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TOPIC 12 Reproductive System

Biology 221 Anatomy & Physiology II. TOPIC 12 Reproductive System. Chapter 28 pp. 1071-1107. E. Lathrop-Davis / E. Gorski / S. Kabrhel. Male Anatomy Overview. Consists of: Testes Ducts epididymus ductus (vas) deferens ejaculatory duct urethra Penis Accessory glands

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TOPIC 12 Reproductive System

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  1. Biology 221 Anatomy & Physiology II TOPIC 12 Reproductive System Chapter 28 pp. 1071-1107 E. Lathrop-Davis / E. Gorski / S. Kabrhel

  2. Male Anatomy Overview Consists of: • Testes • Ducts • epididymus • ductus (vas) deferens • ejaculatory duct • urethra • Penis • Accessory glands • seminal vesicles • prostate • bulblurethral (Cowper’s) http://www.msms.doe.k12.ms.us/biology/anatomy/reproductive/376a.gif Fig. 28.1, p. 1071

  3. Male: Testis • Located in scrotum • temperature regulation (keeps them at about 33oC) • Structure of testis • seminiferous tubules • interstitial cells (cells of Leydig) • rete testis Fig. 28.3, p. 1073

  4. Male: Testis – Seminiferous Tubules • Produce sperm • Sustentacular (Sertoli) cells (5) – support spermatocytes and spermatozoa, and produce inhibin (inhibits FSH/LH secretion) http://www.usc.edu/hsc/dental/ghisto/rep/d_74.html http://www.usc.edu/hsc/dental/ghisto/rep/d_74.html

  5. Male: Testis – Interstitial Cells and Rete Testis • Interstitial cells (between seminiferous tubules) – produce testosterone (promotes sperm formation) • Rete testis • first collection area • network of tubules on posterior side • Lead to epididymus http://www.usc.edu/hsc/dental/ghisto/rep/d_74.html http://www.usc.edu/hsc/dental/ghisto/rep/d_75.html Fig. 28.3, p. 1073

  6. Male: Testis Coverings • tunica vaginalis (TV) – connective tissue, derived from peritoneum • tunica albuginea (TA) – fibrous capsule • septa (S; singular = septum) – extensions of tunica albuginea; divide testis into sections Fig. 28.3, p. 1073 http://www.usc.edu/hsc/dental/ghisto/rep/d_72.html

  7. Male: Duct System • Epididymis – site of sperm maturation • Ductus (vas) deferens – carries sperm away from testis to ejaculatory duct • Ejaculatory Duct – extends from where ducts from seminal vesicles join ductus deferens to urethra Fig. 28.1, p. 1071 http://www.msms.doe.k12.ms.us/biology/anatomy/reproductive/376a.gif

  8. Male: Urethra • Prostatic urethra – runs through prostate gland • Membranous urethra – runs from prostate to penis • Penile urethra – runs through penis Fig. 28.4, p. 1075 http://www.nku.edu/~dempseyd/REPRODUCTION_2.htm

  9. Male: Penis • Designed to deliver sperm into vagina of female • Erectile tissues • Corpora cavernosa (CC) • Corpus spongiosum (CS) – surrounds urethra Fig. 28.4, p. 1075 http://wbiomed.curtin.edu.ou/teach/humanbiol/hb134/134hist/penis.htm

  10. Male Accessory Glands & Semen • Semen = sperm plus products of the accessory glands that support and nourish the sperm + sperm • Glands (overview) • Seminal vesicles (SV) • Prostate gland • Bulbourethral (Cowper’s) glands Fig. 28.1, p. 1071

  11. Male Accessory Glands: Seminal Vesicles • produce about 60% of all semen • alkaline fluid – neutralizes acidity of vagina • fructose – nourishes sperm Fig. 28.1, p. 1071

  12. Male Accessory Glands: Prostate • encircles urethra below bladder • produces about 30% of semen • products play a role in activating and protecting sperm • citrate nourishes sperm http://www.usc.edu/hsc/dental/ghisto/rep/d_96.html Fig. 28.1, p. 1071

  13. Male Accessory Gland:Bulbourethral Glands • Lie near base of penis • Produce mucus that neutralizes acidity of traces of urine in urethra Fig. 28.1, p. 1071

  14. Male Reproductive Physiology: Sperm Production Overview • Sperm (and ova) are produce by meiotic cell division • Sperm production involves two stages: • Spermatogenesis – in which diploid cells divide by meiotic cell division to yield haploid gametes • Spermiogenesis – maturation of spermatids into functional spermatozoa (sperm)

  15. Single division 2 divisions • Meiosis I – reduces number of chromosomes by half • Meiosis II – separates chromatids into 4 separate haploid cells Produces 2 genetically identical diploid daughter cells Produces 4 genetically distinct haploid daughter cells Comparison of Mitosis & Meiosis Mitosis Meiosis Fig. 28.6, p. 1078

  16. Male: Spermiogenesis Development of: • Flagellum for movement • Acrosome (contains digestive enzymes for egg penetration) • Midpiece (mitochondria -energy for movement) Fig. 28.9, p. 1082

  17. Male: Sustentacular Cells • Also called Sertoli cells • Surround and support developing spermatocytes and spermatids • Extend from basal lamina to lumen of tubule Fig. 28.8, p. 1081

  18. Male: Sustentacular Cells • Form blood-testis barrier • cells joined by tight junctions - prevents contact between developing sperm and blood • produce fluid different from surrounding interstitial fluid (higher in androgens, amino acids, potassium) • important because sperm are first produced after immune system has developed sense of “self” • sperm would be recognized as foreign if contacted blood

  19. Male: Hormonal Regulation of Function Hypothalamus secretes GnRH (Gonadotropin-releasing hormone)  Stimulates anterior pituitary to release FSH LH  • indirectly stimulates stimulates testosterone secretion testosterone • stimulates spermatogenesis secretion • stimulates inhibin secretion (inhibits FSH and LH production) Fig. 28.10, p. 1085 http://www.uronet.org/visual/nov99/3.htm

  20. Male: Testosterone Stimulates • spermatogenesis • development and maintenance of male secondary sex characteristics (e.g., facial hair, large muscles, etc.) and male reproductive organs • development of sexual drive in CNS • protein synthesis in muscle cells and growth of muscle and bone Fig. 28.10, p. 1085 http://www.uronet.org/visual/nov99/1.htm

  21. Female Anatomy Overview Consists of: • Ovaries • Fallopian (uterine) tubes (oviducts) • Uterus • Vagina • Mammary glands • Supporting structures http://www.med.umich.edu/lrc/coursepages/M1/anatomy/html/radiology/pelvis/hysterosalpingogram.html Fig. 28.11, p. 1086

  22. Female: Ovaries • Located lateral to uterus • Ligaments anchor ovary to other structures • ovarian ligament – anchors ovary to uterus • broad ligament – parietal peritoneal tissue • suspensory ligament – anchors ovary to lateral pelvic wall • mesovarium – holds ovary between ovarian and suspensory ligaments • Contains oocytes surrounded by follicles • Release secondary oocytes into pelvic cavity Fig. 28.14, p. 1089

  23. Female: Uterine (Fallopian) Tubes • Carry oocyte toward uterus • Fimbriae (F) immediately pick up secondary oocyte released from ovary and transfer it into UT • Smooth muscle and cilia of simple columnar epithelium help move oocyte toward uterus Fig. 28.14, p. 1089 http://www.med.umich.edu/lrc/coursepages/M1/anatomy/html/radiology/pelvis/hysterosalpingogram.html

  24. Female: Uterus • Normal site of implantation of fertilized ovum and development of fetus • Layers • endometrium (inner layer) • myometrium (smooth muscle) • perimetrium (covering of visceral peritoneum) Fig. 28.14, p. 1089

  25. Female: Uterus – Endometrium • Consists of two sublayers • stratum functionalis (f) – undergoes cyclical changes every month • stratum basalis (b) – overlies myometrium (m) and forms a new stratum functionalis • Forms maternal part of placenta http://www.usc.edu/hsc/dental/ghisto/rep/d_33.html http://www.usc.edu/hsc/dental/ghisto/rep/d_34.html

  26. Female: Myometrium & Perimetrium • Myometrium • consists of smooth muscle • contracts to expel sloughed off endometrial tissue or fetus • Perimetrium(serosa) • peritoneal covering Fig. 28.14, p. 1089

  27. Female: Cervix and Vagina • Cervix – narrow “neck” of uterus • Vagina • “birth canal” • lined with stratified squamous epithelium Fig. 28.14, p. 1089

  28. Mammary Glands • Modified sweat glands • Only functional in females • Produce milk to nourish newborn • Hormonal control • prolactin - stimulates milk production in lactating female • oxytocin - stimulates milk ejection Fig. 28.17, p. 1093

  29. Female: Ovarian Cycle Overview • Consists of two phases: Follicular (1-6 in diagram) & Luteal (7-9 in diagram) Fig. 28.20, p. 1097

  30. Follicular Phase – 1st to 14th Day • Several primordial follicles develop into primary follicles • Primary follicle develops into secondary follicle • zona pellucida (thick, transparent membrane around oocyte) • begins to produce estrogens • antrum (opening around oocyte) forms • Secondary follicle (when antrum is present) becomes Vesicular follicle (Graafian follicle) • corona radiata forms (cells surrounding oocyte) • primary oocyte divides (finishes meiosis I) to form 1 secondary oocyte and 1 polar body Fig. 28.12, p. 1087 Fig. 28.19, p. 1095

  31. Ovulation and Luteal Phase – 14th to 28th day • Ovulation = release of secondary oocyte (arrested in metaphase of meiosis II) from ovary • Luteal Phase – 14th to 28th day • cells of ruptured Graafian follicle become corpus luteum which begins to secrete progesterone and continue to secrete estrogen • corpus luteum degenerates in about 10 days if pregnancy does not occur then becomes corpus albicans Fig. 28.12, p. 1087

  32. Ovarian Cycle: Hormonal Control • Hypothalamus secretes GnRH (gonadotropin releasing hormone) • GnRH stimulates release of FSH (follicle stimulating hormone) and LH (lutenizing hormone) from anterior pituitary • FSH (& LH) stimulate follicle growth Fig. 28.21, p. 1098

  33. Ovarian Cycle: Hormonal Control • Enlarged follicles begin to secrete estrogens • Rising estrogen levels initially inhibitrelease of FSH & LH from anterior pituitary, but also stimulate it to produce and accumulate these hormones (i.e., accumulate FSH and LH) Fig. 28.21, p. 1098

  34. Ovarian Cycle: Hormonal Control • Once estrogen levels reach critical level, exert positive feedback on hypothalamus & pituitary • result is sudden surge of LH • Surge of LH results in: • completion of meiosis I • release of secondary oocyte from Graafian follicle (i.e., ovulation) • Ovulation results from positive feedback influence of estrogen on secretion of LH Fig. 28.21, p. 1098

  35. Ovarian Cycle: Hormonal Control • Surge of LH causes ruptured follicle to become corpus luteum and stimulates production of estrogens and progestins from it • Increased progesterone and estrogen cause decline in LH; corpus luteum is less stimulated and eventually becomes corpus albicans Fig. 28.21, p. 1098

  36. Uterine (Menstrual) Cycle • Cyclical changes in the endometrium that prepare it for implantation of a fertilized ovum. • Three phases: menstrual, proliferative, secretory Fig. 28.15, p. 1091 Fig. 28.22, p. 1100

  37. Menstrual Phase (Days 1-5) • Stratum functionalis is shed (passes through vagina as menstrual flow) • This is a response to declining estrogen levels http://lpc1.clpccd.cc.ca.us/lpc/zingg/anat/alecture/ach27f/sld021.htm

  38. Proliferative Phase (Days 6-14) • Stratum functionalis rebuilt by stratum basale in response to stimulation from ovarian estrogens • Endometrial glands become larger • Estrogen induces formation of additional progesterone receptors • Increased blood supply

  39. Secretory Phase (Days 15-28) • Endometrium continues to develop in response to ovarian progesterone • Secretion of nutrient substances begins • Toward end, decline in progesterone results in declining condition of blood vessels in stratum functionalis, eventually resulting in its loss (start of next menstrual phase)

  40. Correlation of Hormones With Cycles • During menstrual phase, all hormones are at their lowest levels • During proliferative phase, estrogens secreted by ovary cause proliferation of endrometrial cells such that stratum functionalis is rebuilt from stratum basale • During secretory phase, • high levels of progesterone continue to stimulate development of stratum functionalis • Levels of estrogen decrease somewhat Fig. 28.22

  41. Disorders of Reproduction: STDs • Gonorrhea – infection by Neisseria gonnorrhoeae bacteria; causes inflammation of the urethra and can lead to pelvic inflammatory disease in females • Syphilis – infection by Treponema pallidum bacteria • Chlamydia – infection by Chlamydia bacteria; causes pelvic inflammatory disease, urethritis, among other things • Genital warts – infection by human papillomavirus (HPV); causes warts in genital area; increases probability of developing cervical or penile cancer • Genital herpes – infection by herpes simplex virus; causes lesions on genital area; treated with acyclovir

  42. Other Disorders of Reproduction • Pelvic inflammatory disease (PID) - severe inflammation of lower peritoneal cavity generally caused by STDs • Ectopic pregnancy – implantation of embryo outside uterus (e.g., in oviduct or pelvic cavity) • Hypertrophy of prostate – enlargement of the prostate;impinges on prostate urethra making urination difficult and increasing the likelihood of bladder infection; common in elderly males • Breast cancer - cancer of the mammary gland; strikes 1:8 women

  43. Important Developmental Milestones • 8 weeks • ossification begins • blood cells begin to be formed by liver • all systems present (at least as basic plan) • 9-12 weeks • bone marrow begins to form blood cells • 26 weeks • surfactant production begins in lung • 38-42 weeks • birth • if less than 38 weeks, systems not as developed • if more than 42 weeks, placenta starts to degrade

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