Chapter 27Female Reproductive System II

Lecture 20

Hormonal Control, Menstrual Cycle/Estrogens, the Climacteric, Female Breast

Marieb’s HumanAnatomy and

PhysiologyNinth Edition

Marieb Hoehn

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Review of Female Reproductive Cycle

Figure from: Hole’s Human A&P, 12th edition, 2010

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Ovarian Cycle – Preovulatory (Follicular) PhaseFigure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

(FSH)Thecal and granulosa cells produce estrogens

8-10 days after beginning of cycle

10-14 days

Meiosis I

LH

Meiosis II started

Many OneFew

(Graafian)

1.5 cm

Estrogen

(FSH)

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Ovarian Cycle – Postovulatory (Luteal) Phase

(Day 14)

LH

Lipids used to synthesize progestins, e.g., progesterone (prepares uterine lining for implantation)

12 days post ovulation

If fertilization has not occurred

Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

LH

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Hormonal Control of the Female Reproductive Cycle

• Ovarian and uterine (menstrual) cycles must be coordinated

• GnRH (Gonadotropin Releasing Hormone) is the controlling hormone of reproduction– Pulse frequency and amplitude (amount)– Without pulses, LH/FSH secretion (also in

pulses) will stop– Changes in GnRH pulse frequency are

controlled by estrogen (increase) and progestins (decrease)

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Hormonal Regulation of Ovarian Activity

Figure from: Saladin, Anatomy & Physiology, McGraw Hill, 2007

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Hormonal Regulation of Ovarian Activity

Figure from: Marieb, Anatomy & Physiology, Pearson, 2004

Estrogen is the predominant hormone prior to ovulation (follicular phase)

Progesterone is the predominant hormone after ovulation (luteal phase)

inhibits LH and FSH during most of the reproductive cycle

(Day 10)

16-24 GnRH pulses/day

48GnRH pulses/day

36 GnRH pulses/day

1-4 GnRH pulses/day

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Pathways of Steroid Hormone Synthesis

Androstenedione is secreted by thecal cells (LH) of the primary follicles and then absorbed by the granulosa cells (FSH) and converted to estrogens.

Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

Most abundant

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Effects of Estrogens (20 sex characteristics)•development of breasts and ductile system of the mammary glands

• increased adipose tissue in breasts, thighs, and buttocks

• increased vascularization of skin

• Maintenance of the function of accessory reproductive glands/organs

• CNS effects, e.g., sex drive, “feminization”

•Repair/growth of endometrium (following menses)

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Uterine (Menstrual) Cycle

Proliferative phase – functional layer of endometrium thickens under the influence of estrogen

Secretory phase – Arteries elaborate and uterine glands enlarge, coil, and begin secreting glycogen under progesterone’s influence

Functional

Basilar

*

Figure from: Hole’s Human A&P, 12th edition, 2010

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Menarche and the Menstrual Cycle

• Menarche– First menstrual cycle (Latin mensis = month)– Typically begins around age 11-12– If menarche does not appear by age 16,

considered amenorrhea (rhe(o)- = flow)

• Menstrual cycles– Occur monthly unless interrupted by illness,

stress, starvation, or pregnancy– Lack of menstrual period for 6 months or more

is considered amenorrhea (secondary)– Painful menstruation is called dysmenorrhea –

may result from uterine inflammation or conditions involving adjacent pelvic structures

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Overview of Female Reproductive Cycle

You should understand these events, and their timing, for the exam

Figure from: Hole’s Human A&P, 12th edition, 2010

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Events of the Female Reproductive Cycle

Table 22.4 in Hole’s Anatomy & Physiology

Good textual review table for combined ovarian and uterine cycles

Figure from: Hole’s Human A&P, 12th edition, 2010

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Male and Female Climacteric

• usually occurs in late 40s or early 50s (perimenopause)• reproductive cycles stop for 6 months to 1 year• ovaries no longer produce as much estrogen and progesterone due to depletion of ovarian follicles• some female secondary sex characteristics may disappear• sustained rise in GnRH and LH/FSH may produce hot flashes (LH) and fatigue• risk of atherosclerosis increases• hormone therapy may prevent effects on bone tissue

Female climacteric = menopause

Male climacteric (andropause)• more gradual than female climacteric • usually occurs after age 50• slowly declining levels of testosterone• sperm (gamete) production continues (even into 80s!)

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Mammary Glands

Mammary glands as shown are for women in last trimester of pregnancy or who are nursing.

The areola, a ring of pigmented skin, covers large sebaceous glands that give it a bumpy appearance. Sebum reduces chapping and cracking of the nipple.

Figures from: Martini, Anatomy & Physiology, Prentice Hall, 2001

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Mammary Glands

Milk production = lactation

Figures from: Martini, Anatomy & Physiology, Prentice Hall, 2001

Inactive (resting) mammary gland is dominated by a duct system rather than by active glandular cells. Size of mammary glands in a nonpregnant/nonlactating woman reflects amount of adipose tissue present.

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Review

Figure from: Marieb, Anatomy & Physiology, Pearson, 2004

Estrogen is the predominant hormone prior to ovulation (follicular phase)

Progesterone is the predominant hormone after ovulation (luteal phase)

inhibits LH and FSH during most of the reproductive cycle

(Day 10)

Estrogen maintains secondary sex characteristics in females

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ReviewFigure from: Hole’s Human A&P, 12th edition, 2010

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Review

• Climacteric– Women

• Called menopause

• Occurs around 40-50 years of age

• Cessation of reproductive cycles – no oocytes

• Ovaries no longer produce much estrogen

– Men• Occurs more gradually

• Sperm production continues well into old age

• Levels of testosterone decline gradually