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Reproductive System

Reproductive System. Chapter 27. Male Reproductive System. Male Reproductive Anatomy Overview. Testes in scrotum Epididymis Vas deferens Ejaculatory duct Urethra (3 parts) Seminal vesicles Prostate Bulbourethral glands.

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Reproductive System

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  1. Reproductive System Chapter 27

  2. Male Reproductive System

  3. Male Reproductive Anatomy Overview • Testes in scrotum • Epididymis • Vas deferens • Ejaculatory duct • Urethra (3 parts) • Seminal vesicles • Prostate • Bulbourethral glands http://www.everydayhealth.com/mens-health-pictures/male-anatomy-and-the-reproductive-system.aspx , with illustrations by Catherine Delphia

  4. Anatomical Structures • Scrotum (5) • Superficial sac for testes = 3° lower than core • Requirement w/ sperm production • Muscles facilitate • Dartos: smooth muscle wrinkles for insulation • Cremaster: ontracts w/ cold = pulled closer; hot = opposite • Testes (1) • Two tunics • Tunica vaginalis: outer from peritoneum • Tunica albuginea: inner fibrous layer that divides into lobules • Seminiferous tubules where spermatogenesis occurs • Surrounded by testosterone producing interstitial cell • Converge at rete testes before epididymis • Testicular cancer: most common in young; regular self-exam increases early detection

  5. Anatomical Structures (cont.) • Penis (2) • Root w/ free shaft ending in glans penis • Foreskin (prepuce) covers; removed w/ circumcisition • 3 regions of erectile tissue • Corpus spongiosum(1) surrounds urethra; forms glans • Corpora cavernosa(2) • Epididymis (3) • Stores non-motile sperm till maturation • ~ 20 days  swimmers • Released w/ejaculation • Stereocilia absorbs excess fluids and supplies nutrients

  6. Anatomical Structures (cont.) • Vas deferens • W/ blood, nerves, and lymph to testes = spermatic cord • Peristalsis propels sperm • Joins seminal vesicle  ejaculatory duct (4) • Vasectomy: male sterilization technique: ~ 50% reversal success • Urethra • Urinary and reproductive function • 3 parts (prostatic, membranous, and spongy)

  7. Anatomical Structures (cont.) • Seminal vesicles • ~60% semen • Viscous, alkaline solution, w/fructose (ATP) and prostaglandins (down cervical mucus viscocity) • Prostate • ~33% semen • Milky, acidic solution w/ citrate, enzymes, and specific antigens • Hypertrophy: difficulty urinating or having an erection • Prostatis: inflammation • Bulbourethral gland • < 5% • Thick, alkaline mucus to neutralize traces of urine & lubricate • Semen • Alkalinity ~ 7.3 – 7.7 • Neutralizes vagina • Survival < 48 hrs after ejaculation • Sterility: reduced production of sperm

  8. Male Sexual Response: Erection • PNS releases NO = penis engorges w/ blood • Relaxes penile tissue • Vasodilate vascular supply • Corpora cavernosa compresses vein drainage to maintain • Corpus spongiosum maintains urethral opening during ejaculation • PNS signals bulbourethral secretions to lubricate glans

  9. Male Sexual Response: Ejaculation • Spinal reflex of SNS triggers • Climax/ orgasm • Bladder sphincter constricts  urine retention • Contraction of ducts and accessory glands • Penile muscles rapidly contract to propel • Resolution follows • Muscular and physiological relaxation • Latent period prevents consecutive erection • Erectile dysfunction: inability to attain an erection

  10. Gametogenesis • Nuclear division reduces chromosome number to produce gametes • Humans w/ 23 pairs (46) homologous chromosomes • Gametes w/23 chromosomes = haploid (n) • Gamete + gamete = fertilization = diploid (2n) • Occurs in gonads (testes and ovaries) • 1 parent cell produces ‘4’ daughter cells

  11. Meiosis • Phases mirror mitosis (pro-, meta-, ana-, telophase) • Replication of DNA prior to • Meiosis I • Homologs synapse and crossing over occurs at chiasma(prophase I) • 1 cell  2 cells w/ ½ DNA amount • Meiosis II • Chromatids separate • Resembles mitosis • Introduces genetic variability • Nondisjunction w/ failure to separate in anaphase I or II • Chromosomal number abnormalities

  12. Spermatogenesis • Formation of sperm • ~ age 14 to death • ~400 million a day • Spermatogonium (stem) divides into multiple primary spermatocytes (mitosis) • Primary to secondary spermatocytes (meiosis I) • Secondary to spermatids (meiosis II) Spermiogenesis: Spermatids to sperm (fig 27.8) • Circular cell to 3 distinct regions • Head w/ acrosome (genetic), midpiece (metabolic), tail (locomotor)

  13. Spermatogenesis (cont.)

  14. Hormonal Regulation • Hypothalamus: GnRH AP: FSH/LH  testes (review) • FSH: indirect spermatogensis stimuli by maintaining high [testosterone] • LH: prods seminiferous tubules to produce testosterone • Spermatogenesis push • High [testosterone] effects other targets • Maturation of sex organs • Development/ maintenance of 2° sex characteristics • Stimulates sex drive • Inhibits GnRH • Inhibinup w/ increase [sperm]  inhibits FSH/LH release

  15. Female Reproductive System

  16. Female Reproductive Anatomy Overview • Ovaries • Uterine tubes • Uterus • Vagina • External genitalia • Mammary glands http://www.drmalpani.com/book/chapter2a.html

  17. Anatomical Structures • Ovaries • Held in place by ligaments (ovarian, broad, and mesovarium) • Two tunics • Germinal epithelium: cuboidal cells of peritoneum • Tunica albuginea: inner fibrous layer • Contain sac-like follicles w/ oocytes • Uterine tubes (Oviducts) • Fimbriae ‘sweep’ ovulated 2° oocyte into infundibulum to ampulla for fertilization • Ectopic pregnancy: fertilization outside uterine tube • Pelvic inflammatory disease: bacterial infection

  18. Anatomical Structures (cont.) • Uterus • 3 walled organ (peri-, myo-, and endometrium) • 3 regions (fundus, body, cervix) • Isthmus, cervicalcanal, external and internalos • Endometrial layers • Stratumfunctionalis: cylic changes w/ ovarian hormones; sloughed ~ every 28days • Stratumbasalis: forms new functionalis; unresponsive to ovarian hormones • Cervical cancer • Prolapse: uterus sinks to external vagina from muscle weakening • Vagina • 3 layers (fibroelastic adventitia, smooth muscularis, strat. squam. mucosa w/ rugae) • Passageway for birthing and menses • Acidic environment impairs sperm mobility and resist bacteria

  19. Anatomical Structures (cont.) • External Genitalia • Mons pubis • Labia majoraand minora • Clitoris • Glans and prepuce • Corpora cavernosaonly • Vestibule • Vestibular glands lubricate and moisten • Mammary glands • Present in males & females, but fxn in females only • Stimulated by PRL and oxytocin • Areola w/sebaceous glands (minimize chapping) and nipple • Suspensory ligaments naturally support • Milk in lobules from alveoli cells to lactiferous duct and collects in lactiferous sinus in nipple w/ nursing

  20. Oogenesis • Formation of ova (egg) • Fetus to birth and puberty to menopause • 7 million to 2 million and 250, 000 to < 500 • Oogonia(stem) divide into multiple primary oocytes in primordial follicles (mitosis) • Primary start meiosis, but stall at prophase I (birth) • LH surge activates multiple, but only 1 finish meiosis I • First polar body • Secondary oocyte stalls at metaphase II before ovulation • Fertilization completes meiosis II • One ovum (functional) • Second polar body

  21. Oogenesis (cont.)

  22. Comparing Gametogenesis Oogenesis Spermatogenesis Mitotic division puberty to death 4 functional sperm Continuous production • Mitotic division completed at birth • 1 functional ova and 3 polar bodies (degenerate) • 1 ova per cycle (~ 28 days)

  23. Ovarian Cycle • Maturation of ova events • Typically 28 days • 21 – 40 more common • Follicular phase (variable) • Follicle grows • Day 1 to 14 • Luteal phase (constant) • Corpus luteumactivity • Day 14 -28 • Ovulation is midcycle

  24. Follicular Phase • Primordial to primary follicle • Outer sim. squa outer sim. cub. • Primary to secondary follicle • Sim. cub  strat. squam (granulosacells) • Granulosa and thecal cells secrete estrogen • Zonapellucidaencapsulates oocyte • Antrum forms • Secondary to vesicular follicle • Growing antrum isolates granulosa  corona radiata • Bulges at surface for ovulation • Fraternal vs. identical twins • Meiosis I completed • Fig 27.18

  25. Luteal Phase • Corpus luteum formed after ovulation • Antrum w/ blood • Granulosa cells increase size • Progesterone (some estrogen) secretion starts • ~ 10 days till degeneration • Scar, corpus albicans, results • Pregnancy prevents • Hormone secretion as bridge w/ placenta (~3 months)

  26. Ovarian Cycle Hormonal Control • GnRH LH and FSH  estrogen and progesterone • Estrogen inhibits GnRH (childhood) • Hypothalamus less responsive approaching puberty • Adult pattern reached = menarche • Day 1: GnRH stimulates LH and FSH release • Stimulate follicle growth, development, and estrogen release • Rising estrogen • Inhibits LH and FSH release • High levels produce LH surge  primary to secondary oocyte • Day 14: LH surge triggers ovulation • Corpus luteum formation (estrogen, progesterone, and inhibin) • Inhibit LH and FSH • Days 26 – 28: ovarian hormones drop • LH and FSH NOT inhibited • Cycle repeats • Fig 27.19

  27. Uterine Cycle • Cyclical changing of endometrium • FH and FSH govern • Linked w/ ovarian cycle • Days 1 – 5 • Menses, ‘sloughing off’ of endometrium • Ovarian hormones low; LH and FSH rising • Days 6 - 14 • Proliferative phase rebuilds endometrium • Estrogen increases  cervical mucus thins • Days 15 -28 • Secretory phase preps uterus for embryo • Progesterone increase creates cervical plug from cervical mucus

  28. Ovarian and Uterine Cycles http://www.theholisticcare.com/cure%20diseases/Menstruation.htm

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