1. 6.6 Reproduction

2. Sexual reproduction is the only method of reproduction in humans
Sexual reproduction involves the fusion of specialised sex cells (gametes):- sperm (male gamete) & egg cell (female gamete).
The fusion of the nuclei male gamete and female gamete is called fertilisation.
Fertilisation results in the formation of a zygote from which a new individual develops.

3. Male reproductive system
Functions of the male reproductive system are:
production of male gametes (sperms)
transfer of sperm into the female reproductive system
produces male sex hormone testosterone

4. ureter
urinary bladder
sperm duct
Seminal Vesicle
Prostrate gland
cowper’s gland
urethra
penis
testiss
scrotum

5. Functions of parts of male reproductive system
scrotum -
Testes -
Sperm ducts -
Prostate gland -
Urethra -
Penis -
holds testes at cooler temperature than core body temperature
produces male gametes (sperms) & sex hormone testosterone
passage of sperms travel from testes to urethra during intercourse
secretes seminal fluid in which sperm swim
passage of semen (seminal fluid + sperm) during ejaculation
inserted into vagina during intercourse where it deposits semen

6. Female reproductive system
Functions of the female reproductive system are:
to produce the egg cells (female gametes)
to provide a safe place for fertilisation
to provide protection and nourishment for a developing foetus
to produce sex hormones (oestrogen & progesterone)

7. Female reproductive system
oviduct
ovary
uterus
cervix
vagina
vulva

8. Functions of parts of female reproductive system
Ovary –
Oviduct –
Uterus –
Cervix –
Vagina –
produce female gamete & sex hormones oestrogen & progesterone
site of fertilisation & movement of egg cell and (or) embryo from ovary to uterus
site of implantation of embryo, foetus development & muscular wall contracts to push out foetus during birth
directs sperm into uterus ,mucus plug during pregnancy prevents infections & dilates at the beginning of birth
site of deposition of sperm during intercourse & it’s the birth canal – it stretches during birth to allow passage of foetus out of the body

9. Menstrual cycle
It is characterised by changes in the uterus and ovaries
The cycle lasts 28 days and if implantation does not occur, the cycle repeats itself
The menstrual cycle is controlled by hormones released by pituitary gland and the ovary

12. Interaction of hormones in the menstrual cycle

13. Follicle stimulating hormone (FSH)
released by anterior lobe of pituitary glad
stimulates growth of follicles in the ovaries
stimulates secretion of oestrogen

14. Oestrogen estrogen is secreted from follicle cells in the ovary
it stimulates the repair of endometrium (uterus lining)
increase in estrogen inhibit FSH & LH secretion by –ve feedback
rapid increase in the middle of the cycle stimulates LH & FSH production by +ve feedback
if no fertilization, lower concentration of estrogen allows disintegration of endometrium & menstruation occurs

15. Luteinising Hormone (LH)
LH is secreted by anterior lobe of pituitary
it stimulate ovulation
It causes the development of the corpus luteum from empty follicle
it stimulates secretion of progesterone & estrogen by corpus luteum

16. Progesterone
progesterone is secreted from follicle cells & corpus luteum in the ovary
it stimulates final thickening of endometrium & maintains the thickening
high levels inhibits secretion of FSH & LH through –ve feedback
if no fertilization occurs, low levels of progesterone causes disintegration of endometrium & menstruation occurs

18. Roles of testosterone in males.
pre-natal development of male genitalia
promotes development of primary sexual characteristics:
development of genitalia, ducts, glands
Spermatogenesis
promotes development of secondary sexual characteristics:
larynx growth – deepening of voice
facial, body, and pubic hair
muscle and bone development
male behavior pattern
maintenance of sex drive

19. Reasons for infertility in humans
Low sperm count of the male. This can be rectified by concentrating the male sperm before being placed into the uterus of the female.
Blockage of the cervix which again can be overcome by simple procedures and the mechanical introduction of sperm through this passage.

20. Assisted reproductive technology
In complex cases of infertility it is necessary to fertilize the egg cell outside of the body before introducing the embryos into the uterus for implantation.
One of the assisted reproductive technologies is called 'In Vitro fertilisation' or IVF. First performed by Sir Robert Winston in 1978 Oldham England. Louise Brown was the first of millions of 'test tube babies'.

21. In Vitro fertilisation ( IVF)
The egg is fertilized by the sperm outside the woman body then embryo is introduced into the uterus for implantation
IVF is a major treatment for infertility
It was first performed by Sir Robert Winston in 1978 at Oldham England

23. Process of In Vitro fertilisation ( IVF)
(IVF) is fertilization outside the female body i.e. "in glass"
drugs are injected to stop normal menstrual cycle
FSH is injected to stimulate ovaries to produce eggs
HCG is injected to matures the follicles
eggs are harvested from follicles in the ovaries using a fine needle
male provides (donates) sperm
washing of sperms i.e. capacitation of sperm is done
eggs are mixed with sperms and incubated for 24 hours to allow fertilization to occur
2-3 embryos are selected and implanted into uterus
pregnancy test is done to see if implantation & pregnancy has occurred
additional embryos frozen for future use

24. Ethical Issues associated with IVF
Disadvantages of IVF
Advantages of IVF
chance for infertile couples to have children of their own
decision to have children is clearly a conscious one due to difficulty of becoming pregnant
genetic screening of embryos could decrease suffering from genetic diseases
spare embryos can safely be stored for future pregnancies or for use in stem cell research
IVF is expensive and might not be equally accessible to all infertile couples
success rate is low therefore it is stressful for the couple
it is not natural, thus it faces cultural & religious objections
could lead to eugenics (i.e. improving the qualities of the human species) & (or) gender choice
could lead to (unwanted) multiple pregnancies with associated risks
production and storage of unused embryos may raise legal issues such as stem cell research which many consider unethical
inherited forms of infertility might be passed on to children