c2.2 neural signalling Flashcards
neurone
cell within the nervous system that carry electrical impulses
sensory neurone function
- sense stimuli
- send to spine
sensory neurone shape
cell body at the end
relay neurone function
travel
motor neurone function
move
what allows electrical impulses to be faster
myelin sheath
how does myelin sheath allow electrical impulses to be faster
reduce distance electrical impulse has to travel so the speed is much faster
location of the myelin sheath
layers surrounding the axon
how is an impulse generated + how does it travel [3]
- part of axon going thru action potential, the rest is at resting potential
- electrical impulse will cause resting potential to turn into action potential
- the action potential will trigger a new action potential in the adjacent section of the axon in one direction
- previous part of action potential will go back to resting
why cant the electrical impulse go back
-80mV too negative so sodium voltage gated channel cant open
synapse
junction between 2 neurones in the nervous system
what can synapse be in between [2]
- between sensory receptor cells and neurones
- between neurones and muscle fibre or glands
acetylcholine released by + function
being released by motor neurones to control muscle contraction
what happens to acetylcholine once it activates the action potential
recycled and broken down
what happens if acetylcholine is not broken down
muscle spasms
characteristic of acetylcholine
can bind to completely different receptors
why can acetylcholine bind to 2 completely different receptors
made up of 2 parts: acetyl CoA and choline
- so head and tail are diff shapes
enzyme that breaks down acetylcholine
acetylcholinesterase
why does the electrical current only go one way during depolarisation
the one before is at hyperpolarisation (-80mV) but the one next is at -70 mV so its easier to get the -70mV up to action potential
what is depolarisation caused by
sodium ions rushing in
what is repolarisation caused by
potassium ions rushing out
what is the node of revere
gaps between the myelin sheath
why are gaps between the myelin sheath needed
insulation prevent ions movement
how do gaps between the myelin sheath cause the distance travelled reduced
reduces ion exchange so ion exchange only happens at the nodes and less energy is required
exogenous chemical
enters the body of an organism from an outside source
eg. through the skin, lungs, gut
function of neonicotinoids
blocks synaptic transmission
how does neonicotinoids block synaptic transmission
binds to the acetylcholine receptor in the cholinergic synapses in the central nervous system of insects
why is the binding of neonicotinoids to cholinergic synapses irreversible
acetylcholinesterase doesnt break down neonicotinoids
how does neonicotinoids cause death to an insect
blocks their receptors bc binding between neonicotinoids to cholinergic synapses are irreversible
why doesnt neonicotinoids affect humans [2]
- fewer receptors
- binding not as strong
function of cocaine
promotes synaptic transmission
role of cocaine
acts at synapses that use dopamine as neurotransmitter
mechanism of cocaine
- binds to dopamine reuptake transporters in the presynaptic neurone
- dopamine builds up in the synaptic gap → postsynaptic neurone is continuously excited
what are dopamine reuptake transporters
membrane proteins that pump dopamine back into the presynaptic neurone
temporal summation
multiple firing form one input
why is temporal summation needed
might have to fire more than once to hit the threshold
spacial summation
all or nothing
- add all five synaptic neurone then decides activity
2 types of spacial summation
- excitatory
- inhibitory
excitatory neurotransmitters function
excites post-synaptic neurone to cause depolarisation
excitatory neurotransmitters summation
leads to EPSPs (excitatory post-synaptic potentials)
inhibitory neurotransmitters function
inhibits post-synaptic neurones by causing hyperpolarisation
inhibitory neurotransmitters summation
leads to IPSPs (inhibitory post-synaptic potentials)
inhibitory neurotransmitters egs
anaesthesia
mechanism for perception of pain [2]
- free nerve endings in the skin have channels for positively charged ions that respond to stimuli
- entry of positively charged ions will cause threshold potential to be reached and the nerve impulse will be passed to the brain and perceived as pain
consciousness
property that emerges from the interaction of individual neurones in the brain
consequences of interaction eg
emergent properties- consciousness
