Hormones and Fertility - TOPIC 7 Flashcards
what are hormones
chemical messengers which travel in the blood to activate cells in target organs
where are hormones produced
endocrine glands
what is the endocrine system using hormones for
to react to changes in the environment or changes inside the body
what are the six glands in the endocrine system
pituitary gland
thyroid gland
pancreas
adrenal glands
ovaries
testes
what does the thyroid gland do
produce thyroxine which is involved in regulating things like rate of metabolism and heart rate
what does the pancreas produce
insulin
what do adrenal glands produce
adrenaline which is used to prepare the body for a flight or fight response
what do the ovaries do
produce oestrogen which is involved in the menstrual cycle
what do the testes do
produce testosterone which controls puberty and sperm production in males
differences between nerves and hormones
nerves are faster
nerves act for a shorter time
nerves act on a precise area
when and how is adrenaline released
in response to stressful or scary situations. The brain detects fear or stress and sends nervous impulses to the adrenal glands which respond by releasing adrenaline
how does adrenaline get the body ready for flight or fight
by triggering mechanisms that increase the supply of oxygen and glucose to cells
what happens when adrenaline binds to specific receptors in the heart, to heart rate and blood pressure
heart muscle contract more frequently and with more force so the heart rate and blood pressure increase
what happens when heart rate and blood pressure increases from adrenaline
increase in blood flow to muscles, so cells receive more oxygen and glucose for increased respiration and this gives the muscles extra energy for muscle contraction
how does adrenaline cause increase in glucose
adrenaline binds to receptors in the liver and this causes liver to break down its glycogen stores to release glucose.
what is glucose released from adrenaline used for
it is used to fuel muscle contraction in the fight or flight response
what does thyroxine do
regulate basal metabolic rate
what is negative feedback
when levels of certain substance in the body go above or below a normal level, the body triggers responses that help to bring these levels into a normal range
what does negative feedback system do to amount of thyroxine in blood
keep it at the right level
what happens when level of thyroxine in blood is lower than normal
The hypothalamus is stimulated to release TRH
TRH stimulates the pituitary gland to release TSH
TSH stimulates thyroid gland to release thyroxine
So, blood thyroxine level rises back to normal
what happens when level of thyroxine in blood is higher than normal
release of TRH from hypothalamus is inhibited (stopped) and this reduces the amount of thyroxine released form thyroid gland and so level of thyroxine falls.
what is the menstrual cycle
monthly sequence of events in which the female body releases an egg and prepares the uterus in case the egg is fertilised
how long is the menstrual cycle
28 days
what happens in stage 1 of the menstrual cycle (day 1 to 4)
day 1 is when menstruation/ bleeding starts and uterus lining breaks down and is released
what happens in stage 2 of the menstrual cycle
lining of uterus is repaired, from day 4 - 14, and ready for a fertilised egg to implant there
what happens in stage 3 of the menstrual cycle
an egg is released from the ovary at day 14 which is also known as ovulation
what happens in stage 4 of the menstrual cycle
lining is then maintained for about 14 days until 28 days.
what happens if no fertilised egg has landed on the uterus wall by day 28
spongy lining starts to break down again and the whole cycle starts again
hormones in the menstrual cycle
oestrogen and progesterone
what does oestrogen do
stimulate the growth of the uterus lining during stage 2 of the menstrual cycle
what does progesterone do
maintain the uterus lining during stage 4 and stops the release of FSH and LH
what does follicle stimulating hormone (FSH) do
causes a follicle to mature in one of the ovaries and stimulates ovaries to produce oestrogen
what does luteinising hormone (LH) do
stimulate the release of an egg at day 14 / ovulation
what happens when the level of progesterone falls and there is a low oestrogen level
uterus lining breaks down and low progesterone level allows FSH to increase and therefore allows the whole cycle to start again
why does level of progesterone stay high during pregnancy
to maintain the lining of the uterus during pregnancy
what does infertile mean
they cannot reproduce naturally
what happens if women have FSH level that is too low
eggs cannot mature and therefore no eggs are released and women can’t get pregnant
what are the 2 hormonal ways people can use to get pregnant
clomifene therapy
IVF ( in vitro fertilisation)
what does clomifene do
it is a drug, which works by causing more FSH and LH to be released by the body, which stimulates egg maturation and ovulation
how does IVF work
it involves collecting eggs from the woman’s ovaries and fertilising them in a lab using the man’s sperm. Fertilised eggs are then grown into embryos and once they are tiny balls of cells, one or two of them are transferred to the womens uterus
why is FSH and LH given before egg collection in IVF
to stimulate egg production so more than one egg can be collected
what are contraceptives used for
preventing pregnancy
why is oestrogen and progesterone used as contraceptives
they reduce the fertility
how does oestrogen prevent egg release and pregnancy
if taken every day to keep the level of oestrogen permanently high, it stops FSH production and after a while egg maturation and therefore egg release stop and stay stopped