Membrane ionic gradients across

Figure 2.1 (a) Resting ionic gradients across a nerve cell membrane. Concentrations [ ] are in... 

Thus, the Gibbs Free energy expression for such an ionic gradient across the membrane consisting of an positively charged species C, would be of the form of the following expression ... 

Simply put, the action potential is caused by a state of disequilibrium between ideal electrical potentials for two ions, sodium and potassium. The equilibrium potentials for Na" " and K can be thought of as the electrical force required to maintain the given ionic gradients across the cell membrane for each ion. For Na" ", the equilibrium potential is approximately 50 mV (with respect to the inside of the membrane) for K +, it is approximately —75 mV. (These values apply to the giant squid axon on which the early investigations on action potentials were conducted. Of course, these values... 

ATP-Powered Ion Pumps Generate and Maintain Ionic Gradients Across Cellular Membranes... 

The ion pumps discussed in this section are largely responsible for establishing and maintaining the usual ionic gradients across the plasma and Intracellular membranes. In carr3dng out this task, cells expend considerable energy. For... 

The aCSF mimics the extracellular environment of neurons and provides the necessary ingredients that allow neurons to survive m vitro for at least several hours. Because metabolic processes and the maintenance of the ionic gradient across the cell membrane constantly consume ATP, glucose and oxygen must be supplied to generate energy. 

The electrical signals are carried by the movement of charged ions across the cell membrane. This makes use of the potential energy stored across the cell membrane in the form of ionic gradients. Concentration gradients for the principal ions across a typical nerve cell membrane are indicated in Fig. 2.1(a). The cell interior has a high concentration of K+ ions and a low concentration of Na+, Cl and Ca + ions relative to the exterior. 

Potassium, like sodium, is involved in ionic equilibria, and the opening and closing of sodium and potassium ion channels create the electrochemical gradients across cell membranes that transmit nerve impulses and other information and regulate cellular function. 

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