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Chapter Summary
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Chapter 21: Female Reproductive System
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Introduction to the Female Reproductive System
(pp. 707–709)
- The reproductive period of a female is the period
between puberty (about age 12) and menopause (about age 50). In the course
of this age span, cyclic ovulation and menstruation patterns occur in nonpregnant
females.
- The functions of the female reproductive system
are to produce ova; secrete sex hormones; receive sperm from the male; provide
sites for fertilization, implantation, and development of the embryo and fetus;
facilitate parturition; and secrete milk from the mammary glands.
- The female reproductive system consists of (a)
primary sex organs—the ovaries; (b) secondary sex organs—those that are essential
for sexual reproduction, characterized by latent development; and (c) secondary
sex characteristics—features that are sexual attractants, expressed after
puberty.
Structure and Function of the Ovaries (pp. 709–714)
- The ovaries are supported by the mesovarium,
which extends from the broad ligament, and by the ovarian and suspensory ligaments.
- The ovarian follicles within the ovarian cortex
undergo cyclic changes.
- Primary oocytes, arrested at prophase I
of meiosis, are contained within primordial follicles.
- Upon stimulation by gonadotropic hormones,
some of the primordial follicles enlarge to become primary follicles.
- When a follicle develops a fluid-filled
antrum, it is called a secondary follicle.
- Generally only one follicle continues to
grow to become a vesicular ovarian follicle.
- The vesicular ovarian follicle contains
a secondary oocyte, arrested at metaphase II of meiosis.
- In the process of ovulation, the vesicular
ovarian follicle ruptures and releases its secondary oocyte, which becomes
a zygote upon fertilization.
- After ovulation, the empty follicle becomes
a corpus luteum.
Secondary Sex Organs (pp. 714–719)
- The uterine tube, which conveys ova from the
ovary to the uterus, provides a site for fertilization.
- The open-ended portion of each uterine tube
is expanded; its margin bears fimbriae that extend over the lateral surface
of the ovary.
- Movement of an ovum is aided by ciliated
cells that line the lumen and by peristaltic contractions in the wall
of the uterine tube.
- The uterus is supported by the broad ligaments,
uterosacral ligaments, cardinal ligaments, and round ligaments. The regions
of uterus are the fundus, body, and cervix. The cervical canal opens into
the vagina at the uterine ostium.
- The endometrium consists of a stratum basale
and a stratum functionale; the superficial stratum functionale is shed
during menstruation.
- The myometrium produces the muscular contractions
needed for labor and parturition.
- The vagina serves to receive the erect penis,
to convey menses to the outside, and to transport the fetus during parturition.
- The vaginal wall is composed of an inner
mucosa, a middle muscularis, and an outer fibrous layer.
- The vaginal orifice may be partially covered
by a thin membranous hymen.
- The external genitalia, or vulva, include the
mons pubis, labia majora and minora, clitoris, vaginal vestibule, vestibular
bulbs, and vestibular glands.
- Impulses through parasympathetic nerves stimulate
erectile tissues in the clitoris and vestibular bulbs; in orgasm, muscular
contraction occurs in the perineum, uterus, and uterine tubes.
Mammary Glands (pp. 719–721)
- Mammary glands, located within the breasts,
are modified sweat glands.
- Each mammary gland is composed of 15 to
20 lobes; the lobes are subdivided into lobules that contain mammary alveoli.
- During lactation, the mammary alveoli secrete
milk. The milk passes through mammary ducts, lactiferous ducts, and lactiferous
sinuses and is discharged through the nipple.
- The nipple is a cylindrical projection near
the center of the breast, surrounded by the circular pigmented areola.
Ovulation and Menstruation (pp. 722–723)
- Ovulation and menstruation are reproductive
cyclic events that are regulated by hormones secreted by the hypothalamus,
the anterior pituitary, and the ovaries.
- The menstrual cycle is divided into menstrual,
proliferative, and secretory phases.
- The principal hormones that regulate ovulation
and menstruation are estrogen, progesterone, follicle-stimulating hormone
(FSH), and luteinizing hormone (LH).