Biology of controlling fertility Flashcards
Describe the fertility of men and women
Men show continuous fertility, continually producing sperm from the onset of puberty.
Women show cyclic fertility, only being fertile for a few days during each menstrual cycle.
A woman’s body temperature rises by around 0.50C after ovulation and her cervical mucus becomes thin and watery. This is how the fertile period of a women can be identified.
describe stimulating ovulation
Ovulation can be stimulated by drugs that prevent the negative feedback effect of oestrogen on FSH secretion.
Other ovulatory drugs mimic the action of FSH and LH.
These drugs can cause super ovulation (the development of up to three follicles).
This can result in multiple births of be used to collect ova for in vitro fertilisation (IVF) programmes.
describe artificial insemination
Several semen samples are collected over a period of time and injected directly into the uterus/vagina/female reproductive system.
• This process is used if the male has a low sperm count or if the male is sterile a donor may be used to provide semen.
Describe ivf
Eggs are surgically removed from the ovaries after hormone stimulation. Eggs are mixed with sperm in a culture dish and the zygotes (fertilised eggs) are incubated until they have formed at least eight cells and are then transferred to the uterus for implantation.
IVF can be used in conjunction with pre-implantation genetic diagnosis to identify single gene and chromosome abnormalities.
describe ICSI
A process similar to IVF but if the sperm are defective or very low in number, ICSI can be used. The head of the sperm is drawn into a needle and injected directly into the egg to achieve fertilisation.
Describe the barrier method of contraception
Condom
Placed on the penis and prevents sperm entering the female reproductive system therefore preventing fertilisation.
Female condom
Placed inside the female reproductive system and collects sperm to prevent fertilisation.
Diaphragm/cap
A dome shaped structure placed over the cervix to prevent sperm from penetrating the uterus preventing fertilisation.
Sponge
Contraceptive sponge that is soaked in a spermicide that is inserted into the vagina. The sponge covers the cervix preventing sperm from entering the uterus, thus preventing fertilisation.
Describe a vasectomy
Vasectomy
Occurs in males, a small incision and the vas deferens is cut and cauterised to prevent from sperm from travelling and being ejaculated.
Describe tubal ligation
Occurs in females, the oviducts are cut and clipped (or cauterised) to prevent ova from reaching the uterus and prevent sperm from reaching the ova.
describe contraceptive pill
The contraceptive pill is a chemical method of contraception. It contains a combination of synthetic oestrogen and progesterone that mimics negative feedback preventing the release of FSH and LH from the pituitary gland. Therefore, it prevents the development of any follicles.
describe progesterone only pill
The progesterone only (mini pill) thickens cervical mucus preventing the sperm from entering the uterus.
describe the morning after pill
The emergency or morning after pill prevent or delay ovulation. It can be taken up to 72 hours or 120 hours after unprotected sex depending on which type of pill is used.
