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Sexual Reproduction in the Human

Sexual Reproduction in the Human. Depth of treatment (1/2). General structure of the reproductive system – male and female Functions of the main parts Role of meiosis in the production of sperm cells and egg (ova) Definition of “secondary sexual characteristics”

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Sexual Reproduction in the Human

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  1. Sexual Reproduction in the Human

  2. Depth of treatment(1/2) • General structure of the reproductive system – male and female • Functions of the main parts • Role of meiosis in the production of sperm cells and egg (ova) • Definition of “secondary sexual characteristics” • Role of oestrogen, progesterone and testosterone • The menstrual cycle: the events and outlined role of oestrogen and progesterone

  3. Depth of treatment(1/2) • Copulation • Location of fertilisation • Implantation, placenta formation and function • Birth – outline of process • Milk production and breastfeeding

  4. Contemporary Issues and Technology • Birth control – natural, mechanical, chemical and surgical methods of contraception • Infertility • One cause of male infertility from the following disorders: low sperm count, low sperm mobility, endocrine gland failure • Availability of corrective measures

  5. Contemporary Issues and Technology • One cause of female infertility from the following disorders: blockage of the Fallopian tube, endocrine gland failure • Availability of corrective measures • In-vitro fertilisation and implantation • Biological benefits of breastfeeding

  6. Main topics to learn about... • Male reproductive system • Female reproductive system • The menstrual cycle • Sexual intercourse • Human embryo development ( higher level) • Placenta, birth and lactation • Birth control • Infertility

  7. Part 1: Male reproductive system • Objectives: • Outline the general structure of the male reproductive system • State the functions of the main parts of the reproductive system • Outline the role of meiosis to produce sperm cells • Define the term secondary sexual characteristics • Outline the role of testosterone in males

  8. Structure of the male reproductive system

  9. Bladder Seminal Vesicle Prostate gland Cowper’s Gland Penis Sperm duct Urethra Epididymis Testis Scrotum

  10. Testes A gonad is an organ that produces sex cell in animals. • Male gonads are called testes and they are held in the scrotum. • This means they are kept at slightly lower than body temperature (35°) which is the ideal temperature for sperm production.

  11. Seminiferous tubules inside the testes are lined with sperm producing cells. Cells between the tubules produce the hormone testosterone. Internal structure of testes Seminiferous tubule Sperm producing cells (2n) Sperm Sertoli cell – nourishes sperm Blood capillary Interstitial cells – produce testosterone

  12. Epididymis All the seminiferous tubules join to form the epididymis. Sperm mature and are stored here.

  13. Sperm duct and urethra • The sperm duct brings sperm from the epdidymis to the urethra.

  14. Glands • Seminal Vesicle • Prostate Gland • Cowper’s Gland • These glands produce seminal fluid which nourishes the sperm and provides a medium in which to swim. Seminal fluid + Sperm = Semen

  15. Urethra • The urethra carries semen and urine out of the body • Facts about sperm • The volume of semen in a single ejaculation may vary from 1.5 to 6.0 ml. • There are usually between 50 to 150 million sperm per milliliter of semen

  16. Bladder Seminal Vesicle Prostate gland Cowper’s Gland Sperm duct Urethra Epididymis Testis Scrotum Functions of the main parts of the Male reproductive system Penis Produces 1. Sperm2 Testosterone

  17. Bladder Seminal Vesicle Prostate gland Cowper’s Gland Sperm duct Urethra Epididymis Testis Scrotum Functions of the main parts of the Male reproductive system Penis Stores sperm

  18. Bladder Seminal Vesicle Prostate gland Cowper’s Gland Sperm duct Urethra Epididymis Testis Scrotum Functions of the main parts of the Male reproductive system Penis Carries sperm from the epididymis to the urethra

  19. Bladder Seminal Vesicle Prostate gland Cowper’s Gland Sperm duct Urethra Epididymis Testis Scrotum Functions of the main parts of the Male reproductive system Penis Produces Seminal Fluid- For sperm to swim in- Nourishment for sperm

  20. Bladder Seminal Vesicle Prostate gland Cowper’s Gland Sperm duct Urethra Epididymis Testis Scrotum Functions of the main parts of the Male reproductive system Penis Tube through which the sperm travel through the penis

  21. Bladder Seminal Vesicle Prostate gland Cowper’s Gland Sperm duct Urethra Epididymis Testis Scrotum Functions of the main parts of the Male reproductive system Penis Keeps testes at a lower temperature

  22. Bladder Seminal Vesicle Prostate gland Cowper’s Gland Sperm duct Urethra Epididymis Testis Scrotum Functions of the main parts of the Male reproductive system Penis Places sperm in the females body

  23. Summary of functions of main parts of male reproductive system

  24. Sperm

  25. Sperm Structure Acrosome (contains digestive enzymes) Head Nucleus (contains 23 chromosomes) Collar (contains mitochondria) Middle Flagellum (allows sperm to swim) Tail Diploid sperm producing cells (46 chromosomes) divide by meiosis to form haploid sperm cells (23 chromosomes )

  26. Male Hormone - Testosterone • Testosterone is the hormone responsible for • Development of male sex organs • Sperm production • development of the secondary male sexual characteristics

  27. Male Secondary Sexual characteristics Secondary sexual characteristics refer to features that distinguish males from females, apart from the sex organs themselves • The growth of pubic, facial and body hair • The enlargement of larynx and ‘breaking’ of the voice • Increased muscular development and bone development • A growth spurt at puberty • An increased secretion of sebum in the skin

  28. Part 1: Male reproductive system • Can you.. • Outline the general structure of the male reproductive system? • State the functions of the main parts of the reproductive system? • Outline how sperm cells are produced? • Define the term secondary sexual characteristics and give examples? • Outline the role of testosterone in males

  29. Part 2: Female reproductive system • Outline the general structure of the female reproductive system • State the functions of the main parts of the reproductive system • Outline the role of meiosis to produce egg cells • Define the term secondary sexual characteristics

  30. Objectives for today • Outline the general structure of the female reproductive system • State the functions of the main parts of the reproductive system • Outline the role of meiosis to produce egg cells

  31. Structure of the female reproductive system

  32. The Ovary • These produce the eggs and some female hormones. Diploid egg producing cells (46 chromosomes) divide by meiosis to form haploid egg cells (23 chromosomes )

  33. The Fallopian tube • Catch the egg after it is released from the ovary. • The egg is moved along the tube by cilia and muscular peristalsis

  34. The Uterus (womb) • Inner lining of the womb is called the endometrium • This lining thickens each month with cells and blood vessels to nourish the embryo.

  35. The cervix • separates the uterus from the vagina. • The vagina • Allows entry of sperm. • Is the birth canal for the exit of a baby.

  36. Structure of the Female reproductive system Fallopian tube Funnel Ovary Uterus Lining of uterus (endometrium) Cervix Wall of uterus Vagina

  37. Functions of the main parts of the female reproductive system Fallopian tube (Oviduct) Funnel Ovary Uterus Lining of uterus (endometrium) Cervix Wall of uterus Vagina • Produces : • Egg • Oestrogen • Progesterone Vulva

  38. Functions of the main parts of the female reproductive system Fallopian tube (Oviduct) Funnel Ovary Ovarian Ligament Uterus Lining of uterus (endometrium) Cervix Wall of uterus Vagina • Catches the egg after release from ovary • Transports egg from ovary to womb • Site of fertilisation Vulva

  39. Functions of the main parts of the female reproductive system Fallopian tube (Oviduct) Funnel Ovary Uterus Lining of uterus (endometrium) Cervix Wall of uterus Vagina • Implantation • Hold foetus • Forms placenta

  40. Functions of the main parts of the female reproductive system Fallopian tube (Oviduct) Funnel Ovary Uterus Lining of uterus (endometrium) Cervix Wall of uterus Vagina • Allows entry of sperm into female system • Birth canal to allow exit of baby

  41. Summary of functions of main parts of female reproductive system

  42. Female Hormones • A combination of oestrogen and progesterone hormones at puberty causes the development of the secondary female sex characteristics: • The maturing and enlargement of the breasts. • The widening of the pelvis to allow for birth. • The growth of pubic and underarm hair. • A growth spurt.

  43. Ordinary level Part 3: The menstrual cycle • Be able to outline the events in the menstrual cycle with reference to oestrogen and progesterone. • Menstrual disorders • one example of a menstrual disorder from the following: endometriosis and fibroids • one possible cause, prevention and treatment

  44. Ordinary level The Menstrual Cycle The menstrual cycle is a 28 day sequence of events when the body prepares the uterus lining so that it is able to receive a fertilized egg Summary of events in the menstrual cycle

  45. Ordinary level Events in the menstrual cycle • Days 1 – 5 • Menstruation (period).The old lining of the uterus (endometrium) breaks down and leaves the body. • A new egg is produced in the ovary by meiosis. This new egg is surrounded by the Graafian follicle.

  46. Ordinary level The Menstrual Cycle • Days 6 - 14 • The hormone oestrogen is produced by the developing Graafian follicle: • - It causes the lining of the uterus (endometrium) to build up again in preparation for implantation. • - Oestrogen also prevents the development of any more eggs. • Day 14 • Ovulation. This occurs when the Graafian follicle bursts to release the egg into the fallopian tube.

  47. Ordinary level • Days 14 - 28 • The Graafian follicle now develops into the Corpus Luteum : • - It causes the endometrium to thicken even further. • - It also prevents new eggs from forming. If fertilisation does not take place The egg that was released will die by day 16 if it is not fertilised. the Corpus Luteum starts to degenerate at day 22. This results in a reduction in progesterone levels. As a result the lining of the uterus breaks down again on day 28. The menstrual cycle begins again with day 1.

  48. Ordinary level The fertile period • This is the time in the cycle when the woman could get pregnant after having sex. When is the fertile period? Between days 11 and days 16 of the menstrual cycle

  49. Ordinary level 28 1 2 27 3 26 4 25 5 24 23 6 22 7 21 8 20 9 19 10 18 17 11 16 12 13 15 14 If fertilisation has not occurred the cycle begins again with the breakdown of the endometrium. The Menstrual Cycle DAY 1-5 : Blood from the womb lining is shed from the body After day 5 the lining of the uterus repairs and builds up again Fertile period Ovulation occurs on Day 14 Implantation may happen

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