Psyc 4, Ch 4

1. Action Potential (Electrical) - generated with the cell body at the axon hillock

2. Chemical - the action potential ruptures the synaptic vesicles at the axon terminal and neurotransmitters spill out, cross the synaptic gap, and bind with receptors

3. Electrical - after neurons are locking into receptors, there is a flurry of activity in the post synaptic neuron; a week new electrical signal may be generated via ions

Most important: sodium, potasium, calcium, chloride

Polarized - in a resting state a neuron's interior has a slightly negative charge; outside the neuron has a slightly positive charge

Depolarized - ions flow in and out of neurons through inon gates, which are unlocked by receptors; when the firing threshold (critical number of positive ions) is reached, a new action potential is generated

Hyperpolarized - inhibitory neurons bind with receptors to stop the neuron from firing; negative ion flow in and positive ions flow out

When a neurotransmitter's work is done, it is released and returns to the synpatic gap; it must then be inactivated to prevent it from continuing its work

There are four methods...

Neurotransmitter drifts out of the gap where it can not longer activate neurons

Astrocytes mop-up the neurotrasmitters from the gap

The neurotransmitter is transported back to the axon terminal and:

• a. repackaged
• b. degraded by enzymes into its basic parts
• c. used to make new neurotrasmitters

Enzymes in the synpatic gap degrade the neurotrasmitter so it is no longer recognized by the receptor