Electrical Properties of Neurons

Flashcards about the electrical properties of neurons including resting potential, action potential, and neurotransmitter release.

What causes local changes in electrical charge at the dendrites and soma of a neuron?

Chemical input from other cells, resulting in post-synaptic potentials.

What happens if post-synaptic potentials raise the voltage at the axon hillock beyond a certain threshold?

An action potential is generated and conducted down the length of the axon.

What is the resting potential?

The negative electrical charge inside a neuron relative to the outside when at rest, ranging from -50 to -80mV.

What maintains the relatively negative interior of a neuron at rest?

The gradient distribution of different ions across the cellular membrane.

What are ion channels?

Proteins that span the neuron's membrane, allowing ions to pass through from one side to the other.

What two forces determine whether ions enter or exit the neuron through ion channels?

Diffusion (chemical pressure) and electrostatic force.

What is the role of the sodium/potassium pump?

It pulls 2 K+ ions into the cell for every 3 Na+ ions it removes, powered by ATP, to maintain the ion gradient.

What is hyperpolarization?

When the charge inside the neuron becomes more negative, due to negatively charged ions entering or positively charged ions exiting.

What is depolarization?

When the charge inside the neuron gets more positive, due to positively charged ions entering or negatively charged ions exiting.

What are ionotropic receptors?

Ion channels that open when neurotransmitters bind to them, causing either depolarization or hyperpolarization.

What is an excitatory postsynaptic potential (EPSP)?

When ionotropic receptors allow positively charged ions into the neuron, causing a brief, local depolarization.

What is an inhibitory postsynaptic potential (IPSP)?

When ionotropic receptors allow negatively charged ions into the neuron, causing a brief, local hyperpolarization.

What is spatial summation?

Combining the influence of PSPs across space; PSPs closer in space are more likely to sum together.

What is temporal summation?

Combining the influence of PSPs across time; PSPs closer in time are more likely to sum together.

What happens when the axon hillock depolarizes to its threshold (around -40mV)?

An action potential is generated and conducted down the length of the axon.

What causes the rapid depolarization during the rising phase of an action potential?

Voltage-gated sodium channels open, allowing Na+ ions into the axon.

What causes the rapid hyperpolarization during the falling phase of an action potential?

Potassium ions (K+) are forced out through potassium channels, and voltage-gated potassium channels open.

What is the refractory period?

A brief period after opening and closing when voltage-gated sodium channels will not open again.

How is an action potential propagated down the axon?

Na+ entering at one segment depolarizes the next segment to threshold, causing voltage-gated sodium channels to open and repeat the process.

How does myelin speed up the action potential?

By insulating segments of the axon and allowing saltatory conduction, where the action potential jumps from node to node (Nodes of Ranvier).

What is saltatory conduction?

The process by which the action potential jumps from node to node of a myelinated axon.

How does the action potential lead to neurotransmitter release at the axon terminal?

The action potential opens voltage-gated calcium (Ca2+) channels, allowing Ca2+ to enter the terminal and trigger the rupture of synaptic vesicles, releasing neurotransmitters.