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Introduction to Neuroscience > Lesson Three > Flashcards

Lesson Three Flashcards

Neurophysiology: Generation, Transmission and Integration of Neural Signals (88 cards)

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1
Q

Which of the following sentence is correct:
a. Each proton has an electron
b. Each proton has one positive electrical charge
c. Each proton has one negative electrical charge
d. Each electron has one positive electrical charge

A

b. Each proton has one positive electrical charge

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2
Q

The period immediately after an AP during which another AP cannot be elicited is called:
a. Transmission
b. Action Potential
c. Refractory period
d. Depolarisation

A

c. Refractory period

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3
Q

Which ions are in charge of generating action potential?
a. Chloride
b. Protein
c. Sodium
d. Potassium

A

c. Sodium

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4
Q

In neurotransmission, intensity is coded by:
a. Intensity of action potentials
b. Frequency of action potentials
c. Strength of action potentials
d. Localisation of action potentials

A

b. Frequency of action potentials

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5
Q

Neurons transmits signals by the flow of:
a. Dendrites
b. Hormones
c. Cells
d. Ions

A

d. Ions

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6
Q

The imbalance of electrical charge that exists between the interior of electrically excitable neurons and their surroundings is defined as:
a. Sodium-Potassium pump
b. Resting membrane potential
c. Nerve transmission
d. Action potential

A

b. Resting membrane potential

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7
Q

The magnitude of an action potential is
a. Fixed
b. Stronger with time
c. Variable
d. Lower than a synapse

A

a. Fixed

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8
Q

The movement of particles from high to low concentration is called:
a. Synapse
b. Action potential
c. Balancing
d. Diffusion

A

d. Diffusion

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9
Q

The neuronal cell mebrane is:
a. Transpirant
b. Permeable
c. Impermeable
d. Semipermeable

A

d. Semipermeable

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10
Q

Which sentence is NOT correct:
a. The action potential is ‘all-or-none’
b. The action potential is a rapid depolarisation of the membrane.
c. The action potential is stronger is there are more ions
d. The action potential is always the same size

A

c. The action potential is stronger is there are more ions

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11
Q

What do atoms consist of?

A

Nucleus - protons and neurons
Orbited by electrons

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12
Q

Are the charges of protons and electrons positive or negative?

A

Protons - Posotive
Electrons - Negative

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13
Q

Are the number of protons and electrons equal or unequal?

A

Equal

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14
Q

How are atoms held together?

A

Electrostatic force

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15
Q

Explain the relationship of attraction between opposite charges and same charges:

A

Opposite charges attract
Same charges repel

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16
Q

What is the net charge of an atom and why?

A

0 as positive and negative charges cancel each other out

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17
Q

What is an ion?

A

An atom or molecule with a net electrical charge

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18
Q

What is a cation?

A

A positively charged ion - ion has lost an electron

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19
Q

What is an anion?

A

An ion with a negative charged - has gained an electron

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20
Q

Ions are cruicial for neuron signalling - true or false?

A

True

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21
Q

What ions are involved in neural signalling?

A

Sodium - Na+
Potassium - k+
Calcium - Ca2+

Chloride - Cl-
Proteins - An-

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22
Q

What is the purpose of sodium Na+ in neural signalling?

A

Generates action potentials

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23
Q

What is the purpose of Potassium K+ in neural signalling?

A

Maintains resting potential

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24
Q

What is the purpose of calcium Ca2+ in neural signalling?

A

Synaptic transmission

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25
What is the purpose of chloride Cl- in neural signalling?
Suppresses Action Potentials
26
What is the purpose of proteins An- in neural signalling?
Maintaining resting potentials
27
What is diffusion?
The movement of particles (atoms, ions, molecules) in a gas or liquid from an area of high concentration to an area of low concentration
28
What is viscosity?
The difficulty in particles traveling through a medium
29
What effects the speed of diffusion
Particle size, temperature and the difficulty in traveling through a liquid
30
What is the cellular membrane also known as?
The plasma membrane
31
Is the cellular membrane perimeable or semipermeable?
Semipermeable
32
What is the purpose of the cellular membrane?
Separates and protects the inside of the cell from the outside enviroment
33
What is the membrane made up of?
Fluid lipid barrier and proteins
34
What is the membrane critical for?
The structure and function of cells
35
Are lipid heads and fatty acid tails hydrophilic or hydrophobic?
Lipid heads - hydrophilic - love water Fatty acid tails - hydrophobic - hate water
36
Is diffusion passive or active transport?
Passive
37
What is the difference between a semipermeable and permeable membrane?
A semipermeable membrane only allows some substances to cross - a fully permeable membrane allows all molecules through
38
What ions is the cellular membrane highly permeable too and what ions is it slightly permeable too?
Highly permeable - Potassium Ions - K+ Slightly permeable - Chloride Ions - Cl- and Sodium Ions - Na+
39
What are pores on a cellular membrane?
Ion channels - made up of large proteins and allow certain ions to pass through the membrane
40
What is the membrane potential?
The voltage difference across the neuron’s cell membrane
41
What is the typical range of the membrane potential?
-40 to -90 millivolts (mV)
42
How is the membrane potential generated?
By an unequal distribution of charged ions across the cell membrane - specifically sodium, potassium and chlorine
43
What two factors result in the membrane potential?
Differences in intra and extracellular ions The ion channels only allowing certain ions to enter and exit the cell
44
What tool is used to measure the membrane potential?
Tiny electrodes
45
Where does the neurons electric potential occur?
Across their membrane
46
Is the electrical potential of a membrane at rest negative or positive?
Negative
47
Define the resting membrane potential?
The electrical potential difference across the plasma membrane when the cell is in a non-excited state
48
What is an action potential in regards to the membrane voltage?
Rapid change in voltage across a neuron’s membrane that allows neurons to communicate with other cells
49
What does the negative charge inside the neuron (compared to outside the neuron) cause?
A difference in electric potential/voltage - across the neuronal cell membrane
50
What is electrostatic pressure?
The force exerted by attraction/repulsion of cations and anions
51
What is electrostatic equilibrium?
A state of no net ionic flux across a membrane because ion concentration and opposing transmembrane potentials are in balance
52
Explain the four factors that contribute to the resting potential being negative:
The cell membrane is semipermeable - only K+ ion channels are open When at rest - only K+ ions can freely pass The concentration of K+ ions higher intracellular than extracellular - some K+ leave by diffusion An- cannot cross membrane and remain inside the cell, resulting in more negative than positive ions inside the cell
53
How does concentration difference and electrostatic force determine the resting membrane potential?
Concentration difference - Drives K+ out the cell - inside becomes more negative Electrostatic force - opposite charges attract so K+ is drawn back into the negative inside of the cell
54
The equilibrium potential when all forces are balanced is…
The resting potential
55
Why is there more K+ inside the cell?
The sodium potassium pump = Na+/K+ pump
56
What is the ration of sodium to potassium movement in the sodium potassium pump?
3 sodium (Na+) out for every 2 Potassium (2K+) in
57
What is most of the brains energy consumed by?
The sodium potassium pump
58
Explain the process of the sodium potassium pump?
Three sodium ions bind to ATP ATP splits - provides energy to change the shape of the channel - sodium ions go through the channel (intracellular to extracellular) Sodium ions released to the outside of the membrane - new channel shape allows two potassium ions to bind The release of phosphate allows channel to go back to original form - releases potassium ions on the inside of the membrane
59
What does depolarization mean? In terms of ion channels?
The rapid rise in potential is caused by sodium ion channels opening in the plasma membrane
60
What does repolarization mean in terms of ion channels?
The return to resting potential caused by potassium ion channels opening
61
What does propagation mean?
The action potential travelling along the axon
62
Does hyperpolarisazion cause an increase or decrease in resting membrane potential?
Increase in resting potential - mV becomes more negative
63
Does depolarization cause an increase or decrease in resting membrane potential?
A decrease in resting potential - MV becomes less negative
64
What is the resting membrane potential?
The imbalance of electrical charge between the interior and exterior of electrically excited neurons
65
What is the membrane potential the sum of?
The depolarization and hyperpolarization
66
Do all stimuli cause an action potential?
No
67
What is required of a stimuli to cause an action potential?
Stimuli must have a sufficient electrical value which will reduce the negativity of the nerve cell to the threshold of an action potential
68
What is the usual action potential threshold?
-50 to -55m
69
What are the four phases of an action potential?
1 - Stimuli meets the threshold of excitation 2 - Depolarization- Inside of cell becomes more positive until the electrochemical electrium of sodium is met (+61 mV). This is the overshoot phase 3 - Repolarization - restores the resting membrane potential by K+ ions leaving the cell 4 - Hyperpolarization - Membrane potential is more negative that the default membrane potential
70
What occurs with the ions during depolarization?
Sodium ions flow into the cell through voltage gated channels - changes the cell’s polarity and increases the membrane potential
71
What occurs in repolarization in regards to ions?
Potassium ions move out of the cell, restoring the negative potential of the cell
72
How is intensity of a stimulus coded for in regards to action potentials?
Intensity is coded by frequency - more frequent firing - more intense stimuli
73
What is the refractory period?
The time after initiation of an AP when it is impossible/more difficult for a second AP to generate
74
What causes the refractory period?
Inactivation of the voltage-gated sodium channels
75
Give a summary of an action potential:
The action potential begins with a partial depolarization - sodium ions enter cell When the excitation threshold is met, large depolarization occurs Rapid repolarization - potassium leaving the cell A brief hyperpolarization - where the membrane potential is more negative than the resting Refractory period occurs after where no depolarization can occur
76
How are action potentials propagated along the axon?
Via local currents
77
What is the propagation of an AP?
Process in which a nerve impulse transmits along an axon
78
What does it mean when APs are described as - self-propagating
Once initiated, they travel along at a constant velocity
79
How are local currents involved with the propagation of an action potential?
Local currents induce depolarization of the adjacent axonal membrane
80
Why do action potentials only travel in one direction?
The area of the membrane that has recently depolarised will not depolarise again due to the refractory period
81
Why can a segment of the axon not depolarise again?
The inactivation of sodium channels and the opening of potassium channels
82
What are the two types of propagation?
Passive and Saltatory
83
What is passive propagation and when/where does it occur?
Occurs in unmyleinated axons, propagation occurs by the opening of sodium channels (depolarisation) in adjacent axon membranes
84
What is saltatory propagation and where does it occur?
Occurs in myelinated axons - myelin sheath insulates the axon other than nodes of ranvier. Action potential jumps from node to node, increases speed of propagation
85
What is the speed difference between passive and saltatory propagation?
Saltatory faster than passive 150 m/s compared to 0.5 to 10 m/s for passive propagation
86
Are most mammal axons myelinated or unmyleinated?
Myelinated
87
Myelin is insulating - what does this mean about the passage of ions?
The passage of ions is prevented when the myelin sheath is present
88
Other than increasing the speed of propagation, what else does the myelin sheath do?
Increase brain connectivity

Introduction to Neuroscience (9 decks)

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