Neuro

What ions are found in higher concentration extracellularly at rest?

Na+

What ions are found in higher concentration intracellularly at rest?

K+ and negatively charged organic molecules (proteins)

What is depolarization?

A potential difference that is reduced, becoming more positive.

What is repolarization?

The return to resting membrane potential, becoming more negative.

What is hyperpolarization?

A state more negative than the resting membrane potential.

What triggers an action potential?

A stimulus causes Na+ channels to open, and if enough sodium enters, an action potential starts.

How is an action potential described?

Like flipping a switch—once triggered, it’s all or nothing.

What is the absolute refractory period?

The axon membrane is incapable of producing another action potential.

What is the relative refractory period?

The axon membrane can produce another action potential, but it requires a stronger stimulus.

What is saltatory conduction?

A fast rate of conduction that occurs by leaping from node to node in myelinated axons.

What are electrical synapses characterized by?

Direct flow of ions through gap junctions, no delay, very fast, and usually bidirectional.

What are chemical synapses characterized by?

Electrical signals trigger the release of neurotransmitters, slower than electrical synapses, and unidirectional.

What does EPSP stand for and what is its function?

Excitatory postsynaptic potential, which causes a small depolarization to excite the neuron.

What neurotransmitters are involved in EPSP?

Glutamate, acetylcholine, norepinephrine, epinephrine.

What does IPSP stand for and what is its function?

Inhibitory postsynaptic potential, which causes a small hyperpolarization to inhibit the neuron.

Which neurotransmitter is primarily involved in IPSP?

GABA.