3. THE MECHANISM OF THE NERVOUS SYSTEM
Nervous System
The nervous system is a very complicated and complex system. It is associated with the muscular functions that adjusted our body to the environment both inside and outside our body. This nervous system can be divided into 3 parts.
1. CENTRAL NERVOUS SYSTEM (CNS).
This system is comprised of the brain and the spinal cord.
1.1 BRAIN FUNCTIONS
Control of memory, thought, and intellect.
Control of muscle movement. The left side of the brain controls the muscles of the right and the right side of the brain controls the muscles of the left side of our body.
Control of speech, sight, and hearing.
Control of the metabolism, hunger and thirst.
Control of eye movement, opening and shutting of the iris.
Control of muscles associated with body balance.
Control of respiratory process, heartbeat and the contraction and expansion of the blood vessels.
The midbrain controls the motor areas and plans body movement. Finally, the motor area sends the commands to the spinal cord.
1.2 FUNCTIONS OF THE SPINAL CORD
Transmit neural signals to the brain for interpretation and command and at the same time, transfer neural signals from the brain to the other organs.
Control of reflexes, enabling us to react immediately for protection and risk avoidance to our body. For instance, when we step on a sharp thorn we will step away immediately, not waiting for a command from the brain to do so.
Control of organ growth connected with the spinal cord, which is called the trophic function.
2. Peripheral Nervous System (PNS).
It consists of nerves and ganglia outside the Central Nervous System. One part of this system is the ‚Cranial Nerves‛ attached to the brain, the other part is the ‚Spinal Nerves‛ originating from the spinal cord. If any spinal nerve in any part is destroyed, it will affect the movement and the control of the organ connected to that spinal nerve. For example, if the spinal nerves at the hips and the bottom are damaged, both legs will be affected which may result in paralysis of the legs and immobility.
3. Autonomic Nervous System (ANS).
The Autonomic Nervous System controls primarily the functions of the internal organs which are beyond the control of the mind. These can be divided into 2 groups:
3.1 SYMPATHETIC NERVOUS SYSTEM (SNS).
The purpose of this system is to accelerate the functions of the internal organs, to work faster and harder. It also plays part in controlling emotions which accelerate the heartbeat, increase the blood pressure, and increase the function of the glands. It includes reflexes for fright, fear, anger, and pain or for safety of the body in emergency cases. The neurons in this system are connected to the spinal cord at the chest and hip regions.
3.2 PARASYMPATHETIC NERVOUS SYSTEM (PNS).
The main function of this nervous system is to slow down organ functions while our body needs to rest. The nerve fibers of this group of nerve are connected to the CNS and spinal nerves.
Both groups of nerves (SNS and PNS) work simultaneously and if either of these groups works hard, the other will work less. Sometimes they help each other control the amount of water or the temperature in the body to be normal. They also control the internal organs and the glands to work efficiently and appropriately.
Source: https://clinicalgate.com/nervous-system/