BIO12 nerve impulses and synapses

Nerve impulse vs action potential

Nerve impulse is the spread of an action potential along dendrite or axon

Action potential is the movement of ions across the membrane

Why do Na diffuse along axon into the adjacent spot?

There is a charge attraction between Na and negative ions

Why does AP only spread one direction?

The previous section is still in the refractory period, actively resorting the rest conditions so the Na in that area will eventually be pumped out

Why can’t mylinated area undergo action potential

Myelinated region does not have a resting potential, bc myelin prevents anything outside form crossing the inside

What makes nodes of rancher so important?

Nodes can depolarize due to no layer

AP doesn’t need to spread all through the membrane, so 50x faster

Saltatory conduction

Jumping conduction from node to node

How are info passed by between neurons

Not physical contact!

Through synapses

Synapse

Region of communication between neurons or neuron-effector

Steps of synaptic transmission

1 Ca gate open bc of nerve impulse, Ca diffuse in

2 Ca cause contraction of micro tubules that pull vesicles in

3 vesicals contain neurotransmitters that leave presynaptic membrane

4 neurotransmitters bind to protein receptors on postsynaptic membrane

5 neurotransmitters are removed by reputable or enzymatic destruction to return to rest

What is a neurotransmitter

Chemical substance that can diffuse across synaptic cleft, via exocytosis in vesicles

1 kind of transmitter

Ach- acetylcholine

Why are mitochondria involved in synaptic transmission

Vesicles and contents continuously made, using a lot of ATP

Excitory effect

Slight depolarization due to Na diffusion

Inhibitory effect

Slight hyper-polarization due to K diffusion