What Is the Prostate? A Guide to Its Form and Function and Some Common Problems

The prostate is a gland and reproductive organ located directly beneath the urinary bladder.

About the size and shape of a walnut, the prostate is only found in males and is an important part of the male reproductive system. (1)

Note that although females do not have a prostate, they do have the Skene's gland, or paraurethral gland, which is located at the lower end of the urethra and considered homologous to the prostate gland. (2)

Numerous health issues may affect the prostate as men get older, including prostatitis (prostate inflammation), prostate infections, enlarged prostate, and prostate cancer. (1)

The prostate is situated between the bladder and penis, just in front of the rectum (lower end of the bowel). It is above the muscles of the pelvic floor.

The urethra, a narrow tube that carries urine and semen out of the body through the penis, runs through the center of the prostate, which weighs less than 1 ounce (20 to 30 grams).

The word "prostate" comes from the Greek word "prostates," which means "one who stands before," aptly describing the position of the gland. That is, when viewed from below, the prostate "stands before" the bladder.

Because the rectum is behind the prostate, it is possible to feel the prostate with a finger when inserted through the rectum. The prostate feels elastic because it's surrounded by a supportive tissue called the stroma, which is made of flexible smooth muscle fibers and connective tissue (the prostate itself also contains many smooth muscle cells).

The muscle cells contract during ejaculation, forcing fluid stored in the prostate into the urethra. (3,4)

The prostatic fluid accounts for 20 to 30 percent of the volume of seminal fluid (semen). (2)

As mentioned before, this fluid contains enzymes, proteins, and minerals that protect and nourish sperm — and are necessary for the proper functioning of sperm cells.

What's more, research, such as one paper published in July 2015 in the journal PloS One, has suggested the alkalinity (or basic pH level) of the fluid helps ensure the viability of sperm in reproduction. (6)

More in Reproductive Health

What Men and Women 35 and Older Must Know About Fertility, Infertility, and Getting Pregnant

The prostatic fluid mixes with sperm and fluid from the seminal vesicles — which makes up the majority of semen and contains various other components, including the fructose that provides the main energy source for sperm outside of the body — inside of the urethra. (7)

Changes in the composition or secretion of the prostatic fluid affects the health and function of sperm, impacting male fertility.(5) These changes may arise due to various health issues with the prostate.

Learn More About the Form and Function of the Prostate

Noncancerous prostate enlargement is the most common prostate problem for men over 50 years old, according to the NIDDK. (10)

It's not well understood what causes prostate enlargement, also known as benign prostatic hyperplasia (BPH), but research suggests age-related hormonal changes may be to blame. Men younger than 40 rarely experience symptoms of BPH.

In men with BPH, the prostate presses into and pinches the urethra as it enlarges.

This pressure can negatively affect the urine-holding bladder, which is connected to the urethra, by weakening it and preventing it from emptying completely.

Prostate enlargement can cause a number of related urination symptoms, such as:

• Increased urinary frequency and urgency
• Weak or interrupted urine stream
• Urine with an unusual color or smell
• Nocturia, or frequent urination during periods of sleep
• Pain after urination (or after ejaculation)

Over time, BPH may cause complications, including urinary tract infections, damage to the bladder or kidneys, and bladder stones, among other things.

Treatment of BPH includes lifestyle changes, medication, and surgery, which may be minimally invasive. (10,11)

Learn More About Benign Prostatic Hyperplasia

If you’re having prostate trouble, you’re concerned about a friend or family member who is, or you’d like to stay up to date on prostate health and research, there are a number of organizations that provide online educational material, comprehensive medical information, emotional support, and avenues for financial assistance.

Learn More About Resources for Prostate Health