Menstrual Cycle & Plant Hormones Flashcards
Describe the four stages in the menstrual cycle
Stage 1: When the bleeding starts, the uterus lining breaks down for about four days.
Stage 2: lining builds up again from day 4 to day 14, into a thick spongy layer full of blood vessels, ready to receive a fertilised egg.
Stage 3: An egg is developed and then released from ovary at day14.
Stage 4: Wall is maintained for about 14 days, until day 28. If no fertilised egg has landed on uterus wall by day 28, lining starts to break down again and the cycle restarts.
What does the hormone FSH do during the Menstrual cycle?
FSH causes an egg to mature in one of the ovaries
Stimulates the ovaries to produce oestrogen.
What does the hormone Oestrogen do during the Menstrual cycle?
Causes Pituitary gland to produce LH.
Inhibits the further release of FSH
What does the hormone LH do during the Menstrual cycle?
Stimulates the release of an egg at around the middle of the menstrual cycle
How can Hormones be used to Reduce Fertility?
Oestrogen can be used to prevent the release of an egg, so it can be used as a method of contraception. If Oestrogen is taken everyday to keep the level of it permanently high, it inhabits the production of FSH. Egg development and production stop and stay stopped.
Progesterone also reduces fertility by stimulating the production of thick cervical mucus preventing any sperm getting through and reaching an egg.
The first pill made in the 1950s contained high levels of Oestrogen and progesterone and was known as the combined oral contraceptive pill.
However there were concerns about links between Oestrogen in the pill and side effects like blood clots. The pill now contains lower doses of oestrogen so has fewer side effects.
What are the pros and cons of taking the pill?
Pros:
1) the pill’s over 99% effective at preventing pregnancy
2) it reduces the risk of getting some types of cancer
Cons:
1) it isn’t 100% effective - there’s still a chance of getting pregnant
2) it can cause side effects like headaches, nausea, irregular periods and fluid retention
There is also a progesterone only pill, it has fewer side effects than the pill but it’s not as effective.
How can Hormones be used to increase fertility?
The Hormones FSH and LH can be injected by these women to stimulate eggs release in their ovaries.
What are the pros and cons of using FSH and LH to increase fertility?
Pro:
It helps a lot of women to get presents when previously they couldn’t
Con:
1) it doesn’t always work - some women may have to do it many times, which can be expensive
2) too many eggs could be stimulated, resulting in unexpected multiple pregnancies (twins, triplets)
How can Hormones be used to Reduce Fertility?
Oestrogen can be used to prevent the release of an egg, so it can be used as a method of contraception. If Oestrogen is taken everyday to keep the level of it permanently high, it inhabits the production of FSH. Egg development and production stop and stay stopped.
Progesterone also reduces fertility by stimulating the production of thick cervical mucus preventing any sperm getting through and reaching an egg.
The first pill made in the 1950s contained high levels of Oestrogen and progesterone and was known as the combined oral contraceptive pill.
However there were concerns about links between Oestrogen in the pill and side effects like blood clots. The pill now contains lower doses of oestrogen so has fewer side effects.
What are the pros and cons of taking the pill?
Pros:
1) the pill’s over 99% effective at preventing pregnancy
2) it reduces the risk of getting some types of cancer
Cons:
1) it isn’t 100% effective - there’s still a chance of getting pregnant
2) it can cause side effects like headaches, nausea, irregular periods and fluid retention
There is also a progesterone only pill, it has fewer side effects than the pill but it’s not as effective.
How can Hormones be used to increase fertility?
Women who have levels of FSH that are too low aren’t able to mature their eggs
Explain how IVF works
In vitro fertilisation involves collecting eggs from the women’s ovaries and fertilising them in lab using the mans sperm. These are then grown into embryos.
Once the embryos are tiny balls of cells, one or two of them are transferred to the women’s womb to improve the chance of pregnancy.
FSH and LH are given before egg collection to stimulate egg production (so more than one egg can be collected).
What are the pros and cons of IVF?
Pro:
1) Fertility treatment can give an infertile couple a child
Cons:
1) Some women have a strong reaction to the Hormones - abdominal pain, vomiting, dehydration
2) There have been some reports of an increased risk of cancer due to the hormonal treatment
3) Multiple births can happen if more than one embryo grows into a baby - higher risk of miscarriage and still birth
What is Auxin and how does it work?
Auxin is a plant hormone that controls growth near the tips of shoots and roots
It controls the growth of a plant in response to light (phototropism) Gravity (gravitropism) and moisture
Auxin is produced in the tips and moves backwards to stimulate the cell elongation process which occurs in the cells just behind the tips
If the tip of the shoot is removed then no auxin is available and shoot may stop growing
Auxin Promotes Growth in a plants shoots. Shoots grow towards…?
Shoots grow towards light. When a shoot tip is exposed to light more auxin accumulates on the side that’s in the shade than the side that’s in the light.
This makes the cells grow faster on the shaded side, so the shoot bends towards the light.
