2.2 Biological Control Of Fertility Flashcards
(41 cards)
What factors can affect fertility?
Weight, stress, disease and pollutants (e.g. Cigarette smoke)
What are the two types of fertility?
Continuous fertility and cyclical fertility
Why do men have continuous fertility
Men have potential to become a father from onset of puberty due to the negative feedback control of testosterone
Describe the negative feedback effect of testosterone
It maintains a constant level of the pituitary hormones FSH & ICSH in the bloodstream, resulting in the steady release of testosterone
Why is fertility in women described as cyclical
Women produce eggs from puberty onwards until menopause. Menopause is when ova are no longer released from the ovaries and menstruation no longer occurs.
What age does menopause occur from
45-55
When can a woman fall pregnant
A few limited days either side of ovulation
How long does the fertility period in women last for
1-2 days
What indicators in the rhythm method are used when calculating a woman’s fertile period
Body temperature rise of 0.5’C and a change in the consistency of the cervical mucus
What is the state of the cervical mucus when a woman is infertile
Thick and sticky
What is the state of the cervical mucus when a woman is fertile and why
The mucus is thinner, slippery and stretchy which allows easy access for the sperm to the female reproductive system
Why causes the cervical mucus to become thinner, slippery and stretchy when a woman is fertile
The increasing oestrogen levels in the follicular phase
What advances have helped treatment of infertility
Modern medicine advances
What treatments are there for infertility
Stimulating ovulation, artificial insemination, in vitro fertilisation (IVF) and intra cytoplasmic spent injection
What drugs are given to help stimulate ovulation
Drugs that mimic the negative feedback effect of oestrogen on FSH secretion. Drugs that mimic the normal action of FSH & LH
What can the drugs used for ovulation stimulation cause
Can cause ‘super ovulation’ resulting in multiple births or be used to collect ova for IVF
What is artificial insemination
The insertion of semen into the female reproductive tract by means other then sexual intercourse
What are the two situations of artificial insemination
Low sperm count - several samples of semen collected over a period of time and each preserved by freezing. Then they are defrosted and released together into the female reproductive tract at the fertile time. Donor sperm required - If a male is sterile then semen samples may be obtained from a donor
What is IVF
The solution to infertility in which it enables fertilisation to occur outside the body in a culture dish.
What can IVF be used in conjunction with and why
PGD - to identify any known single gene disorders or chromosomal abnormalities
Outline stage one of IVF
Woman is given hormonal treatment to stimulate multiple ovulation
Outline stage two of IVF
Surgical procedure to remove several ova from around the ovary using equipment similar to a syringe
Outline stage three of IVF
The eggs are mixed with sperm I’m a culture dish of nutrient medium to allow fertilisation to occur. Alternatively sperm would be injected into an egg at this point
Outline stage four of IVF
The fertilised eggs are incubated in the nutrient medium for 2-3 days to allow cell division to occur and form embryos each composed of 8 cells or more.
