B11 Hormones and response Flashcards
What are hormones?
- Chemical molecules released into the blood
- Only affect target organs
What do hormones control?
- Things which need constant adjustment
What are the effects of hormones?
long lasting
What does the pituitary gland produce?
- Many hormones
- releases hormones to act on other glands
What do ovaries produce?
oestrogen for the menstrual cycle
What do the testes produce?
testosterone to control puberty and sperm production
What does the thyroid produce?
thyroxine which regulates:
- the rate of metabolism
- heart rate
- temperature
what does the adrenal gland produce?
adrenaline for ‘fight or flight’
what does the pancreas produce?
insulin to regulate blood sugar levels
what is the endocrine system?
it consists of a number of gland which secrete hormones directly into the bloodstream
what are some differences between the nervous system and the endocrine system?
- nervous system uses electrical impulses that travel down neurones while the endocrine system uses hormones in the bloodstream
- nervous system’s signals are very fast, endocrine system has a more long lasting and slower effect
where are the adrenal glands?
above the kidneys
what does insulin do?
trigger body cells to take up glucose from the blood
it also triggers the liver and muscle cells to store excess glucose as the molecule glycogen
what happens when someone has type 1 diabetes?
the pancreas does not produce enough insulin
what happens to someone that has type 2 diabetes?
the body cells stop responding to insulin produced by the pancreas
what can be used to treat type 1 diabetes?
patients can inject themselves with insulin after meals
what can be used to regulate type 2 diabetes?
a carbohydrate controlled diet
exercise regularly
what is a risk of diabetes?
obesity
what happens when the blood glucose levels fall?
the hormone glucagon is released into the blood stream
what does glucagon trigger?
it triggers liver cells to convert glycogen stores back into glucose which is then released into the blood
why do insulin and glucagon form a negative feedback cycle?
they have opposite effects on blood glucose levels
what is ovulation?
when an egg is released from the ovaries
what are the stages of the menstrual cycle?
an egg is released, and the uterus’ lining grows
egg then reaches the uterus
(if sperm is present the egg is fertilised and implants into the lining)
the egg and uterus lining are released
what is the function of FSH?
it causes the egg to be fertilised in the ovary
what does LH do?
causes ovulation
what do oestrogen and progesterone do?
they are involved in maintaining the uterus lining in case the egg is fertilised
when is FSH released?
at the beginning of the cycle
what does FSH trigger?
the egg to mature
the ovaries to produce oestrogen
what does oestrogen trigger?
the lining of the uterus to become thick
the pituitary gland to stop producing FSH
when is LH produced?
when the production of FSH is stopped
when is progesterone produced?
once the egg has been released?
what does progesterone trigger?
stops the pituitary gland producing LH and FSH to stop any more eggs being released
keeps the uterus lining thick in case the egg is fertilised
what is the main effect of adrenaline?
heart rate increases
this causes more oxygen and glucose to be delivered to the brain and muscles
what effect does thyroxine have?
it stimulates the body’s basal metabolic rate
it plays an important role in growth and development
how is the levels of thyroxine regulated?
the levels of thyroxine are monitored by the brain
if the levels of thyroxine fall too low, the pituitary gland releases TSH which stimulates the thyroid to produce more thyroxine
the brain now detects the increase in thyroxine and prevents the pituitary gland from releasing more TSH
as the levels of TSH falls, the thyroid releases less thyroxine
what is phototropism?
when plants grow towards the light
what is auxin?
a plant hormone found in the tip of the shoots which triggers growth
how do plants grow towards light?
light causes auxin to concentrate on the dark side of the shoot
auxin now spreads down the dark side of the shoot, causing the cells on that side to grow faster than the cells on the light side
this causes the shoot to grow towards the light
what is gravitropism/geotropism?
when plant roots grow towards the force of gravity
how does gravitropism work?
gravity causes auxin to concentrate on the lower side of a root
in roots, auxin inhibits cell growth so the lower side grows slower than the upper side
this causes the roots to grow towards the force of gravity
what are giberellins?
hormones which start the germination of seeds
what does ethene do?
control cell division and the ripening of fruits
what are the variables when investigating the effect of light intensity on plants?
independent - light intensity
dependent - height of seedlings
control - amount of water, type of seed, amount of seedlings
what are the uses of auxins?
weedkillers
rooting powders
promoting growth in tissue cultures
what are the uses of giberellins?
ending seed dormancy
encourages plants to flower
make fruit grow larger
what is ethene used for?
trigger fruits to ripen
what is contraception?
ways to prevent fertilisation
what do oral contraceptives do?
they contain hormones that prevent the body from producing FSH
what are the advantages and disadvantages of the pill?
highly effective if taken correctly
it must be taken every day
risk of side effects
does not protect against STIs
what do hormone injections, patches and implants have in them and what does it to?
the hormone progesterone
this stops the eggs from maturing and being released
what are the advantages and disadvantages to hormonal patches, injections and implants?
more convenient than pills
side effects
do not protect against STIs
what are some barrier methods to contraception?
condom or diaphragm
what are the advantages and disadvantages of contraception?
does not involve hormones so no side effects
condoms can reduce risk of STIs
can break or slip off
more effective if used with a spermicide gel
what does an IUD or coil do?
prevent an embryo from implanting
some also release hormones to reduce the chances of fertilisation
what are the advantages and disadvantages of an IUD?
few side effects
effective for a long time
do not protect from STIs
what are the advantages and disadvantages of sterilisation?
highly effective
difficult to reverse
do not protect against STIs
what is a natural form of contraception?
abstaining during ovulation
what is the issue with natural contraception?
it is difficult to tell when the woman has ovulated
what is a ‘fertility drug’?
when a woman is given FSH and LH to help with infertility
it causes a woman to ovulate more so increases her chances of becoming pregnant
what is IVF?
when fertilisation takes place outside the body
how does IVF work?
the woman is given LH and FSH to mature several eggs
they are then fertilised in the lab with sperm that has been collected
the fertilised egg then forms an embryo and is implanted into the mother’s womb
what are the issues with IVF?
the success rates are not high
it is stressful for the parents - physically demanding on the mother
can lead to multiple babies
expensive
what can be unethical about IVF?
not all embryos will be implanted in the mother
this means many have to be destroyed
