animal coordination, control and homeostasis Flashcards
Describe where hormones
- hormones are produced and secreted by endocrine glands
describe how the pituitary gland transports hormones to its target organ
- produces many hormones that regulate body conditions
- pituitary gland is the master gland situated at the base of brain
- releases hormones that act on other glands to release hormones that bring about change
- ADH targets the kidneys
describe how the thyroid gland transports hormones to its target organ
- produces thyroxine (regulates things like rate of metabolism, heart rate and temperature)
- located at the front of your neck
- targets liver and kidneys
describe how the pancreas transports hormones to its target organ
- produces insulin
- targets liver
describe how the adrenal gland transports hormones to its target organ
- adrenalin
- liver, heart
describe how the ovaries transports hormones to its target organ
- oestrogen and progesterone
- targets uterus
describe how the testes transports hormones to its target organ
- testosterone
- male reproductive organs
Explain that adrenalin is produced by the adrenal glands
to prepare the body for fight or flight
a) increased heart rate and blood pressure
- adrenaline binds specific receptors in the heart
- heart muscle contracts now more frequently and with more force
- heart rate and blood pressure increase
Explain that adrenalin is produced by the adrenal glands
to prepare the body for fight or flight
b) increased blood flow to the muscles
- blood pressure and heart rate increases which increases blood flow to muscles
- so the cells receive more oxygen and glucose for increased respiration
Explain that adrenalin is produced by the adrenal glands
to prepare the body for fight or flight
c) raised blood sugar levels by stimulating the liver to
change glycogen into glucose
- binds receptors to the liver so it breaks down its glycogen stores to release glucose
- this increase blood glucose levels so there is more glucose in the blood to be transported to the cells
what is “fight or flight”
- adrenaline prepares body to either stand its ground in face of a threat or run away by activating processes that increase supply of oxygen and glucose to the cells
Explain how thyroxine controls metabolic rate as an
example of negative feedback
a) low levels of thyroxine stimulates production of TRH
in hypothalamus
hypothalamus (structure in brain) produces TRH
- lower means hypothalamus is stimulated to release TRH
low levels of thyroxine stimulates production of TRH
in hypothalamus
b) this causes release of TSH from the pituitary gland
- TRH stimulates pituitary gland to release TSH
low levels of thyroxine stimulates production of TRH
in hypothalamus
c) TSH acts on the thyroid to produce thyroxine
- TSH stimulates thyroid gland to release thyroxine
- so blood thyroxine levels rise back towards normal
Explain how thyroxine controls metabolic rate as an
example of negative feedback
d) when thyroxine levels are normal thyroxine inhibits
the release of TRH and the production of TSH
- when higher than normal the release of TRH is inhibited which reduces production of TSH so blood thyroxine levels fall
what is negative feedback on hormones
- body detects level of substance has gone above or below the normal level it triggers a response to bring the level back up to normal
Explain the interactions of oestrogen, progesterone, FSH
and LH in the control of the menstrual cycle
- FSH released by pituitary gland causes a follicles (egg and surrounding cells) to mature in one of the ovaries which stimulates oestrogen production
-oestrogen released by ovaries causes lining to thicken and grow and a high level stimulates and LH surge - LH released by pituitary gland, the surge stimulates ovulation at day 14 and the follicle release egg, stimulates the remains of the follicle to develops structure called corpus luteum which secrets progesterone
- progesterone released by corpus luteum after ovulation maintains lining of uterus, inhibits release of FSH and LH and when progesterone levels fall and there’s a low oestrogen level the uterus lining breaks down, low progesterone levels allows FSH to increase and cycle starts again
Describe the stages of the menstrual cycle, including the roles
of the hormones oestrogen and progesterone
- oestrogen repairs and thicken uterus lining and progesterone maintains uterus lining
1. lining of uterus breaks down
2. uterus lining is repaired
3. egg develops and is released from ovary (ovulation)
4. lining is maintained
Explain how hormonal contraception influences the menstrual
cycle and prevents pregnancy a) oestrogen
- prevents the release of an egg
- if taken every day to keep level of oestrogen permanently high it inhibits production of FSH
Explain how hormonal contraception influences the menstrual
cycle and prevents pregnancy b) progesterone
- reduces fertility
- stimulates production of thick cervical mucus which prevents sperm getting through uterus cervix and reaching egg
Explain how hormonal contraception influences the menstrual
cycle and prevents pregnancy c) oestrogen and progesterone
- combined pill and contraceptive patch
Evaluate hormonal and barrier methods of contraception
hormonal
-when used correctly hormonal methods are more effective at preventing barrier methods
- don’t have to stop and think about contraception
barrier
- protect against sexually transmitted infection (only condoms do this)
- hormonal methods can have side effects like headaches, acne and mood changes
Explain the use of hormones in Assisted Reproductive
Technology (ART) in clomifene therapy
- clomifene is used when women are infertile because they don’t ovulate or don’t ovulate regularly
- causes more FSH and LH to be released by the body which stimulates egg maturation and ovulation
- knowing when woman will be fertile couple can have intercourse during the time period
Explain the use of hormones in Assisted Reproductive
Technology (ART) in IVF
- IVF collects eggs and fertilises them in a lab
- ART is a fertility treatment where eggs are handled and fertilised outside the body
- once developed into embryos and the embryos are tiny balls of cells some of them are transferred to the woman’s uterus
- FSH and LH are given before egg collection, to stimulate egg production (so more than one egg can be collected)
