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Reproductive System

Reproductive System. Introduction Overview of the Reproductive System Male Reproductive System Female Reproductive System Physiology of Sexual Intercourse. Introduction. Meiotic Cell Division Sex Determination Functions of the Reproductive System Reproductive System Overview Male

damian-clements
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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

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