Action Potentials

Question 1

Why are AP’s imp for dentists

Answer 1

for local anaesthesia and pain etc

Question 2

what are the diffenret chemical singling of the body

Answer 2

short distance - synapse

long distance - hormones

Question 3

how fast is the chemical singling in the body

Answer 3

relatively slow

Question 4

what are the types of electrical signalling in the body

Answer 4

graded potentials

AP’s

Question 5

what are graded potentials

Answer 5

short distance
vary
fizzle out at nerve endings

Question 6

what are AP’s

Answer 6

long distance
all or none
fast 120m/s

Question 7

is the nerve membrane a good insulator

Answer 7

no poor as phospholipids are leaky and in aq enviro

Question 8

is the cytoplasm good conductor

Answer 8

no poor

Question 9

what happens to signals in nerves over 2-3mm and what is this due to

Answer 9

decays

due to high resistance and poor insulation

Question 10

what is used in nerves to help with propagations of signals

Answer 10

AP’s

Question 11

what is a resting mem pot

Answer 11

Separation of opposite charges across a membrane

Question 12

what causes a rest mem pot

Answer 12

perm of key ions
corn grad for key ions
gradients maintained by active transporters

Question 13

do all cells have rest me pot

Answer 13

yes

Question 14

what are excitable cells

Answer 14

nerve and muscle

Question 15

what are the extra/intracellular conc and relative perm of Na, K an anion

Answer 15

Na
extra - 150
intra - 15
RP - 1

K
extra - 5
intra - 150
RP - 25-30

anion
extra - 0
intra - 65
RP - 0

Question 16

roughly explain the Na/K pump

Answer 16

uses ATP
transports 3 Na out
2 K in
helps maintain conc grads

Question 17

si the mem perm or imperm to K

Answer 17

perm at rest

Question 18

what is the electrochem gradient for K

Answer 18

chemical - k out

electrical - protein anions cant flow out so k attracted in

Question 19

what is the nernst value for K equilibrium potential

Answer 19

-90mV

Question 20

what si the mem at rest like toward Na

Answer 20

much less perm to Na

Question 21

what si the nernst eon value for Na

Answer 21

+60mV

Question 22

how si the resting mem potential formed

Answer 22

due to effects of K and Na

ion with > perm drives mem potential

Question 23

at rest what is the RMP closer to

Answer 23

K equilibrium potential

Question 24

what is the RMP based on

Answer 24

based upon all ions in goldman eqn

Question 25

what is the importance of -50mV

Answer 25

threshold for AP all or none

Question 26

what is depolarisation

Answer 26

going upward more positive cause potential to go up sodium channels open

Question 27

what happens after depolarisation overshoot

Answer 27

K channels delay open and Na channels inactivate rapid depolarisation
K out

Question 28

what is hyperpolarsation

Answer 28

below threshold K channels close and N channels reset

Question 29

what is the hodgkins cycle

Answer 29

threshold depo
Na channels open 
increase na perm 
Na moves into cell 
Depo
N channel open

Question 30

how do ‘caine’ anaesthetics affect he hodgkins cycle

Answer 30

hold Na channels reversibly closed

Question 31

what is AP propagation

Answer 31

local current flow to adjacent area 
raise pot to threshold 
voltage gated N channel open 
poitve feedback 
porpaget along axon

Question 32

what si a refractory period

Answer 32

time when cannot reactivate a Na channel

Question 33

what are th two types of refractory period

Answer 33

absolute and relative

Question 34

what is an absolute refractory period

Answer 34

Na channels not in rest configuration

an AP can’t occur

Question 35

what is a relative refractory period

Answer 35

K gates open
mem is hyper polarised
an AP can occur need larger stimulus

Question 36

what does a refractory period do in terms of directions

Answer 36

means that nerve signals cannot backfire only propagated in one direction

Question 37

what does the width of an axon do to conduction velocity

Answer 37

increase axon diameter
lower resistance
faster conduction

Question 38

what does myelination do to conduction velocity

Answer 38

insulates
node ranvier jumps
local current flow node to node
depo jumps

Question 39

what re the types of nerve fibres

Answer 39

C
A delta
A beta
A alpha

Question 40

what does a C nerve do

Answer 40

slow burning pain
high resistance coz thin and non myelin
smallest nerve slow velocity

Question 41

what is a A delt nerve

Answer 41

faster sharp pain

myelin sheath so faster condition and is wider

Question 42

what is a A beta nerve

Answer 42

wider and myelinated

sensory ones, mechanoreceps

Question 43

what is a A alpha

Answer 43

biggest nerve
motor to muscles
widest and myelinated

Question 44

why rent all nerve A alpha

Answer 44

to big to fit in body need small to fit in places or would be huge

Question 45

what re incoming nerves

Answer 45

afferent from periphery to centre

Question 46

what are outgoing nerves

Answer 46

efferent from center to periphery

Question 47

what are the fastest nerves linked to

Answer 47

proprioception - knowing about self form and what body doing

Question 48

what is good to keep in mind about nerve size with dentistry

Answer 48

affects diff with LA

Question 49

what are the easiest yes of nerves to block

Answer 49

smallest most difficult widest

Question 50

what are he first type of nerves to be blocked

Answer 50

pain then touch