Nervous System 2: Membrane Potentials, Action Potentials & Conduction Study Guide

What is the basic functional unit of the nervous system?

Neuron

What are the two types of cytoplasmic extensions in neurons?

Dendrites and Axons

What is the function of dendrites?

To receive information

What is the function of axons?

To send signals

What is the axon hillock?

The base of the axon where signals are generated

What type of neuron carries signals from sensory receptors to the nervous system?

Sensory (afferent) neurons

What type of neurons interact only with other neurons?

Interneurons

What type of neuron carries signals from the nervous system to effectors?

Motor (efferent) neurons

What is membrane potential?

The potential energy across a selectively permeable membrane due to differences in charge

What is the typical resting potential of a neuron?

-60 to -80 mV

What is the role of the sodium-potassium pump?

To move 3 Na+ out and 2 K+ in, creating a negative membrane potential

What causes hyperpolarization in a neuron?

Moving further from 0, making the inside more negative

What is depolarization?

Moving closer to 0, making the inside less negative

What is the threshold potential required to trigger an action potential?

-55 mV

What happens during the rising phase of an action potential?

Voltage-gated Na+ channels open, causing rapid depolarization

What occurs during the falling phase of an action potential?

Voltage-gated Na+ channels close and K+ channels open, causing repolarization

What is the all-or-nothing principle of action potentials?

An action potential either occurs fully or not at all

What is continuous conduction?

Propagation of action potentials in unmyelinated axons

What is saltatory conduction?

Propagation of action potentials in myelinated axons, jumping from node to node

What are Nodes of Ranvier?

Gaps in the myelin sheath where depolarization occurs

How much faster is saltatory conduction compared to continuous conduction?

50 times faster

What is the role of leaky potassium channels?

To allow K+ to diffuse out, contributing to the negative resting membrane potential

What is the significance of the refractory period?

It prevents the action potential from traveling backward along the axon

What determines the intensity of a sensation?

The number of neurons activated and the frequency of action potentials