section 2 BMB

resting neuron is …

polarized, inside more negative than outside

diffusion

ions move from high to low concentration

Electrostatic pressure

Ions move towards oppo charge 

Selective Permeability 

membrane only lets certain ions in/out

ungated ion channels

always open

voltage gated channels

open/close in response to voltage channels

ligand - gated channels

open when a specific chemical binds

sodium - potassium pump

3 NA out, 2 K in

resting

all channels closed

threshold + depolarization 

Na open, K closed 

repolarization

Na closed, K opened

hyperpolarization

extra K leaves, membrane overshoots negative, K opened, Na closed

return to rest 

sodium potassium pump restores balance 

absolute refractory period

no new AP possible 

relative refractory period 

new AP possible, but hard 

saltatory conduction 

AP jumps from node to node (Nodes of Ranvier), Myelin allows faster conduction

EPSP

excitatory

IPSP

inhibitory

synaptic transmission

Ap reaches axon terminal, Ca channels open, synaptic vesicles fuse with membrane, NT binds to postsynaptic receptors, axon hillock determines if AP will fire

spatial summation

Inputs from different locations add up

temporal summation 

Inputs arriving close in time add up

terminating signal via degradation

enzyme breaks down the NT 

terminating signal via reuptake

NT is taken back into presynaptic terminal 

terminating signal via autoreceptors

NT binds back to presynaptic neuron to inhibit further release

Ligand

molecule that binds to receptor

Endogenous

Made in body

Exogenous

from outside body

Ionotropic vs Metabotropic Receptors

Ion faster acting

Glutamate

main excitatory

GABA

main inhibitory

Acetylcholine

learning, memory, muscle

Dopamine

reward, movement, motivation

norepinephrine 

alertness, mood

serotonin

mood, sleep, appetite

endogenous

pain, mood, pleasure

endocannabinoids

mood, appetite, pain

nitric oxide

retrograde signaling

excitatory

depolarize, increase chance of AP (glutamate)

Inhibitory

hyperpolarize, decrease chance of AP (GABA)

affinity 

strength of ligand - receptor binding 

axon hillock is the “ xx “

trigger zone

Nodes have ____ that ‘rejuvinate’ the AP 

sodium channels 

Neurophysiology is the

sudy of life processes of neurons.