topic 7 - animal coordination, control and homeostatis Flashcards
What are hormones?
chemicals released directly in the blood to target organs
What do hormones do?
Control things in organs and cells that need constant adjustment
What is the pituitary gland?
- It produces many hormones that regulate body conditions
- located in the brain
What is the thyroid gland
- produces thyroxine
- located in the neck
- regulates metabolism, temperature, heart rate
What is the adrenal gland?
- produce adrenaline
- prepares the body for a fight or flight response
What does the pancreas do in terms of hormones?
- produces insulin
- used to regulate blood glucose levels
What is the ovaries in producing hormones
- only in females
- produces oestrogen
What is the testes in terms of hormones
- males only
- produces testosterone which controls sperm production and puberty
When adrenaline is secreted, what does it do to the body
- increased heart rate
- increased blood pressure
- increased blood flow to the muscles
- raised blood sugar levels by stimulating the liver to change glycogen to glucose
What is negative feedback
When the body detects that the level of a substance has gone above or below the normal level
How does thyroxine control metabolic rate when it’s too low
- low levels of thyroxine stimulates production of TRH in the hypothalamus
- this causes release of TSH from the pituitary gland
- TSH acts on the thyroid to produce thyroxine
- when thyroxine levels are normal thyroxine inhibits
the release of TRH and the production of TSH
Graves disease is a condition whether the immune system produces an antibody that has the same effect as TSH. Explain why this can lead to an abnormally high blood thyroxine level
TSH stimulates the release of thyroxine in the blood, but the amount of TSH falls when the level of thyroxine gets above the normal level. This negative feedback won’t affect the antibody, so it will keep stimulating the release of thyroxine above the normal level.
What is stage one of the menstrual cycle
- day one is when menstruation starts
- lining of the uterus breaks down and is released
what is stage two of the menstruation cycle?
- uterus lining is repaired, from day 4 to day 14, until it becomes a thick spongy layer full of blood vessels ready for a fertilised egg to implant there
what is stage 3 of the menstrual cycle?
- an egg develops and is released from the ovary at about day 14
what is stage 4 of the menstrual cycle
- lining is maintained for about 14 days, until day 28
- if no fertilized egg has landed on the uterus wall by day 28, the spongy lining starts to break down again and the whole cycle starts over
What is FSH
- follicle-stimulating hormone
- released by the pituary gland
- causes a follicle to mature in the ovaries
- stimulates oestrogen production
What is oestrogen
- released by the ovaries
- causes the lining of the uterus to thicken and grow
- high level stimulates an LH surge
What is LH
- luteinising hormone
- released by the pituitary gland
- LH surge stimulates ovulation at day 14 - follicle ruptures and the egg is released
- stimulates the remains of the follicle to develop into a structure called corpus luteum - which secretes progesterone
What is progesterone
- released by the corpus luteum after ovulation
- maintains the lining of the uterus
- inhibits release of FSH and LH
- when levels of progesterone falls, and there’s low oestrogen level, the uterus lining breaks down
- a low progesterone level allows FSH to increase and then the whole cycle starts again
What happens to progesterone levels if the woman becomes preganant
Stay high to maintain lining of the uterus breaks down
How can oestrogen be used to prevent pregnancy
- Oestrogen is taken every day to keep the level of it permanently high, it inhibits the production of FSH and egg development and production stop
How can progesterone reduce fertility?
Stimulating the production of a thick cervical mucus which prevents any sperm getting through the uterus and reaching an egg
What hormonal contraceptives both contain oestrogen and progesterone?
- combined pill
- contraceptive patch
