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Reproductive System
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Reproductive System

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  1. Reproductive System • Introduction • Overview of the Reproductive System • Male Reproductive System • Female Reproductive System • Physiology of Sexual Intercourse

  2. Introduction • Meiotic Cell Division • Sex Determination • Functions of the Reproductive System • Reproductive System Overview • Male • Female

  3. Learning Objectives • Meiosis: • Outline the major stages & phases of meiotic cell division • SexDetermination: • Explain how sex is determined genetically & describe the consequences of the “Sry” gene • Introduction: • Summarize the functions of the human reproductive system and its principle components

  4. Meiotic Cell Division • Interphase – preparatory stage • Meiosis I – 1st nuclear division: halving of the chromosomenumber • 1st Cytokinesis – division of the cytoplasm: 2 daughter cells formed

  5. Meiotic Cell Division • (Interkinesis) – in some kinds of organisms • Meiosis II – 2nd nuclear division in both cells from meiosis I: separation of the sister chromatids • 2nd Cytokinesis – division of the cytoplasm in both cells from meiosis I: 4 daughter cells formed

  6. Interphase • G1 Phase • cell grows larger; organelles duplicated • S Phase • synthesis of DNA: replication of chromosomes to form sister chromatids • G2 Phase • cell growth continues; necessary materials for division are synthesized

  7. Meiosis I: Reduction Division • Prophase I (includes Prometaphase) • similar to mitosis except: homologous chromosomes pair in synapsis to form tetrads • Metaphase I • similar to mitosis except: homologs line up across the metaphase plate • Anaphase I • similar to mitosis except: homologs are separated to opposite poles of the cell • Telophase I • similar to mitosis except: nuclei may or may not reform completely

  8. 1st Cytokinesis • Begins w/ telophase I; ends after telophase I • Results in 2 daughter cells • Daughter cells contain ½ of original chromosomes; haploid cells

  9. Interkinesis • Occurs in some species after telophase I & 1st cytokinesis • Nuclei of daughter cells completely reform • Chromosomes –still as joined as sister chromatids – decondense • G phases may occur; NO S phase

  10. Meiosis II:Equational Division • Prophase II (includes Prometaphase) • Metaphase II • Anaphase II • Telophase II • same processes as mitosis for all phases

  11. 2nd Cytokinesis • Begins w/ telophase II; ends after telophase II • Results in 4 daughter cells • Daughter cells contain ½ of original chromosomes; haploid cells • 1 or more will form gametes

  12. Review ofMeiotic Cell Division

  13. Human Karyotype 2 sets Chromosomes = diploid =46 1 set Chromosomes = haploid = 23 Note: 23 pairs of chromosomes = 2 sets

  14. Sex Determination • Autosomes • Chromosomes that carry most of the structural genes; NO sex characteristics • 22 pairs • Sex Chromosomes • Chromosomes that carry sex genes & determine sex in combination • 1 pair

  15. Sex Chromosomes • Genetic characteristics • X = female characteristics • X chromosome carries basic sex characteristic genes & some structural genes • Y = male characteristics • Y chromosome carries “SRY” gene that produces testosterone & almost NO other genes • Sex Determination • XX = female • XY = male

  16. Comparison: Male & Female Development 2 Months 3 Months 4 Months 7 Months Birth

  17. Functions of the Reproductive System • Perpetuation of the species • Maintenance of secondary sex characteristics • Promotion of pair bonding

  18. Overview of the Reproductive System • Gonads Reproductive organs that produce reproductive cells & hormones • Male – testes • gametes – sperm • hormones – testosterone; inhibin • Female – ovaries • gametes – ova • hormones – estrogens; progesterone

  19. Animal Life Cycle

  20. Overview of the Male Reproductive System • Duct System • Epididymus • Ductus (vas) deferens • Ejaculatory duct • Urethra • Function • Deliver sperm & supporting secretions into the female reproductive system

  21. Overview of the Male Reproductive System • Accessory Organs: Glands • Seminal vesicles • Prostate gland • Bulbourethral glands • General Functions • Provide nourishment & protection for spermatozoa(sperm)

  22. Overview of the Female Reproductive System • Duct System • Uterine tubes (oviducts/fallopian tubes) • Uterus • Vagina • Functions • Deliver ovum or embryo to the uterus • Provide environment for development of an embryo/fetus • Serve as the birth canal • Serve as an exit for menstrual fluids

  23. Overview of the Female Reproductive System • Accessory Organs: Glands • Vestibular glands • Mammary glands • Functions • Produce lubricating fluids to aide coitus • Provide nourishment for offspring

  24. Male Reproductive System • Testes • Spermatogenesis • Spermiogenesis • Accessory ducts • Accessory glands • Semen composition & function • External genitalia • Hormonal controls

  25. Learning Objectives • MaleReproductiveSystem: • Describe internal & external components of the male reproductive system • Describe the roles of the accessory ducts & glands • Spermatogenesis & Spermiogenesis: • Outline the stages of sperm development & maturation

  26. Learning Objectives • SemenComposition: • Discuss the composition of semen & describe the function of the various glandular secretions • HormonalControl: • List the hormones associated w/ male reproductive physiology & describe the role of each

  27. Testes • Testicular lobules • Seminiferous tubules • Produce gametes – sperm • Produce hormones – testosterone;inhibin • Straight tubules • Carry sperm from seminiferous tubules • Rete testis • Carry sperm to efferent ducts • Efferent ducts • Carry sperm to epididymus

  28. Spermatogenesis Diploid Haploid

  29. Spermiogenesis

  30. Special Cells • Sustentacular (Sertoli) cells • Locus: w/in seminiferous tubules • Function: nourish developing sperm; stimulate spermatogenesis & spermiogenesis; secrete inhibin • Interstitial (Leydig) cells • Locus: spaces btw seminiferous tubules • Function: stimulate activity of sustentacular cells; secrete testosterone

  31. Accessory Ducts • Epididymus • sperm maturation & storage • Ductus (vas) deferens • sperm duct from epididymus to seminal vesicles • Ejaculatory duct • sperm duct from seminal vesicle to urethra • Urethra: prostatic/membranous/penile • sperm duct into female

  32. Male Reproductive System

  33. External Genitalia • Penis • intromittent organ for delivery of sperm into female reproductive tract • Scrotum • pouch containing testes; maintains sperm development at 35.9 oC (96.6 oF)

  34. Penis • Root – crura: connective tissue attached to pubic bone • Shaft – body of penis • Erectile tissues • Corpora cavernosa • Corpora spongiosum • Glans – “head” of penis • Prepuce (foreskin) cover – often circumcised • Stimulation function • Urethral meatus – opening

  35. Penis

  36. Accessory Glands • Seminal vesicles • Contribute to semen • Prostate gland • Contribute to semen • Bulbourethral glands • Preejaculatory fluid

  37. Semen Composition • Ejaculate volume • 2 – 5 mL • Analysis: • Spermatozoa – ~1% • Count – ~60 million • Motility – ~60% beating flagella • Morphology – ~60% “normal shape”

  38. Semen Composition • Analysis: (cont) • Seminal fluid: • From seminal vesicles ~ 60% • From prostate gland ~ 30% • From sustenacular cells of seminal tubules & small glands in epididymus ~ 5% • From bulbourethral glands ~ 4%

  39. Seminal Fluid Function • Seminal vesicle secretion • Fructose – nourished spermatozoa • Prostaglandins – stimulate contractions along male & female reproductive tracts • Fibrinogen – forms temporary clot in vagina • Alkaline fluid – neutralize prostatic fluid & vaginal acidity

  40. Seminal Fluid Function • Prostatic fluid • Seminalplasmin – antibiotic • Slightly acidic fluid • Bulbourethral gland secretion • Alkaline mucus – preejaculatory neutralizes acidity of urethra • Lubricates glans

  41. Male Reproductive Hormones • GnRH (gonadotropin releasing hormone) • Released by – hypothalamus of brain • Target tissue – anterior pituitary • Function/effect– stimulaterelease of gonadotropic hormones FSH & LH • FSH (follicle stimulating hormone) • Released by – anterior pituitary • Target tissue – testes: sustenacular cells • Function/effect– stimulation of spermatogenesis & spermiogenesis – release of inhibin

  42. Male Reproductive Hormones • LH (leutinizing hormone) • Released by– anterior pituitary • Target tissue– testes: interstitial cells of testes • Function/effect– stimulateproduction of testosterone • Inhibin • Released by –sustentacular cells of seminiferous tubules • Target tissue –anterior pituitary • Function/effect –feedback inhibition of FSH

  43. Male Reproductive Hormones • Testosterone • Released by –interstitial cells of testes • Target tissue –various • Function/effect: • Stimulation of spermatogenesis & spermiogenesis • Maintenance of accessory glands & organs • Establishment & maintenance of secondary sex characteristics • Stimulation of bone & muscle growth • Effects on CNS: libido; aggression (?)

  44. Female Reproductive System • Ovaries • Oogenesis • Accessory ducts & organs • Accessory glands • External genitalia • Hormonal controls

  45. Learning Objectives • FemaleReproductiveSystem: • Describe internal & external components of the female reproductive system • Describe the roles of the accessory ducts, organs, & glands • Oogenesis: • Outline the stages of ova development & maturation

  46. Learning Objectives • OvarianCycle: • Discuss the development of follicles in the ovary, ovulation, & formation of the corpus luteum & relate each stage to hormonal influences • UterineCycle: • Discuss the changes in the endometrium of the uterus relative to the ovarian cycle and menstruation

  47. Learning Objectives • MammaryGlands: • Describe the structures associated with female mammary gland function • HormonalControl: • List the hormones associated w/ female reproductive physiology & describe the role of each

  48. Ovaries • Follicles • Primordial follicles • Present at birth: 2million oocytes arrested at meiosis I prophase; 300,000 remain by age 7 • Primary oocyte (2n); 1 layer follicular cells • Primary follicles • Form after sexual maturity • Primary oocyte; layers of follicular cells – granulosa cells

  49. Ovaries • Follicles (cont) • Secondary follicles • Primary oocytes; granulosa cells • Follicular fluid forms in follicle • Tertiary (Graafian) follicles • Meiosis I completes  secondary oocyte (n) • Oocyte in antrum • Follicle bulges from ovarian surface Note: 400-500 ova will reach this stage from puberty to menopause

  50. Oogenesis Diploid Haploid