The human nervous system consists of two groups: the central nervous system and the peripheral nervous system. The central nervous system consists of the brain and the spinal cord. It is the control center of all human functions. It is where the responses to stimuli are being processed. The information and reaction is then communicated throughout the body through the peripheral nervous system which is composed of the nerves and ganglia.
Neurons are nerve cells which serve as the basic unit of the nervous system. Neurons communicate from cell to cell through some chemical and electrical signals. A neuron consists of a cell body, an axon and dendrites. The signals that are processes inside the cells are then conducted through the axons. The signals are then received by the dendrites which are the tiny filaments at the end of the axon. Dendrites are also found projecting from the cell body. The signals transmitted through the axon are received by the dendrites of another cell body. Thus communication between cells occurs.
The brain is composed of billions of neurons. Thus, it has a great capacity to process, store and transmit information. A human reaction to a stimulus is processed in the billions of neurons in the brain and it instructs certain parts of a body to react. The brain structure is divided into the cerebrum, cerebellum and the brain stem. The cerebrum is located in the upper part of the brain. It is the largest part of the brain which is divided into two hemispheres. The cerebrum controls a variety of human activities. It is responsible for the proper functioning sensory organs of the body. It controls body movements, perception, emotions, memory and complex abilities like calculations, logic and critical thinking. The brain stem connects the cerebrum to the spinal cord. The motor and sensory signals processed in the cerebrum are transmitted by the brain stem to the spinal cord. The cerebellum is that small structure that lies in the base of the cerebrum. It is responsible for attention and precision in the body's motor skills.
The Spinal Cord
The spinal cord is the elongated tissue protected by the vertebral column. It transmits signals from the brain to different parts of the body. It controls reflexes. There are sense receptors near the skin that is connected to the nerve fibers in the spinal cord. Damage to the spinal cord greatly affects mobility.
The Peripheral Nervous System
The peripheral nervous system is composed of the nerves and ganglia. The peripheral nervous system channels the impulses from the brain to the body surface and to the different internal organs. Nerves are composed of organized arrangement of the axons and dendrites in many neurons. Sensory nerves are the nerves that send signals from an external stimuli and internal organs to central nervous system. Motor nerves carry the signals from the central nervous system to the different organs. These are the nerves that carry the signal to skeletal muscles which then creates movements like walking and running. Neurons when grouped comprised the ganglia.
The human nervous system is a complex biological structure that controls all bodily functions. Senses, perception, emotions and movement are processed by the nervous system. It has an important role in human anatomy.