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Reproductive System Chapter 27. MALE REPRODUCTIVE SYSTEM.

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

1 Reproductive System Chapter 27


3 Male Reproductive Anatomy Overview Testes in scrotum Epididymis Vas deferens Ejaculatory duct Urethra (3 parts) Seminal vesicles Prostate Bulbourethral glands 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 Inhibin up w/ increase [sperm]  inhibits FSH/LH release


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

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 luteum activity – 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 (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 – 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

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