1. Sexual Reproduction in Humans
How to make a Human Being

2. Male Reproductive System

6. Testes Male gonads (animal organs that produce sex cells)
Temperature of testes is maintained at 35°C (optimal temp for meiosis)
Each testis contains sperm-producing cells

7. Testosterone is also produced
stimulates sperm production
promotes sexual maturity
induces secondary sexual characteristics

10. Structure Function Scrotum Sac of skin in which the testes are held
Produces sperm and testosterone
Epididymis
Sperm storage and maturation
Sperm Duct (vas deferens)
Carries sperm from the epididymis to the urethra
Seminal Vesicles
Produce milky seminal fluid (sugary alkaline fluid in which sperm are suspended, nourished and protected from the acidic vagina)
Cowper’s Gland
Produces clear sticky fluid which neutralises any urine which remains in the urethra.
Prostate
Produces another milky nourishing fluid which goes to make up part of the semen (semen = sperm plus fluid)
Penis
Transfer of sperm into the vagina. Becomes engorged with blood during sexual arousal. Once hard and erect, it can penetrate the soft tissue of the vagina.
Urethra
Carries sperm along and out of the penis.

11. Structure of a Sperm Cell
Tail

12. Sperm Cells
Diploid cells in the testis divide by meiosis to produce haploid sperm cells
First produced in the testes at the onset of puberty (12-13 years old in males)
The acrosome in the head contains digestive enzymes to allow it to penetrate the ovum.
The collar contains lots of mitochondria to provide energy for movement using the tail
The nucleus contains 23 chromosomes

14. Male Reproductive Hormones
Testosterone
causes primary and secondary male characteristics
produced in the testes
production increases at puberty
FSH
produced by the pituitary gland at puberty
stimulates cells in the testis to produce sperm cells LH
produced in the pituitary at puberty
stimulates the testes to produce testosterone

15. HL
2007 Q15 a 2010 Q15 a OL
2010 Q14 a 2014 Q14 a

16. 2010 Q15 a

17. Female reproductive system

18. Female Reproductive System

19. Ovaries Each ovary contains many sac-like structures
these are called Graafian follicle
Each follicle produces a potential female gamete by meiosis
female gametes are called ova or eggs
Only one Graafian follicle releases a mature ovum every 28 days
Ovulation is the release of an egg from the Graafian follicle

23. Female Reproductive System
Structure
Function
Ovary
Produce eggs (ova) and female hormones
Fallopian Tubes
Have funnel-shaped ends that catch the eggs as they are released from the ovaries
Carry eggs to the uterus by cilia and peristalsis
Site of fertilisation
Uterus (Womb)
Site of implantation
Outer muscular wall which contracts to push baby our during birth
Inner lining (endometrium) nourishes and protects embryo.
Cervix
Opening between the uterus and the vagina containing a plug of mucus which protects uterus from infection
Dilates during labour to allow passage of baby into the vagina
Vagina
Receives penis and sperm during intercourse
It is the birth canal - allows the exit of the baby during birth
Acid produced by normal resident bacteria protect from infection

24. Secondary Sexual characteristics
Features that distinguish males from females, other that the presence of the sex organs
Male
Female
Growth of underarm, facial and pubic hair
Growth of underarm and pubic hair
Enlargement of the larynx, deepening of the voice
Enlargement of breasts
Widening of the shoulders
Widening of the pelvis
Increase in sebum production in the skin
Increase in body fat

25. Menstrual Cycle

26. Begins at puberty and ends at menopause
A series of changes that occurs in the female reproductive system every 28 days on average
changes in hormone levels cause changes in the endometrium
Begins at puberty and ends at menopause
menopause is the end of a womans reproductive life (usually between 45 and 55)
Ranges from 21 to 40 days in length
The Fertile period is the time during the menstrual cycle in which fertilisation is most likely to occur

28. Day 1 to 5 Meiosis occurs in new oocytes in the ovary
Oestrogen and progesterone levels fall
this allows the pituitary to secrete FSH
Low oestrogen causes menstruation
Menstruation occurs
Menstruation is the shedding of the blood-filled lining of the womb.

29. Days 6-14
FSH stimulates the production of an egg within a Graafian follicle
The developing Graafian follicle produces oestrogen
Oestrogen causes the thickening of the endometrium
Rising oestrogen levels inhibit FSH production
this prevents further follicles from maturing
normally only one Graafian follicle is produced during each cycle
Very high oestrogen levels eventually stimulate the production of LH just before day 14

30. Day 14 LH causes the release of the egg from the Graafian follicle
Ovulation occurs
The egg passes into the funnel of the Fallopian tube and begins to move along towards the uterus
LH causes the remains of the Graafian follicle to become the corpeus luteum

31. Days 15-26
Oestrogen and progesterone are secreted by the corpeus luteum (in the ovary)
High progesterone levels
further causes the building and up of the endometium and maintains it
inhibits the secretion of FSH and LH from the pituitary gland
prevents uterine contractions
An unfertilised egg will die by day 16
The corpus luteum starts to degenerate (day 22)

32. Days 26-28
The corpeus luteum dies if implantation does not occur by day 26
This causes a drop in progesterone (and oestrogen)
the corpus was producing these hormones
Low levels of progesterone and oestrogen eventually cause (day 28)
uterine contractions
loss of the endometrium
a new cycle begins with menstruation
a rise in FSH production (no more FSH inhibition)

35. Degenerating Corpus luteum
Graafian Follicle
Egg
Oestrogen

36. Role of Oestrogen Produced in the ovary (by the Graafian follicle)
Causes the endometrium to thicken for first 14 days
Inhibits FSH production (negative feedback)
prevents further Graafian follicles from maturing
this ensures only one egg produced per cycle
High levels stimulate the pituitary to produce LH

37. Role of Progesterone Produced in the ovary (by the corpus luteum)
Causes the endometrium to thicken for last 14 days and maintains its structure
Inhibits FSH production (negative feedback)
stops the development of more Graafian follicles
Inhibits LH production
prevents ovulation
Prevents muscular contractions of the uterus

38. Role of Follicle Stimulating Hormone
Produced in the pituitary
Causes Graafian follicles (containing eggs) to develop and mature
Indirectly causes the production of oestrogen
since the Graafian follicle produces oestrogen

39. Role of Luteinising Hormone
Produced in the pituitary gland
Causes ovulation
Causes the remains of the Graafian follicle to become the corpus luteum
Indirectly results in the production of progesterone
since the corpus luteum produces progesterone

40. Menstrual Disorder - Fibroids
Benign tumours of the uterus
Most common in year olds
If they grow too large they can cause pain, heavy bleeding, miscarriage, infertility
Cause is thought to be abnormal response to oestrogen
Treatment
if small, no treatment
if large, surgery to remove them
hysterectomy in severe cases

42. Infertility
Infertility (male or female) is the inability to produce offspring
Affects 1 in 6 couples, but 50% are successfully treated
Infertility
Cause
Treatment
Male
Low sperm count due to smoking, alcohol/drug abuse, stress.
Stop or reduce smoking, drugs, alcohol, stress.
Female
Failure to ovulate (due to hormone disorder).
Hormone treatment (e.g. FSH stimulates ovulation)

43. Male Infertility
Male infertility is the inability to produce sperm capable of fertilizing an egg cell
Cause: low sperm count
due to excessive alcohol or drug use; stress
Treatment: avoidance of possible reasons for low sperm count
alcohol and drug use
stress

44. Female Infertility Female infertility is the inability to conceive.
Cause: failure to ovulate
due to hormone deficiency
Treatment: hormone therapy

45. 2009 Q14 a

46. In-vitro fertilisation (IVF)
Method of treating infertility
Eggs are removed from the ovary
Fertility drugs are given to encourage egg development.
Eggs are surgically removed on day 14.
Sperm and eggs are incubated together in vitro (in a glass dish).
If fertilisation occurs, a number of embryos are placed in the uterus to implant.

47. Stages in Sexual Intercourse
Sexual Arousal
penis becomes erect
vagina becomes lubricated
Copulation
coitus or sexual intercourse
Orgasm - involuntary muscle spasms cause
ejaculation in males
uterine and vaginal contractions in female
Insemination
Release of semen into the vagina

48. Fertilisation
Fertilisation is the fusion of the sperm nucleus with the nucleus of the egg to form a diploid zygote
Occurs in the Fallopian tube, usually at the top near the ovary
Digestive enzymes produced by acrosome in the head of the sperm make an opening in the egg
Once the sperm nucleus enters the egg, the membrane of the egg changes to prevent entry of other sperm.

49. Conception The embryo then secretes a hormone (hCG)
Implantation is the embedding of the fertilised egg into the lining of the womb
Occurs 6-9 days after fertilisation
Fertilisation followed by implantation is called conception
The embryo then secretes a hormone (hCG)
this prevents the degeneration of the corpus luteum
progesterone continues to be produced
the endometrium is maintained
the menstrual cycle stops

50. Stages to Implantation

51. Birth Control Abortion – the termination of a pregnancy.
Contraception – using methods to prevent fertilisation.

52. Natural contraception
– intercourse is avoided at times in the menstrual cycle when it may result in fertilisation. Body temperature recorded – rises after ovulation. Mucus secreted by cervix – texture changes after ovulation. Past menstrual cycles – rhythm method.

53. Mechanical contraception
– using physical barriers to stop the sperm and egg meeting. Condom – male on penis, female in vagina. Diaphragm – dome shape fitted into vagina before intercourse. Cap – small rigid rubber device, covers cervix.

54. Chemical contraception
– using chemicals to kill sperm or hormones to prevent ovulation. Spermicides – used along with mechanical methods. The ‘Pill’ – oestrogen and progesterone, prevents ovulation

55. Surgical contraception
- involves surgery (usually irreversible). Female sterilisation – cutting tying the fallopian tubes. Vasectomy – The vas deferens (sperm duct) is cut. Sperm is not present in the semen.

57. Early Development of the Zygote
The zygote divides several times to form a ball of cells called the morula
5 days after fertilisation the morula develops a cavity and further divides to become a blastocyst
The outer cell layer of the blastocyst is the trophoblast which later forms the membranes surrounding the embryo
i.e. the chorion and the amnion
The inner cell mass of the blastocyst later forms the embryo

58. Development of the Blastocyst

59. Embryonic Development
The inner cell mass of the blastocyst forms 3 germ layers
Each germ layer gives rise to different tissues
Germ Layer
Tissue/Organ
Ectoderm
Nervous system, epidermis of skin
Mesoderm
Muscles, skeletal and circulatory system, kidneys.
Endoderm
Digestive system, liver, pancreas

61. Formation of the Placenta
After implantation, the embryo forms an outer membrane
this is called the chorion
It later forms the placenta along with tissue from the mothers of the endometrium.
Therefore the placenta is formed from the tissue of 2 different individuals, the mother and the embryo

62. The Placenta Pancake-shaped temporary organ
Contains blood vessels of mother and foetus
Mothers blood and foetal blood do not mix
blood groups may not be compatible
mother’s blood pressure would be too great
Vessels are close enough to allow exchange of materials

63. Waste is transferred from foetus to mother
Nutrients and antibodies are transferred from mother to foetus

64. Functions of the Placenta
Supply of Nutrients
Gas exchange
O2 and CO2
Production of Hormones
Removal of Waste
Urea, CO2 etc.

66. The first 8 weeks Heart forms and is beating after 4 weeks
By week 5, other internal organs are forming
By week 6, ears, nose, eyes and mouth are distinguishable
By week 8
ovaries and testes have formed
ossification of cartilage to bone starts to occur
The tail is no longer a feature and we now refer to the embryo as a foetus

67. By 12 weeks All major organs are formed
Nerves and muscles become co-ordinated
Limbs begin to move, the foetus can kick
Teeth grow, breathing starts
Urinary system begins to work

68. Week 12 to birth No new organs are formed
Growth and development is rapid
Gestation is the length of time spend in the uterus from fertilisation to birth
Gestation time is 38 weeks from the day of fertilisation

70. Hormones during Pregnancy
The corpus luteum produces progesterone and oestrogen during the first 10 weeks
The placenta takes over this role after this
Just before birth
Progesterone production stops
Oestrogen production increases

71. Birth Stage 1 - Dilation Stage 2 - Delivery Stage 3 - Placental
Cervix dilates to allow passage of the baby
Amniotic fluid is released from the amniotic sac
Muscular contractions begin
The mucus plug in the cervix is lost
Stage 2 - Delivery
Contractions increase as oxytocin levels increase
Baby passes through the birth canal head first
Stage 3 - Placental
Release of the placenta and foetal membrane

74. Lactation Milk Production by the mammary glands
Colostrum is the first milk produced in the days just after the birth
rich in protein and antibodies (passive natural immunity)
Prolactin is produced
this hormone promotes milk production
progesterone inhibits prolactin secretion during pregnancy

76. Benefits of Breast-feeding
Mother milk is the perfectly balanced source of nutrients for the baby
Contains antibodies which provide natural passive immunity to the baby
Helps the mother recover after the birth by helping the uterus to tighten again
Helps the mother lose fat put on during pregnancy