1. Chpt. 42: Human Reproduction

2. Organisation
Both the male and female reproductive system are composed of:
a pair of structures to produce sex cells.
a series of transport tubes
glands which secrete hormones

3. Male Reproductive System LS

4. The Male Reproductive System
Main Parts:
Testes
Scrotum
Epididymis
Sperm Duct (vas
deferens)
Associated Glands
Sperm
Penis

5. The Male Reproductive System
Testes (Testis):
consists of a coiled mass of tubules
produces sperm by meiosis
makes testosterone (hormone)
Scrotum:
contains the testes
temperature in scrotum is 35o C i.e. below body temperature.
Epididymis:
located outside each testis
stores and matures sperm cells

6. The Male Reproductive System
Sperm Duct (vas deferens):
transports sperm from the testes to the urethra
Note: urethra is tube located in centre of penis and is responsible for carrying urine or sperm out of body)
Associated Glands:
Seminal Vesicles – provides liquid for sperm to swim
in and produces fructose which gives sperm energy
Prostate Gland – produces liquid to nourish sperm
Cowper’s Gland – produces a fluid to lubricate the urethra
Note: when seminal fluid is added to sperm cells the resulting liquid is called semen.

7. The Male Reproductive System
Sperm (Spermatozoa):
Sperm are produced by meiosis in the testes
sperm are haploid cells i.e. they only contain 23 chromosomes.

8. The Male Reproductive System
Penis:
carries sperm into the female reproductive system.
swollen tip of penis called glans.
foreskin (fold of skin) partially covers the glans.

9. The Male Reproductive System
Male Hormones:
At puberty: two hormones are produced by the male pituitary gland:
FSH(Follicle Stimulating Hormone): stimulates the sperm-producing cells in the testes to divide by meiosis and produce sperm.
LH (Luteinising Hormone): stimulates the production of testosterone in the testes.
Before puberty: the testes produce small amounts of the hormone testosterone.
Testosterone: causes primary and secondary male characteristics.

10. Sexual Characteristics
Primary sexual characteristics: are the growth of reproductive organs.
Secondary sexual characteristics: are the features that distinguish males from females apart from the sex organs themselves.
Secondary male characteristics:
growth of pubic, facial and body hair
enlargement of larynx
growth spurt
widening of the shoulders
increased sebum production – acne
increased muscular and bone development

11. Infertility is the inability to produce offspring
Male infertility: - Low Sperm Count
Cause: - persistent smoking of cigarettes
- alcohol abuse
- use of marijuana or anabolic steroids
- low levels of male hormones
- mumps in adult life
Treatment:
changes in diet and lifestyle i.e. no smoking, no drugs, reducing alcohol intake, reducing stress levels.
Hormonal therapy
In-vitro fertilisation

12. Female Reproductive System LS

13. The Female Reproductive System
Main Parts:
Ovaries
Fallopian Tubes
Uterus (womb)
Cervix
Vagina

14. The Female Reproductive System
Ovaries:
produces eggs (ovum) by meiosis
produces female hormones
after puberty (11-12 yrs.) approx. 20 eggs produced by meiosis each month – only 1 survives.
This haploid egg is surrounded by a Graafian follicle which produces the female hormone oestrogen.
This Graafian follicle matures on the surface of the ovary and bursts at ovulation to release the egg.
After ovulation this follicle becomes the corpus luteum – secretes the hormone progesterone.

15. The Female Reproductive System
Fallopian Tubes:
moves egg down tube by cilia and muscular peristalsis.
site of fertilisation
funnel of Fallopian tube catches the egg after ovulation.
Oviduct : Fallopian tubes and uterus.

16. The Female Reproductive System
Uterus (Womb):
lined with the endometrium which nourishes the embryo.
Cervix:
opening into the uterus.
Vagina:
muscular tube which allows entry of sperm into the female system
birth canal

17. The Female Reproductive System
Vagina:
Labia – folds of skin which protect vagina and are collectively known as the vulva.
Hymen – ring of tissue which may partially block the vagina entrance.

18. The Female Reproductive System
The Menstrual Cycle
The menstrual cycle is a series of changes that happen about every 28 days in the female body.
The menstrual cycle takes place:
between puberty and the menopause
only when a female is not pregnant

20. The Female Reproductive System
Main events in the average menstrual cycle:
Days 1 to 5:
If fertilisation does not occur blood and tissue from the inner lining of the uterus (endometrium) is released – Menstruation (period).
Meiosis in ovary produces new egg which becomes surrounded by Graafian follicle.
Days 6 to 14:
Graafian follicle produces oestrogen, causing the endometrium to thicken.

21. The Female Reproductive System Main Events in the Menstrual Cycle
Day 14:
Ovulation occurs – this is the release of an egg from the ovary
Egg passes into the funnel of the fallopian tube.
Endometrium continues to thicken.
Day 14 – 28:
Graafian follicle develops into corpus luteum and produces progesterone.
Progesterone causes endometrium to thicken even more and prevents new eggs forming.

22. The Female Reproductive System Main events in the Menstrual Cycle
If fertilisation has not occurred:
around day 22 corpus luteum begins to break down.
Progesterone levels decrease, causing endometrium to break down.
Menstruation and cycle begins again.

24. The Female Reproductive System
Female Hormones:
Oestrogen:
- causes endometrium to thicken in first half of cycle.
- at puberty high oestrogen levels cause the primary female sexual characteristics.
- prevents eggs from developing.
Progesterone:
- causes the endometrium to thicken for the last 14 days.
Combination of oestrogen and progesterone at puberty:
- causes secondary female characteristics.

25. Sexual Characteristics
Secondary Female Characteristics:
Growth of pubic and underarm hair
widening of hips
maturing and enlargement of breasts
increased body fat
growth spurt

26. Infertility
Female Infertility: - The failure to release eggs i.e. ovulate
Cause: - hormonal disorder (endocrine gland failure)
i.e. failure to produce FSH – no eggs
failure to produce LH – no ovulation
- stress
- tumour on ovary
- no obvious cause
Treatment: - for hormonal disorder- hormonal treatment.
- reduce stress
- surgery on the ovary
- in-vitro fertilisation

27. Hormonal Control of Menstrual Cycle
(Higher Level Only)
Four hormones are involved in the menstrual cycle:
- 1. FSH – follicle stimulating hormone
- 2. Oestrogen
- 3. LH – luteinising hormone
- 4. Progesterone

28. FSH:
- produced by the pituitary gland
- produced early in cycle – days 1 – 5
Oestrogen:
- produced by the graafian follicle
- produced from days 5 – 14
- causes the endometrium to develop and inhibits FSH production
- increased levels of oestrogen at day 14 cause LH to be produced
FSH causes eggs to develop which are surrounded
by graafian follicles
Graafian follicles secrete oestrogen (indirectly FSH
controls oestrogen production)

29. 3. LH:
- produced by the pituitary gland.
- produced on day 14
- it causes ovulation to occur and the remains of the graafian follicle to become the corpus luteum
4. Progesterone:
- produced by the corpus luteum
- produced from days 14 to 28
- maintains the structure of the endometrium
- inhibits the production of FSH and LH
- prevents contractions of the uterus

30. If pregnancy does not occur the corpus luteum breaks down – day 22
Day 28 – as a result of low levels of progesterone and oestrogen the following happens:
- FSH secretion is no longer inhibited - new eggs begin to develop
- uterus contracts and endometrium is shed from the body - menstruation

31. Menstrual Disorder – Fibroids
Fibroids are benign tumours of the uterus.
Cause: unknown although may be associated with
oestrogen levels
Treatment:
- small fibroids frequent check ups
- large fibroids – surgery
- large no. of fibroids – possible hysterectomy
Symptoms: none when small but when large cause prolonged periods, pain, heavy periods, miscarriage, infertility

32. Sexual Intercourse (Copulation)
Common Level
Copulation (sexual intercourse): is where the erect penis of the male is placed in the vagina of the female.
Stages of Copulation:
Sexual Arousal:
- in the male blood flow into penis increases and out of penis decreases – penis becomes erect
- in the female vagina becomes enlarged and produces lubricants
Copulation (Coitus or sexual intercourse):
- penis moves inside the vagina
- breathing and heart rates increase

33. Sexual Intercourse 3. Orgasm: - is the climax of sexual excitement.
- in the female the outer vagina and uterus contract
- ejaculation occurs – this is the emitting of semen from the penis.
4. Behaviour of sex cells:
- insemination occurs – this is when semen is released into the vagina just outside the cervix.
- sperm is pushed to an egg (if present) in fallopian tube.
- if egg present it releases a chemical attracting the sperm – chemotaxis.

34. Fertilisation
Fertilisation: occurs when the nucleus of the sperm fuses with the nucleus of the egg, forming a diploid zygote.
normally takes place in the fallopian tube.
many sperm swarm egg but only one enters egg
upon entering sperm loses its tail and the membrane of the egg undergoes a rapid chemical change forming a fertilisation membrane
This membrane prevents other sperm from entering.

35. Fertilisation Fertile Period
Sperm can survive in female reproductive system for up to 3 days therefore pregnancy can occur if female has intercourse 3 days before ovulation.
Egg can survive for 2 days therefore pregnancy can occur if female has intercourse 2 days after ovulation.
As a result, in a typical menstrual cycle fertile period lasts from day 11 to day 16.
Due to irregular menstrual cycles the fertile time is really days 9 to 18

36. Birth Control
Birth Control: involves taking steps to reduce the number of children born.
Abortion: involves the termination of a pregnancy.
Contraception: is the deliberate prevention of fertilisation or pregnancy. There are four methods:
Natural
Mechanical
Chemical
Surgical
Abortion
Contraception

37. Birth Control
Natural Contraception: involves not having intercourse around the time of ovulation.
natural methods of contraception try to identify the time of ovulation based on:
- body temperature
- mucous secreted in the cervix
- past menstrual cycles (rhythm method)
Mechanical Contraception: involves using physical barriers to prevent sperm reaching egg.
condoms
diaphragms
caps

38. Birth Control
Chemical Contraception: involves the use of spermicides or hormones.
Vaginal spermicides
The pill
Surgical Contraception: involves sterilisation of the female and vasectomy for males.
Tubal Ligation
Vasectomy

40. Implantation
Implantation: is the embedding of the fertilised egg into the lining of the uterus.
occurs 6 to 9 days after fertilisation
during implantation amnion develops around the embryo
amnion secretes amniotic fluid which protects the embryo.

42. Early Development of the Zygote
Higher Level Only
Fertilised egg contains 46 chromosomes
Zygote divides many times by mitosis to form a ball of
cells called the morula (after 3 days)
Approx 5 days after fertilisation and further mitosis,
morula forms a hollow ball called blastocyst
Implantation occurs – blastocyst embeds in uterus
Inner cells form the embryo and outer cells form
amnion which secretes amniotic fluid which protects
embryo
Placenta forms from embryonic and uterine tissues

43. Placenta produces hormones (oestrogen and
progesterone) and allows the exchange
of materials between mother and baby to occur –
wastes, antibodies, nutrients etc.

44. Embryonic Development
Higher Level Only
10 days after fertilisation cells of inner cell mass of the
blastocyst form embryonic disc which gives rise to
three layers of cells called primary germ layers.
Each of these layers give rise to different tissues:
GERM LAYER
TISSUE/ORGAN
Ectoderm
Skin, nails, hair & nervous system
Mesoderm
Muscles, skeleton, excretory , respiratory & circulatory systems
Endoderm
Liver, pancreas, inner lining of digestive, respiratory & excretory tracts

45. 4th week – heart is formed and beating
- umbilical cord formed
5th week – internal organs and limbs have started to form
6th week – eyes visible
- mouth, nose, ears are forming
8th week – all major organs are formed and is now called a foetus
12th week – eyes low and widely spaced, cartilage replaced by bone (ossification), nerve and muscle coordinate, movement of the legs & arms, sex organs distinguishable, baby teeth begin to grow, the foetus sucks its thumb and can kick, breathe and urinate

46. After week 12 the baby continues to grow
Pregnancy – Gestation:
is the length of time spent in the uterus from
fertilisation to birth ( 9 months – 40 weeks)

47. Birth
Common Level
For the first weeks oestrogen and progesterone
are produced by the corpus luteum, after that they are
made by the placenta
Before birth the production of progesterone stops and
oestrogen increases – walls of uterus begin to contract
Pituitary gland of mother produces hormone called
oxytocin – causes contractions of uterine muscle
resulting in onset of labour.

48. Birth Labour may be divided into three stages: Stage 1
- foetus rotates towards cervix
- cervix widens
- amniotic fluid is released
- contractions begin
Stage 2
- contractions become stronger & more frequent
- foetus is pushed head first through the vagina
Stage 3
- the placenta & foetal membranes are expelled (after birth)

50. Lactation is the production of milk by the mothers breast
(mammary glands)
prolactin produced by the pituitary gland stimulates
milk production
for first few days after birth colostrum produced from
breasts. This has less fat and sugar than breast milk but
is higher in minerals, proteins and antibodies.

51. Benefits of Breastfeeding
provides baby with antibodies to protect against
infection
promotes a close bond between mother & baby
it can reduce the risk of breast cancer in the mother
uterus recovers faster as oxytocin stimulates uterine
muscle contractions as well as stimulating milk
secretion during lactation

52. In-Vitro Fertilisation (IVF) See notes for IVF Method
is a method of treating infertility.
it involves removing eggs from an ovary and
fertilising them outside the body.
IVF may be used:
in females if fallopian tubes are
blocked or the ovaries cannot produce
eggs naturally
in males if they have low sperm counts
See notes for IVF Method

53. Note: umbilical cord connects the embryo with the placenta
Placenta Formation
After implantation embryo forms an outer membrane
called the chorion completely surrounding amnion and
embryo.
Chorion develops projections called villi
Together these villi and the mother’s blood vessels
form the placenta
Placenta does not become fully functional until about
12 weeks
Note: umbilical cord connects the embryo with the placenta

55. Placenta Functions of the Placenta:
allows materials to pass from the mothers blood to
the embryo e.g. oxygen, food, antibodies drugs etc.
and from the embryo’s blood to the mothers e.g.
CO2, salts, urea.
produces hormones
prevents the blood supplies of the embryo and
mother from mixing. This separation is essential
because:
- they might have different blood groups and bloods would clump if mixed
- blood pressure of mothers system would cause damage to embryo.