Unit 2 KA3 - The Biology of Controlling Fertility
Men are fertile...
continuously
Women are fertile...
for a few days during the menstrual cycle
Women experience.. (in cycles)
Cyclical fertility
How much does a womens body temperature rise after ovulation?
0.5 degrees celcius
What happens to a womens cervical mucus during fertile periods
It becomes thin and watery
Treatment for infertility: Stimulating Ovulaton
Ovulation is stimulated by drigs that prevent negative feedback effect of oestregen on FSH secretion
Other ovulatory drugs mimic the action of FSH and LH. These drugs can cause super ovulation that can result in multiple birthd or be used to collect ova for IVF programmes
Treatment for Infertility: Artificial insemination
Several samples of semen are collected over a long period of time.
Artificial insemination is particularly useful if a male has a low sperm count.
If a oartner is sterile a donor may be used to provide semen.
Treatment for infertility: ICSI
If mature sperm are defective or very low in number ICSI can be ised.
The head of the sperm is frawn into a needle and injected directly to the egg to achieve fertilisation
Treatments for infertility: IVF
to achieve IVF the female is first given hormone stimulation
Eggs are collected from ovaries via surgical removal
Eggs are mixed with sperm in a culture dish to achieve fertilisation
Fertilised eggs are then incubated until they have formed atleast 8 cells and then are transferred to the uterus for implantation
Zygotes can undergo a PGD to identify any single gene disorders and chromosome abnormalities
Physical barrier methods of contraception
Condom
Diaphragm
Cervical Cap
Avoiding the fertile period
IUD
Chemical Methods of contraception: Oral contraceptive pill
Contains a combination of synthetic progesterone and synethetic oestregen
The pill mimics negative feedback preventing the release of FSH and LH from the pituitary gland
Chemical methods of contraception: Morning after pill
Emergency hormonal contraceptive pills which prevent or delay ovulation
These pills are referred to as the morning after pill but can be taken up to 72 hours after unprotected sex, depending on which type of pill is used
Chemical methods of contracetion: mini pill
thickens the cervical mucus