Flashcards in 2.3. The Biology of Controlling Fertility Deck (25):
When are the fertile periods and how can you measure when it is for:
a) Men are continuously fertile.
b) Females are fertile for a few days each month. There is a period of five days around the time of ovulation where women are most fertile. There is usually a slight rise in body temperature and cervical mucus thickens.
Give some reasons for infertility.
- Health and Lifestyle (anorexia, obesity, drug misuse etc.)
Female infertility can be caused by the inability to ovulate, how would this come about?
The pituitary gland fails to secrete FSH and LH.
How would you treat a woman's inability to ovulate?
With drugs that mimic LH and FSH or with drugs that interfere with normal negative feedback control blocking oestrogen receptors. This may cause superovulation.
What is superovulation?
When a women produces more than one ovum in one cycle.
What is artificial insemination?
The collection of semen and the insertion into the woman.
What is donor insemination?
Artificial insemination with sperm from a sperm donor.
If a man has a low sperm count, what would be a helpful fertility treatment?
Artificial insemination and Intracytoplasmic Sperm Injection.
What does IVF stand for?
When would IVF be a suitable fertility treatment?
When a woman has a blocked oviduct.
Describe the process of IVF.
Ova are removed from the ovaries of the woman after ovulation is stimulated. Outside the womb, the ova and sperm are mixed and incubated until the zygote becomes a blastocyst. The most suitable embryo is implanted into the uterus. Unused embryos can be used at a later date.
Describe the process of ICSI (intracytoplasmic sperm injection).
The sperm is directly inserted into the ovum with a needle.
Give some biological reasons for infertility in women.
- Ovulation problems
- Poor egg quality
- Tube blockages
- Polycystic ovary syndrome (hormonal imbalance)
Give some biological reasons for infertility in men.
- Sperm tube blockages
- Low sperm count
- Sperm allergy
How do barrier methods of contraception work?
Prevent sperm being released into the female.
Give examples of barrier methods of contraception?
Condoms and cervical caps.
What is an intra-uterine device?
A small device (often T-shaped) with copper parts. It is fitted into the uterus to prevent the implantation of an embryo in the endometrium.
What is sterilisation? What are the most common methods of sterilisation for both genders?
An often permanent method of contraception which involves surgical procedures. Vasectomy in men, tubal ligation in women.
Describe the process of a vasectomy.
Cutting and closing the sperm tube of each testis.
Describe the process of tubal ligation.
Cutting and closing each oviduct.
How do chemical methods of contraception work?
They contain synthetic versions of oestrogen and progesterone that mimic negative feedback and stop the production of FSH and LH and stop ovulation, implantation or thickening cervical mucus.
Give examples of chemical methods of contraception and explain them briefly.
Combination contraceptive pill - Synthetic progesterone and oestrogen which inhibit the secretion of FSH and LH.
Mini pill - Contains synthetic progesterone which inhibits ovulation and causes the thickening of cervical mucus which prevents sperm entry.
Morning-after pill - A high dose of synthetic progesterone and oestrogen which decreases chances of ovulation and implantation. Also thickens cervical mucus.
What risks do fertility drugs carry?
The risk of multiple pregnancies. You can also get OHSS (ovarian hyperstimulation syndrome) which is when ovaries become unusually enlarged and fill with fluid.
What are the ethics of Pre-Implantation Genetic Diagnostics?
Some support it as it can help identify genetic disorders in children.
Some are against it as it may encourage selective breeding or they believe it's wrong to interfere with conception.