Male reproductive system

Urology (from Greek οὖρον ouron "urine" and -λογία -logia "study of"), also known as genitourinary surgery, is the branch of medicine that focuses on surgical and medical diseases of the urinary system and the male reproductive organs. Organs under the domain of urology include the kidneys, adrenal glands, ureters, urinary bladder, urethra, and the male reproductive organs (testes, epididymides, vasa deferentia, seminal vesicles, prostate, and penis).

The urinary and reproductive tracts are closely linked, and disorders of one often affect the other. Thus a major spectrum of the conditions managed in urology exists under the domain of genitourinary disorders. Urology combines the management of medical (i.e., non-surgical) conditions, such as urinary-tract infections and benign prostatic hyperplasia, with the management of surgical conditions such as bladder or prostate cancer, kidney stones, congenital abnormalities, traumatic injury, and stress incontinence.

A man is an adult male human. Before adulthood, a male child or adolescent is referred to as a boy.

Like most other male mammals, a man's genome usually inherits an X chromosome from the mother and a Y chromosome from the father. Sex differentiation of the male fetus is governed by the SRY gene on the Y chromosome. During puberty, hormones which stimulate androgen production result in the development of secondary sexual characteristics that result in even more differences between the sexes. These include greater muscle mass, greater height, the growth of facial hair and a lower body fat composition. Male anatomy is distinguished from female anatomy by the male reproductive system, which includes the testicles, sperm ducts, prostate gland and epididymides, and penis. Secondary sex characteristics include a narrower pelvis and hips, and smaller breasts and nipples.

The prostate is an accessory gland of the male reproductive system and a muscle-driven mechanical switch between urination and ejaculation. It is found in all male mammals. It differs between species anatomically, chemically, and physiologically. Anatomically, the prostate is found below the bladder, with the urethra passing through it. It is described in gross anatomy as consisting of lobes and in microanatomy by zone. It is surrounded by an elastic, fibromuscular capsule and contains glandular and connective tissue.

The prostate produces and contains fluid that forms part of semen, the substance emitted during ejaculation as part of the male sexual response. This prostatic fluid is slightly alkaline, and milky or white in appearance. The alkalinity of semen helps neutralize the acidity of the vaginal tract, prolonging the lifespan of sperm. The prostatic fluid is expelled in the first part of ejaculate, together with most of the sperm, because of the action of smooth muscle tissue within the prostate. In comparison with the few spermatozoa expelled together with mainly seminal vesicular fluid, those in prostatic fluid have better motility, longer survival, and better protection of genetic material.

In human anatomy, the penis (/ˈpiːnɪs/; pl.: penises or penes; from the Latin pēnis, initially 'tail') is an external sex organ (intromittent organ) through which males ejaculate and urinate. Together with the testes and surrounding structures, the penis functions as part of the male reproductive system.

The main parts of the penis are the root, body, the epithelium, including the shaft skin, and the foreskin covering the glans. The body of the penis is made up of three columns of tissue: two corpora cavernosa on the dorsal side and corpus spongiosum between them on the ventral side. The urethra passes through the prostate gland, where it is joined by the ejaculatory ducts, and then through the penis. The urethra goes across the corpus spongiosum and ends at the tip of the glans as the opening, called the urinary meatus.

Prostate cancer is the uncontrolled growth of cells in the prostate, a gland in the male reproductive system below the bladder. Abnormal growth of the prostate tissue is usually detected through screening tests, typically blood tests that check for prostate-specific antigen (PSA) levels. Those with high levels of PSA in their blood are at increased risk for developing prostate cancer. Diagnosis requires a biopsy of the prostate. If cancer is present, the pathologist assigns a Gleason score; a higher score represents a more dangerous tumor. Medical imaging is performed to look for cancer that has spread outside the prostate. Based on the Gleason score, PSA levels, and imaging results, a cancer case is assigned a stage 1 to 4. A higher stage signifies a more advanced, more dangerous disease.

Most prostate tumors remain small and cause no health problems. These are managed with active surveillance, monitoring the tumor with regular tests to ensure it has not grown. Tumors more likely to be dangerous can be destroyed with radiation therapy or surgically removed by radical prostatectomy. Those whose cancer spreads beyond the prostate are treated with hormone therapy which reduces levels of the androgens (masculinizing sex hormones) which prostate cells need to survive. Eventually cancer cells can grow resistant to this treatment. This most-advanced stage of the disease, called castration-resistant prostate cancer, is treated with continued hormone therapy alongside the chemotherapy drug docetaxel. Some tumors metastasize (spread) to other areas of the body, particularly the bones and lymph nodes. There, tumors cause severe bone pain, leg weakness or paralysis, and eventually death. Prostate cancer prognosis depends on how far the cancer has spread at diagnosis. Most men diagnosed have low-risk tumors confined to the prostate; 99% of them survive more than 10 years from their diagnoses. Tumors that have metastasized to distant body sites are most dangerous, with five-year survival rates of 30–40%.

Testosterone is the primary male sex hormone and androgen in males. In humans, testosterone plays a key role in the development of male reproductive tissues such as testicles and prostate, as well as promoting secondary sexual characteristics such as increased muscle and bone mass, and the growth of body hair. It is associated with increased aggression, sex drive, dominance, courtship display, and a wide range of behavioral characteristics. In addition, testosterone in both sexes is involved in health and well-being, where it has a significant effect on overall mood, cognition, social and sexual behavior, metabolism and energy output, the cardiovascular system, and in the prevention of osteoporosis. Insufficient levels of testosterone in men may lead to abnormalities including frailty, accumulation of adipose fat tissue within the body, anxiety and depression, sexual performance issues, and bone loss.

Excessive levels of testosterone in men may be associated with hyperandrogenism, higher risk of heart failure, increased mortality in men with prostate cancer, and male pattern baldness.

Men's health is a state of complete physical, mental, and social well-being as experienced by men, and not merely the absence of disease. Differences in men's health compared to women's can be attributed to biological factors, behavioral factors, and social factors (e.g., occupations).

Men's health often relates to biological factors such as the male reproductive system or conditions caused by hormones specific to, or most notable in, males. Some conditions that affect both men and women, such as cancer, and injury, manifest differently in men. Some diseases that affect both sexes are statistically more common in men. In terms of behavioral factors, men are more likely to make unhealthy or risky choices and less likely to seek medical care.

The human reproductive system includes the male reproductive system, which functions to produce and deposit sperm, and the female reproductive system, which functions to produce egg cells and to protect and nourish the fetus until birth. Humans have a high level of sexual differentiation. In addition to differences in nearly every reproductive organ, there are numerous differences in typical secondary sex characteristics.

Human reproduction usually involves internal fertilization by sexual intercourse. In this process, the male ejaculates semen and sperm through his erect penis into the female's vagina. A small proportion of the sperm pass through the cervix into the uterus and then into the fallopian tubes for fertilization of the ovum. Only one sperm is required to fertilize the ovum. Upon successful fertilization, the fertilized ovum, or zygote, travels out of the fallopian tube and into the uterus, where it implants in the uterine wall. This marks the beginning of gestation, better known as pregnancy, which continues for around nine months as the fetus develops. When the fetus has developed to a certain point, pregnancy is concluded with childbirth, involving labor. During labor, the uterine muscles contract, and the cervix dilates typically over a period of hours, allowing the infant to pass from the uterus through the vagina. Human infants are entirely dependent on their caregivers and require parental care. Infants rely on their caregivers for comfort, cleanliness, and food. Food may be provided by breastfeeding or formula feeding.

The ejaculatory ducts (ductus ejaculatorii) are paired structures in the male reproductive system. Each ejaculatory duct is formed by the union of the vas deferens with the duct of the seminal vesicle. They pass through the prostate, and open into the urethra above the seminal colliculus. During ejaculation, semen passes through the prostate gland, enters the urethra and exits the body via the urinary meatus.

In human male anatomy, the radix (/reɪ.dɪks/) or root of the penis is the internal and most proximal portion of the human penis that lies in the perineum. Unlike the pendulous body of the penis, which is suspended from the pubic symphysis, the root is attached to the pubic arch of the pelvis and is not visible externally. It is triradiate in form, consisting of three masses of erectile tissue; the two diverging crura, one on either side, and the median bulb of the penis or urethral bulb. Approximately one third to one half of the penis is embedded in the pelvis and can be felt through the scrotum and in the perineum.

In male human anatomy, the glans penis or penile glans, commonly referred to as the glans, (/ɡlænz/; from Latin glans meaning "acorn") is the bulbous structure at the distal end of the human penis that is the human male's most sensitive erogenous zone and primary anatomical source of sexual pleasure. The glans penis is part of the male reproductive organs of humans and most other mammals where it may appear smooth, spiny, elongated or divided. It is externally lined with mucosal tissue, which creates a smooth texture and glossy appearance. In humans, the glans is located over the distal end of the corpora cavernosa and is a continuation of the corpus spongiosum of the penis. At the tip is the urinary meatus and the base forms the corona glandis. An elastic band of tissue, the frenulum, runs across its ventral surface. In men who are not circumcised, it is completely or partially covered by a fold of skin called the foreskin. In adults, the foreskin can generally be retracted over and past the glans manually or sometimes automatically during an erection.

The glans penis develops as the terminal end of the genital tubercle during the embryonic development of the male fetus. The tubercle is present in the embryos of both sexes as an outgrowth in the caudal region that later develops into a primordial phallus. Exposure to male hormones (androgens) initiates the tubercle's development into a penis making the glans penis anatomically homologous to the clitoral glans in females.

Emasculation is the removal of the external male sex organs, which includes both the penis and the scrotum, the latter of which contains the testicles. It is distinct from castration, where only the testicles are removed. Although the terms are sometimes used interchangeably, the potential medical consequences of emasculation are more extensive due to the complications arising from the removal of the penis. There are a range of religious, cultural, punitive, and personal reasons why someone may choose to emasculate themselves or another person.

The term emasculation may be used in a metaphorical sense, referring to the perceived loss of attributes traditionally associated with masculinity, such as strength, power, or autonomy.

Testicular cancer is cancer that develops in the testicles, a part of the male reproductive system. Symptoms may include a lump in the testicle or swelling or pain in the scrotum. Treatment may result in infertility.

Risk factors include an undescended testis, family history of the disease, and previous history of testicular cancer. More than 95% are germ cell tumors which are divided into seminomas and non-seminomas. Other types include sex-cord stromal tumors and lymphomas. Diagnosis is typically based on a physical exam, ultrasound, and blood tests. Surgical removal of the testicle with examination under a microscope is then done to determine the type.

Odynorgasmia, or painful ejaculation, also referred to as dysejaculation, dysorgasmia, and orgasmalgia, is a physical syndrome described by pain or burning sensation of the urethra or perineum during or following ejaculation. Causes include: infections associated with urethritis, prostatitis, epididymitis; use of anti-depressants; cancer of the prostate or of other related structures; calculi or cysts obstructing related structures; trauma to the region.

In female humans and other mammals, the clitoral hood (also called preputium clitoridis, clitoral prepuce, and clitoral foreskin) is a fold of skin that surrounds and protects the glans of the clitoris; it also covers the external clitoral shaft, develops as part of the labia minora and is homologous with the foreskin (also called the prepuce) in the male reproductive system.The clitoral hood is composed of mucocutaneous tissues; these tissues are between the mucous membrane and the skin, and they may have immunological importance because they may be a point of entry of mucosal vaccines.