28.2 Puberty & Menopause

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⭐️ 28.2 Puberty & Menopause — In-Depth Study Guide (Organized Outline Format)

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I. Hormones That Regulate Female Reproductive Function

(Learning Objective: Name the hormones that regulate female reproductive function and state their roles.)

A. Hypothalamic Hormone

• GnRH (Gonadotropin-Releasing Hormone) conductor of orchestra 8-10 girls

  • Secreted by hypothalamus

  • Triggers puberty

  • Stimulates anterior pituitary to release: gondatropins

    • FSH

    • LH

B. Pituitary Gonadotropins

1. FSH (Follicle-Stimulating Hormone) Stimulates ovarian follicles

• Follicles then secrete:

  • Estrogen

  • Progesterone

  • Inhibin

  • Small amounts of androgens

2. LH (Luteinizing Hormone)

• Surges mid-cycle to cause ovulation- release of mature egg

• Supports corpus luteum development- left behind after ovulation

• Stimulates progesterone production

C. Ovarian Hormones

1. Estrogens- physcial characteristcs

• Estradiol (most abundant), estriol, estrone

• Feminizing hormones with widespread effects

• Major puberty roles: estradiol

  • Breast development

  • Vaginal metaplasia

  • Growth of secondary sex organs

  • Fat deposition (breasts, hips, thighs)

  • Skin thickening but still softer and warmer than males

  • Growth hormone stimulation → height increase, pelvis widening

2. Progesterone- thickening the lining

• Prepares uterus for pregnancy

• Acts mainly during second half of menstrual cycle

• Supports uterine lining for potential implantation

• no pregnancy, progesterone drops… menstruation

3. Androgens “male hormones”

• Small amount from ovaries and adrenal cortex

• Responsible for:

  • Pubic and axillary hair (pubarche)

  • Sebaceous and sweat gland activity

  • Libido (sex drive)

4. Inhibin

• Secreted by follicles

• Selectively suppresses FSH

• Helps regulate follicle recruitment

• preventing from too many maturing in one month

II. Principal Signs of Puberty

(Learning Objective: Describe the principal signs of puberty.)

A. Onset of Puberty

• Begins age 8–10 in most U.S. girls

• Triggered by rising GnRH

B. Thelarche — Breast Development (First Sign)

• Earliest visible sign of puberty

• Hormones involved:

  • Estrogen

  • Progesterone

  • Prolactin

• Breast development pattern:

  • Ducts and lobules form under estrogen and progesterone

  • Completion regulated by:

    • Glucocorticoids

    • Growth hormone

  • Enlargement due to:

    • Adipose tissue

    • Fibrous tissue

C. Pubarche — Appearance of Hair & Gland Activity

• Pubic hair

• Axillary hair

• Sebaceous glands (oil)

• Apocrine sweat glands

• Stimulated by androgens (ovarian + adrenal)

D. Menarche — First Menstrual Period

• Requires ~17% body fat in teens

• Improved nutrition → average age now ~12

• Leptin from body fat stimulates GnRH and gonadotropins

• If leptin or body fat too low:

  • FSH & LH decline

  • Cycle may stop (amenorrhea)

• Menstruation stops at <22% body fat in adult women

• First cycles usually anovulatory

  • Ovulation becomes regular ~1 year later

E. Estradiol’s Role in Puberty

Stimulates:

• Vaginal epithelium to undergo metaplasia (cuboidal → stratified squamous) strengthen it

• Growth of ovaries and secondary sex organs

• Growth hormone secretion

  • Height increase

  • Pelvic widening- for childbirth

• Fat deposition (breasts, hips, thighs)

• Skin thickening

  • But girls’ skin still thinner and softer than boys

F. Cyclic Hormone Secretion

• FSH, LH, estrogen, and progesterone follow a monthly cycle- menstrual cycle

• Negative feedback:

  • Estrogens & progesterone ↓ FSH and LH= preventing overstimulation

  • Inhibin ↓ FSH selectively= control environment for follicle development

III. Female Climacteric and Hormonal Changes

(Learning Objective: Describe the hormonal changes of female climacteric and their effects.)

A. Definition of Climacteric

• Midlife decrease in reproductive hormone secretion

• Occurs as ovaries lose follicles: transitional era

B. Follicle Depletion

ovaries runnning out of “fuel”

• Female born with ~2 million eggs

• Climacteric begins when only ~1,000 follicles remain

• Remaining follicles less responsive to FSH & LH

• Ovaries secrete:

  • Less estrogen

  • Less progesterone

C. Systemic Effects of Decreased Estrogen/Progesterone

1. Reproductive Organ Atrophy

• Uterus shrinks

• Vagina thins (increased fragility)

• Breasts atrophy

• Intercourse may become uncomfortable due to dryness

2. Increased Infection Risks

• Vaginal epithelium thins → less glycogen → pH increases

• Vaginal infections more common

3. Skin Changes

• Becomes thinner due to loss of estrogen

• Loss of dermal collagen

4. Cardiovascular Effects

• Cholesterol levels rise

• Increased risk of heart disease

5. Skeletal Effects

• Rapid bone mass loss

• Increased risk of osteoporosis

6. Vasomotor Instability

• Blood vessels dilate and constrict unpredictably

• Causes hot flashes:

  • Sudden warmth spreading from abdomen → chest → neck → face, sweating and palpitations

D. Hormone Replacement Therapy (HRT)

• Treatment: low-dose estrogen + progesterone

• Helps relieve:

  • Hot flashes

  • Vaginal dryness

  • Bone loss

• Risks and benefits are still debated (depends greatly on patient’s health profile)

IV. Menopause vs. Climacteric

(Learning Objective: Define and describe menopause, and distinguish menopause from climacteric.)

A. Climacteric (transitional period) begin years before menopause

• Broad transition period

• Involves hormonal decline, especially estrogen and progesterone

• Occurs gradually over several years

B. Menopause (Specific Event) end of climactic

• Defined as cessation of menstrual cycles

• Occurs between 45–55 (average ~51)

• Age has increased due to improved nutrition/health

• Menopause is complete when:

  • No menstruation for 1 full year

C. Key Distinction