Central Nervous System. The CNS consists of the brain and the spinal cord.
The brain and the spinal cord are protected by the skeleton – brain by the cranium and spinal cord by the the vertebral column.
Brain. It is the highest coordinating center in the body.
The brain is broadly divided into three region:Fore-brain,mid-brain, hind-brain.
Force-brain includes cerebrum and olfactory lobes. Fore-brain is the main thinking part of the brain dome-shaped roof of the brain.
It is the largest part of the brain.
Different areas of cerebrum have different functions.
For example, the cerebrum has sensory areas where information is received from the sense organ called receptors.
Similarly , cerebrum has motor areas from where instructions are sent to the various muscles of the body called effectors to do the various jobs.
There are specific regions in cerebrum for each kind of stimulus and response. for example. Occipital lobe is the region for hearing, i.e, visual reception, Temporal lobe is the region for hearing , i.e., auditory reception.
Frontal lobe is the region for speech , facial muscular activities and higher mental activities.
Parietal lobe is the region for taste, smell touch and conscious association.
Olfactory lobes in the fore-brain lie below the cerebrum. They contain olfactoreceptors which are the organ of smell.
Mid-brain connects the fore-brain to hind-brain. It controls reflex movements of the head, neck and truck in response to visual and auditory stimuli.
Hind brain consists of three center called cerebellum, pons and medulla oblongata
Cerebellum. lies at the roof of the hind-brain. This region controls the coordination of body movements and posture.
Medulla oblongata lies at the floor of the hind-brain and continues into the spinal cord. It is also the regulating center for swallowing . coughing, sneezing and vomiting.
Function of Brain
– The brain receives information carrying impulses from all the sensory organs of the body.
– The brain responds to the impulses brought in by sensory organs by sending causing them to function accordingly.
– The brain correlates the various stimulli from different sense organs and produces the most appropriate and intelligent response.
– The brain coordinates the bodily activities so that the mechanisms and chemical reactions of the body work together efficiently.
– The brain stores ‘information’ so that behaviour can be modified according to the past experience, This function makes brain the organ of thought and intelligence.
Spinal Cord – It is a cylindrical structure and a part of the central nervous system. It is made up of nerves which supply information to think.
– it begins in coordination with medulla oblongata and extend downwards.
– it is enclosed in a bony cage called vertebral column.
– A total of thirty one pairs of spinal nerves arise from the spinal cord.
Functions of Spinal Cord – Spinal cord is the main center of reflex action. it is concerned with the conduction of nerve impulses to and from the brain.
Peripheral Nervous System – Constitute the cranial and spinal nerves along with their branches.
– Cranial nerves arise from the brain and spread throughout the head. There are twelve pair of cranial nerves.
– Spinal Nerves arise from the spinal cord along most of it length and spread throughout the body.
– There are 31 pairs of spinal nerves – eight in the neck region, twelve in chest region, five in abdominal region, five in help region and one in the coccyx is the last bone of the vertebral column.
Autonomic Nervous System (ANS) means ‘self governing nervous system’
– Autonomic nervous system is called visceral nervous system.
– It lies outside and parallel to CNS.
– ANS consists of a pair of chain of nerves and ganglia found on both sides of the vertebral column.
– The autonomic nervous system can be classified anatomically and functionally into sympathetic and parasympathetic nervous system.
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