All cell membranes contain a sodium \'pump\' - an enzyme known as Na^+ -K^+ ATPa

Question

All cell membranes contain a sodium 'pump' - an enzyme known as Na^+ -K^+ ATPase, which moves sodium from the inside to the outside of the cell. Depending on the cell type, there are between 800,000 and 30 million pumps on the surface of cells. As the sodium leaves the cell, potassium enters. It is this activity of the sodium pump which is responsible for the electrical charges in the cell membrane. What essential purpose do these electrical charges perform? Refer to the Hodgkin-Huxley model and to the cell's resting membrane potential to answer this question.

Explanation / Answer

In order to understand the importance of the electric charges in cell membrane caused by the activity of the sodium pump, let us first look into the Hodgkin- Husley model.

Hodgkin-Husley model is a mathematical model that describes how action potentials in neurons are initiated and propagated, that approximates the electrical characteristics of excitable cells such as neurons and cardiac myocytes.

This action potential is nothing but hte difference of charges in the cell membrane. These chargers are a result of the activity of the sodium “pump” described in the question.

This model treats each component of an excitable cell as an electrical element, in which ion pumps are represented by current sources and the membrane potential or the action potential. The membrane potential depends upon the maintenance of ionic concentration gradients across it.

The maintenance of these concentration gradients requires active transport of ionic species. An excitable cell at its stable and resting postition has a voltage known as the resting potential. Any change in this potential suggests an incoming of a stimulus(chemical form), through axon terminals.

This change is due to the loss of negative nature of cell and there is an inflow of Na+ inflow inside cell. Now the cell responds to the stilumulus, after which the help of Na-K+ pumps NA+ back to the cell so that it returns to it negative state, making it ready to be stimulated again.

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