Chapter 1.2, Problem 1EIQ

Summary Introduction

Introduction:

The neuron’s membrane depolarizes if charged ions flow freely across the membrane. It is selectively permeable because certain chemical substances can pass through it more freely than others do. The membrane has channels that are always open to molecules such as oxygen, carbon dioxide, urea, and water to cross freely. The membrane has other channels that are sometimes open and sometimes closed. Several biologically important ions, such as sodium, potassium, calcium, and chloride, can cross through these channels. When the membrane is at rest, the sodium and potassium channels are closed, and there is no flow of sodium and only a small flow of potassium.