Chapter 12 part 2: Nervous Tissue

Electrical potential?

A difference in the concentration of charged particles (ions) one point and another

Acts as potential (stored) energy that can produce a current (action potential)

This potential energy (voltage) in a cell is called → polarization

Electrical current?

A flow of charged particles (ions) from one point to another

The movement of ions changes the charge of cells

This creates and moves a nerve impulse

Living cells are polarized (have potential voltage) and have a what?

Resting membrane potential

Cells have more negative particles on inside of the membrane than outside

Neurons are −70 mV (millivolts) at resting membrane potential

In a resting (“unstimulated”) neuron

Continuation of resting membrane potential?

This charge (-70mV) is created by ion distribution

In the body, electrical currents are movements of ions, Na+ (sodium ions) or K+ (potassium ions), through channels in the plasma membrane

Gated channels are opened or closed by various → stimuli

Enables the cell to turn electrical currents → on and off

Resting membrane potential (RMP)?

Exists because of unequal electrolyte (ion) distribution between extracellular fluid (ECF) and intracellular fluid (ICF)

Neuron is at → rest (unstimulated)

RMP is maintained by three things?

Ions moving down their concentration gradient through the membrane

Some ions can pass through the membrane but others → cannot

Cations and anions are attracted to one another

How do K⁺ and anions help maintain resting membrane potential?

K+ diffuses out of the membrane through leaky-K+-channels into extracellular fluid (ECF) creating a negative charge in the cell

Anions are trapped inside of the cell also creating a negative charge inside of the cell

How does Na⁺ help create the resting membrane potential?

Some Na+ (sodium) diffuses into the membrane because it is attracted to the anions inside of the cell

All together this creates the -70 mV charge

What is the last regulator of resting membrane potential (RMP)?

Last RMP regulator is the sodium-potassium (Na+-K+) pump (primary active transport – Ch. 3)

3 Na+ pump out and 2 K+ into the membrane against their concentration gradients

Uses → ATP