Learning medicine is hard work! Osmosis makes it easy. It takes your lectures and notes to create a personalized study plan with exclusive videos, practice questions and flashcards, and so much more. Try it free today! In benign prostatic hyperplasia, or BPH, prostatic refers to the prostate gland, hyperplasia means an increase in the number of cells, and benign means that these cells aren’t malignant, so they don’t invade neighboring tissues. So, benign prostatic hyperplasia is the non-cancerous growth of the prostate gland. This condition is common in men over 50, and is often considered a normal part of aging. The prostate is a small gland, about the size and shape of a walnut, that sits under the bladder and in front of the rectum. The urethra which is the tube through which urine leaves the bladder, goes through the prostate before reaching the penis. And that part of the urethra is called the prostatic urethra. The prostate is covered by a capsule of tough connective tissue and smooth muscle. Beneath this layer, the prostate can be divided into a few zones. The peripheral zone, which is the outermost posterior section, is the largest of the zone and contain about 70% of the prostate’s glandular tissue. Moving inward, the next section is the central zone which contains about 25% of the glandular tissue as well as the ejaculatory ducts that join with the prostatic urethra. Last, is the transitional zone, which contains around 5% of the glandular tissue as well as a portion of the prostatic urethra. The transitional zone gets its name because it contains transitional cells which are also found in the bladder. At the microscopic level, each of the tiny glands that make up the prostate is surrounded by a basement membrane made largely of collagen. Sitting within that basement membrane, is a ring of cube-shaped basal cells as well as a few neuroendocrine cells interspersed throughout. Finally, there’s an inner ring of luminal columnar cells, which are within the lumen or center of the gland. Luminal cells secrete substances into the prostatic fluid, that make it slightly alkaline that give it nutrients which nourish the sperm and help it survive in the acidic environment of the vagina. During an ejaculation, sperm leave the testes, travel through the vas deferens, into the ejaculatory ducts, and travel through the prostatic urethra. Smooth muscles in the prostate contract and push the prostatic fluid into the urethra where it joins the sperm as well as the semen which is the fluid that comes from the seminal vesicles. The luminal cells also produce prostate specific antigen, or PSA, which helps to liquefy the gel-like semen after ejaculation, thereby freeing the sperm to swim. The basal cells and luminal cells of the prostate rely on stimulation from androgens, or male sex hormones, for survival. The androgens include testosterone, which is produced by the testicles, and dihydrotestosterone, which is produced in the prostate itself. This androgen is produced by the prostatic enzyme 5α-reductase which converts testosterone into the more potent dihydrotestosterone. Since androgens are steroids, so they can cross the cell membrane and bind to the androgen receptors within the cell’s nucleus. This inhibits apoptosis or programmed cell death, allowing luminal and basal cells in the prostate to keep growing and multiplying. Dihydrotestosterone is ten times more potent than testosterone because it can bind to androgen receptors much longer. Now, after the age of 30, men produce about 1% less testosterone per year. But for unclear reasons, 5α-reductase activity increases with age, so even with less testosterone, there could be an increase in dihydrotestosterone. Normal prostate cells respond to the increase in dihydrotestosterone levels by living longer and multiplying - that’s the underlying cause of benign prostatic hypertrophy. This is a normal process of aging, and around 50% of men develop BPH by the age of 60, and over 90% have it by the age of 85. Fortunately, in BPH there’s no increased risk for developing cell mutations that lead to prostate cancer. Rather, the entire prostate gland enlarges pretty uniformly and small hyperplastic nodules can form within it. These nodules are smooth, elastic, and firm and are sometimes mistaken for prostate cancer. Typically, hyperplastic nodules will form in the inner portions of the gland, specifically around the prostatic urethra, called the periurethral zone. When these nodules or the prostate tissue itself compresses the prostatic urethra, it becomes more difficult for urine to pass though. So the urine builds up in the bladder causing it to dilate. In response, the smooth muscle walls of the bladder will contract harder, and this leads to bladder hypertrophy were the walls thicken and become easily irritated. Finally, the stagnation of urine in the bladder also promotes bacterial growth, and can lead to urinary tract infections. Symptoms of BPH start up when the prostatic urethra gets obstructed, and it leads to a weak and inconsistent stream of urine, called dribbling. The person might also have to strain when urinating to overcome the obstruction, have pain during urination called dysuria, or trouble initiating urination called hesitancy. As urine builds up in the bladder it causes a constant sense of incomplete bladder emptying, which increases the frequency of urination at night - called nocturia. Benign prostatic hyperplasia can be identified with a digital rectal examination, which is where a finger is inserted into the rectum to feel against the anterior wall of the rectum which lies along the posterior prostate. An enlarged prostate could indicate benign prostatic hyperplasia, while hard nodules could be a sign of prostate cancer. Levels of prostate specific antigen or PSA, a substance produced by healthy prostate cells, are also elevated in benign prostatic hyperplasia, since there are more cells around making the PSA. Treatment of BPH focuses on relieving the obstruction and allowing the urine to flow normally. This can be done through medications like finasteride, a 5α-reductase inhibitor, which shrinks the prostate gland by inhibiting the conversion of testosterone into dihydrotestosterone. Next, α1-antagonists like phenoxybenzamine can bind to α1 receptors on the smooth muscles in the neck of the bladder, the prostate, and urethra, causing them to relax and allowing urine to pass. In some cases, surgical procedures like transurethral resection of the prostate, or TURP, can be done to remove part or all of the prostate. All right, as a quick recap, benign prostatic hyperplasia, of BPH is a condition caused by increased 5α-reductase activity in the prostate which leads to increased dihydrotestosterone production, and prostate hyperplasia. This is considered to be a normal part of aging and does not increase the risk of developing prostate cancer. The enlarged prostate gland can obstruct the prostatic urethra, which will lead to urine retention, causing the bladder to dilate and hypertrophy. Symptoms of BPH include urinary problems like urinary hesitancy, dysuria, dribbling, feeling of bladder fullness, and nocturia. BPH treatments include medications like 5α-reductase inhibitors, α1-antagonists, or a TURP procedure.