Anatomy & Physiology

Anatomy & Physiology Study Guide

25.9 Aging The most prominent age-related changes in the female reproductive system happen at menopause. Comparable age-related changes in the male reproductive system happen more gradually and over a longer period. Menopause When ovulation and menstruation cease, it is called menopause. Menopause typically occurs at age 45–55, but in the years immediately preceding it, the ovarian and uterine cycles become irregular. This interval is called perimenopause. With the arrival of perimenopause, the number of follicles responding each month drops markedly. As the number of available follicles drops, estrogen levels decline and may not rise enough to trigger ovulation. By age 50, there are often no primordial follicles left to respond to FSH. A variety of neural effects are reported, including “hot flashes,” anxiety, and depression. Hot flashes are associated with surges in LH production. The Male Climacteric Developments in the male reproductive system occur more slowly than do those in the female reproductive system. The period of declining reproductive function, which corresponds to perimenopause in women, is known as the male climacteric, or andropause . Levels of circulating testosterone begin to decline between the ages of 50 and 60, and levels of circulating FSH and LH increase. Although sperm production continues (men well into their eighties can father children), older men experience a gradual reduction in sexual activity. This decrease may be linked to declining testosterone levels. 25.10 Chapter Twenty-Five Review Basic reproductive system structures are gonads, ducts, accessory glands and organs, and external genitalia: • The human reproductive system produces, stores, nourishes, and transports functional gametes (reproductive cells). Fertilization is the fusion of male and female gametes. • In males, the testes produce spermatozoa, which are expelled from the body in semen during ejaculation. The ovaries of a sexually mature female produce oocytes (immature ova) that travel along uterine tubes toward the uterus. The vagina connects the uterus with the exterior of the body. Spermatogenesis occurs in the testes, and hormones from the hypothalamus, adenohypophysis, and testes control male reproductive functions: • Spermatozoa travel along the epididymis, the ductus deferens, the ejaculatory duct, and the urethra before leaving the body. Accessory organs (notably the seminal glands, prostate gland, and bulbo-urethral glands) secrete fluids into the ejaculatory ducts and the urethra. The scrotum encloses the testes, and the penis is an erectile organ.

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