Detailed Explanation of the Location, Structure, and Physiological Functions of the Prostate

**Prostate Health**

**I. Basic Knowledge about the Prostate**

[Location of the prostate] The prostate is a gland unique to men, located at the bottom of the pelvic cavity, above the bladder, below the urethra, in front of the pubic bone, and behind the rectum.

This is why the prostate can be felt by moving forward during a digital rectal examination.

The prostate is fixed to the left and right by many ligaments and fascia, which determines its hidden location.

Located below the bladder neck and surrounding the junction of the bladder opening and the urethra, this part of the urethra is therefore called the "prostatic urethra," meaning that the duct formed in the middle of the prostate constitutes the upper part of the urethra.

In other words, the prostate gland guards the upper opening of the urethra, and if there is a lesion in the prostate gland, urination will be the first thing affected.

The prostate is closely adjacent to the vas deferens and seminal vesicles. The ejaculatory duct enters the prostate from the top and opens into the recess in the middle of the prostate. This physiological position easily explains why prostate diseases often affect sexual function. In fact, prostatitis and seminal vesiculitis can be called "unfortunate brothers".

[Structure of the prostate] The prostate can be divided into the external gland group and the internal gland group, which are separated by a layer of muscle fiber tissue.

The external gland group is larger and constitutes the main part of the prostate, including branch glands and the main gland.

The internal gland group is mainly concentrated in the urethral mucosa and submucosa, and is divided into mucosal glands and submucosal glands.

Mucosal glands surround the prostatic portion of the urethra, while submucosal glands are located between the mucosal glands and the septum of myofibril tissue.

Based on this characteristic, the prostate can be divided into the central region, the peripheral region, and the transitional region.

This is a new method for dividing the prostate.

The previous classification method divided the prostate into five lobes: the anterior, middle, and posterior lobes and two lateral lobes.

The anterior lobe is very small, located anterior to the urethra, between the two lateral lobes, and has no significant clinical importance.

The middle lobe, called the prostatic isthmus, is wedge-shaped and located behind the urethra, that is, the glandular tissue between the two ejaculatory ducts and the urethra.

The posterior lobe is located behind the ejaculatory duct, the middle lobe, and the two lateral lobes.

The two lobes are closely attached to the lateral wall of the urethra, located anterior to the lateral part of the posterior lobe, and on either side of the anterior and middle lobes.

[Physiological functions of the prostate] (1) Exocrine function: The prostate is the largest accessory gland in men and is also one of the exocrine glands in the human body.

The prostatic fluid secreted by the sperm is an important component of semen and plays a vital role in the normal function of sperm.

The secretion of prostatic fluid is mainly regulated by androgens.

Prostatic fluid contains some strong proteolytic enzymes and fibrinolytic enzymes, which can promote the union of sperm and egg.

Prostatic fluid contains another substance that makes it easier for nutrients in semen to enter sperm and be converted into energy, thereby enhancing sperm motility.

Prostatic fluid is alkaline, which can buffer the acidic secretions in the vagina, thus helping sperm survive in the female reproductive tract.

(2) Endocrine function: In recent years, it has been found that the prostate also has endocrine function, so the prostate can also be considered an endocrine organ.

The prostate contains abundant 5α-reductase, which can convert testosterone into the more physiologically active dihydrotestosterone.

Dihydrotestosterone plays an important role in the pathogenesis of benign prostatic hyperplasia.

By blocking 5α-reductase, the production of dihydrotestosterone can be reduced, thereby causing the hyperplastic prostate tissue to shrink.

(3) Control of urination function: The prostate surrounds the urethra and is close to the bladder neck, forming the proximal urethral wall. Its circular smooth muscle fibers surround the prostatic part of the urethra and participate in the formation of the internal urethral sphincter.

When the urge to urinate occurs, the detrusor muscle contracts while the internal sphincter relaxes, allowing urination to proceed smoothly.

(4) Transport function: The urethra and two ejaculatory ducts pass through the prostate parenchyma. When ejaculating, the muscles of the prostate and seminal vesicles contract, which can push the contents of the vas deferens and seminal vesicles into the posterior urethra through the ejaculatory ducts and then expel them from the body.

(5) Sensitive areas: Appropriate stimulation of the prostate can induce sexual arousal.

[Composition of Prostatic Fluid] Prostatic fluid is a secretion of the prostate gland.

Under normal circumstances, it is relatively thin, colorless or pale milky white liquid with a protein-like luster, and is weakly acidic with a pH of 6-7.

The secretion of prostatic fluid is controlled by male hormones, with a daily secretion volume of approximately 0.5 to 2 ml.

It is an important component of semen, accounting for about 1/10 to 1/3 of the ejaculated semen volume.

Prostatic fluid contains very little protein and mainly contains high concentrations of zinc ions, acid phosphatase, proteolytic enzymes, and fibrinolytic enzymes.

Among them, proteolytic enzymes and fibrinolytic enzymes can promote semen liquefaction.

Testing for acid phosphatase and citric acid can help determine prostate function and the presence of cancer.

Prostatic fluid is milky white in appearance, has a special odor, and is slightly acidic. In addition to water, it mainly consists of: ① Citric acid: The concentration of citric acid in prostatic fluid is the highest among various tissues in the human body, followed by semen and mammary glands.

② Phosphoric acid: The level of phosphatase in the prostate can be reflected by the serum level. Clinically, the increase of acid phosphatase is used as a reference indicator for prostate cancer and prostate cancer metastasis.

③ Zinc: Zinc is one of the important components of the prostate. Its combination with albumin protects sperm and enables sperm to carry out normal metabolism.

Zinc compounds can form antibacterial factors in the prostate, which can fight against pathogenic microbial infections.

Studies have shown that zinc concentration in the prostate increases during androgen therapy and decreases after orchiectomy or estrogen therapy.

④ Other enzymes: such as coagulating enzymes and cellulosic enzymes, play important physiological roles in the coagulation and liquefaction of semen.

⑤ Small molecules such as sodium, potassium, calcium, and oxygen, as well as lipids and proteins.

Prostatic fluid and semen are different, but they are closely related.

Prostatic fluid is a component of semen and is mainly secreted by the prostate gland, while semen contains secretions from various glands.