The Biology Of Controlling Fertility Flashcards
(18 cards)
What are infertility treatments and contraception based on?
The biology of fertility
What is fertility like in males?
Males are constantly fertile as they continually produce sperm in their testes
Negative feedback of testosterone keeps a constant level of pituitary hormone FSH and ICSH
What is fertility like in females?
Females show cyclical fertility leading to a fertile period
They are only fertile for a few days during each menstrual cycle (controlled by delicate balance of pituitary and ovarian hormones)
How can you identify the fertile period?
After the surge in LH triggers ovulation. A woman’s body temperature increases by around 0.5°c after ovulation
Her cervical mucus also become thin and watery
What are the five infertility treatments for woman?
Stimulating ovulation
Artificial insemination
Intra-cytoplasmic sperm injection(ICSI)
In vitro fertilisation(IVF)
Pre implantation genetic diagnosis(PGD)
What is stimulating ovulation?
Ovulation is stimulated by drugs that prevent the negative feedback effect of oestrogen on FSH secretion
Other ovulatory drugs mimic the action of FSH or LH
These drugs can sometimes cause ‘super ovulation’ resulting in multiple births or can be used to collect ova for IVF programmes
What is artificial insemination?
Several samples of semen are collected over a period of time and inserted into the female reproductive tract
This is effective if the male has a low sperm account
If a pretend is sterile a donor may be used to provide semen
What is intra-cytoplasmic sperm injection(ICSI)
If mature sperm cells are defective or very low in number, ICSI can be used
The head of the sperm cell is drawn into a needle and injected directly into the egg to achieve fertilisation
What is in vitro fertilisation(IVF)?
Hormones are given to stimulate egg production. After hormone stimulation the eggs are surgically removed from the uterus
The eggs are mixed with the sperm in a culture dish and fertilised eggs are incubated until they are at least 8 cells/zygotes before being transferred back to the uterus for implantation
What is pre implantation genetic diagnosis(PGD)?
PGD is used in conjunction of IVF
This checks for/identified some single gene disorders and chromosomal abnormalities
What is contraception?
The intentional prevention of conception or pregnancy by natural or artificial means
What are the 3 types of physical barriers of contraception?
Barrier method- condoms, femidoms, diaphragm
Sterilisation- vasectomy, tubule ligation
Intra-uterine device (IUD)
What is the intra-uterine device?
It’s a T-shaped plastic structure with copper wound round its outside
It stimulates the presence of white blood cells which attack sperm and prevents sperm from reaching the egg
It also imitates the lining of the uterus making it difficult for an embryo to become implanted
What is sterilisation?
Females- oviducts are either tied, cut or sealed with heat in order to prevent the release of an egg
Males- the tubes that carry the sperm from a man’s testes to the penis are cut, blocked or sealed with heat meaning the sperm cannot enter the man’s semen
What are the chemical barriers of contraception?
Mini pill(eg progesterone only)
Morning after pill
Oral contraceptive pills
What are the oral contraceptive/combined pills?
They contain a combination of synthetic oestrogen and progesterone that mimics negative feedback preventing the release of FSH and LH from the pituitary gland
What is the oral mini pill?
The progesterone-only mini pill causes thickening of the cervical mucus
Morning after pill
Emergency contraceptive pills that prevent or delay ovulation
Taken up to 72-120 hours after unprotected sec spending on type
