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Chapter 81: Female Physiology Before Pregnancy and Female Hormones Guyton and Hall, Textbook of Medical Physiology, 12 edition

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Physiologic Anatomy of the Female Sexual Organs Fig. 81.1 Female reproductive organs

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Physiologic Anatomy of the Female Sexual Organs Fig. 81.2 Internal structure of the uterus, ovary, and a uterine tube

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Female Hormonal System Gonadotropin releasing hormone (GnRH) Anterior pituitary sex hormones: follicle stimulating hormone (FSH) and leutinizing hormone (LH) Ovarian Hormones-Estrogen and Progesterone

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Female Hormonal System Fig. 81.3 Approximate plasma concentrations of the gonadotropins and ovarian hormones during the normal female sexual cycle

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Monthly Ovarian Cycle Gonadotropin Hormones and Their Effects on the Ovaries a.Ovarian changes that occur during the menstrual cycle are due entirely to FSH and LH b.Ovaries remain inactive until 9-12 years of age when the pituitary secretes FSH and LH leading to puberty c.Menarche-the first menstrual cycle d.Cyclic variations (see Fig. 81.3)

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Monthly Ovarian Cycle Gonadotropin Hormones and Their Effects on the Ovaries e.The stimulatory effects result from activation of the cAMP second messenger system in the cell cytoplasm f.Causes the formation of protein kinases and the phosphorylation of key enzymes

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Monthly Ovarian Cycle Follicular Phase of the Cycle Fig. 81.4 Stages of follicular growth in the ovary, also showing formation of the corpus luteum

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Monthly Ovarian Cycle Follicular Phase of the Cycle a.Moderate enlargement of the ovum initially b.Development of antral and vesicular follicles c.Only one follicle matures fully each month d.Ovulation-surge of LH is necessary

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Monthly Ovarian Cycle Follicular Phase of the Cycle Fig. 81.5 Postulated mechanism of ovulation

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Monthly Ovarian Cycle Luteal Phase a.Development of the corpus luteum within hours after ovulation b.Leutinizing effect of LH c.Secretion by the corpus luteum-progesterone and estrogen d.Involution of the corpus luteum and onset of the next ovarian cycle

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Functions of the Ovarian Hormones Chemistry of the Sex Hormones-Estrogens a.Estrogens-in the normal nonpregnant female estrogens are secreted in significant quantities only by the ovaries b.During pregnancy tremendous quantities are secreted by the placenta c.Only 3 estrogens are present in significant quantities: beta-estradiol, estrone, and estriol. The prinicpal estrogen secreted by the ovary is beta-estradiol

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Functions of the Ovarian Hormones Chemistry of the Sex Hormones Fig. 81.6 Synthesis of the principal female hormones

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Functions of the Ovarian Hormones Chemistry of the Sex Hormones-Progestins a.Most important is progesterone b.In normal nonpregnant females, it is secreted only during the latter half of the ovarian cycle (by the corpus luteum) c.During pregnancy, it is produced by the placenta, especially after the 4 th month

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Functions of the Ovarian Hormones Chemistry of the Sex Hormones-Progestins Fig. 81.7 Interaction of follicular theca and granulosa cells in the production of estrogens

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Functions of the Ovarian Hormones Chemistry of the Sex Hormones-Progestins d.Estrogens and progesterone are transported in the blood bound to plasma proteins e.The liver functions in estrogen degradation f.Progesterone is degraded almost immediately after secretion

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Functions of the Ovarian Hormones Functions of the Estrogens-Effects on Primary and Secondary Sex Characteristics a.At puberty, the ovaries, fallopian tubes, uterus, and vagina all increase several times in size b.External genitalia also change with added fat deposition c.Cause the glandular tissues of the fallopian tubes to proliferate d.Act on the breasts to (1) development of the stromal tissues, (2) growth of extensive ductile system, and (3) deposition of fat

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Functions of the Ovarian Hormones Functions of the Estrogens-Effects on Primary and Secondary Sex Characteristics e.Inhibit osteoclastic activity of the bones and therefore stimulate bone growth f.Cause uniting of the epiphyses of the long bones (effects of estrogen on the female are stronger than the effects of testosterone in the male) g.Osteoporosis of the bones is caused by estrogen deficiency in old age h.Slightly increase protein deposition

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Functions of the Ovarian Hormones Functions of the Estrogens-Effects on Primary and Secondary Sex Characteristics i.Increase body metabolism and fat deposition j.Have little effect on hair distribution k.Cause the skin to become more vascular, smooth, and soft l.Can cause sodium and water retention by the kidney tubules, but is generally of little significance

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Functions of the Ovarian Hormones Functions of Progesterone a.Promotes secretory changes in the uterus; preparing the uterus for the implantation of the ovum b.Promotes increased mucosal secretions by the Fallopian tubes c.Promotes the development of the breasts; the lobules and the alveoli to become secretory in nature

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Functions of the Ovarian Hormones Monthly Endometrial Cycle and Menstruation a.Proliferation of the uterine endometrium b.Development of secretory changes in the endometrium c.Desquamation of the endometrium (menstruation)

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Functions of the Ovarian Hormones Monthly Endometrial Cycle and Menstruation Fig. 81.8 Phases of endometrial growth and menstruation during each monthly female sexual cycle

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Functions of the Ovarian Hormones Proliferative Phase (Estrogen Phase) a.Under the influence of estrogens, the stromal and epithelial cells proliferate rapidly b.Before ovulation occurs, the endometrium thickens due to growth of cells, glands, and vessels c.Endometrial glands secrete a thin stringy mucus (helps to guide sperm)

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Functions of the Ovarian Hormones Secretory Phase (Progestational Phase) a.After ovulation occurs, progesterone and estrogen are secreted in large quantities by the corpus luteum b.Estrogen causes additional cell proliferation and progesterone causes swelling and secretory development of the endometrium c.Whole purpose is to produce an endometrium that contains large amounts of stored nutrients for the ovum if implanted d.Uterine secretions provide nutrition for the implanting ovum (uterine milk)

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Functions of the Ovarian Hormones Menstruation a.If the ovum is not fertilized, about 2 days before the end of the monthly cycle, the corpus luteum involutes and estrogen and progesterone production decreases b.Rapid involution of the endometrium, blood vessels become vasospastic and initiates necrosis c.Gradually the necrotic layers separate from the endometrium and sloughing occurs

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Regulation of the Female Monthly Rhythm Hypothalamus Secretes GnRH, Which Causes the Anterior Pituitary to Release FSH and LH a.Intermittent pulsatile secretion of GnRH stimulates the pulsatile release of LH b.The neuronal activity that causes the pulsatile release is primarily in the arcuate centers

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Regulation of the Female Monthly Rhythm Hypothalamus Secretes GnRH, Which Causes the Anterior Pituitary to Release FSH and LH Fig. 81.9 Upper curve: pulsatile change in LH in the peripheral circulation Lower curve: minute by minute recording of multi-unit electrical activity

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Regulation of the Female Monthly Rhythm Negative Feedback Effects of Estrogen and Progesterone to Decrease FSH and LH Fig. 81.10 Feedback regulation of the hypothalamic-pituitary-ovarian axis in females.

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Regulation of the Female Monthly Rhythm Negative Feedback Effects of Estrogen and Progesterone to Decrease FSH and LH a.Estrogen has a strong effect to inhibit the production of both FSH and LH b.These effects operate mainly on the anterior pituitary but also on the hypothalamus to a lesser extent c.Inhibin from the corpus luteum inhibits mainly FSH and to a lesser extent, LH

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Regulation of the Female Monthly Rhythm Positive Feedback Effect of Estrogen Before Ovulation a.For reasons unknown, the anterior pituitary secretes increased amounts of LH for 1-2 days beginning 24-48 hours prior to ovulation b.Ovulation does not occur unless this pre-ovulatory surge does

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Regulation of the Female Monthly Rhythm Feedback Oscillation of the Hypothalamic- Pituitary-Ovarian System a.Postovulatory secretion of the ovarian hormones and depression of the pituitary gonadotropins b.Follicular growth phase-2-3 days before menstruation, the corpus luteum has regressed and secretion of estrogen, progesterone, and inhibin decreases; this releases the hypothalamus and anterior pituitary from the negative feedback control of those hormones

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Regulation of the Female Monthly Rhythm Feedback Oscillation of the Hypothalamic- Pituitary-Ovarian System c.A day or so later, FSH and LH begin to increase d.This initiates follicle growth Preovulatory Surge of LH and FSH Causes Ovulation

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Regulation of the Female Monthly Rhythm Puberty and Menarche a.Puberty-onset of adult sexual life b.Menarche-the beginning of the cycle of menstruation; usually begins between the ages of 11-16 (average 13)

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Regulation of the Female Monthly Rhythm Puberty and Menarche Fig. 81.11 Total rates of secretion of gonadotropic hormones throughout the sexual lives of females and males Fig. 81.12 Estrogen secretion throughout the sexual life of the human female

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Abnormalities of Secretion by the Ovaries Hypogonadism- reduced secretion by the ovaries Hypersecretion by the Ovaries

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Female Sexual Act Stimulation of the Female Sex Act Female Erection and Lubrication Female Orgasm