biology 5
what is homeostasis?
the regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes
name 3 things that are controlled by homeostasis
blood glucose concentration, body temperature and water levels
what do all control systems include?
receptors, effectors and coodination centres
name an example of a receptor
specialised cells
name examples of coordination centres
brain, spinal cord, pancreas
name examples of effectors
muscles, glands
what do receptors do?
detect stimuli
what do coordination centres do?
recieve and process information
what do effectors do?
bring responses to restore optimum levels
what is the order of the nervous system?
stimulus, receptor, sensory neurone, relay neurone, motor neurone, effector, response
what is the role of the nervous sytem?
to react to the surroundings and to coordinate our behaviour
what does cns stand for?
central nervous system
which two organs make up the cns?
brain and spinal cord
what is the function of the nerve cell?
to carry electrical impulses rapidly around the body
name some parts of the nerve cell (revise where these are)
cell body, dendrites, myelingheath, axon, synapse, nucleus
what is the function of dendrites?
it can make lots of connections to other nerve cells
name two functions of the axon
its very long to carry the nerve impulse a long way and its insulated so the impulses travel rapidly
why does the cell body have lots of mitochondria?
to transfer the energy needed to make transmitter chemicals
why are reflexes important?
reflexes happen rapidly and automatically you dont have to think about them. this helps you to avoid danger/harm. bodily functions like breathing and food digestion happen via reflexes
what is the first step of the reflex arc?
the receptor is stimulated
what is the second step of the reflex arc?
an electrical impulse travels along the sendory neurone to the cns
what is the third step of the reflex arc?
at the synapse a chemical is released, it diffuses across the synapse
what is the fourth step of the reflex arc?
an electrical impulse is triggered in the relay neurone
what is the fifth step of the reflex arc?
when the impulse reaches the next synapse, a chemical is released which travels across the synapse
what is the sixth step of the reflex arc?
an electrical impulse is triggered in the motor neurone
what is seventh step of the reflex arc?
the impulse reaches the effector which is stimulated to respond
what are all the parts of the reflex arc (revise where they are)
receptor, effector, sensory neurone, motor neurone, relay neurone, synapse, spinal cord
describe the endocrine system
the endocrine system produces a chemical responce to a stimulus. the glands of the endocrine system secrete hormones into the blood stream. the blood carries hormones to target organs which have receptors to pick up the hormone. hormonal effects are slower than the nervous system but last for longer
name the main endocrine glands
pituitary, thyroid, adrenal, pancreas, ovaries, testes
how does insulin control blood glucose levels?
glucose is taken in by cells, glucose is converted to glycogen in the liver and muscles, blood glucose falls, normal level of blood glucose, pancreas, insulin released
what causes type 1 diabetes?
the pancreas does not make enough insulin, so blood glucose isnt controlled and it gets very high after eating a meal
when does type 1 diabetes usually start?
in children and teenagers
how is type 1 diabetes treated?
with insulin injections
what causes type 2 diabetes?
the cells in the body no longer respond to the insulin that is produced by the pancreas
what are the risk factors for type 2 diabetes?
obesity and lack of exercise
how is type 2 diabetes treated?
a carbohydrate controlled diet and an exercise routine
what will happen to someone who has diabetes after they eat?
their blood glucose concentration rises high after they have a meal
what is the main reproductive hormone in the female?
oestrogen
what is ovulation?
when a mature egg is released from an ovary
what is the main reproductive hormone in the male?
testosterone
what does testosterone do?
stimulates sperm production
what does fsh stand for?
follicle stimulating hormone
what does lh stand for?
luteinising hormone
what do fsh do?
causes maturation of an egg in the ovary
what does lh do?
stimulates the release of an egg
what does oestrogen and progesterone do?
maintains the uterus lining
how does oral contraceptive work?
contains hormones that inhibit fsh production so that no eggs mature
how do barrier methods work?
prevents the sperm from reaching en egg
how does abstinence work?
avoids intercourse when an egg might be in the oviduct
how do surgical methods work?
sterilise the male or female by cutting or tying tubes to prevent the egg or sperm reaching their target area
how do intrauterine devices work?
prevent the implantation of the embryo or releases a hormone
how does progesterone work?
inhibits the maturation and release for a number of months or years
how do spermicidal agents work?
kill or disable sperm
what are nerve cells?
nerve cells are called neurones. they are adapted to carry electrical impulses from one place to another , a bundle of neurones is called a nerve
where is the pituitary gland?
at the base of the brain below your hypothalamus
where is the thyroid gland?
in the front of the neck and above the collarbones
where is the adrenal gland?
on top of each kidney
where is the pancreas?
high up in your abdomen
what hormones does the pituitary gland release?
fsh and lh
what hormone does the thyroid gland release?
thyroxine
what is the synapse?
the junction between neurones. chemicals called neurotransmitters diffuse across the synapse
what is the dendron?
tiny branches that recieve impulses from other neurones