5.) Neurophysiology

Front 1

Concentration Gradients

Back 1

high concentration of substances diffuses to the low concentration to balance out

Front 2

Electrostatic pressure

Back 2

propensity of charged molecules or ions to move toward areas with opposite charge -- opposites attract and similar repel

Front 3

ion

Back 3

atom or molecule that has electric charge by gaining or lose electrons

anion: negatively charged ion
cation: positively charged ion

Front 4

resting potential

Back 4

neuron's resting potential: negatively charged, usually -60 milivolts BECAUSE:

- sodium ions (Na+)
- Potassium (K+)
- proteins (anions)

1. intracellular fluid negatively charged
2. K+ channels allow K+ cations to pass through membrane, eventually balance at -60 mV
3. some Na+ cations from extracellular fluid leak through membrane, but Na+ expelled by Na+/K+ pump (3 Na+ out for every 2 K+ in)

Front 5

hyperpolarizing

Back 5

cell becomes more negative

Front 6

depolarizing

Back 6

cell becomes more positive, closer to 0

Front 7

action potential

Back 7

after threshold has been reached, an all or none electrical charge is propogated down the axon

1. ntx results in slight positive charge which allows some voltage-gated Na+ channels to open (depolarizes)
2. if threshold reached, additional voltage-gated Na+ channels open, causing rapid change in charge to positive charge
3. Na+ channels slam shut and voltage-gated K+ channels open and now positive charges inside cell push K+ cations out of their membrane channels, returning cell to resting potential

Front 8

refractory states

Back 8

absolute refractory
- no amount of stimulation can induce action potential (happens first, immediately after action potential)

relative refractory
- very strong stimulation can induce another action potential (prior to return to resting potential)

Front 9

unmyelinated axon action potential

Back 9

slower. due to inactivation of channels behind action potential, doesn't allow it to back-propogate

Front 10

myelinated axon action potential

Back 10

saltatory conduction: nerve impulse jumps from node of ranvier to node of ranvier very rapidly

travels much faster

Front 11

EPSPs

Back 11

depolarizing potential in postsynaptic neuron that is caused by excitatory presynaptic inputs (opening voltage-gated Na+ channels in postsynaptic neuron)

Front 12

IPSPs

Back 12

hyperpolarizing potential in postsynaptic neuron that is caused by inhibitory presynaptic inputs (opening voltage-gated CI- chloride channels in postsynaptic neuron)

Front 13

spatial summation

Back 13

when EPSPs or IPSPs happen in DIFFERENT AREAS of the cell

2 presynaptic cells acting on same postsynaptic cell giving EPSPs/IPSPs at same time (along axon), they will summate and create an action potential

Front 14

temporal summation

Back 14

WHEN EPSPs or IPSPs happen quickly around same time

where an event happens in time repeatedly, one after another

if you have an ipsp and an epsp they will cancel each other out