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lesson 4.2 Human Reproduction


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lesson 4.2 Human Reproduction

  1. 1. Male and female
  2. 2.  The male sexual organs consist of the testis (plural: testes) and penis.  The two testes lie outside the abdominal cavity in a special sacs called the scrotum.  In this position, the testes are maintained at a temperature about 2 C lower than the body temperature. This favours sperm production.  Each testis is connected to the epididymis and sperm duct.  The two sperm duct lead to the urethra, which runs through the penis to the exterior.
  3. 3. The urethra at different times carries either urine or sperms. The penis contains many blood spaces which during copulation, become filled with blood. This erects the penis, allowing it to penetrate the female’s vagine. The head of the penis, called the glans, is covered by the foreskin. The foreskin is removed by an operation known as circumcision. Three glands open into the sperm ducts-the prostate gland, Cowper’s glands and seminal vesicle.
  4. 4. Structure Function Testis  Produce sperm Scrotum  Holds the testes outside the body  Protects the testes Penis  Places sperm in the vagina during sexual intercourse Epididymis  Stores sperm Sperm ducts  Carry sperm from the testis to the urethra Urethra  Carries sperm and urine out of the body Seminal vesicle  Secretes fluid that provides nourishment to the sperms Prostate gland  Secretes fluid that neutralizes the acidity of urine and the female vagina Cowper’s gland  Secretes a lubricating fluid that aids sperm movement
  5. 5. The role of sperms in reproduction • The male gametes are the sperms. • Each sperm consists of a head, a middle piece and a long tail. • The role of the sperm is to swim towards the female gamete (ovum) and fuses with it to form a zygote. The zygote will develop into an adult individual.
  6. 6. Changes in the male during puberty •Growth of hair on the face, chest in pubic region and armpits. •Voice box (larynx) enlarges. The voice ‘breaks’ and becomes deeper. • Body becomes more muscular. • Chest becomes broader. • Rapidly growth of long bones to increase height. • The penis, scrotum and prostate become larger. • Production of sperm by the testes. •Certain mental and emotional changes, e.g. greater interest in females.
  7. 7. The Female Reproductive System • A female has a pair of ovaries attached to the lower part of the abdomen. • The Fallopian tubes( oviducts) are thin, muscular tubes. • At one end , the fallopian tubes open out as funnel-shaped structures close to the ovaries. At the opposite, they lead into the uterus (womb) • The pear-shaped uterus has thick, muscular wall. • The uterus is connected to a muscular tube called the vagina.
  8. 8. Female reproductive system Front view
  9. 9. Side view
  10. 10. • The cervix is a ring of muscles at the lower end of the uterus where it join the vagina. • The vagina opens to the outside through the vulva.
  11. 11. Structure Function Ovary • Produce ovum(egg). Fallopian tube • Carries ovum from ovary to uterus. Uterus • Place where the embryo develops. Cervix • Secrets mucus that enhances sperm movement into the uterus. • Prevents large foreign bodies from entering uterus. Vagina • Place where sperms are deposited. • Birth canal.
  12. 12. The role of an ovum in reproduction • The female gamete is the ovum. • The ovum is larger than the sperm and it is spherical-shaped. • The female fuses with the sperm to form a zygote during fertilisation. • The ovum stores some food in its cytoplasm. The food is used to nourish the embryo which develops from the zygote.
  13. 13. The structure of a human ovum
  14. 14. Changes in the female during puberty • Growth of hair in the pubic region and armpits. • Commencement of menstruation. • Fat deposits on hips and thighs. • Growth and development and breast.
  15. 15. Aspect Male Female gamete Notes Size • Very small • Larger than the sperm • The human egg is 0.1 mm in diameter while the sperm has a width of 0.0025 mm at the widest region of the sperm head. Number • very large numbers • Very few • A healthy male produces about 300 million sperms every day. The ovaries each produce one egg on alternate months. Motility • Motile • Non-motile • Whip-like movements of the tail propels the sperm towards the ovum.
  16. 16. The Menstrual cycle • The menstrual cycle is the repeated cycle of events which occur every 28 days from puberty(when ovum production begins)to menopause (when ovum production stops. The menstrual cycle
  17. 17. •The main function of the menstrual cycle is to provide a favourable environment in the uterus for the development of the zygote. •In most woman, the menstrual cycle varies from 24 to 34 days, averaging 28 days. •The menstrual cycle starts when the female is about 12 years old and menopause occurs when the female is about 45 years old.
  18. 18. •Menstruation is the discharge of the uterus lining and blood through the vagina. •The start of the menstrual cycle is considered as the first day of menstruation (day 1) and ends the day before the next menstruation starts.
  19. 19. Days in the cycle Events in the menstrual cycle 1 - 5 •Menstruation – discharged of unfertilized egg, uterus lining and blood. 6 - 13 •Rebuilding and thickening of the uterus lining. 14 •Ovulation – release of ovum from the ovary 15 - 25 •Continued thickening of the uterus lining by increasing blood supply and tissue. 26 - 28 •Uterus lining begins to break down.
  20. 20. •The fertile period is the period around the time of ovulation when a woman can become pregnant if she has an intercourse. It is between day 11 and the day 17 of the cycle. •The fertile period is calculated on the assumption that sperms can survive up to three days in the woman’s body while ovulation can occur any time between day 13 and day 15 and the ovum lives for about 36 hours after the ovulation.
  21. 21. Personal hygiene during menstruation •Sanitary pads (sanitary towels) are worn as lining on the underwear to absorb the menstrual discharge. This will prevent the discharge from staining the clothes. •The sanitary should be change about every four hours to prevent unpleasant odour. •Some women prefer to wear tampons which are inserted into the vagina by means of an applicator.
  22. 22. •Tampons should not be used continually throughout the menstrual period. •Tampons should be changed every four hours during the day and external sanitary pads should be worn at night.