session 3 Flashcards
synapses
microscopic spaces between communicating neurons
Charles Sherrington
inferred that synapses must exist by studying the reflex arc in dogs (how long it took for their leg to react)
Temporal Summation
one light pinch would not elicit a reflex, but several lights pinches in a row would be enough stimulation
Spatial summation
two light pinches at the same time in a nearby location will work also
Excitatory post-synaptic potentials (EPSPs)
small depolarizations that were not enough to bring the neurons to threshold
Inhibitory post-synaptic potentials (IPSPs)
small hyperpolarization’s that move a neuron slightly farther away from firing
Step 1: In Neurotransmitter action
neurotransmitters are synthesized in the cell body or near the synapse
-made from amino acids (which we receive from our diet)
-primarily influences by genetics
Step 2 & 3 of Neurotransmitter action
stored in vesicles, neurotransmitters outside of vesicles are recycled by enzymes
-package them for “delivery”, preparing them to be “shipped” to the pos-synaptic neuron
-primarily influenced by genetics
Reuptake
neurotransmitters will come back into the presynaptic neuron after they’re released but they will be broken down because they’ve left the vesicle
Step 4: Neurotransmitter action
where action potentials cause neurotransmitter release
-can be modified by psychoactive drugs
Exocytosis
where action potentials cause an influx of calcium at the axon terminal, then prompt the vesicles to dump their neurotransmitters
Step 6
neurotransmitters move across the synapse and bind with the postsynaptic receptor, causing either depolarization or hyperpolarization
Step 5
Negative feedback:
some neurotransmitters bind with the neuron they just came out of, their job is to stop the neuron from releasing more neurotransmitters
Step 7
neurotransmitters are inactivated, either broken down enzymatically or go through reuptake
