General Physio: Chapter 5c

What is membrane potential?

Separation of charges across the plasma membrane

What is a conductor?

Allows separated charges to move freely

What is an insulator?

Resists the movement of separated charges

What is resting membrane potential?

Electrical gradient between ECF & ICF

Has reached a steady state and it is not changing

What is the electrochemical gradient?

Created by the transport of ions across the membrane

What is the chemical gradient?

Difference in ion concentration across the membrane

What is the electrical gradient?

Created when more positive charges are moved out than in

What is the equilibrium potential?

When the movement of a single ion down the concentration gradient is equal but opposite in direction to the ion movement down the electrical gradient

What is Nernst equation?

Used to determine the equilibrium potential of an ion

What is Na⁺/K⁺-ATPase?

Transports 3 Na⁺ ions to the ECF per 2 K⁺ ions to the ICF

What is the electrogenic pump?

A pump that helps maintain an electrical gradient

What is the patch-clamp experiment?

Method used to measure charge accumulation of a cell

What is relative permeability?

An ions ability to cross the membrane

What is a leak channel?

Channels through which ion movement primarily determines the magnitude of the membrane potential

What is depolarization?

A change in membrane potential caused by closure of the KATP channel in the beta cell

What is the intracellular signal?

The role of Ca²⁺ entry in the beta cell that triggers exocytosis and insulin secretion

What is the law of conservation of electrical charges?

Amount of electrical charge produced in any process is zero; every (+) charge is accompanied by (-) charged ion

What is measuring electrochemical gradient?

Charges that accumulate in the cell are measured relative to charges within the ECF

What is uneven distribution of solutes amongst body compartments?

Creates electrical and chemical gradients

What is relative permeability?

An ion’s contribution to membrane potential is proportional to its ability to cross the membrane

K⁺ = 50–75
Na⁺ = 1
Cl⁻ = 100
Anions = 0

What is potential?

An electrical gradient is found across the cell membrane in virtually every cell in the body

What does resting mean?

The membrane potential has reached steady state and is not changing

What is osmotic equilibrium?

When cells remain in osmotic equilibrium

What is chemical disequilbrium?

Body compartments are in a state of chemical disequilibrium

What is electrical disequilibrium?

It is important to electrical signaling in nerves and muscles

What are the channels involved in establishing membrane resting potential?

Created by a flow of of ions; Na⁺/K⁺ pump “sets up” the gradient; ion movement through leak channels primarily determines the magnitude of membrane potential

What is the potassium equilibrium potential?

-90 mV

What is the sodium equilibrium potential?

+60 mV

What is the resting membrane potential in real cells?

Most cells are 50-75x more permeable to K⁺ than Na⁺; resting membrane potential is much closer to EK than ENa

What is exocytosis?

Ca²⁺ signal triggers exocytosis, and insulin is secreted