The Biology Of Controlling Fertility

Question 1

What are infertility treatments and contraception based on?

Answer 1

The biology of fertility

Question 2

What do women show in terms of fertility?

Answer 2

Cyclical fertility leading to fertile periods.

Question 3

What do men show in terms of fertility

Answer 3

Continuous fertility, meaning they are always fertile.

Question 4

What is the difference between men and women in terms of fertility?

Answer 4

Women are only fertile for a few days during each menstrual cycle (4-5 days after ovulation) displaying cyclical fertility.
Men continually produces perm in their testes so show continuous fertility.

Question 5

How can we identify a fertile period within women?

Answer 5

A woman’s body temperature rises by around 0.5 degrees celcius after ovulation and her cervical mucus becomes thin and watery to allow for penetration by sperm.

Question 6

What can ovulation be artificially stimulated by?

Answer 6

Ovulation can be stimulated by drugs that prevent the negative feedback of oestrogen on FSH secretion

Question 7

What can ovulatory drugs cause?

Answer 7

Ovulatory drugs mimic the action of FSH and LH: these drugs can cause SUPER-OVULATION that can result in multiple births or be used to collect ova for in vitro fertilisation ( IVF ) programmes.

Question 8

Describe artificial insemination

Answer 8

1. Several samples of semen are collected over a period of time.
2. Artificial insemination is particularly useful where the male has a low sperm count
3. If a partner is sterile a donor may be used to provide semen

Question 9

Describe the process of Intra Cytoplasmic Sperm Injection ( ICSI ) ( 2 things )

Answer 9

1. If mature sperm are defective or low in number, ICSI can be used.
2. The head of the speed is drawn into a needle and injected directly into the egg to achieve fertilisation.

Question 10

Describe the process of IVF ( in vitro fertilisation )

Answer 10

1. Eggs are surgically removed from the ovaries after hormone stimulation
2. Eggs are mixed with sperm in a culture dish.
3. The fertilised eggs are incubated until they have formed at least 8 cells
4. The fertilised eggs ( zygotes ) are then transferred to the uterus for implantation
5. IVF is used in conjunction with pre-implantation genetic diagnosis (PGD) to identify single gene disorders and chromosomal abnormalities.

Question 11

What physical methods can prevent pregnancy?

Answer 11

Intra-Urine devices and sterilisation procedure ( Vasectomy or Tubal Ligation )

Question 12

What is the purpose of the oral contraceptive pill?

Answer 12

It contains a combination of both synthetic oestrogen and progesterone that mimics negative feedback preventing the release of FSH and LH from the pituitary gland.

Question 13

What is the purpose of the progesterone only ( mini-pill )?

Answer 13

It causes the thickening of cervical mucus

Question 14

What is the purpose of the morning after pill?

Answer 14

The purpose of the morning after pill is to prevent ovulation or implantation.