The prostate is part of a man's reproductive system. It's an organ located in front of the rectum and under the bladder. The prostate surrounds the urethra, the tube through which urine flows.

A healthy prostate is about the size of a walnut. If the prostate grows too large, it squeezes the urethra. This may slow or stop the flow of urine from the bladder to the penis.

The prostate is a gland. It makes part of the seminal fluid. During ejaculation, the seminal fluid helps carry sperm out of the man's body as part of semen.

Male hormones (androgens) make the prostate grow. The testicles are the main source of male hormones, including testosterone. The adrenal gland also makes testosterone, but in small amounts.

Dictionary Terms

A small gland that makes steroid hormones, adrenaline, and noradrenaline. These hormones help control heart rate, blood pressure, and other important body functions. There are two adrenal glands, one on top of each kidney. Also called suprarenal gland.

A type of hormone that promotes the development and maintenance of male sex characteristics.

The organ that stores urine.

The release of semen through the penis during orgasm.

An organ that makes one or more substances, such as hormones, digestive juices, sweat, tears, saliva, or milk. Endocrine glands release the substances directly into the bloodstream. Exocrine glands release the substances into a duct or opening to the inside or outside of the body.

One of many chemicals made by glands in the body. Hormones circulate in the bloodstream and control the actions of certain cells or organs. Some hormones can also be made in the laboratory.

A part of the body that performs a specific function. For example, the heart is an organ.

An external male reproductive organ. It contains a tube called the urethra, which carries semen and urine to the outside of the body.

The last several inches of the large intestine closest to the anus.

The organs involved in producing offspring. In women, this system includes the ovaries, the fallopian tubes, the uterus, the cervix, and the vagina. In men, it includes the prostate, the testes, and the penis.

The fluid that is released through the penis during orgasm. Semen is made up of sperm from the testicles and fluid from the prostate and other sex glands.

Fluid from the prostate and other sex glands that helps transport sperm out of the man's body during orgasm. Seminal fluid contains sugar as an energy source for sperm.

The male reproductive cell, formed in the testicle. A sperm unites with an egg to form an embryo.

One of two egg-shaped glands inside the scrotum that produce sperm and male hormones. Also called testis.

A hormone made mainly in the testes (part of the male reproductive system). It is needed to develop and maintain male sex characteristics, such as facial hair, deep voice, and muscle growth. Testosterone may also be made in the laboratory and is used to treat certain medical conditions.

The tube through which urine leaves the body. It empties urine from the bladder.