The Nervous System

Structure

The nervous system is subdivided into two main parts: the central nervous system and the peripheral nervous system. The central nervous system consists of the brain and the spinal cord, while the peripheral nervous system is made of the branching nerves that lead to the rest of the body. The peripheral nervous system is also subdivided into two parts: the somatic nervous system and the autonomic nervous system.

The brain, which controls almost everything in the body, is not that big compared to the rest of the body; it is only about 2 percent of the total body weight. It is subdivided into three sections: the massive paired hemispheres of the cerebrum, the brainstem,ck consisting of the thalamus, hypothalamus, epithalamus, subthalamus, midbrain, pons, and medulla oblongata, and the cerebellum. The left hemisphere controls mostly speech, comprehension, arithmetic, and writing. The right hemisphere controls creativity, spatial ability, artistic and musical skills.

The basic unit of the nervous system is the neuron. The human brain has around 100 billion neurons. Like cells, neurons have nuclei. They are connected to the nervous system by axons. They also have so-called dendrites. Both dendrites and axons allow the neurons to communicate with each other.

Function

The main function of the nervous system is communication between different body parts and the brain. It controls various functions of the body. Here are some examples:

• Brain growth and development
• Sensations (such as touch or hearing)
• Perception (the mental process of interpreting sensory information)
• Thought and emotions
• Learning and memory
• Movement, balance, and coordination
• Sleep
• Healing and rehabilitation
• Stress and the body’s responses to stress
• Aging
• Breathing and heartbeat
• Body temperature
• Hunger, thirst, and digestion
• Puberty, reproductive health, and fertility

The sensing organs are responsible for our body sensing the surroundings. Each sensing organ sends impulses through the nervous system to the brain. The brain reacts to these impulses and translates the received information, to which the body reacts. If we feel pain, then the reaction is to try to escape the pain.