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Higher Human 2.3
2.3- The biology of controlling fertility
Question | Answer |
---|---|
What kind of fertility is shown in females? | cyclical fertility |
What kind of fertility is shown in males? | continuous fertility |
What does cyclical fertility mean? | Women are only fertile for a few days during each menstrual cycle. |
What does continuous fertility mean? | Men continually produce sperm in their testes so show continuous fertility |
What can be used as Identification of the fertile period? | A woman’s body temperature rises by around 0·5°C after ovulation and her cervical mucus becomes thin and watery |
Ovulation can be stimulated by drugs that prevent the negative feedback effect of what hormones? | oestrogen on FSH secretion |
Other ovulatory drugs mimic the action of FSH and LH. What can this lead too? | These drugs can cause super ovulation |
What can super ovulation result in? | multiple births or be used to collect ova for in vitro fertilisation (IVF) programmes. |
Describe the process of artificial insemination. | Several samples of semen are collected over a period of time. The doctors implants semen into cervix or uterus. |
When is artificial insemination particularly useful? | Artificial insemination is particularly useful where the male has a low sperm count |
What can be used for artificial insemination if the partner is sterile? | donor sperm |
Describe Intra-cytoplasmic sperm injection (ICSI) | The head of the sperm is drawn into a needle and injected directly into the egg to achieve fertilisation. |
When will Intra-cytoplasmic sperm injection (ICSI) be used? | If mature sperm are defective or very low in number, ICSI can be used. |
Describe In vitro fertilisation (IVF). | 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. |
How are eggs for IVF obtained? | Surgical removal of eggs from ovaries after hormone stimulation |
The use of IVF in conjunction with pre-implantation genetic diagnosis (PGD) helps to indentify? | single gene disorders and chromosomal abnormalities. |
What are some physical methods of contraception? | barriers (condoms) intra-uterine devices sterilisation procedures |
What are some chemical methods of contraception? | The oral contraceptive pill The progesterone-only (mini) pill Emergency hormonal contraceptive pills |
What does the The oral contraceptive pill do? | It contains a combination of synthetic oestrogen and progesterone that mimics negative feedback preventing the release of FSH and LH from the pituitary gland. |
What does the progesterone-only (mini) pill do? | causes thickening of the cervical mucus |
When can Emergency hormonal contraceptive pills be taken? | they can be taken up to 72 hours or 120 hours after unprotected sex, depending on which type of pill is used’. |
What does the Emergency hormonal contraceptive pill do? | prevent or delays ovulation. |