Neuronal Signalling

Question 1

In excitable cells, ____ are usually used for ‘‘signalling’’ changes

Answer 1

Ions

Question 2

In muscle cells
____ mV means the cell wants to contract

____ mV means the cell wants to relax

Answer 2

+20mV means the cell wants to contract

-90mV means the cell wants to relax

Question 3

Define Voltage

Answer 3

The difference in electric potential energy between two points.

In physiology, difference in potential energy across a membrane

Question 4

Define Current

Answer 4

A flow of electric charge through a medium

Question 5

Define Resistance

Answer 5

The measure of opposition to the passage of electric current

Question 6

Define Conductance

Answer 6

The measure of how easily electric current flows long a certain path

Question 7

What is Transmembrane potential(Vm)

Answer 7

It is the measurement of voltage (electrical potential energy) across a membrane

Question 8

Transmembrane potential(Vm) depends on 2 things. List them.

Remember V=IR

Answer 8

1. Electrical current flow

2. Resistance/conductance

Question 9

Fully permeable membrane occurs in _______ . Resistance is __, So transmembrane potential (Vm) is __.

Answer 9

Fully permeable membrane occurs in DEATH. Resistance is 0, so transmembrane potential (Vm) is 0.

Question 10

The preference of Na+ channels for conducting only Na+ ions, likewise for K+ ion channels with K+ ions only is called

Answer 10

Specificity/Selectivity

Question 11

How is a positive membrane potential generated

Answer 11

Sodium ion channels open, sodium ion moves into the cell. The cell becomes positive = membrane voltage is postive

Question 12

How is a negative membrane potential generated

Answer 12

Potassium ion channels open. potassium ions move out of the cell down its concentration gradient. The cell becomes negative = membrane voltage is negative

Question 13

What is Equilibrium potential

Answer 13

Each ion has an Equilibrium potential. It is an ion’s preferred voltage.

Question 14

Outline the Equilibrium potential of Na, K, Ca, and Cl

Answer 14

Ca = +123mV
Na = +60mV
Cl = -40mV
K = -90mV

a CAt is as easy as 1-2-3
a NAg counts 60 seconds
a fight CLub has 40 people
a King will die at 90

1st 2 are +ve
Last 2 are -ve

Question 15

If Na+ channels only are open, the membrane potential will go to ___

Answer 15

+60mV

Question 16

If K+ ion channels only are open, the membrane potential will go to ____

Answer 16

-90mV

Question 17

if both Na+ ion channel and K+ ion channels are open and they are equally permeable. The membrane potential will go to ____

Answer 17

-15mV.
The average of both Na+ and K+ equilibrium potential.

+60 + -90 = -30
-30/2 = -15mV

Question 18

Which ion are membrane more permeable to at rest ?

Answer 18

K+ ions.

That is why at rest, the membrane potential is negative.
-90mv for muscle cells
and -70mV for neuron cells

Question 19

At rest, what is the membrane potential value of a neuron

Answer 19

-70mV

Question 20

During an action potential, the cells become more permeable to which 2 ions

Answer 20

1. Na+ ions

2. Ca2+ ions

Question 21

During an action potential, the membrane potential increases to ____

Answer 21

+40mV

Question 22

When the membrane potential of a neurone cell goes pass its threshold voltage (-50mV), the cell is committed to ___ or ____ action potential. This is a ________ ________ _____

Answer 22

When the membrane potential of a neurone cell goes pass its threshold voltage (-50mV), the cell is committed to ALL or NONE action potential. This is a POSTIVE FEEDBACK LOOP.

Question 23

There has to be a delay in when the Na+ channel opens and when the K+ channel opens for an Action Potential to be generated. True or False

Answer 23

True

Question 24

In the refractory period, new A.P can be initiated. True or False

Answer 24

False

Question 25

During Hyper-polarisation. membrane potential moves closer to the equilibrium potential of K+ (-90mV). True or False

Answer 25

True

Question 26

Action Potential leads to _______ in calcium ions which can lead to either ________ _________or ________ __________

Answer 26

Action Potential leads to INCREASE in calcium ions which can lead to either SYNAPTIC TRANSMISSION or MUSCLE CONTRACTION

Question 27

What is a Neurotransmitter

Answer 27

An endogenous chemical released by neurones that travels across a synapse to a neuron/myocyte/endocrine cell. Used as a signal/messenger.

Question 28

Name an example of a Neurotransmitter family. Giving 3 examples of the family type

Answer 28

``` Neurotransmitter family: Catecholamines Example: 1. Dopamine 2. Noradrenaline 3. Adrenaline ```

Question 29

List 2 places neurotransmitters are synthesized ?

Answer 29

1. Soma of the neuron | 2. Axon terminal

Question 30

Depolarisation of pre-synaptic bouton causes __________ which leads to ____________ from vesicles that are fused to presynaptic membrane

Answer 30

Depolarisation of pre-synaptic bouton causes RELEASE OF CA2+ ions into synaptic cleft, which leads to SECRETION OF NEUROTRANSMITTER from vesicles that are fused to presynaptic membrane

Question 31

Transfer of neurotransmitter across synapse to post-synaptic neuron can cause the cell to depolarise and start an A.P, this is know as _______ inputs. Some receptors do the opposite and prevent the post-synaptic cell from having an A.P. This is known as _________ inputs.

Answer 31

Transfer of neurotransmitter across synapse to post-synaptic neuron can cause the cell to depolarise and start an A.P, this is know as EXCITORY inputs. Some receptors do the opposite and prevent the post-synaptic cell from having an A.P. This is known as INHIBITORY inputs.

Question 32

Neurotransmitters can be metabolised or recycled after its use at the post-synaptic neuron. True or False

Answer 32

True