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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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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 • seminal vesicles • prostate • bulblurethral (Cowper’s) http://www.msms.doe.k12.ms.us/biology/anatomy/reproductive/376a.gif Fig. 28.1, p. 1071
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
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
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
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
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
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
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
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
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
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
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
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)
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
Male: Spermiogenesis Development of: • Flagellum for movement • Acrosome (contains digestive enzymes for egg penetration) • Midpiece (mitochondria -energy for movement) Fig. 28.9, p. 1082
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
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
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
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
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
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
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
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
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
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
Female: Cervix and Vagina • Cervix – narrow “neck” of uterus • Vagina • “birth canal” • lined with stratified squamous epithelium Fig. 28.14, p. 1089
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
Female: Ovarian Cycle Overview • Consists of two phases: Follicular (1-6 in diagram) & Luteal (7-9 in diagram) Fig. 28.20, p. 1097
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
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
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
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
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
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
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
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
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
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)
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
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
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
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