Lecture 12: Sensory Neurons and Action Potentials

Vocabulary flashcards covering the mechanisms of sensory neurons, action potential propagation, and the role of myelin based on Lecture 12.

Threshold of an Action Potential

The membrane potential of $-55\,mV$ at which voltage-gated $Na^+$ channels open to initiate an action potential.

TRP Channel

Channels that allow cations to enter a sensory neuron, leading to a graded potential when exposed to temperature stimulus.

Resting Membrane Potential Channels

The specific channels open during resting membrane potential, which include Leak $K^+$ channels and Leak $Na^+$ channels.

$Na^+/K^+$ Pump

An active transport mechanism in the cell membrane that requires ATP to function.

Effect of Increased $K^+$ Permeability

An increase in the permeability to $K^+$ causes the resting membrane potential to decrease.

Effect of Increased $Na^+$ Permeability

An increase in permeability via opening a voltage-gated $Na^+$ channel causes the membrane potential to increase.

Axonal Threshold Trigger

Halfway down an axon, the threshold for voltage-gated $Na^+$ channels is reached due to $Na^+$ from previous voltage-gated $Na^+$ channels.

Ball and Chain Deactivation

The mechanism of the voltage-gated $Na^+$ channel that causes the absolute refractory period.

Multiple Sclerosis

An autoimmune and demyelinating disease of the central nervous system.

Myelin

A substance that insulates the axon and increases the speed of the action potential.

Demyelination Consequence

The loss of myelin may cause enough current leak that depolarization reaching the node is no longer above the threshold for voltage-gated $Na^+$ channels.