Midterm study

What is the resting membrane potential of neurons?

Around -70 mV due to ion distribution.

What does polarization refer to in neurons?

The resting state where the inside of the cell is negative relative to the outside.

What happens during depolarization?

The membrane potential decreases, making the cell more positive.

What is hyperpolarization?

An increase in membrane potential, making the cell more negative than the resting state.

What are voltage-gated channels?

Ion channels that open in response to changes in membrane potential.

What occurs during the equilibrium potential of K⁺?

It is approximately +90 mV, where there is no net movement of K⁺.

What function does the Na⁺/K⁺ pump serve?

It actively expels 3 Na⁺ ions for every 2 K⁺ ions imported, maintaining ion gradients.

What initiates an action potential?

A stimulus reaching the 55 mV threshold.

What occurs during the repolarization phase of an action potential?

K⁺ channels open, K⁺ exits the cell, restoring negativity.

What is the difference between the absolute and relative refractory periods?

In the absolute refractory period, no action potential can occur; in the relative refractory period, a stronger stimulus can initiate one.

What is electrotonic current flow?

Passive local current flow that depolarizes adjacent regions of the neuron membrane after an action potential.

What are discrete synapses?

Synapses located at axonal terminals where neurotransmitters are released from specific active zones.

What characterizes non-peptide neurotransmitters?

They include small molecules like amino acids and amines and are synthesized in the axon terminal.

What is the role of Ca²⁺ in neurotransmitter release?

Calcium regulates vesicle docking and neurotransmitter release.

What are Excitatory Post-Synaptic Potentials (EPSPs)?

Changes that depolarize the post-synaptic cell by allowing Na⁺ entry.

How are neurotransmitter actions terminated?

Through reuptake, enzymatic degradation, or diffusion away from the synaptic cleft.

What is convergence in the context of synaptic transmission?

Multiple neurons innervate a single post-synaptic neuron.

What is the difference between fast and slow synaptic transmission?

Fast involves direct ion channel opening, while slow involves second messengers or longer-lasting changes.