Week 2 - Communication Within The Neuron

Question 1

What is the resting membrane potential?

Answer 1

The difference in electrical charge across the cell membrane, typically around -70 mV.

Question 2

What forces contribute to the resting membrane potential?

Answer 2

• Diffusion
• Electrostatic pressure
• Transporter activity

Question 3

What is the role of the transporter in maintaining resting membrane potential?

Answer 3

Moves sodium cations out of the cell, using energy to maintain the potential.

Question 4

What is the charge distribution inside and outside the cell at resting potential?

Answer 4

Outside is positive (+ve); inside is negative (-ve).

Question 5

What is the importance of the action potential in neurons?

Answer 5

It reflects the fundamental concept of electrical excitability and triggers signal transmission.

Question 6

True or False: The cell membrane is completely impermeable to ions.

Answer 6

False

Question 7

Fill in the blank: The resting membrane potential is maintained at approximately _______.

Answer 7

-70 mV

Question 8

What is the primary reason diffusion of chemicals is insufficient for signaling in neurons?

Answer 8

It would be too slow.

Question 9

What happens to sodium cations at rest in a neuron?

Answer 9

They tend to move into the cell but are pushed back out by the transporter.

Question 10

What type of charge do cations carry?

Answer 10

Positive charge (+ve)

Question 11

What type of charge do anions carry?

Answer 11

Negative charge (-ve)

Question 12

How does electrostatic pressure affect ion movement?

Answer 12

Ions with the same charge repel each other, while ions with different charges attract each other.

Question 13

Which ion is more permeable across the cell membrane, sodium or potassium?

Answer 13

Potassium

Question 14

What does the term ‘electrical excitability’ refer to?

Answer 14

The ability of neurons to generate action potentials.

Question 15

What percentage of the brain’s energy is used to maintain the resting potential?

Answer 15

A substantial proportion.

Question 16

What is the overall nature of communication within a neuron?

Answer 16

Electrical signaling

Question 17

What is the resting membrane potential?

Answer 17

The electrical charge across the neuronal membrane when the neuron is not active

It is essential for the initiation of action potentials.

Question 18

What triggers an action potential?

Answer 18

A change in the resting membrane potential that reaches the threshold of excitation

This involves the opening of voltage-gated sodium channels.

Question 19

What is the threshold of excitation?

Answer 19

The critical level to which the membrane potential must be depolarized to initiate an action potential, typically around -55 mV

Question 20

List the phases of an action potential.

Answer 20

• Resting state
• Depolarization
• Repolarization
• Hyperpolarization
• Return to resting state

Question 21

How do signals transmit from one neuron to another?

Answer 21

Through the release of neurotransmitters across a synapse

This involves the presynaptic neuron releasing neurotransmitters that bind to receptors on the postsynaptic neuron.

Question 22

What is the difference between an action potential and a post-synaptic potential?

Answer 22

An action potential is a large, all-or-nothing signal, while post-synaptic potentials are small changes in membrane potential that can be excitatory or inhibitory

Question 23

Fill in the blank: The action potential follows the _______ law, meaning it either occurs or does not occur.

Answer 23

[all-or-none]

Question 24

What is the role of the myelin sheath in neuronal communication?

Answer 24

It insulates the axon, allowing action potentials to jump between nodes, increasing speed and efficiency

This process is known as saltatory conduction.

Question 25

What happens during the depolarization phase of an action potential?

Answer 25

Sodium channels open, allowing Na+ ions to flood into the neuron, making the membrane potential less negative

Question 26

What occurs during the repolarization phase of an action potential?

Answer 26

Potassium channels open, allowing K+ ions to exit the neuron, restoring the negative charge inside

Sodium channels close at this stage.

Question 27

What is hyperpolarization?

Answer 27

A phase where the membrane potential becomes more negative than the resting potential

This occurs after repolarization due to the continued exit of K+ ions.

Question 28

What are excitatory post-synaptic potentials (EPSPs)?

Answer 28

Small depolarizations that make the postsynaptic neuron more likely to fire an action potential

They result from the opening of cation channels.

Question 29

What are inhibitory post-synaptic potentials (IPSPs)?

Answer 29

Small hyperpolarizations that make the postsynaptic neuron less likely to fire an action potential

They result from the opening of anion channels.

Question 30

True or False: Action potentials can vary in size and shape.

Answer 30

False

Action potentials are always the same size and shape.

Question 31

What is the significance of neurotransmitter receptors in the postsynaptic neuron?

Answer 31

They bind released neurotransmitters, leading to changes in conductance and the generation of post-synaptic potentials

Question 32

What is the function of the presynaptic neuron?

Answer 32

To bring information to the synapse and release neurotransmitters into the synaptic cleft

Question 33

What is the synaptic cleft?

Answer 33

The physical gap between the presynaptic and postsynaptic neurons, approximately 20 nm wide