homeostasis + the systems + thermo

What is homeostasis?

process of maintaining stable internal conditions despite changing conditions

Names + roles of components in automatic control systems (3)

• receptors - detect a change or stimuli

• coordination centres - interpret change + decide what needs to be done

• effectors - e.g muscles + glands carry out change

What does the nervous system do? (2)

• sends fast and precise electrical impulses via nerves

• allows us to respond quickly

What does the endocrine system do? (4)

• hormones in the bloodstream

• travel throughout whole body

• only affect certain cells with the right receptors

• slower, more long-lasting than the nervous system

Describe structure of nerve cell (neuron) + what they have adapted to do (4)

• adapted to carry electrical impulses from one point to another

• long, thin

• branches allow them to pass message

• connected by synapses

Describe synapses and what they do (4)

• connection between nerve cells

• electrical impulse causes release of chemicals

• chemicals diffuse across gap

• chemicals trigger another electrical impulse

How does the CNS (central nervous system) work? + what does it consist of?

• made of brain and spinal chord

• receptors all over body give sensory information to the brain

• impulses sent back to the body via motor neurons to effectors

What is a reflex arc?

The nerve pathway that underlies our unconscious reflexes

What is the role of a relay neuron?

transfer a signal from a sensory neuron to a motor neuron

Describe what happens when we are too cold (4)

• blood vessels constrict (vasoconstriction)

• so less blood flows near surface, so less heat lost to surroundings

• erector muscles contract so hair stands on end to trap a small layer of insulating air

• shivering (muscles contract + relax, requires a lot of energy from res, energy lost as heat)

Describe what happens when we are too hot (4)

• blood vessels expand (vasodilate)

• allows more thermal energy to be transferred to surroundings

• erector muscles relax

• sweat (takes thermal e away with it when it evaporates)

Why do we have to maintain our body temp at 37 degrees or any other homeostasis function?

optimise enzyme function and prevent damage

Describe what the pituitary gland/master gland is associated with (NOT PART OF THE BRAIN) (3)

• releases many hormones

• some tell the body what to do

• some tell other glands to release their own hormones e.g TSH to stimulate the thyroid to produce more thyroxine

Describe what the thyroid gland is associated with (3)

• produces thyroxine

• regulates rate of metabolism

• encourages growth and development

Describe what the adrenal gland is associated with (2)

• produces adrenaline (fight or flight response)

• increases heart rate, blood pressure increases, blood flow to muscles increases

Describe what the pancreas is associated with (2)

• produces insulin

• helps regulate blood glucose concentrations

How does the body respond to high glucose levels vs low glucose levels?

h: pancreas produces insulin, binds to receptors on certain cells, liver and muscle tissue take up extra glucose forming glycogen

l: pancreas produces glucagon, binds mainly to liver cells, breaks down glycogen into glucose

Type 1 diabetes + solution (4)

• occurs in childhood, lifelong

• pancreas stops/produces very little insulin

• nausea, could kill them

• s: inject insulin after a meal - amount of insulin needed depends on what they ate + how much exercise they do

Type 2 diabetes + solution (3)

• often happens in older people, long term unhealthy diet

• cells have become resistant to insulin

• s: healthy low sugar diet and regular exercise

3 internal conditions homeostasis regulates

• blood glucose

• body temp

• water levels