Central Nervous System Research Paper

The Nervous System

The Central Nervous System (CNS) consists of the brain and the spinal cord. It acts as the body’s control center and coordinates body’s activities. Nerve cells, called neurons, send signals in the body that travel through impulses to reach their destinations. The CNS contains specific neurons called interneurons that transmit impulses between other nerve cells.

Peripheral Nervous System (PNS) consists of all the nerves in the body that are not in the brain or spinal cord. These nerves carry messages to and from the central nervous system throughout the body.

The CNS and the PNS work in conjunction making rapid changes in the body in response to external and internal stimuli. The PNS can be divided into: Somatic Nervous

• Interneurons: found in the brain and spinal cord, process incoming impulses and pass them on to motor neurons.

• Motor Neurons: carry impulses away from the brain and spinal cord to voluntary muscle.

Neurons communicate via an electrochemical signal called an action potential that sends information down an axon and away from the cell body. They are based on the movements of ions through channels in the membrane of an axon. A molecular message is sent to neighboring neurons when an action potential is reached. This is an all or nothing process. Triggering Action Potential:

At rest, a neuron holds a balance of excitatory and inhibitory signals. If the excitatory signals exceed the inhibitory signals, the threshold for sending a molecular message is reached. If the inhibitory signals exceed the excitatory signals, then that threshold is NOT reached. When this threshold is reached an electrical impulse is fired down the axon. This is an action

This movement against a concentration gradient is known as an active transport process which makes ATP the currency of the cell.

• The stimulus received by the dendrites of a neuron causes the Na+ channels to open. An influx of N+ ions via diffusion starts to drive the potential to be positive. Even though neurons are sensitive to external stimuli, certain stimuli might not cause the potential to rise to the threshold level. This will tend to make the neuron revert to equilibrium. However, if the stimulus is sufficient, the potential will rise from -70 mV to -55 mV and the process will continue. Once the threshold for action potential has been reached it will fire into a full signal. This is known as the all or nothing process.

• Once the threshold has been reached, more Na+ gates open and Na+ ions rush into the neuron, raising the voltage of the membrane rapidly. This transition is known as “voltage-gated” and occurs very quickly. Na+ ions are driven by the concentration gradient and the voltage gradient causing the rapid