Why do nerve cells require a continuous supply of energy?

Nerve cells require a continuous supply of energy to maintain their resting potential and transmit nerve impulses.

Nerve cells, also known as neurons, are the fundamental units of the brain and nervous system. They are responsible for receiving sensory input from the external world, sending motor commands to our muscles, and transforming and relaying the electrical signals at the core of all these processes. To perform these functions, neurons require a constant supply of energy.

The primary source of this energy is adenosine triphosphate (ATP), a molecule that stores and releases energy as needed by the cells. ATP is produced by the mitochondria within the cells through a process called cellular respiration, which requires glucose and oxygen. This is why a constant supply of blood, carrying glucose and oxygen, is crucial for the functioning of nerve cells.

One of the main energy-consuming processes in nerve cells is the maintenance of the resting potential. The resting potential is a state of electrical charge that exists across the cell membrane of a neuron, which is essential for the transmission of nerve impulses. This is maintained by the sodium-potassium pump, a protein that uses ATP to pump sodium and potassium ions across the cell membrane, against their concentration gradients. This process is energy-intensive and requires a continuous supply of ATP.

Furthermore, the transmission of nerve impulses, or action potentials, also requires energy. When a nerve impulse is transmitted, ion channels open to allow sodium and potassium ions to flow across the cell membrane. This changes the electrical charge across the membrane, creating the nerve impulse. After the impulse has passed, the ions need to be pumped back to their original positions to restore the resting potential, again requiring ATP.

In conclusion, nerve cells require a continuous supply of energy to maintain their resting potential and transmit nerve impulses. This energy is primarily provided by ATP, produced by the mitochondria within the cells through cellular respiration.