Lecture Notes on Cell Communication and Action Potentials

These flashcards cover essential terms and definitions related to cell communication and action potentials, focusing on the mechanisms and principles discussed in the lecture.

Resting Membrane Potential

The electrical potential difference across the plasma membrane of a resting cell, typically around -70 mV.

Action Potential

A rapid rise and fall in voltage or membrane potential across a cellular membrane, triggered by a stimulus.

Depolarization

A decrease in the membrane potential, leading to a more positive internal cell environment.

Repolarization

The process of returning the membrane potential to its resting state after depolarization.

Hyperpolarization

An increase in membrane potential, making the inside of the cell more negative compared to the resting state.

Ion Channels

Proteins that span the plasma membrane and allow specific ions to move across the membrane.

Voltage-Gated Channels

Ion channels that open or close in response to changes in the membrane potential.

Chemically Gated Channels

Ion channels that open in response to the binding of a specific chemical messenger, such as a neurotransmitter.

Sodium-Potassium ATPase

An enzyme that actively transports 3 sodium ions out and 2 potassium ions into the cell, maintaining the resting membrane potential.

Equilibrium Potential

The membrane potential at which there is no net movement of a specific ion, determined by both concentration and electrical gradients.

Electrochemical Gradient

The combined difference in electrical charge and concentration gradient of ions across the membrane.

Graded Potential

Changes in membrane potential that vary in size and are proportional to the strength of the stimulus.

Threshold

The critical level to which a membrane potential must be depolarized to initiate an action potential, typically around -55 mV.

Absolute Refractory Period

The phase during the action potential when no new action potential can be initiated, regardless of stimulus strength.

Relative Refractory Period

The phase immediately following an action potential where a stronger than normal stimulus is needed to elicit another action potential.