Lecture Outline - Chapter 15

15.1 Male Reproductive System (p. 312, Fig. 15.1, Table 15.1)
	1.	The male gonads (the testes) are suspended in the scrotum, where temperature is less than within the body core.
		a.	Sperm are produced within seminiferous tubules of the testes and mature within the tightly coiled epididymis. Sperm are stored in the epididymides and vasa deferentia until released during ejaculation.
		b.	The penis is a vehicle for both urination and sexual intercourse (Fig. 15.2).
		c.	Semen is a viscous fluid consisting of mature sperm cells plus the fluids produced by the seminal vesicles, prostate gland, and bulbourethral glands. These fluids add nutrients, activate sperm, and provide mucus for lubrication.
		d.	Sexual arousal can result in ejaculation, the release of semen from the penis. A refractory period follows, during which an erection does not occur.
	2.	Testes Produce Sperm and Hormones (p. 314, Fig. 15.3)
		a.	Spermatogenesis, the production of sperm, occurs within the seminiferous tubules. The process involves meiosis, which produces haploid sperm cells, and sustentacular (Sertoli) cells, which nourish and regulate developing sperm cells.
		b.	Mature sperm have a head that contains the nucleus, a midpiece with mitochondria to provide energy for locomotion, and a tail, which is a flagellum. At the tip of the head, a cap called an acrosome releases enzymes to dissolve a path into the female's egg.
	3.	Hormonal Regulation in Males (p. 315, Fig. 15.4)
		a.	The hypothalamus triggers the release of two hormones from the anterior pituitary: follicle-stimulating hormone (FSH) promotes spermatogenesis, and luteinizing hormone (LH) triggers interstitial cells (between seminiferous tubules) to produce and release testosterone.
		b.	Testosterone Is the Male Sex Hormone (p. 315)
			Testosterone is responsible for the secondary sex characteristics, like the muscular build and deeper voice of males, and it promotes body hair development and sex drive.
15.2 Female Reproductive System (p. 316, Fig. 15.5, Table 15.2)
	1.	Organs of the female reproductive system include the ovaries, which produce egg cells monthly, the uterus, which houses the developing fetus, and the vagina, which serves both as a birth canal and as the pathway for sexual intercourse.
	2.	Ovaries and Oviducts (p. 317)
		a.	Female gonads, called ovaries, are held in position by ligaments. Each month, one egg is released during ovulation.
		b.	The Oviducts Are Tubes to the Uterus (p. 317)
			The oviducts (fallopian tubes) lead from the ovaries to the uterus and are the site of fertilization. Occasionally, tubal pregnancies occur and must be surgically terminated. Ectopic pregnancies occur outside the uterus.
	3.	The Uterus and Vagina (p. 317)
		a.	The uterus is a thick-walled, muscular organ that opens at the cervix into the vagina. 
		b.	The lining of the uterus, the endometrium, is shed monthly during menstruation. It also nourishes a developing embryo.
		c.	The cervix is the opening to the uterus.
		d.	The vagina is a pathway opening from the cervix to the outside. It is lined with mucous membrane, which lies in folds and allows this passageway to stretch during childbirth or intercourse.
	4.	Females Have External Genitals (p. 317, fig. 15.6)
		The external female genitals, known collectively as the vulva, are made up of the labia majora and labia minora. The clitoris is a shaft of erectile tissue anterior to the vagina.
15.3 Female Hormone Levels (p. 318, Figs. 15.7, 15.8)
	1.	The hypothalamus secretes GnRH (gonadotropin-releasing hormone) that targets the anterior pituitary. The anterior pituitary, in turn, releases FSH (follicle-stimulating hormone) and LH (luteinizing hormone), which stimulate various events in the menstrual cycle.
	2.	The Ovarian Cycle (p. 318)
		a.	Oogenesis is the process of producing a mature egg through meiosis. 
		b.	During the follicular phase of the ovarian cycle, FSH is released, which promotes the maturation of a follicle (area surrounding an oocyte) in the ovary. The follicle is glandular and produces increasing amounts of estrogen, which causes the endometrium to thicken. 
		c.	LH triggers ovulation, after which the corpus luteum develops from the follicle. 
		d.	The corpus luteum produces increasing levels of progesterone, which causes the endometrium to become secretory.
		e.	Menstruation occurs when progesterone production tapers off as the corpus luteum ages.
	3.	The Uterine Cycle (p. 321, Fig. 15.9, Table 15.3)
		a.	During days 1-5 of the uterine cycle, low levels of sex hormones trigger menstruation.
		b.	During days 6-13, the ovarian follicle increases its output of estrogen, causing the endometrium to thicken during what is called the proliferative phase of the cycle.
		c.	Ovulation usually occurs on the fourteenth day.
		d.	During days 15-28, the corpus luteum produces progesterone, which causes the uterine lining to proliferate further during the secretory phase of the cycle. The endometrium is prepared to accept an embryo.
	4.	Pregnancy Follows Fertilization (p. 321, Fig. 15.10)
		a.	If fertilization occurs, the embryo begins its development as it travels to the uterus. The placenta forms from tissues of the fetus and the mother. The early fetal placenta produces human chorionic gonadotropin (HCG), which helps to maintain the corpus luteum and thus, the lining of the uterus.
		b.	High levels of estrogen and progesterone during pregnancy inhibit the anterior pituitary from releasing FSH and LH, and no further ovulations, or menstruation, occur.
	5.	Estrogen and Progesterone Are Female Sex Hormones (p. 322)
		a.	Estrogen is responsible for female secondary sex characteristics, such as deposition of subcutaneous fat and development of axial and pubic hair. It also promotes the buildup of the endometrium in the uterus.
		b.	Progesterone, along with estrogen, is required for breast development and helps the endometrium become luxuriant.
	6.	After Menopause the Ovaries Don't Respond (p. 322)
		a.	Menopause occurs in most women between ages 45 and 55, and is when ovarian and uterine cycles cease. The ovaries are unable to respond to anterior pituitary hormones and stop secreting estrogen and progesterone.
		b.	Side effects of menopause include temporary hot flashes, headaches, dizziness, abnormal sleep patterns, and depression.
15.4 Development of Male and Female Sex Organs (p. 322, Fig. 15.11)
	1.	Gonads begin developing during the seventh week of gestation. Genes on the Y chromosome code for testes development.
	2.	In the absence of the Y chromosome, fetuses are female and develop a vagina, uterus, and ovaries.
	3.	Males and females have somewhat analogous development during various fetal stages.
15.5 Control of Reproduction (p. 324)
	1.	Birth Control Is Varied (p. 324, Table 15.4, Fig. 15.12)
		a.	Popular and effective means of birth control are contraceptive pills taken by the woman, and barrier methods (condoms, diaphragms) that are barriers to conception and offer some control over the transmission of sexually transmitted diseases.
		b.	A number of conception control methods have side effects or are unpredictable, and care should be taken when employing them (see Table 15.4).
		c.	Searching for Other Means of Birth Control (p. 325)
			Contraceptive vaccines are now under study to immunize women against human chorionic gonadotropin produced by the developing embryo. An antisperm vaccine might also be possible. A "male pill" has long been investigated but must be given by injection.
			HEALTH FOCUS: Endometriosis (p. 326, fig. 15A)
			i.	In endometriosis, the endometrium migrates upward and covers tissues in the abdominal cavity. It is a painful condition that can lead to blocked oviducts and fertility problems.
			ii.	Treatment involves hormone therapy or surgery.
		d.	Morning-after Pills (p. 327)
			The morning-after pill (RU-486) causes the loss of an implanted embryo by blocking progesterone receptors in the uterine lining. The embryo is sloughed off with menstruation.
	2.	Some Couples Are Infertile (p. 327)
		a.	An estimated 15% of all couples in the United States are infertile.
		b.	What Causes Infertility? (p. 327, Fig. 15.13)
			Infertility can be caused by blocked oviducts (the result of pelvic inflammatory disease [PID] or endometriosis), by lack of regular ovulation, or by low sperm count in males. Many couples choose to adopt when they cannot conceive.
	3.	Alternative Methods of Reproducing Are Available (p. 328)
		a.	Artificial insemination involves inseminating the woman in the doctor's office, using sperm from a stranger, from the woman's husband, or a combination of the two.
		b.	In vitro fertilization is conception in lab glassware. Eggs are removed from the ovaries, sperm are added to them, and the eggs are placed in the woman's uterus after fertilization.
		c.	Gamete intrafallopian transfer is a means of removing a woman's eggs and placing them in the oviduct along with her husband's sperm. The advantages are lower cost and that it is a one-step procedure.
		d.	Surrogate mothers are sometimes employed to bear children for women who, for various reasons, cannot.
			ECOLOGY FOCUS: Fertility and the Environment (p. 328, Fig.15B)
			During the last half of the 1900s, use of chemicals increased dramatically, with a corresponding decrease in human fertility. This does not verify a direct cause-and-effect relationship, but there appears to be a link.
15.6 Working Together (p. 328)
	The Working Together box on page 329 illustrates how the reproductive system functions in conjunction with other body systems to maintain homeostasis.