Chapter 26 Reproductive Systems

Introduction The reproductive system produces the cells and hormones necessary for reproduction.

Male Reproductive System Testes The testes, or testicles, are the male gonads. The testis is composed of lobules with two types of cells: the seminiferous tubules, which produce sperm, and the interstitial cells, which secrete testosterone.

Male Reproductive System - cont’d Genital Ducts and Glands The sperm move through a series of genital ducts: the epididymis, the vas deferens, the ejaculatory ducts, and the urethra. Three glands—the seminal vesicles, the prostate gland, and the bulbourethral glands—secrete into the genital ducts. The mixture of sperm and glandular secretions is called semen.

Male Reproductive System - cont’d External Genitals The male genitals consist of the scrotum and the penis. The penis performs two functions: it is the organ of copulation (sexual intercourse), and it carries urine.

Male Reproductive System - cont’d Male Sexual Response Erection Emission Ejaculation Orgasm

Male Reproductive System - cont’d Male Sex Hormones The most important being testosterone. Testosterone determines the primary and secondary sex characteristics. The male reproductive system is controlled by hormones from the hypothalamus and from the anterior pituitary gland.

Female Reproductive System Ovaries The ovaries are the female gonads. Each ovarian follicle consists of an oocyte and follicular cells. On day 14 (of a 28-day cycle), ovulation occurs. The ovarian follicular cells become the corpus luteum. The ovaries secrete two hormones, estrogen and progesterone.

Female Reproductive System - cont’d Genital Tract The genital tract includes the fallopian tubes, the uterus, and the vagina. The fallopian tubes transport the egg from the ovaries to the uterus, and are the site of fertilization. The uterus is the baby’s cradle during pregnancy. The uterus has three layers: epimetrium, myometrium, and endometrium.

Female Reproductive System - cont’d External Genitals: called the vulva (labia majora, labia minora, clitoris, and the vestibular glands) Female Sexual Response Erection Orgasm

Female Reproductive System - cont’d Hormonal Control of the Female Reproductive Cycles Two cycles are the ovarian cycle and the uterine cycle. The ovarian cycle is divided into the follicular phase and the luteal phase. During the follicular phase the ovarian follicle matures and secretes estrogen.

Female Reproductive System - cont’d Hormonal Control of the Female Reproductive Cycles—cont’d The luteal phase of the ovarian cycle begins immediately after ovulation and is dominated by the secretion of progesterone by the corpus luteum. In the nonpregnant state the corpus luteum deteriorates. In the pregnant state the corpus luteum stays alive because of human chorionic gonadotropin (hCG).

Female Reproductive System - cont’d Hormonal Control of the Female Reproductive Cycles—cont’d The uterine cycle is divided into the menstrual phase, the proliferative phase, and the secretory phase. The menstrual phase refers to the loss of a part of the endometrial lining and blood (“having your period”). During the proliferative phase, the inner endometrial lining thickens and becomes vascular, primarily in response to estrogen. During the secretory phase, the endometrial lining is becoming lush and moist from increased secretory activity; the secretory phase is dominated by progesterone.

Female Reproductive System - cont’d Hormonal Control of the Female Reproductive Cycles—cont’d See Figure 26-6 for a summary of the day-to-day hormonal relationships between the anterior pituitary gland, the ovaries, and the uterus.

Methods of Birth Control The regulation of childbearing can be achieved with the use of barrier methods, hormonal contraceptives, surgical methods, intrauterine devices, behavioral methods, and drugs used for emergency contraception.