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Reproductive System Chapter 27.

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Presentation on theme: "Reproductive System Chapter 27."— Presentation transcript:

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 , 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 Inhibin up 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

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, cervical canal, external and internal os Endometrial layers Stratum functionalis: cylic changes w/ ovarian hormones; sloughed ~ every 28days Stratum basalis: 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 majora and minora Clitoris Glans and prepuce Corpora cavernosa only 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 completed at birth 1 functional ova and 3 polar bodies (degenerate) 1 ova per cycle (~ 28 days) Mitotic division puberty to death 4 functional sperm Continuous production

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

24 Follicular Phase Primordial to primary follicle
Outer sim. squa  outer sim. cub. Primary to secondary follicle Sim. cub  strat. squam (granulosa cells) Granulosa and thecal cells secrete estrogen Zona pellucida encapsulates 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 Days 1 – 5 Days 6 - 14
FH and FSH govern Linked w/ ovarian cycle Days 1 – 5 Menses, ‘sloughing off’ of endometrium Ovarian hormones low; LH and FSH rising Days Proliferative phase rebuilds endometrium Estrogen increases  cervical mucus thins Days Secretory phase preps uterus for embryo Progesterone increase creates cervical plug from cervical mucus

28 Ovarian and Uterine Cycles

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