Biology of controlling fertility Flashcards
What are infertility and contraception based on?
Biology of fertility
Why are males continuously fertile?
Due to relatively constant levels of pituitary hormones
When is the highest likelihood of pregnancy resulting from sexual intercourse?
A few days before until 1-2 days after ovulation
How can the time of ovulation be estimated?
By the number of days after menstruation, slight rise in body temperature on the day of ovulation and the thinning of cervical mucus
Why might a female be infertile?
Failure to ovulate, which is usually the result of a hormone imbalance
How can you stimulate ovulation?
Ovulatory of fertility drugs
What do some ovulatory drugs work to prevent?
Negative feedback effect of oestrogen on FSH secretion
What do some ovulatory drugs mimic the action of?
FSH and LH
What can ovulatory drugs cause?
Superovulation, which can result in multiple births
What can ovulatory drugs be used to collect?
Ova for IVF programmes
What is artificial insemination
A treatment in which semen is inserted into the female reproductive tract without intercourse haven taking place
When would you use artificial insemination
When the male has a low sperm count
What does artificial insemination involve?
The collecting and combining several samples of semen
Why might sperm from a donor be used in artificial insemination?
If male is infertile (sterile)
What does IVF involve?
The surgical removal of eggs from ovaries after hormone stimulation, mixing with sperm to achieve fertilisation, incubation of zygotes and uterine implantation
When can intracytoplasmic sperm injection be used during IVF?
If mature sperm are defective or very low in number
What does ICSI involve?
The head of a sperm being drawn into a needle and injected directly into the egg to achieve fertilisation
What is preimplantation genetic diagnosis used in conjunction with IVF for?
To identify single gene disorders and chromosomes abnormalities
What do methods of contraception act by preventing?
Fertilisation or implantation
Why do we use contraception?
Intentional prevention of pregnancy by natural or artificial methods
What does contraception include?
Physical and chemical methods
What do physical methods of contraception include?
Barrier methods, avoiding fertile periods, intrauterine devices and sterilisation procedures
What are chemical contraceptives based on?
Combinations of synthetic progesterone and oestrogen that mimic negative feedback preventing the release of FSH/LH from the pituitary
What are problems with fertility treatments
Risks and ethical issues
Physical methods of contraception
Condom,diaphragm, calendar based methods, Intra urenince device, vasectomy and tubal ligation
Chemical methods of contraception
Combination contraceptive pill, mini pill and morning after pill
What do women show that leads to a fertile period
cyclical fertility
How does stimulating ovulation help infertility
Ovulation is stimulated by drugs that prevent the negative feedback effect of oestrogen on FSH secretion
What is the process of IVF
- Surgical removal of eggs from ovaries after hormone stimulation
- Eggs are mixed with sperm in a culture dish
- The fertilised eggs are incubated until they have formed at least eight cells and are then transferred to the uterus for implantation
- Incubation of zygotes and uterine implantation
What does the mini pill do?
causing thickening of the cervical mucus
What does the morning after pill do?
ovulation and implantation
