acids, immunoglobulins and other trace elements. The secret also contains immunity factors that allow the prostate to perform a barrier function, which consists in preventing the penetration of pathogenic microflora from the urethra into the urinary tract and preventing the spread of microorganisms from the urethra to the vas deferens. The presence of zinc ions in secret protects the male genital tract from infection. The work of the gland is controlled by pituitary and steroid hormones, estrogens.

Spermatogenesis (production of seminal fluid) is carried out under the influence and control of hormonal substances. It starts from the moment of puberty (11-15 years), therefore, until this age, spermatozoa are not produced in the boy’s body. When testosterone reaches the age-appropriate level in a teenager, this leads to the activation of stem cells in the testicles (spermogonia). Spermogonium is converted into spermatocytes containing a double chromosome set. Spermatocytes divide, forming, in turn, secondary spermatocytes, which contain one chromosome set each.