Chapter II - Male Reproduction
Male Reproductive System
The human male reproductive system is a series of organs located outside of the body and around the pelvic region of a male. They consist of
Bulbourethral glands - Cowper's glands - Ejaculatory duct - Epididymis - Foreskin - Frenulum - Glans penis - Penis - Prostate - Scrotum - Seminal vesicles - Spermatic cord - Testes - Urethra - Vas deferens
The males contribute to reproduction by ejaculating sperms into the female's vagina. The sperms then fertilize the egg in the female body and the fertilized egg gradually develop into a foetus, and later born as a child.
The prostate is an exocrine gland of the male mammalian reproductive system. Its main function is to secrete and store a clear, slightly basic fluid that constitutes up to one-third of the volume of semen. The prostate differs considerably between species anatomically, chemically, and physiologically. A healthy human prostate is slightly larger than a walnut. It surrounds the urethra just below the urinary bladder. It is located in front of the rectum and can be felt during a rectal exam.
The male urethra has two functions: to carry urine from the bladder during urination and to carry semen during ejaculation. Within the prostate, the urethra coming from the bladder is called the prostatic urethra and merges with the two ejaculatory ducts. Semen is composed of sperm and seminal fluid; about 10-30% of the seminal fluid is produced by the prostate gland, the rest is produced by the two seminal vesicles. The prostate also contains some smooth muscle that helps to expel semen during ejaculation.
Prostatic secretions vary between species. They are generally composed of simple sugars, and are often slightly basic. In human prostatic secretions, the protein content is less than 1% and includes proteolytic enzymes, acid phosphatase, and prostate-specific antigen. Its secretions also contain zinc and citric acid.
To work properly, the prostate needs male hormones (androgens). Male hormones are responsible for male sex characteristics. The main male hormone is testosterone, which is produced mainly by the testicles. Some male hormones are produced in small amounts by the adrenal glands.
Prostate glands are found only in males; Skene's glands in females are homologous to the prostate gland in males.
Disorders of the prostate
Inflammation of the prostate gland is known as prostatitis. If the prostate grows too large it may constrict the urethra and impede the flow of urine, making urination difficult and painful and in extreme cases completely impossible. Prostatitis is treated with antibiotics, prostate massage or surgery.
In older men, the prostate often enlarges to the point where urination becomes difficult. This is known as benign prostatic hyperplasia and can be treated with medication or with surgery that removes part of the prostate. The surgery most often used in such cases is called transurethral resection of the prostate (TURP or TUR). In TURP, an instrument is inserted through the urethra to remove prostate tissue that is pressing against the upper part of the urethra and restricting the flow of urine.
Prostate cancer is one of the most common cancers affecting elderly men in developed countries and a major cause of death. Regular rectal exams are recommended for elderly men to detect prostate cancer early. There is also a blood test that measures the concentration of a protein, Prostate Specific Antigen (PSA), which is normally very low. Elevated test results may be an indicator of disorder within the prostate, either prostatitis, benign hyperplasia or prostate cancer. The PSA test cannot distinguish between them, but can lead a doctor to investigate further. Prostate cancer is treated with hormone manipulation (prevention of production of testosterone), radiation and/or surgery. It has recently been found that the drug Docetaxel can be effective in the treatment of prostate cancer.
Benign Prostatic Hyperplasia
Benign prostatic hyperplasia (BPH) also known as benign prostatic hypertrophy or benign enlargement of the prostate (BEP) refers to the increase in size of the prostate in middle-aged and elderly men. To be accurate, the process is one of hyperplasia rather than hypertrophy, but the nomenclature is often interchangeable, even amongst urologists (who should know better!). In BPH, the prostate grows larger and presses against the urethra and bladder, interfering with the normal flow of urine. It leads to symptoms of urinary hesitancy, frequent urination, increased risk of urinary tract infections and urinary retention. There is remarkably little correlation between BPH symptoms and the presence of prostate cancer.
Urinary symptoms of hesitancy, sensation of incomplete voiding and frequently passing small amounts of urine are all suggestive of BPH in middle-aged and elderly men. Due to the incomplete voiding, there is stasis of bacteria in the bladder residue and an increased risk of urinary tract infections.
A small proportion presents with urinary retention, in which inadequate amounts of urine are passed and the bladder distends greatly. Untreated, this leads to a decrease in renal function and hydronephrosis (obstructive uropathy).
Rectal examination (palpation of the prostate through the rectum) may reveal a markedly enlarged prostate. It is dependent on the skills of the doctor.
Often, blood tests are performed to rule out prostatic malignancy: elevated prostate specific antigen (PSA) levels suggest prostate cancer. It has to be borne in mind that rectal examination can increase PSA levels in patients without malignancy.
Ultrasound examination of the testicles, prostate and kidneys is often performed, again to rule out malignancy and hydronephrosis.
Alpha-blockers (α1-adrenergic receptor antagonists) (such as doxazosin, prazosin and tamsulosin) and certain antiandrogens such as the 5α-reductase inhibitors (finasteride) are used, often together, in suppressing the symptoms.
There is also some evidence of the efficacy of Serenoa repens (saw palmetto) preparations in alleviating BPH symptoms. A systematic review of evidence found comparable efficacy to finasteride. (Wilt et al., 2002)
If medical treatment fails, transurethral resection of prostate (TURP) surgery may need to be performed. This involves removing (part of) the prostate through the urethra. There are also a number of new methods for reducing the size of an enlarged prostate, some of which have not been around long enough to fully establish their safety or side effects. These include various methods to destroy or remove part of the excess tissue while trying to avoid damaging what's left. Transurethral electrovaporization of the prostate (TVP), laser TURP, visual laser ablation (VLAP), TransUrethral Microwave ThermoTherapy (TUMT), ethanol injection, and others are studied as alternatives.
Prostate cancer is a disease in which cancer develops in the prostate, a gland in the male reproductive system. Cancer occurs when cells of the prostate mutate and begin to multiply out of control. These cells may spread (metastasize) from the prostate to other parts of the body, especially the bones and lymph nodes. Prostate cancer may cause pain, difficulty in urinating, erectile dysfunction and other symptoms.
It is the second most common type of cancer in men; among men, it is responsible for more deaths than any other cancer except lung cancer. However, many men who develop prostate cancer never have symptoms, undergo no therapy, and eventually die of other causes. Many factors, including genetics and diet, have been implicated in the development of prostate cancer, but as of 2005, it is not a preventable disease.
Prostate cancer is most often discovered by physical examination of the prostate gland by a physician, systematic or prompted by clinical signs and symptoms or by screening blood tests, such as the PSA (prostate specific antigen) test, systematic or prompted by evidence of metastatic disease. However, there is some current concern about the accuracy of the PSA test and its usefulness. Suspected prostate cancer is typically confirmed by removing a piece of the prostate (biopsy) and examining it under a microscope. Further tests, such as X-rays and bone scans, may be performed to determine whether prostate cancer has spread.
Prostate cancer can be treated with surgery, radiation therapy, hormone therapy, occasionally chemotherapy, or some combination of these. The age and underlying health of the man as well as the extent of spread, appearance under the microscope and response of the cancer to initial treatment are important in determining the outcome of the disease. Since prostate cancer is a disease of older men, many will die of other causes before the prostate cancer can spread or cause symptoms. This makes treatment selection difficult.[
Surgical removal of the prostate, or prostatectomy, is a common treatment either for early stage prostate cancer, or for cancer which has failed to respond to radiation therapy. The most common type is radical retropubic prostatectomy, when the surgeon removes the prostate through an abdominal incision. Another type is radical perineal prostatectomy, when the surgeon removes the prostate through an incision in the perineum, the skin between the scrotum and anus. Prostatectomy can cure about seventy percent of cases of prostate cancer.
Radical prostatectomy is highly effective for tumors, which have not spread beyond the prostate. However, it may cause nerve damage that significantly alters the quality of life of the prostate cancer survivor. The most common serious complications are loss of urinary control and impotence. As many as forty percent of men will be left with some urinary incontinence, usually in the form of leakage when they sneeze, cough or laugh. Impotence is also a common problem. Although penile sensation and the ability to achieve orgasm usually remain intact, erection and ejaculation are often impaired. Medications such as sildenafil (Viagra), Cialis, or Levitra may restore some degree of potency. In some men with smaller cancers, a more limited "nerve-sparing" technique may help avoid urinary incontinence and impotence.
Radical prostatectomy has traditionally been used alone when the cancer is small. However, courses of hormone therapy prior to surgery may increase cure rates and are currently being studied. Surgery may also be offered when a cancer is not responding to radiation therapy. However, because radiation therapy causes tissue changes, prostatectomy after radiation has a higher risk of complications.
Transurethral resection of the prostate, commonly called a "TURP," is a surgical procedure performed when the tube from the bladder to the penis (urethra) is blocked by prostate enlargement. TURP is generally for benign disease and is not meant as definitive treatment for prostate cancer. During a TURP, a small tube (cystoscope) is placed into the penis and the blocking prostate is cut away.
In metastatic disease, where cancer has spread beyond the prostate, removal of the testicles (called orchiectomy) may be done to decrease testosterone levels and control cancer growth.
Radiation therapy, also known as radiotherapy, uses X-rays to kill prostate cancer cells. X-rays are a type of ionizing radiation that can damage or destroy the DNA crucial to cancer cell growth. Two different kinds of radiation therapy are used in prostate cancer treatment: external beam radiation therapy and brachytherapy.
Brachytherapy involves the placement of about 100 small "seeds" containing radioactive material (such as iodine-125 or palladium-103) with a needle through the skin of the perineum directly into the tumor. These seeds emit lower-energy X-rays, which are only able to travel a short distance. Brachytherapy seeds will stay in the prostate permanently, but men with implanted seeds are not at risk of exposing others to radiation.
Cryosurgery is another method of treating prostate cancer. It is less invasive than radical prostatectomy, and general anesthesia is less commonly used.
Hormonal therapy uses medications or surgery to block prostate cancer cells from getting dihydrotestosterone (DHT), a hormone produced in the prostate and required for the growth and spread of most prostate cancer cells. Blocking DHT often causes prostate cancer to stop growing and even shrink. However, hormonal therapy rarely cures prostate cancer because cancers, which initially respond to hormonal therapy typically become resistant after one to two years. Hormonal therapy is therefore usually used when cancer has spread from the prostate. It may also be given to certain men undergoing radiation therapy or surgery to help prevent return of their cancer.
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Chapter II - Male Reproduction