In biology, the nervous system is the highly complex part of an animal that coordinates its actions and sensory information by transmitting signals to and from different parts of its body.
In another definition: The nervous system is the major controlling, regulatory, and communicating system in the body. It is the center of all mental activity including thought, learning, and memory. Together with the endocrine system, the nervous system is responsible for regulating and maintaining homeostasis. Through its receptors, the nervous system keeps us in touch with our environment, both external and internal.
Like other systems in the body, the nervous system is composed of organs, principally the brain, spinal cord, nerves, and ganglia. These, in turn, consist of various tissues, including nerve, blood, and connective tissue. Together these carry out the complex activities of the nervous system.
The various activities of the nervous system can be grouped together as three general, overlapping functions:
1. Sensory
2. Integrative
3.Motor
Millions of sensory receptors detect changes, called stimuli, which occur inside and outside the body. They monitor such things as temperature, light, and sound from the external environment. Inside the body, the internal environment, receptors detect variations in pressure, pH, carbon dioxide concentration, and the levels of various electrolytes. All of this gathered information is called sensory input.
Sensory input is converted into electrical signals called nerve impulses that are transmitted to the brain. There the signals are brought together to create sensations, to produce thoughts, or to add to memory; Decisions are made each moment based on the sensory input. This is integration.
Based on the sensory input and integration, the nervous system responds by sending signals to muscles, causing them to contract, or to glands, causing them to produce secretions. Muscles and glands are called effectors because they cause an effect in response to directions from the nervous system. This is the motor output or motor functions.
The nervous system consists of two main parts:
1. Central Nervous System (CNS): Includes the brain and spinal cord.
2. Peripheral Nervous System (PNS): Comprises nerves that connect the CNS to the rest of the body.
Subdivisions of the Peripheral Nervous System, the PNS is further divided into:
1. Somatic Nervous System: Controls voluntary movements.
2. Autonomic Nervous System: Regulates involuntary functions, such as heart rate, digestion, and breathing.
Importance of the Nervous System
The nervous system plays a vital role in maintaining overall health and function. Damage to the nervous system can lead to various disorders, such as paralysis, Parkinson’s disease, and multiple sclerosis.
In summary, the nervous system is a complex network that enables communication, control, and coordination within the body. Its proper functioning is essential for maintaining overall hea
lth and well-being.