Women s bodies: Anatomy

1. Women�s bodies: Anatomy Topics: skeletal anatomy, fat distribution, reproductive organs, mammary glands males & females identical in most respects most diffs. are average diffs. with overlapping distributions skeletal anatomy exhibits gender differences (5/206 bones)

2. Female skeleton 5 bones are unique: 3 in head, 2 in pelvis skull bone diffs.: mandible larger in males temporal bone has larger opening in males frontal bone larger in males diffs. in pelvis (ossa coxae): broader, flatter in females rounder pelvic inlet

3. Female pelvis os coxa made of 3 smaller, fused bones: illium (joined to sacrum) ischium pubis (joined by pubic symphysis) pubic symph. and sacroiliac joints are immobile except during pregnancy, childbirth pelvic inlet is round (vs. elongated oval) men have 32% more bone mass (due to density, diameter) on average, men have longer arms and legs relative to body size women have greater pelvic tilt, smaller �Q angle�

4. Body composition men have more muscle, women more fat results from diff. sex hormone ratios Sex hormones cause secondary sex characteristics Female sex hormones: estrogens Estradiol Estrone Estriol Male sex hormones: androgens Dihydrotestosterone (DHT) Testosterone androstenedione

5. Sex hormones Sex hormones made from cholesterol (steroids) Chemical properties allow them to act inside cell Act through nuclear receptors (Fig. 3-3)

6. Testosterone effects on fat storage in muscle cells, increases production of proteins that trigger cell growth, multiplication in adipocytes, increases production of proteins that cause lipid breakdown also changes cell membranes, limiting amount of lipid they take from bloodstream

7. Body composition, cont�d. estrogen downregulates androgen receptors in fat cells: decreased rate of lipid degradation high uptake of lipids effects of T + high fat diet in men = arteriosclerosis also accounts in part for increased incidence of heart disease in postmenopausal women sex hormones affect fat storage patterns: high E, low T > stored in alpha adipocytes (extremities) low E, high T > stored in beta ad. (abdomen)

8. Physiological effects of body composition women have higher fat : muscle ratio (.42 vs. .24) men have more blood vessels for their size, greater blood volume, bigger heart, more hemoglobin explains diffs. in athletic performances other roles of fat: cushions internal organs insulation stores fat-soluble vitamins, energy

9. Reproductive anatomy: Breasts specialized skin glands (modified sweat glands) found in mammals found in both sexes; nonfunctional in males develop in response to estrogen at puberty lobules: made of alveoli (sacs), ducts milk production occurs in sacs each alveolus empties into lactiferous duct > lactiferous sinus > through nipple

10. Breasts, cont�d. alveoli: epithelial cells (milk-producing) myoepithelial cells (milk-ejecting) lobules are separated, supported by connective tissue & fat all women have same amount of mammary tissue size, lumpiness varies with menstrual cycle cyclic changes promote growth of benign cysts or fibroid tumors 70-90% of women experience fibrocystic changes in their breasts

11. External genitals called pudendum (pudere, �to be ashamed) includes vulva, clitoris vulva = 2 sets of labia labia majora labia minora (no fat or hair; hood of clitoris) role: protection; sexual arousal contain sebaceous glands role of sebum: repels urine, menstrual blood, bacteria

12. Clitoris arises from genital tubercle sole function: sexual arousal, orgasm generous blood, nerve supply becomes erect due to vasocongestion during orgasm, congestion relieved; rhythmic contractions of surrounding muscles below clitoris: opening to urethra (passageway for urine to exit bladder) below urethra: vaginal opening, surrounded by membranous fold (hymen)

13. Internal genitals: vagina muscular organ connected to uterus passageway with �potential space� inner surface = hairless skin and glands mechanisms for preventing infection: outer layers of skin shed, broken down flow of cervical mucus vaginal lubrication by vestibular glands (at entrance) water released by surface blood vessels

14. Vaginal flora discharge fed upon by good bacteria (lactobacilli) produce lactic acid acidic environ. keeps yeast in check decrease in lactobacilli > yeast infections contributing factors: antibiotics pregnancy suppressed immune system (stress, AIDS) soaps, toilet paper dyes, perfumes douching

15. Uterus at 90 degree angle to vagina lies on top of bladder in most women (80%) others > on top of rectum (�tipped uterus�) exposure to DES during development can lead to T-shaped uterus > compromises fertility size of fist in nonpregnant state wall is 1 cm thick: perimetrium, myometrium, endometrium lower region = cervix; opening = os childbirth changes os (dot to dash) dilates slightly during orgasm and 30 min. following

16. Oviducts extension of top of uterus not attached to ovaries fimbria and suction direct movement of eggs suction due to movement of cilia blockage: increased risk of tubal pregnancy impairment of fertility women have risk of peritonitis due to opening of oviducts into abdomen

17. Ovaries at birth, 1-2 million germ cells present lost progressively throughout life (99% never ovulate) 1+ eggs ovulated per month eggs surrounded by follicles after ovulation, follicle becomes corpus luteum: secretes estrogen, progesterone prepares body for pregnancy functional cysts can develop