2.3 controlling fertility

Question 1

Difference between male and female fertility

Answer 1

Males have continuous fertility from the onset of puberty until death.
Females have cyclical fertility and are only able to conceive for a few days within each menstrual cycle.

Question 2

When does fertility begin in females

Answer 2

Females are fertile from onset of puberty until menopause so their fertile period is much shorter than males.

Question 3

How long can ova and sperm survive for?
(Calculate the fertile period within a menstrual cycle of a female 1)

Answer 3

Ova can survive for approximately 24 hours after ovulation. Sperm can survive for approximately 3 days in the female reproductive tract.

Question 4

When does the fertile period begin?
(Calculate the fertile period within a menstrual cycle of a female 2)

Answer 4

Therefore, the fertile period starts approximately 3 days before ovulation and ends the day after ovulation

Question 5

When does the fertile period start?
(Calculate the fertile period within a menstrual cycle of a female 3)

Answer 5

In an average 28-day menstrual cycle, assuming that ovulation occurs on day 14, the fertile period would start on day 11 and end on day 15 of the cycle.

Question 6

For successful fertilisation and implantation the following events must be possible and co-ordinated

Answer 6

Production of viable gametes by both male and female
· Ovum able to travel through fallopian tube
· Sperm able to swim through the female reproductive tract
· Endometrium ready to receive blastocyst for implantation
Infertility is the result when any of these events does not happen.

Question 7

4 causes of infertility

Answer 7

• failure to ovulate (no ovum released)
  -low sperm count
  -blockage of fallopian tubes
  -failure to implant

Question 8

what causes a failure to ovulate and a low sperm count?

Answer 8

Likely to be the result of hormone imbalance. Risk factors include : high alcohol intake, smoking, obesity and high stress levels.

Question 9

Whats the treatment for the failure to ovulate

Answer 9

Treated using fertility drugs that mimic the action of FSH and LH.

Question 10

treatment of low sperm count

Answer 10

Can be treated using testosterone to boost sperm production. Alternatively, artificial insemination, IVF or ICSI processes could be used

Question 11

What causes the blockage of fallopian tubes

Answer 11

Can be the result of infection or abnormal tissue growth.

Question 12

Treatment for blocked fallopian tubes

Answer 12

Surgical treatment to remove blockages or IVF treatment.

Question 13

What causes the failure to implant

Answer 13

Likely to be the result of hormone imbalance preventing co-ordination between the events in the ovary and the thickening and vascularisation of the endometrium.

Question 14

Whats the treatment for not being able to implant

Answer 14

Treated using fertility drugs to co-ordinate the ovarian and uterine processes.

Question 15

does artificial insemination include sexual intercourse

Answer 15

nah

Question 16

Where is the semen injected (artificial insemination)

Answer 16

female reproductive tract

Question 17

What is artificial insemination used to treat

Answer 17

Low sperm count

Question 18

Explain artificial insemination

Answer 18

Collection of several semen samples can be taken over a period of time that are then used to produce a higher quality sample. The semen sample is then inserted into the female reproductive tract using a catheter. If the male is infertile and viable sperm are not produced, semen from a donor can be used for the insemination process.

Question 19

is ivf surgical or non surgical?

Answer 19

This involves the surgical removal (harvest) of ova from ovaries after hormone stimulation

Question 20

explain the IVF process

Answer 20

The ova are then mixed with sperm in a culture dish to allow fertilisation to occur. (This is why the technique is called in vitro which means ‘in glass’). The fertilised eggs (zygotes) are then incubated until they have formed at least eight cells (blastocyst stage) and then inserted into the uterus for implantation.

Question 21

when is ICSI used

Answer 21

This technique is used when mature sperm are defective or very low in number

Question 22

Explain ICSI

Answer 22

Sperm can be collected after ejaculation or directly from the epididymis or testes. A single sperm is selected and the head of the sperm is drawn into a syringe needle and injected directly into the egg to achieve fertilisation. If fertilisation is successful then the blastocyst is inserted into the uterus for implantation.

Question 23

what is PGD : Pre-implantation genetic diagnosis

Answer 23

Analysis of the chromosome complement of a developing zygote can be used to identify single gene disorders and chromosomal abnormalities.

Question 24

what is PGD used for

Answer 24

This can be used as part of a screening process during IVF to identify and any zygotes that are unlikely to result in a viable pregnancy.

Question 25

State the definition of contraception.

Answer 25

Contraception is the prevention of fertilisation or implantation.

Question 26

What is a physical method of contraception

Answer 26

These methods place some sort of barrier between the sperm and ovum preventing fertilisation from occurring or preventing implantation.

Question 27

examples of physical barriers

Answer 27

avoiding intercourse during the fertile period (no intercourse = no pregnancy)
· barrier methods such as condoms, cervical cap and diaphragm – prevent sperm entering the uterus
· intra uterine device (aka IUD or coil) - a small plastic and copper T-shaped device that is inserted into the uterus which disrupts the travel of any sperm and prevents a blastocyst from implanting.

Question 28

sterilisation procedures in males

Answer 28

In males = Vasectomy – tubes carrying sperm from the testes to the penis are cut, blocked or sealed with heat to prevent sperm entering the semen.

Question 29

Sterilisation procedures in females

Answer 29

Tubal ligation/occlusion – Fallopian tubes are clamped, blocked or severed and sealed to permanently prevent pregnancy.

Question 30

spermicides

Answer 30

chemicals that kill sperm. These are often used at the same time as barrier methods to increase the effectiveness.

Question 31

Chemical contraceptives

Answer 31

Chemical contraceptives are based on combinations of synthetic oestrogen and progesterone hormones. For example :
The combined pill works by inhibiting the release of FSH/LH from the pituitary gland (mimicking feedback control) and so prevent maturation of follicles and ovulation.

Question 32

mini pill

Answer 32

Progesterone-only (‘mini’) pills work by causing an increase in the volume and viscosity (thickening) of cervical mucus making it impenetrable to sperm so they cannot enter the uterus.

Question 33

morning after pill

Answer 33

The morning-after pill works by inhibiting ovulation and/or preventing successful implantation.