Male Sexual Anatomy and Physiology Chapter 6
Figure 6.1 The internal structure of the penis.
Figure 6.2 The male reproductive organs.
Figure 6.4 Internal structure of the testicle.
Colored scan of seminiferous tubules, each containing a swirl of forming sperm cells (in blue).
The Ejaculatory Route
Ejaculation Begins in the spinal cord once a threshold is reached, and proceeds until the conclusion Once the threshold is reached: Epididymis, seminal vesicles, and prostate empty their fluids into the base of the urethra A sphincter closes off the bladder 5-15 contractions squeeze the base of the urethra Ejaculate is expelled Orgasm Return to flaccid state
Ejaculate/Semen 2-5 milliliters of fluid 50-150 million sperm per milliliter Few sperm reach the ovum Sperm work together in order to fertilize the egg Semen coagulates upon ejaculation; this helps it remain in the vagina and travel into the uterus 5-20 minutes later it thins out due to Prostatic enzymes
Figure 6.6 Puberty: The cycle of male hormones.
Andropause Testosterone levels decrease about 1% per year after 40 years of age In the 70s and 80s, andropause occurs in 2% of men: : decreased spermatogenesis, thinner ejaculate, less ejaculatory force Decreased testosterone: libido decreases, fatigue, mood disturbances, decreased strength Controversy over androgen replacement therapy; has increased significantly in U.S.; no evidence to support link to prostate cancer
Disorders of the Male Reproductive Organs Figure 6.7 Although the testicles of a fetus begin high in the abdomen, they must descend into the scrotum during fetal development. If they do not, the male may become infertile.
Disorders of the Male Reproductive Organs (Cont.) Figure 6.8 Testicular torsion can occur after exercise, sexual intercourse, and even while sleeping.
Disorders of the Male Reproductive Organs (Cont.) Priapism – abnormally prolonged and painful erection that is not associated with sexual desire or excitement; blood is trapped in erectile tissue; common causes include diseases, spinal cord injuries, and drug use; immediate treatment necessary Peyronie’s disease – painful curvature of the penis making penetration impossible; cause is unknown; may disappear within 2 years, or require drugs or surgery
Other Conditions that Affect the Male Reproductive Organs Inguinal hernia – intestine goes through an abdominal opening into the scrotum, creating a bulge; can be due to heavy lifting and straining; surgery may be required Hydrocele – fluid accumulates around testicle; common in newborns Anabolic-androgenic steroid abuse – synthetic testosterone can increase muscle mass and endurance; many physical, psychological, and emotional side effects, including erectile problems
Cancers of the Male Reproductive Organs Male breast cancer Penile cancer Testicular cancer Prostate cancer
Testicular Cancer
A prostate exam.
Prostate Cancer Prostate glands enlarge with age and this is typically unproblematic, other than interfering with urination Prostate cancer is one of the most common in American men, typically in men over 50 years Risk factors: age, high fat diet, race, heredity, BRCA gene Symptoms: pain in the lower back, pelvis, or upper thigh, and urinary abnormalities Detected through rectal exam and blood test
Prostate Cancer (Cont.) Prostate-Specific Antigen (PSA) is blood test for overproduction of molecules made by prostate cells Treatments: “watchful waiting” in older men; radical prostatectomy; radiation; vaccine that that uses patient’s white blood cells to attack cancer cells