The prostate gland is an important part of the male anatomy in humans as well as most other mammals. In humans it’s normally about the size of a walnut and it encircles the urethra, deep within the reproductive tract; it has a number of important purposes, but helping to produce, strengthen, and expel sperm is one of its most significant. It also plays a key role in preventing urine leakage during ejaculation. The gland is usually quite sensitive, both to external pressures and chemical changes in the body. It is more susceptible than most others to inflammation and enlargement, which can lead to a lot of problems in the realm of reproductive function. Its connection to lymphatic tissues and fluids also makes it more likely to develop cancerous growths and lesions, which can be life threatening if not caught quickly. Most medical experts recommend that the gland be checked for size and swelling about once a year.
Anatomical Basics
Like most glands, the prostate is very difficult if not impossible to detect externally. It sits right between the bladder and the top of the penis and the tubal urethra passes through it, effectively connecting all three. The gland also connects various ducts that aid in the production of seminal fluid, and it often acts as a sort of intermediary when it comes to the fluids that are and aren’t permitted to flow into the penis at a given time. It is controlled by the brain in response to various stimulation and arousal signals from the nervous system.
Role in Sperm Production
One of the most significant roles of the gland is to contribute to the volume and alkalinization of semen. Semen is mainly made up of spermatozoa, or sperm, but about 25% of it is comprised of a milky-white, slightly alkaline solution known as seminal vesicle fluid. This fluid helps to counteract the slightly acidic vagina, thereby helping sperm live longer and have a higher chance of fertilizing an egg, causing a pregnancy, and ultimately passing genetic material on to the next generation.
The gland also produces its own fluid, known as prostatic fluid. Unlike semen, which is more or less consistent amongst mammals, prostatic fluid varies widely in composition among species. It is usually made up of simple sugars. Human prostatic fluid contains less than 1 percent protein and has high levels of zinc; its main function is thought to be to lubricate the gland and help aid in the movement of other more significant substances.
Fluid Elimination
In most mammals, the urethra — the tube that carries urine from the bladder out of the body — passes through the prostate. This portion of the urethra is known as the prostatic urethra. When the prostate is tightened during ejaculation, it expands to squeeze the prostatic urethra shut, thereby preventing urination. That muscle contraction also helps expel semen during ejaculation.
Inflammation and Enlargement
The prostate gland is susceptible to several unique health issues, several of which are fairly common. Prostatitis is the inflammation of the prostate gland. It can be caused by a variety of things from bacterial infections to leukocytosis.
Benign prostatic hyperplasia (BPH), or an enlarged prostate, usually occurs in older men where the prostate enlarges sufficiently to interfere with urethral function. In a sense, the prostate expands and squeezes the urethra in these cases. This can result in hesitant and/or frequent but incomplete urination. It has been said that most any man that lives long enough will develop BPH. Treatments range from taking alpha-blockers to surgeries, including transurethral resection of the prostate (TURP).
Cancers and Unusual Growths
An enlarged prostate is also occasionally associated with prostate cancer. This type of cancer is one of the most common cancers suffered by men in developed countries. Fortunately for most it’s also pretty easy to detect early through regular rectal exams and targeted testing of Prostate Specific Antigen (PSA) levels in the blood and semen.
Female Equivalents
Skene's gland, also known as the paraurethral gland, is the female version of the prostate. It’s much smaller and obviously is not involved in sperm production, since the female reproductive system centers on eggs rather than sperm and eggs are housed in the ovaries. The paraurethral gland is similarly involved in closing off the bladder and controlling urine output, however, and in some women it also expels fluid during orgasm. This fluid, or female ejaculate, is typically quite similar to the prostatic fluid produced by the male prostate gland.