ANATOMY LECTURE CRAM SHEET - MINOR TOPICS

what opens Na+VGCs

depolarization , they open fast

what stops the ap peak from rising

Na+ channel inactivation

what opens K+VGC

depolarization , they open slowly

what causes repolarization

K+ leaving the cell

what causes after-hyperpolarization

K+ channels stay open too long

why do graded potentials fade

leak channels & cytoplasmic resistance

why dont action potentials fade

they regenerate at each segment of the axon

what happens if extracellular K+ increases

RMP becomes less negative → neuron easier to reach threshold

what happens if extracellular Na+ increases

ap peak becomes slightly higher

what determines ESPS size

amount of NT released & number of receptors activated

how do EPSP and IPSP interact

they sum at the axon hillock , whichever dominates determines firing

what is the synaptic cleft

space where NT diffuses

how is NT removed from synapse; name 3

1. enzymatic breakdown

2. reuptake

3. diffusion

how does myelin save energy

fewer ions cross membrane → Na/K pumps work less

how does axon diameter affect speed

larger diameter = faster conduction

what happens during demyelination

ap slows or fails due to current leaking out

what determines ap frequency

strength of stimulus → size of graded potential → ap frequency

what opens LGC

NT binding

what opens VGC

changes in membrane voltage

what increases Ca2+ entry

higher ap frequency; Ca2+ entry is proportional to ap frequency