Nerve Flashcards
Whats the Sodium - potassium pump and what does it do?
Intrinsic protein
Actively transports potassium ions into the axon and sodium ions out of the axon
What does the phospholipid bi-layer prevent?
Sodium and potassium ions diffusing out
How many Na+ ions are actively transported out compared to K+ ions transported into the axon
3 Na+ for every 2 K+ ions
What’s it called when the action potential jumps form node to node in a myelinated sheath?
Saltatory conduction
What does the fatty sheath of myelin around the axon act as?
Electrical Insulator
What 3 factors affect the speed of an action potential?
Myelin sheath - saltatory conduction
Diameter of axon - greater diameter = greater speed of conductance as less ion leakage
Temperature - effects rate of diffusion as wells as enzymes used in active transport for sodium-potassium pump
What’s the refractory period?
Once an action potential has been created there is a period after when inward movement of sodium ions is prevented as sodium voltage channels are closed
During this time it is possible for further action potentials to be generated
What’s the all-or-nothing principle?
There is a certain level of stimulus called the Threshold Value which trigger an action potential. If this is not reached then no potential generated but any that does no matter how much above will generate only one action potential
What’s spatial summation?
A number of different presynaptic neurones together release enough neurotransmitter to exceed the threshold value of post synaptic neurone
What’s Temporal summation?
A single prestnaptic neurone releases neurotransmitter many times over a short period
What’s a cholinergic synapse?
One of which the neurotransmitter is a chemical called acetylcholine
Made from two parts: Acetyl and Choline
