Prostate schematic diagram

The Prostate: Definition & Function

The Prostate: Definition & Function
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The where, what, and why of a male-only gland

How can a gland the size of a walnut that weighs only about an ounce cause so much trouble? To answer this question, one must look at the prostate’s position in a very crowded place in the body. The prostate is located in front of the rectum, the last part of the colon, and just below the bladder, the hollow organ that holds urine before it is excreted out the body.

One source of the trouble is the fact that the prostate wraps around the upper part of the urethra, the slender tube that carries urine from the bladder out of the body through the penis. At birth, a baby boy’s prostate gland weighs less than half an ounce, and the gland goes through growth spurts during adolescence and young adulthood.

It’s normal for the prostate to start to grow again when men are in their late 40s and 50s. But when it does, the gland may press on the urethra, preventing urine from flowing freely. That leads to a variety of urinary problems.

But the prostate isn’t just a troublemaker. It’s the job of the testicles to produce sperm, but the prostate gland helps supply the semen, the thick, milky fluid that nourishes and protects sperm cells during their travels. The prostate’s contribution to semen is alkaline, so it helps sperm survive in the acidic environment of the vagina.



Counterintuitively, the base is located at the top of the gland and the apex at the bottom.

The inside of the gland is made up of an intricate series of ducts lined with cells that produce the prostatic fluid. During ejaculation, the prostate pushes that fluid through those ducts and then into the urethra, where it combines with sperm. Seminal vesicles—slender glands that sit on either side of the prostate—also contribute secretions to semen. By volume, their contribution is actually greater than that of the prostate gland.

The prostate is also tied in to the body’s infinitely complex system of hormones. To function properly, it requires adequate amounts of certain hormones, including testosterone, produced by the testicles, as well as other hormones that come from the pituitary gland, which hangs off the base of the brain, and the adrenal glands, which sit on top of the kidneys.

Although the prostate is sometimes depicted as having a simple round shape, the prostate is actually divided into right and left lobes. It’s also tapered at one end. The wider part, called the base, is nestled up next to the bladder, and the tip, or apex, is farthest away from the bladder.

If the prostate were an arrow, it would be pointing down.

If the orientation is front and back, then the front is referred to as the anterior of the gland and the back, the posterior. These divisions of the gland and the medical terms for them matter when it comes to prostate cancer. Cancers that are located near the base have a propensity to spread to the surrounding tissue, including the seminal vesicles. Cancers in the apex can make surgical removal difficult.