Chapter 32 The Reproductive Systems

Vas Deferens

A tube called a vas deferens is connected to each epididymis. These tubes carry sperm cells from the epididymis to the urethra in the male pelvic cavity. When a male has a vasectomy, these tubes are cut and tied, or fulgurated, to prevent sperm from reaching the ovum.

Epididymis

An epididymis sits on top of each testis. It is a highly coiled tube that receives spermatids from seminiferous tubules as these cells are formed. Inside the epididymis, spermatids mature to become sperm cells.

Spermatogonia

At the beginning of spermatogenesis, the cells. they contain 46 chromosomes.

Bulbourethral Glands

Cowper's glands, are inferior to the prostate gland. They produce a mucus-like fluid that is secreted into the urethra before ejaculation. This fluid lubricates the end of the penis in preparation for sexual intercourse.

Spermatogenic

cells of the seminiferous tubules begin the process of making sperm cells, but the sperm cells do not mature until they travel to the epididymis.

Scrotum

Most males have two testes that are held just below the pelvic cavity. They also produce the male hormone testosterone.

Semen

Semen is a mixture of sperm cells and fluids from the seminal vesicles, prostate gland, and bulbourethral glands. This alkaline mixture contains nutrients and prostaglandins. Total semen volume is between 1.5 and 5.0 mL per ejaculate, with a sperm count between 40 and 250 million/mL. A normal sperm count is more than 80 million.

Seminal Vesicles

Seminal vesicles are sac-like organs that secrete an alkaline seminal fluid that is rich in sugars and prostaglandins. Sperm cells use the sugars to make energy, and the prostaglandins stimulate muscular contractions in the female reproductive system. These muscular contractions, known as peristalsis, help to propel sperm forward in the female reproductive tract. Seminal vesicles release their product into the vas deferens just before ejaculation. Seminal fluid makes up approximately 60% of semen volume.

The Head

The head is oval in structure and holds a nucleus with 23 chromosomes. The head is covered with an enzyme-filled sac called an acrosome, which helps the sperm penetrate an ovum at the time of fertilization.

Prostate Gland

The muscular prostate gland surrounds the proximal portion of the urethra. It produces a milky, alkaline fluid and secretes this fluid into the urethra just before ejaculation. The alkaline nature of this fluid helps to protect the sperm when they enter the acidic environment of the female vagina. Prostatic fluid makes up approximately 40% of semen volume. During ejaculation, the muscular contractions of the prostate help expel semen.

Penis

The penis is a cylindrical organ that moves urine and semen out of the body. The shaft, or body, of the penis contains specialized erectile tissue that surrounds the urethra, which runs the length of the penis. The end of the penis is enlarged into a cone-shaped structure called the glans penis. If a male has not been circumcised, a piece of skin, called the prepuce, covers the glans penis. The function of the penis is to deliver sperm to the female reproductive tract. The penis also functions in urination because it contains the urethra, which drains urine from the bladder.

Scrotum

The scrotum is a pouch of skin that holds the testes. It is lined with a serous membrane that secretes fluid to ensure that the testes move freely within it. The scrotum holds the testes away from the rest of the body, keeping their temperature about one degree lower than the rest of the body, which is necessary for the viability of the sperm.

The Tail

The tail is a flagellum that propels the sperm forward in the female reproductive tract.

fetal stage of a male

The testes develop in the abdominopelvic cavity of the fetus. Shortly before or soon after birth, the testes descend into the scrotal sac located just below the pelvic cavity.

meiosis

These cells undergo, and the resulting cells are called primary spermatocytes.

The Midpiece

This portion of the sperm is between the head and tail. It is filled with mitochondria that generate the energy the cell needs to move.

spermatocytes

also contain 46 chromosomes. At about the time of puberty, primary spermatocytes undergo a process called meiosis (see Figures 32-2 and 32-3a). In meiosis, each primary spermatocyte divides to make two secondary spermatocytes. Each secondary spermatocyte divides to make two spermatids. Therefore, from one primary spermatocyte, four spermatids are formed. Spermatids develop flagella to become mature sperm cells. They contain only 23 chromosomes.

Testes

considered the primary organs of the make reproductive system because they produce the male sex cells (sperm).

seminiferous tubules

fibrous capsule encloses each testis and invades the testis to divide it into lobules. which are filled with spermatogenic cells. These cells give rise to sperm cells. interstitial cells, which produce testosterone.

IMPOTENCE or ERECTILE DYSFUNCTION (ED)

is a disorder in which a male cannot achieve or maintain an erect penis to complete sexual intercourse. It is estimated that half of all men between the ages of 40 and 70 years have some degree of impotence. Most causes are physical and not psychological. Causes. Psychological causes include anxiety, stress, and depression. Common physical causes include diabetes; high blood pressure; anemia; coronary artery disease (CAD); peripheral vascular disease (PVD); low testosterone production; various medications; smoking; excessive alcohol consumption; and drugs such as cocaine, marijuana, and heroin. Signs and Symptoms. Signs and symptoms are an inability to achieve an erection or an inability to maintain an erection long enough to complete sexual intercourse. Treatment. The first treatment step should be lifestyle changes to quit smoking and stop using alcohol and/or drugs. Counseling to reduce anxiety and depression may also be helpful. Other treatment options include oral medications such as Viagra or Cialis, penile injections of medications, and penile implants if oral medications do not work.

TESTICULAR CANCER

is a malignant growth of one or both testicles. Unlike prostate cancer, which tends to occur in older males, testicular cancer occurs in males ages 15 to 30 and is a much more aggressive malignancy. Causes. Predisposing factors include cryptorchidism (undescended testicles during infancy). Family history may also be a factor. Signs and Symptoms. A hard, painless lump in one testicle is a common early symptom. Patients may complain of groin or abdominal pain as the disease progresses. Treatment. Orchiectomy or removal of the involved testis is usually performed, followed by radiation therapy and chemotherapy. Caught in the early stages, testicular cancer has up to a 95% success rate, verifying the need for males to perform testicular self-exams on a monthly basis. You will learn how to instruct patients in this important exam technique in the Assisting in Reproductive and Urinary Specialties chapter.

PROSTATITIS

is an inflammation of the prostate gland. If it develops suddenly, it is called acute prostatitis. The slow development of this condition is termed chronic prostatitis. Causes. This condition can be caused by excessive alcohol consumption, bacterial infection, a catheterization, trauma to the urethra or urinary bladder, and scarring of the urethra or prostate because of frequent infections. Urinating frequently can help to prevent this infection. Signs and Symptoms. Signs and symptoms include fever; pain in the scrotum, pelvic area, or abdomen; difficult, frequent, and/or painful urination; blood in the urine; painful ejaculation; blood in the semen; discharge from the urethra; a low sperm count; and white blood cells in urine or semen. Treatment. This condition is treated with antibiotics. Surgery may also be required to repair any damage to the urethra.

EPIDIDYMITIS

is inflammation of an epididymis. Most cases start out as an infection of the urinary tract that spreads to an epididymis. Causes. The causes include the use of certain medications, placement of a catheter in the urethra, and bacteria-especially those that cause gonorrhea and chlamydia. Signs and Symptoms. Signs and symptoms include fever, pain in the testes, a lump in the testes, swelling of the scrotum, painful ejaculation, blood in the semen, pain during urination, discharge from the urethra, and enlarged lymph nodes in the pelvic area. Treatment. Treatment includes pain medication, antibiotics for both the patient and his sexual partner, elevation of the scrotum, and ice packs applied to the scrotum.

PROSTATE CANCER

is one of the most common cancers in men older than age 40, and the risk of developing prostate cancer increases with age. Awareness about this malignancy is growing, and access to screenings such as digital rectal exam (DRE) is becoming widely available. Therefore, many cases in the United States are being diagnosed before symptoms even occur. Causes. The causes are mostly unknown, although decreased testosterone production may contribute to the development of this disease, explaining why risk increases with age. Signs and Symptoms. Common symptoms include anemia, weight loss, incontinence, difficulty starting or stopping urination, painful urination, pain in the lower back or abdomen, pain during bowel movements, high levels of prostate-specific antigen (PSA) in the blood, blood in the urine, and bone pain in advanced cases when cancer cells have spread (metastasized) to the bone. Treatment. Treatments include hormone therapy, chemotherapy, radiation therapy to shrink or destroy the tumor, as well as surgery to remove the prostate, known as prostatectomy.

BENIGN PROSTATIC HYPERTROPHY or BPH

is the nonmalignant enlargement of the prostate gland. This condition is common in older men. Causes. BPH is related to the hormonal changes that occur as part of the aging process. Signs and Symptoms. Men with BPH often complain of frequent urination, especially at night, as well as painful urination and difficulty starting or stopping the urinary stream, including "dribbling" at the end of urination. Treatment. Diagnosis is often confirmed by digital rectal exam (DRE), in which the physician inserts a gloved finger into the rectum and palpates the prostate. Blood tests (PSA) and a biopsy may be done to rule out cancer. Once cancer is ruled out, medications such as Avodart or Flomax may manage the problem, or transurethral resection of the prostate (TURP) may be performed to remove the enlarged tissue.

Testosterone

levels are regulated by negative feedback in the following cycle: Blood testosterone levels increase to above normal levels, which causes the hypothalamus to release GnRH. In response, the anterior pituitary ceases the secretion of LH and FSH, in turn causing the testosterone level to fall. When the testosterone level falls below normal, GnRH is again secreted by the hypothalamus, triggering the release of LH and FSH by the anterior pituitary, and the cycle begins again.

ejaculation

occurs when semen is forced out of the urethra. sympathetic nerve fibers cause the erectile tissue to release blood, and the penis gradually returns to a flaccid or nonerect state.

Testosterone

responsible for the development of male secondary sex characteristics that are typically unique to males. Examples of these characteristics include chest hair, thick facial hair, a thickening and strengthening of muscles and bones, and the thickening of vocal cords that produces a deeper voice. Testosterone also stimulates the maturation of male reproductive organs.

emission

sperm cells are propelled out of the testes toward the urethra. The secretions of the prostate, seminal vesicles, and bulbourethral glands are also released into the urethra. The movement of the sperm and secretions into the urethra is

hypothalamus

the anterior pituitary gland, and the testes secrete hormones that regulate male reproductive functions.

gonadotropin releasing hormone (GnRH)

the onset of puberty and throughout life, the hypothalamus releases a hormone. GnRH stimulates the anterior pituitary gland to release follicle-stimulating hormone (FSH) and luteinizing hormone (LH). FSH causes spermatogenesis to begin, and LH stimulates interstitial cells to produce testosterone.

sexual arousal

the parasympathetic nervous system causes erectile tissue of the penis to become engorged with blood, which produces erection of the penis.

Spermatogenesis

the process of sperm cell formation.