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II - Action Potentials

Q: Where is the action potential started and where does active conduction take place?

The action potential is initiated at the start of the axon which is also called an hillock. Active conduction takes place in the presynaptic and postsynaptic axons.

Q: What is each neuron surrounded by, and what does these molecules act as?

Each neuron is surrounded by a cell membrane that acts as a barrier to the passage of certain chemicals. Within the membrane, certain protein molecules act as gatekeepers and allow particular chemicals in and out under certain conditions.

Q: What are the chemicals inside the membrane and what is the balance between the ions called?

The chemicals consist of charged sodium (Na+) and Potassium (K+). The balance between the ions on the inside and outside of the membrane is such that there is normally a resting potential.

Q: What is the resting potential voltage, and where are voltage gated ion channels found?

The resting potential of a membrane is -70mV. Voltage gated ion channels are of importance in the generation of an action potential, and they are only found in axons . This is why only the axon is capable of producing action potentials.

Q: Which protein enters first during an action potential and when does the cell membrane become completely permable?

If there's a sufficient strenght Na+ (Sodium) enters the channel first which reduces the negative potential in the cell to -50V. The response of the Na+ is that the cell becomes completely permable and the charge in the cell momentarily reverses which causes depolarization and repolarization.

Q: How is the negative potential restored, and what happens during hyperpolarization?

The negative potential is restored via the outward flow of K+ (Potassium) and closing the voltage gated N a+ (Sodium). When the inside is more negative than the rest at the end stage of the action potential hyperpolarisation occurs. The inside of the membrane is more negative than at rest, which makes it difficult for the axon to depolarize and prevents the action from travelling backwards.

Q: What speeds up the conduction of the action potential and in what pathologies is this missing?

The conduction of the action potential along the axon may be speeded up if the axon is myelinated. Myelin is a fatty substance deposited around the axon of some cells and are missing of destructed in pathologies such as multiple sceloris

Q: What events does an action potential initiate and where do neurotransmitters bind to?

When an action potential reaches an terminal, the electrical signal initiates a sequence of events leading to the release of neurotransmitters in the synaptic cleft Protein receptors in the membrane of the postsynaptic neurons bind to the neurotransmitters.

Q: What are the two workhorse neurotransmitters of the brain?

Glutama and GABA are the workhorse neurotransmitters of the brain in that nearly every neuron produces one or the other of those.

14 important questions on II - Action Potentials

Where is the action potential started and where does active conduction take place?

The action potential is initiated at the start of the axon which is also called an hillock.

Active conduction takes place in the presynaptic and postsynaptic axons.

What is each neuron surrounded by, and what does these molecules act as?

Each neuron is surrounded by a cell membrane that acts as a barrier to the passage of certain chemicals.

Within the membrane, certain protein molecules act as gatekeepers and allow particular chemicals in and out under certain conditions.

What are the chemicals inside the membrane and what is the balance between the ions called?

The chemicals consist of charged sodium (Na+) and Potassium (K+).

The balance between the ions on the inside and outside of the membrane is such that there is normally a resting potential.

What is the resting potential voltage, and where are voltage gated ion channels found?

The resting potential of a membrane is -70mV.

Voltage gated ion channels are of importance in the generation of an action potential, and they are only found in axons. This is why only the axon is capable of producing action potentials.

Which protein enters first during an action potential and when does the cell membrane become completely permable?

If there's a sufficient strenght Na+ (Sodium) enters the channel first which reduces the negative potential in the cell to -50V.

The response of the Na+ is that the cell becomes completely permable and the charge in the cell momentarily reverses which causes depolarization and repolarization.

How is the negative potential restored, and what happens during hyperpolarization?

The negative potential is restored via the outward flow of K+ (Potassium) and closing the voltage gated Na+ (Sodium).

When the inside is more negative than the rest at the end stage of the action potential hyperpolarisation occurs. The inside of the membrane is more negative than at rest, which makes it difficult for the axon to depolarize and prevents the action from travelling backwards.

What speeds up the conduction of the action potential and in what pathologies is this missing?

The conduction of the action potential along the axon may be speeded up if the axon is myelinated.

Myelin is a fatty substance deposited around the axon of some cells and are missing of destructed in pathologies such as multiple sceloris

What events does an action potential initiate and where do neurotransmitters bind to?

When an action potential reaches an terminal, the electrical signal initiates a sequence of events leading to the release of neurotransmitters in the synaptic cleft

Protein receptors in the membrane of the postsynaptic neurons bind to the neurotransmitters.

What does the binding of neurotransmitters to protein receptors in the membrane of the postsynaptic neuron cause and what proteins does it contain?

The binding of neurotransmitters to protein receptors in the membrane causes a synaptic potential.

It contains a localised flow of charged Na+, Ka+ and CI-.

What are the two workhorse neurotransmitters of the brain?

Glutama and GABA are the workhorse neurotransmitters of the brain in that nearly every neuron produces one or the other of those.

What effect does GABA have on the postsynaptic neuron and how does this work?

GABA has an inhibitory effect on the postsynaptic neuron which makes it less likely to fire.

GABA makes the inside of the neuron more negative than normal and hence harder to depolarize by opening C1- channels.

What effect does Glutamate have on the postysnaptic neuron and how does this work?

Glutamate is a neurotransmitter which has an excitatory effect on the postsynaptic neuron which makes it more likely to fire.

Are the chemicals GABA and Glutamate responsible for excitatory or inhibitory functions?

It's not the chemical itself yet the effect they have on the ion channels in the membrane which either pump positive or negative ions making action potentials more likely.

What are other common neurotransmitters and hwat functions though they have?

Serotonin, dopamine, acetylcholine and noradrenaline are other common neurotransmitters.

These neurotransmitters are considered to have modulatory functions and cell bodies are localized to the specific brain areas but have axonal projections diffused throughout them.

The question on the page originate from the summary of the following study material:

Biologische Cognitie I- Shannon's Samenvatting

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II - Action Potentials

14 important questions on II - Action Potentials

Where is the action potential started and where does active conduction take place?

What is each neuron surrounded by, and what does these molecules act as?

What are the chemicals inside the membrane and what is the balance between the ions called?

What is the resting potential voltage, and where are voltage gated ion channels found?

Which protein enters first during an action potential and when does the cell membrane become completely permable?

How is the negative potential restored, and what happens during hyperpolarization?

What speeds up the conduction of the action potential and in what pathologies is this missing?

What events does an action potential initiate and where do neurotransmitters bind to?

What does the binding of neurotransmitters to protein receptors in the membrane of the postsynaptic neuron cause and what proteins does it contain?

What are the two workhorse neurotransmitters of the brain?

What effect does GABA have on the postsynaptic neuron and how does this work?

What effect does Glutamate have on the postysnaptic neuron and how does this work?

Are the chemicals GABA and Glutamate responsible for excitatory or inhibitory functions?

What are other common neurotransmitters and hwat functions though they have?

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