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Chapter 9

Chapter 9. Reproduction. Reproduction. Its sexual Its limbic. Considerations. Sex Potency/impotency Fertility/infertility Carrier detection Amniocentesis Behavior Survival of the species. Reproduction. Passing down the instructions for making a new individual

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Chapter 9

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  1. Chapter 9 Reproduction

  2. Reproduction Its sexual Its limbic

  3. Considerations • Sex • Potency/impotency • Fertility/infertility • Carrier detection • Amniocentesis • Behavior • Survival of the species

  4. Reproduction Passing down the instructions for making a new individual A gene is the instructions for making a specific protein A chromosome is a very long DNA molecule that contains the coding sequence for many genes as well as the sequences that control the expression of those genes Certain regulatory proteins control the shape of chromosomes and thus the availability of particular genes to be expressed

  5. DNA A language of molecules A-T G-C

  6. Autosomes > 22 matched sets (44 total) > 100% identical in males and females All sequences for a particular mRNA are not identical (SNPs) Some sequences are defective, some are just a little different

  7. Chromosome Squashes

  8. Genetic Defects

  9. Sex Chromosomes > Males and females are 50% identical XX a potential female XY a potential male

  10. Males and Females Autosomes: 22 matched set Sex chromosomes: the difference

  11. X and Y Chromosomes

  12. Somatic Cell Division 46 chromosomes 46 x 2 chromosomes 46 chromosomes

  13. Germ Cells Female: reductive division before birth Males: reductive division is on going

  14. Fertilization

  15. Fertilization

  16. Some Mistakes • XO Turners syndrome: “Female”, short, some structural deformity, some retardation, sexually immature • XXY Klinefelters syndrome: “Male”, very tall, long arms, immature genitals, some retardation (X inactivation) • XXX superfemale: the more Xs the more retarded, infertile • XYY: male ????????????? • YO: lethal

  17. Environment and Potential < Forks in the road Regardless of genes, during development testosterone = male nothing = female > Pseudohermaphrodites

  18. Sex: Not all or nothing >Females: estrogen>>>>testosterone >males: testosterone>>>>estrogen > Many variations on the theme

  19. The Brain

  20. Hypothalamus/Pituitary LH FSH

  21. Puberty About 7 years old Pineal gland

  22. Sex Steroids

  23. Steroid Hormone Receptors Soluble, not surface membrane Hormone activated transcription factor Binds to Hormone responsive element (HRE) HRE = a DNA sequence that influences transcription

  24. Male Hormone Patterns “In spring a young man’s fancy turns to…” (even an old man’s!) Generally always ready The pineal gland: the third eye

  25. Male Role Make sperm Deliver sperm

  26. Males Negative feedback control

  27. Female Role Produce eggs Receive sperm House and nurture developing embryo Timing is required

  28. Hormonal control in females > Females are not always ready • Reproductive ability is cyclical (~29 days) • One egg released from one ovary each cycle • Body must be ready to maintain if egg is fertilized • Hormones develop egg and prepare uterus

  29. Function of Hormones > Follicle Stimulating Hormone (FSH): Target is ovaries: develops egg and produce estrogen • Luteinizing Hormone (LH): Target is prepared ovary: ovulation and progesterone production

  30. Function of hormones cont. • Estrogen: many targets; build-up lining of uterus; secondary sex characteristics, metabolism; negative feedback to inhibit FSH release from pituitary; when very high positive feedback to cause LH release from pituitary • Progesterone: additional build-up of uterine lining; negative feedback to inhibit LH release; adds to negative feedback on FSH release

  31. Females Day 1 of cycle is beginning of menstruation Feedback and cycles

  32. Pregnancy • Occurs mid-cycle when ovulation occurs • Fertilization occurs in the Fallopian tube • Implantation in the uterus occurs about seven days later • Cells at site of implantation produce and release a new hormone; Human Chorionic Gonadotrophin (HCG) • HCG: takes the place of FSH and LH in supporting the cells of the ovary that produce estrogen and progesterone (positive feedback)

  33. Fertilization Fallopian tube Implantation in uterus about 7 days

  34. Placenta • The place where the mother’s and embryo’s blood come “close” together • An endocrine organ (HCG) • Some molecular screening (eg cortisol)

  35. Pregnancy • The baby dominates the mothers body • Extra 300 calories/day • 20-25 lbs: 7-8 lbs. baby 2 lbs. uterus 2 lbs. breast 4 lbs. water 2 lbs fat 4 lbs placenta

  36. Other Steroid Hormones

  37. Development

  38. Development

  39. Maternal Problems • Type II diabetes • Osteoperosis • Acidosis • Hypertension • Kidney

  40. Birth • Not everything is known • Fetal adrenal sends signal to mother • Mother’s circulating levels of estrogen and progesterone begin to decline • Release of Prolactin from pituitary begins to increase • Oxytocin from anterior pituitary begins to be released • Oxytocin makes uterus irritable and calcium sensitive • Circulating level of glucocorticoids increases • Relaxin and prostaglandins start dilation of uterus

  41. Birth

  42. Lactation >During pregnancy, high levels of estrogen and progesterone sensitize breasts to prolactin >About 5 mo.: A small amount of milk begins to be produced, but high estrogen and progesterone suppresses full milk production >After birth estrogen and progesterone drop and full prolactin induced milk production begins >Suckling causes oxytocin to be released from the anterior pituitary which causes milk ejection >Milk production and ejection will continue as long as mother continues to feed the baby >Oxytocin also causes uterine contractions which helps return it to normal size

  43. Intervention in Reproduction Promoting Pregnancy (male infertility) • Artificial Insemination, structurally abnormal sperm, no sperm, low sperm count (average 500 million, less than 200 million sterile) multiple collections • Other problems: impotency, diabetes, drugs

  44. Preventing Pregnancy Vasectomy: Remove a section of the tube that delivers sperm to seminal fluid Male contraception

  45. Vasectomy

  46. Promoting Fertility Problems with women • Blocked Fallopian Tubes: in vitro fertilization • Failure to produce eggs: fertility drugs (Synthetic HCG)

  47. Female Contraception • Blockage: condoms, diaphragm • Chemical warfare: spermacides • IUDs: chronic inflammation • Birth control pills (old): Negative feedback suppression of FSH secretion • Morning after pill: progesterone antagonist • Tubal ligation: surgical intervention

  48. Tubal Ligation X

  49. Drugs and Reproduction • Diethylstabesterol (DES) • Thalidomide • Nature/Nurture (Potential)

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