A01 CNS

Question 1

CNS

Answer 1

do

Question 2

dendrites function

Answer 2

attached to cell body, receives impulses from other neurones in order to trigger action potential within the neurone - electrical impuldr

Question 3

axon

Answer 3

also attached to cel body, extension of cell body, passes electrical impulses towards axon terminals

Question 4

myelin sheath

Answer 4

outside layer of the axon , full of fatty deposits providing an insulating layer for the axon to help speed up the rate of transmission

Question 5

axon terminals

Answer 5

pass nerve impulses from the neurone to other parts of the body it controls/ activates e.g. muscles, glands, other neurones

Question 6

terminal buttons

Answer 6

bulb shape structures which contain/ store tiny vessels containing NT’s for the next stage in the transmission

Question 7

types of neurones

Answer 7

motor neurones, transmit messages from brain to muscles

inter neurones- connect neurones to other neurones

sensory neurones- transmit messages from senses to brain

Question 8

how does the neurone work

Answer 8

action potential/ electrical impulses are created/ generated in the cell body, these impulses are then passed down through the axon as the myelin sheath increases the speed of transmission towards the synaptic terminals/ terminal buttons which are then triggered by the elctrical impulse to release the neurotransmitters- chemical messengers

Question 9

synaptic transmission

Answer 9

electrical impulses reach synaptic terminal triggering release of NT’s

once NT’s are released, burst open, from the synaptic terminals/ terminal buttons from the pre synaptic neuron, flood the synaptic cleft/ gap, they then travel towards the post synaptic neurone and bind to receptors.

the NT’s can only bind to specific receptors like a lock and key, once they have binded they may have an exhibitory ( dopamine) which speeds up firingof electrical impulses or inhibitory effect which slows down firing of electrical impulses ( seritonin ). once binded to correct receptor absorbed into neurone.

any receptors which aren’t taken up by the receptors are destroyed by enzymes in the synaptic cleft or reuptaken back into the presynaptic neurone and then destroyed by enzymes to shut down the neurone ready for another action potential.

Question 10

action potential

Answer 10

when neurones are at rest and not sending signals they are at -70 millivolts, and the outside of the neurone is positive, because neurones have an eletrical state they are called ions

when an external event/ stimulus stimulates the neurone, action potential occurs and positivly charged ions enter the neurone and negative neurones leave this is depolarisation which occurs at -55mv at this point the neurone opens up its ion channels to allow more positive neurons to enter- threshold level, if it doesnt rwach this level no action potential occurs

at 40mv electrical impulses fire along neurone to axon terminal
once finished
re
repolarisation -70mv sometimes goes past -70- hyper polarisation channels stay open too long
eventually back to -70mv
resting level