Nerves 3 Flashcards
What is the threshold potential?
About -55mV
What will happen when the membrane potential hits -55mV?
An action potential will be fired
What is a generator potential?
A graded potential occurring at sensory nerves
What is an EPSP?
A generator potential that will depolarise the cell
What is a IPSP?
A generator potential that will hyperpolarise the cell
What is the graded potential between a motor neurone and a muscle called?
End plate
What is the function of graded potentials?
To decide whether or not the stimulus is great enough for a response
4 examples of graded potentials
- Generator
- Post synaptic
- Endplate
- Pacemaker
4 key properties of graded potentials
- Excitatory
- Non-propegating
- Decremental
- Local
Why are graded potentials decremental?
The current leaks out of the cell as it travels down it
What is shown by the amplitude of a graded potential?
Signal intensity
How can graded potentials generate an IPSP?
- Opening Cl channels on the post synaptic neurone
How are fast IPSP’s generated?
- Opening ionotropic Cl channels
How are slow IPSP’s generated?
- By binding to g-protein coupled receptors that open potassium channels causing K to leave the cell
What 2 neurotransmitters will trigger an IPSP?
- Glycine
- GABA
How are fast EPSP’s generated?
- Opening Na/K channels
How are slow EPSP’s generated?
- Blocking potassium channels that cause potassium to leave the cell
What is meant by the fact that graded potentials can summate?
- Two excitatory/inhibitory signals can add to each other
What is temporal summation?
Input from the same stimulus add up to each other (turning on a tap, turning it off, then turning it back on again)
What is spatial summation?
2 different stimuli add to each other (turning on 2 taps at the same time)
What is synaptic integration?
- All inputs taken into consideration
- Action potential decided
Why do synapses nearer the axon hillock have a better chance of generating an AP?
- Decremental aspect
- Have to travel less distance so less signal is lost
- Axon hillock is what decided to fire an AP
