Electrophysiology of Excitable Cells and Tissues, with Special Consideration of the Heart Muscle

Abstract

Most living organs are made of “cells” which are surrounded by an “intercellular space” filled with “interstitial fluid.” The most elementary model of a living cell consists of a small spherical bag, containing a “cytoplasm” which is the fundamental living substance. The cytoplasm is a mixture of water, proteins, lipids, carbohydrates, electrolytes, etc. The cells contain also a number of “intracellular organelles:” the nucleus, where the genetic information is deposited; the mitochondria, which are the “power generating units” of the cell; the “endoplasmic reticulum,” which participates in the synthesis of proteins; the Golgi complex, which is involved in the secretory function; etc. Most animal cells are surrounded by a cell membrane, consisting of a double layer of lipids with interspersed islets of protein. The proteins fulfill the following functions:

• a) Channels, which permit and regulate the passage of ions, nutrients, etc.;

• b) Receptors, which bind specific substances that are transported by the blood or are secreted by the nerve endings;

• c) Pumps, which actively transport ions and other substances across the membrane against an electrochemical gradient;

• d) Other functions, such as enzymes, antigens, etc.