ANATOMY LECTURE CRAM SHEET

what does RMP stand for

resting membrane potential

mV for RMP

-70 mV

why is RMP=-70mV negative ; give 3 reasons

1. leaky K+ channel

2. Na+/K+ pump

3. negatively charged proteins inside

mV for threshold

-55mV (approx)

what does AP stand for & what is it

action potential ; Na+ in, K+ out

where does graded (ligated) & action potential (voltage - Na & K) occur

graded : dendrites & soma

action : axon & axon hillocks

where does (voltage - Ca2+) occur

axon terminal

what happens during absolute refractory period ; name 2

1. Na+ channels are inactivated

2. No second AP is possible

what happens during relative refractory period ; name 3

1. Na+ channels reset

2. Membrane hyperpolarized

3. Stronger stimulus needed

differentiate the 3 fibers ; A, B, C

A. fastest , heaviest myelination, large

B. medium, light myelination, medium

C. slowest, no myelination, small

low Ca2+ =

no Ca2+ =

Mg2+ blocks Ca2+ channels =

= less NT release

= zero NT release

= less NT release

define depolarization ; 3 things

1. ESPS

2. Na+ or Ca2+ enters

3. moves towards threshold

define hyperpolarization ; 3 things

1. ISPS

2. K+ leaves OR Cl- enters

3. moves away from threshold

1 things TTX and lidocaine have in common and differ from

common: blocks Na+ VGC

differ: TTX irreversible , lidocaine reversible

define graded potential ; name 2

1. size varies with distance

2. decremental (fades w/ distance)

define action potential ; name 2

1. all-or-nothing

2. same size everytime , doesn’t fade

what is temporal summation

same neurons firing repetitively ; ESPS adds over time

what is spatial summation

multiple neurons firing at once ; ESPS adds together

how do ESPS & ISPS interact (at the axon hillocks)

they combine, if depolarization reaches threshold action potential fires

what is saltatory conduction

action potential ‘jumps’ from node to node along a myelinated axon

where are Na+ channels concentrated on a myelinated axon

nodes de ranvier

list the 7 steps of synaptic transmission

1. action potential arrives at terminal

2. Ca2+VGCs open

3. Ca2+ enters

4. vesicles fuse

5. NT released

6. NT binds receptors

7. graded potential

what triggers NT release

Ca2+ entering axon terminal

what do Na+ channel blockers do (TTX/lidocaine)

block action potential propagation → flaccid paralysis

what do AChE inhibitors cause

prevent ACh breakdown → spastic paralysis

what does botulinum toxin block

vesicle fusion → no NT release → flaccid paralysis

what toxins cause flaccid vs spastic paralysis

flaccid: TTX, lidocaine, botulinum

spastic: AChE inhibitors

difference between flaccid & spastic paralysis

flaccid: muscles go limp

spastic: muscles go stiff