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REPRODUCTIVE SYSTEM

REPRODUCTIVE SYSTEM. Function : Receives penis & semen and serves as birth canal & passage for menstrual flow. Vagina. Function : Provides passageway for sperm, receives blastocyst, retains & nourishes fetus & expells fetus at term. Uterus.

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REPRODUCTIVE SYSTEM

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  1. REPRODUCTIVE SYSTEM

  2. Function: Receives penis & semen and serves as birth canal & passage for menstrual flow. Vagina

  3. Function: Provides passageway for sperm, receives blastocyst, retains & nourishes fetus & expells fetus at term. Uterus

  4. Function: Cervical mucosa secretes mucous blocking cervical canal entrance to uterus. Cervix

  5. Function: Uterine lining in which implantation occurs. Endometrium

  6. Function: Muscular contractions. Myometrium

  7. Function: Passageway for oocyte and site of fertilization. UterineTubes

  8. Function: Produce oocytes & the hormones estrogen and progesterone. Ovaries

  9. Function: Sweep ovarian surface to draw oocyte into ovarian tube. Fimbriae

  10. Mechanisms of Hormonal Action • Direct Gene Activation • lipid soluble, steroid hormones • diffuse through cell membranes • bind to intracellular receptor • activated hormone receptor/complex binds with gene, turning it on • gene transcribes mRNA • ribosomes use mRNA to synthesize enzymes to stimulate cell activity or synthesize structural proteins to be excreted or used within the cell

  11. Direct Gene Activation Steroid Hormone Receptor/hormone Complex

  12. Direct Gene Activation Receptor/hormone Complex Protein Aldosterone Cortisol Testosterone Estrogen Progesterone Thyroxine mRNA

  13. Mechanisms of Hormonal Action • Second Messenger Systems • amino acid & protein based • cannot pass through cell membranes • bind to cell membrane receptors • activate G proteins in membrane to produce cyclic AMP in cytoplasm • cyclic AMP acts as second messenger inside cell activating protein kinases • protein kinases trigger cellular responses

  14. Second Messenger Systems

  15. Hormone Sources & Functions • Gonadotropin-releasing Hormone (GnRH) : • Source: Hypothalamus • Targets & Functions: • Females & Males - Anterior Pituitary • Stimulates the production of Follicle Stimulating Hormone (FSH) & Leutinizing Hormone (LH) • Regulates the release of FSH & LH by the anterior pituitary gland

  16. Hormone Sources & Functions • Follicle Stimulating Hormone: • Source: Anterior Pituitary • Targets & Functions: • Females - Ovaries • Stimulates follicle growth & maturation • Stimulates estrogen production • Males - Seminiferous Tubules • Promotes sperm production (Spermatogenesis) by establishing testosterone receptors on tubules

  17. Leutenizing Hormone: • Targets & Functions: • Females - Ovaries • Stimulates primary oocyte to complete first meiotic division to become secondary oocyte • Triggers ovulation of secondary oocyte • Source: Anterior Pituitary • Transforms ruptured follicle into corpus luteum • Stimulates production of progesterone by corpus luteum • Males - Seminiferous Tubules • Stimulates sperm production (Spermatogenesis) by causing interstitial cells in testes to secrete testosterone Corpus luteum

  18. Estrogen: • Targets & Functions: • Body in general • Stimulates the development of female secondary sexual characteristics • Sources: Maturing Follicles & Corpus Luteum • Uterus • Stimulates proliferative phase of uterine cycle • Ovaries • Promotes oogenesis • Breasts • Stimulates development of milk ducts and sinuses (ampullae) • Anterior Pituitary • Stimulates burst-like release of LH

  19. Corpus luteum Progesterone: • Targets & Functions: • Females - Uterus • Maintains thickened endometrium • Stimulates nutrient release • Quiets myometrium • Source: Corpus Luteum & Placenta • Females - Breasts • Stimulates development of alveoli for milk production • Females - Anterior Pituitary • Inhibits production & release of FSH & LH

  20. Testosterone: • Targets & Functions: • Body in general • Stimulates the development of male secondary sexual characteristics including: • development of male genitalia • male skeleton and muscle development • male patterns for hair growth • increased RBC production & higher metabolic rate • Sources: Interstitial Cells in Testes • Seminiferous tubules • Necessary for the completion of spermatogenesis • Anterior Pituitary • Moderate inhibition of pituitary and hypothalamus

  21. Oxytocin: • Sources: Manufactured by hypothalamus. Stored & released by Posterior Pituitary • Positive Feedback Mechanisms: • 1. Childbirth - Stretching of uterus and cervix • 2. Suckling - Milk letdown reflex • Targets & Functions: • Uterus • Stimulates contraction of uterine myometrium causing lowering of fetus & labor • Breasts • Stimulates contraction of milk ducts and sinuses, releasing milk

  22. Prolactin: • Source: Anterior Pituitary • Targets & Functions: • Breasts • Stimulates alveoli of breasts to produce milk • Regulation • Release of prolactin by anterior pituitary is regulated by hypothalamus production of Prolactin Releasing Hormone (PRH) & Prolactin Inhibiting Hormone (PIH)

  23. Human Chorionic Gonadotropin: • Source: Trophoblasts of blastocyst & Chorion • Target & Functions: • Corpus Luteum • Maintains corpus luteum & causes it to continue producing progesterone in the absence of LH through first four months of pregnancy till placenta produces sufficient estrogen & progesterone to maintain the pregnancy

  24. Hormonal Regulation of Ovarian & Menstrual Cycles 1. Hypothalamus releases GnRH. 2. GnRH stimulates anterior pituitary to release FSH. Estrogen FSH 3. FSH stimulates a follicle to grow & produce estrogen.

  25. Hormonal Regulation of Menstrual & Ovarian Cycles LH 4. Rising levels of estrogen cause anterior pituitary to increase production & storage of LH. Estrogen Estrogen FSH

  26. Hormonal Regulation of Menstrual & Ovarian Cycles 5. High estrogen causes LH to be released in a burst & the endometrium to thicken (proliferative phase). Estrogen Estrogen FSH 6. High LH stimulates first meiotic division of primary oocyte. LH

  27. Hormonal Regulation of Menstrual & Ovarian Cycles 7. High LH triggers ovulation. Estrogen Estrogen 8. High LH causes ruptured follicle to become a corpus luteum. FSH LH

  28. X X Hormonal Regulation of Menstrual & Ovarian Cycles 9. Corpus luteum produces progesterone. Estrogen 10. Progesterone inhibits the production of FHS & LH by the anterior pituitary & stimulates secretory phase . Progesterone Estrogen FSH LH

  29. X X FSH LH Hormonal Regulation of Ovarian & Menstrual Cycles 11. Diminishing levels of FSH & LH cause corpus luteum to deteriorate & produce less progesterone. 12. Dimishing levels of estrogen & progesterone cause inhibition of FSH & LH to end & thickened endometrium to slough (menses). Estrogen Progesterone X

  30. Hormonal Regulation of Ovarian & Menstrual Cycles 13. Increasing levels of FSH cause a new cycle to begin. FSH

  31. X X Hormonal Regulation in Pregnancy Normally dimishing levels of estrogen & progesterone from deterioration of the corpus luteum would cause thickened endometrium to slough (menses) which would terminating a pregnancy. Estrogen Progesterone X

  32. Hormonal Regulation if Pregnancy Occurs Blastocyst produces human Chorionic Gonadotropin (hCG) hormone which maintains corpus luteum in the absence of FSH & LH for the first trimester. hCG Eventually the placenta will produce sufficient estrogen & progesterone to sustain the pregnancy.

  33. Mitosis Interphase Prophase Metaphase

  34. 46 46 Mitosis Anaphase Telophase Interphase • Most cells of the body - growth, replacement, healing. • No change in the number of chromosomes within each cell.

  35. Interphase Prophase Metaphase Meiosis 46

  36. Anaphase Telophase Interphase 23 23 Meiosis Reduction Division

  37. 23 23 23 23 23 23 Meiosis • Only in gonads. • Synapsis & shuffling of genetic information providing variation. • Results in reduction of number of chromosomes by half (haploid).

  38. 23 23 46 46 23 23 23 23 Mitosis/Meiosis Comparison 46 46

  39. Spermatogenesis: produces male gametes (sperm) occurs in the seminiferous tubules of the testes involves meiosis occurs throughout life after puberty may produce 400,000,000 per day Oogenesis: produces female gametes (oocytes) occurs in the ovaries involves meiosis occurs after puberty until menopause humans normally produce one oocyte during each ovarian cycle Gametogenesis: Process through which gametes are formed

  40. Spermatogenesis Spermatogonium (46) Daughter Cells (46) Mitosis

  41. Spermatogenesis Spermatogonium (46) Daughter Cells (46) Mitosis Growth Primary Spermatocyte (46) Meiosis I Secondary Spermatocytes (23)

  42. Spermatogenesis Spermatogonium (46) Spermatogonium Daughter Cells (46) Mitosis Growth Primary Spermatocyte (46) Meiosis I Secondary Spermatocytes (23) Meiosis II Early Spermatids (23)

  43. Spermatogenesis Spermatogonium (46) Spermatogonium Daughter Cells (46) Mitosis Growth Primary Spermatocyte (46) Meiosis I Secondary Spermatocytes (23) Meiosis II Early Spermatids (23) Spermiogenesis Late Spermatids (23)

  44. Spermatogenesis Spermatogonium (46) Spermatogonium Daughter Cells (46) Mitosis Growth Primary Spermatocyte (46) Meiosis I Secondary Spermatocytes (23) Meiosis II Early Spermatids (23) Spermiogenesis Late Spermatids (23) (Lumen) Spermatozoa (23)

  45. Oogenesis Oogonium (46) (Mitosis) Primary Oocyte (46) Primary Oocyte (46)

  46. Oogenesis Oogonium (46) (Mitosis) Primary Oocyte (46) (Meiosis 1) Polar Body (23) Secondary Oocyte (23) Fertilization Ovulation (Meiosis 2)

  47. Definitions & Functions Relative to Reproduction • Hypothalamus: • Produces GnRH which stimulates the production of FSH & LH by the anterior pituitary gland initiating the ovarian cycle. • Produces Oxytocin which is stored in the posterior pituitary gland. • Posterior Pituitary: • Stores & releases hormone Oxytocin to stimulate uterine contractions (Braxton Hicks) & the milk let-down reflex.

  48. Definitions & Functions Relative to Reproduction • Anterior Pituitary: • Produces hormone FSH which stimulates the growth & maturation of a follicle, the production of estrogen in females and stimulates sperm production in males. • Produces & stores hormone LH which causes first meiotic division of primary oocyte, stimulates ovulation, causes the development of and the production of progesterone by the corpus luteum • Produces & stores hormone Prolactin which promotes lactation .

  49. Definitions & Functions Relative to Reproduction • Spermatogonium: • Primordial germ cell in seminiferous tubules of testes from which sperm are produced. • Oogonium: • Primordial germ cell in ovaries of fetus from which primary oocytes in follicles are produced. • Follicle: • Sack-like structure in ovary containing an oocyte surrounded by one or more layers of cells which produces the hormone estrogen.

  50. Definitions & Functions Relative to Reproduction • Mitosis: • Process through which the nucleus of body cells divide to produce identical daughter cells for maintenance, healing & growth. • Meiosis: • Process through which gametes are formed with half of the normal number of chromosomes for sexual reproduction. • Ovum: • Functional female gamete which has completed the first and second meiotic divisions to become haploid.

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