week 4: neurobiology: action potential and autonomic nervous system Flashcards

1
Q

neurones at rest

A

transmembrane potential
outisde:
Na+ =150mM
K+ = 4mM

inside:
Na+= 15mM
K+= 140mM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

difference in inside and outside neurone concentrations at rest due to the

A

sodium potassium pump

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Sodium/ potassium ATP pump

A

uses energy from ATP
ATP>ADP
uses energy to pump Na ut and K in

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

why can sodium and K not cross membrane unless transported

A

charged ions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

inside of cell has very …. charge compared to outside

A

negative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

how can we measure potential difference between outside and inside of cell

A

using electrodes
can be inserted inside neurons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

resting potential of cell

A

-65mV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

electrochemical force

A

electrical driving force and chemical driving force combines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

electrical driving force of a neurone ???

A

inside of a cell is - and attracts +
+ > - ?????

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

chemical driving force of a neurone

A

conc gradient
high conc Na+ outside, low conc inside

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

equilibrium potential

A

membrane potential where electrical force is equal and opposite to the clinical force

can be worked out for any ion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

equilibrium potential

A

membrane potential of cell in which there is no movement of ions

eg
electrical force (driving in) = chemical force (driving out)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Nernst equation Ex=

A

(RT/zF) x (ln[X]o/[X]i)

R=gas constant
(8.314472 JK-1mol-1)
T= absolute temp
z= charge of ion
F= faradays constant
(9.6485309 X10^4 Cmol-1)
[X]o= conc of ion outside cell
[X]i = conc of ion inside cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

simplified Nernst equation
Ex=

A

58 x log ([X]O/[X]i)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

when does the simplified Nernst equation work

A

monocovalent cations at room temp

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

at equilibrium potential, electrical gradient =

A

same magnitude but in opposite direction to chemical gradient

17
Q

ligand gated ion channels

A

on post synaptic membrane
neurotransmitter binds to receptor
conformational change to receptor
ion channel opens
inside of cell becomes less negative

18
Q

are channels directional

A

no
electrochemical force of ion sets direction of travel

19
Q

acetylcholine binds to receptor on post synaptic membrane

A

channel opens
lots of Na+ enters
small amount of K+ leaves
depolarisation occurs ‘inside of cell becomes more +

20
Q

how are neurotransmitters released at a synaptic terminal

A

exocytosis

21
Q

AP 1 - neurotransmitters bind to cell

A

membrane depolarised

22
Q

AP 2- membrane depolarisation reaches threshold potential

A

voltage-gated Na+ open
large influx of Na+
overshoot: membrane potential becomes +

23
Q

AP 3- Na+ channels become deactivated…

A

voltage gated K+ channels open
K+ moves out of cell
repolarisation occurs

24
Q

AP 4- afterhyperpolarisation/ undershoot

A

resets using sodium-potassium ATP pump

25
absolute refractory period
time where cant inject more current and get a second AP sodium channels inactivated no ions can flow through even when they are open
26
relative refractory period
still possible to get a second AP larger stimulus can result in AP membrane potential is more negative than resting potential
27
what does the absolute refractory period ensure
action potential propagation is unidirectional
28
why does AP only propagate in one direction
sodium channels become inactivated after a while cant maintain depolarisation when inactivation is lost, membrane is repolarised so channel is no longer open
29
where are sodium and potassium channels present in myelinated neurones
at nodes of Ranvier
30
saltory conduction
action potentials jump from node to node
31
electrical synapses
no neurotransmitter release protein channels- gap junction channels couple cytoplasm of two cells allows ions and small molecules to flow through change in pre-synaptic neurone fed immediately through to post-synaptic neurone direct and quick signal trasmission
32
chemical synapses
use neurotransmitters most of synapses in brain