All living organisms sense changes or stimuli in their environment and respond to them. For proper response to stimuli, many organs in the body need to work together in coordination.
The coordination in humans takes place through two ways, namely, chemical pathway and nervous pathway.
The nervous system is a control system that sends electrical signals called nerve impulses throughout the body.
The nerve impulse is sent by a specialised cell called neuron or nerve cell.
Neuron is the structural and functional unit of the nervous system. It is made up of the cell body (cyton), dendrites and axon.
The junction between neurons is called a synapse.
A nerve is a bundle of axons enclosed in a tubular sheath. The sheath or the envelope imparts insulation. This prevents escape of impulses to adjacent tissues.
The nerves are of three types:sensory nerves, motor nerves and mixed nerves.
The nervous system can be grouped intocentral nervous system and peripheral nervous system.Peripheral nervous system is further divided into somatic and autonomic nervous system.
Autonomic nervous system is further divided into sympathetic and parasympathetic nervous system.
The brain and spinal cord together constitute the central nervous system.The brain is divided into three main parts: the cerebrum, the cerebellum and the medulla oblongata.
The spinal cord extends from the medulla of the brain.It runs along the length of the backbone. The outer wall of the spinal cord is white and made up of axon. The inner wall is grey and is made up of cell bodies.
Spinal and cranial nerves constitute the peripheral nervous system.
Nerves collect information from the body as well as from the external surroundings and send them to the brain. Brain is the decision maker of the body. Brain processes all the information received from the nerves.
Peripheral Nervous System as well as spinal nerves control reflex actions.
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There are two types of nerves that constitute peripheral nervous system, one is Spinal nerve and the second isMarks:1
Cranial nerves are nerves that emerge directly from the brain stem in contrast to spinal nerves which emerge from segments of the spinal cord.
Involuntary actions like blood pressure, vomiting and salivation are controlled byMarks:1
It controls autonomic functions that are involuntary and relays nerve signals between the brain and spinal cord. The medulla oblongata which is present in hind brain is responsible for controlling several major functions of the body: respiration, blood pressure, heart rate, reflex arcs and vomiting.
Central Nervous System consists ofMarks:1
The central nervous system (CNS) represents the largest part of the nervous system, including the brain and the spinal cord. Together with the peripheral nervous system, it has a fundamental role in the control of behaviour.
Control and coordination is provided byMarks:1
The nervous system receives stimuli, processes the information and sends signals for appropriate action to be taken. It plays the central role along with endocrine system to coordinate and control all body functions.
Neuron is the functional unit of:Marks:1
The neurons are the functional units of nervous system, which respond to stimuli by electrical impulses.