Physiology Week 3 Study Set

Natural movement of ions are controlled/blocked where?

at the cell membrane

Channels

regulate water flow and solutes through membrane

some are gated (depends on electrical voltage)

Pumps

proteins along the cell membrane

pump 3 Na+ out for every 2 K+ ions in to maintain electrical disequilibrium

Resting Potential

prepares the cell to respond very rapidly to input

Action Potential

After a quick, significant change in membrane potential from resting, an electrical message sent through axon potentials initiate just after the axon hillock

Depolarization

inside the cell becomes less negative/more positive

Hyperpolarization

inside the cell becomes even more negative

Threshold

the voltage (mV) depolarization must reach for an action potential to occur

Threshold for neurons

-55 mV

Absolute Refractory Phase

no additional action potentials can be produced

Stimuli that happen too close together won't trigger a new response

Relative Refractory Phase

the phase when after an action potential when a neuron can fire another signal but only if the stimulus is stronger than usual

Saltatory Conduction

the action potential "jumping" from node to node in the axon

Reuptake

NTs absorbed back into the presynaptic axon terminal for recycling

Degradation

rapid breakdown and inactivation of NT in synaptic gap by enzymes

Graded Potentials

changes to postsynaptic cell after a successful action potential in the presynaptic cell

GP: Excitatory postsynaptic potential (EPSP)

partial depolarization of the postsynaptic cell, the postsynaptic neuron brought closer to threshold

GP: Inhibitory postsynaptic potenial (IPSP)

partial hyper polarization of postsynaptic cell, postsynaptic neuron brought further away from threshold

Spatial summation

Multiple EPSPs firing at different locations on the postsynaptic nerve combine to inhibit action potential

Temporal summation

cumulative effect of repeated stimuli within a brief time