Functions of nervous system Classification of nervous system- central nervous system and peripheral nervous system.

1. NERVOUS
SYSTEM
SALMA ASGHAR
M.Sc (NUTRITION
AND DIETETICS)

2. •It is the master controlling and communicating system of the body.
•It controls and coordinates all the activities of the body
FUNCTIONS:
Sensory function: Gathers information from both inside and
outside the body.
Integration function: Processes the information in the brain
and spine.
Motor function: Transmit information to the processing areas
of the brain and spine.

4. CENTRAL NERVOUS SYSTEM (CNS)
~It includes brain and spinal cord.
~It is referred to as central because it combines information from the
entire body and co-ordinates activity across the whole organism.
~ These organs work together to integrate and co-ordinate sensory and
motor information for the purpose of controlling the various tissues,
organs and organ system of the body.
~It is formed by neurons and supporting cells called Neuroglia.
~Brain and Spinal cord are surrounded by three layers of meninges
called the outer dura mater, middle arachnoid mater and the inner pia
mater.

5. BRAIN:
~It is situated in the skull.
~It consists of-
• cerebrum
• cerebellum
• diencephalon
• medulla oblongata
•midbrain and
•pons

6. CEREBRUM:
~It forms bulk of the brain.
~It is divided into two hemisphere - left and right.
~The hemispheres are further divided into 4 lobes-
•Frontal ( Reasoning and thought)
•Parietal (Integrates sensory information)
•Temporal (Processes auditory information from ears)
•Occipital (Processes visual information from the eyes)

7. CEREBELLUM:
~Major functions of cerebellum are
-muscle contraction
-balance
-posture
-muscle tone
-maintenance of movements.

8. DIENCEPHALON:
~It includes thalamus and hypothalamus
THALAMUS:
~It directs sensory impulses to cerebrum.
HYPOTHALAMUS:
~It controls and regulates the functions of ANS
-Temperature, appetite, water balance, sleep, and blood
vessel constriction and dilation.
~It also plays a role in anger, pleasure, pain and affection.

9. MIDBRAIN:
~It is responsible for eye and auditory reflexes.
PONS:
~It is responsible for certain reflex actions.
MEDULLA OBLONGATA:
~It regulates - digestion, respiration, swallowing, coughing,
sneezing, blood pressure, heart and blood vessel function.

10. THE SPINAL CORD:
~It is a link between brain and nerves in the rest
of the body.
~It consists of 4 regions- cervical, thoracic,
lumbar and spinal nerves (efferent and afferent)
~Afferent carries information from body to the
brain.
~Efferent carries information from brain to body
~ It acts as the middleman between the
receptors and the effectors, as it conducts
sensory and motor impulses to and from the
brain.

11. PERIPHERAL NERVOUS SYSTEM:
~ It is formed by the nerves that are associated with the brain (cranial nerves)
and the spinal cord (spinal nerves).
~It connects CNS to the organs, limbs and skin.
~These nerves extend from the CNS to the outermost areas of the body.
~Cranial nerves-12 pairs in man.
~Spinal nerves-31 pairs in man.
~ It is again divided into two subdivisions:
•SOMATIC NERVOUS SYSTEM
•AUTONOMIC NERVOUS SYSTEM

12. SOMATIC NERVOUS SYSTEM:
~It is part of PNS responsible for carrying
sensory and motor information to and fro
from the CNS.
~It is made up of nerves that connect to the
skin, sensory organs and skeletal muscles
~ It is responsible for nearly all voluntary
muscle movements.
~Processes sensory information from
external stimuli (hearing, touch and sight).
.

13. ~The structures that allow this communication to happen
are- afferent sensory neuron
- efferent motor neuron
~ Afferent neurons take information from nerves to CNS.
~ Efferent neurons take information from CNS to muscle
fibres throughout the body.

14. AUTONOMIC NERVOUS SYSTEM:
~The ANS is the portion of the nervous system
that controls most visceral function of the body.
~This system helps to control arterial pressure,
gastrointestinal secretion, urinary bladder
emptying, sweating, body temperature and other
activities.
~One of the most striking characteristics of ANS is
the rapidity and intensity with which it can change
visceral functions.

15. ~ For instance, within 3-5 sec it can increase the heart rate to
twice the normal and within 10-15 sec the arterial pressure
can be doubled.
~At the other extent, the arterial pressure can be decreased
low enough within 10-15 sec to cause fainting.
~ Sweating can begin within seconds and urinary bladder
may empty involuntary also within seconds.
~ The ANS is activated mainly by centres located in the
spinal cord, brainstem and hypothalamus.

16. ~ Autonomic nervous system
consists of two subdivisions:
• Sympathetic division
• Parasympathetic division

17. SYMPATHETIC DIVISION:
~It is otherwise called thoracolumbar outflow because, the preganglionic
neurons are situated in lateral gray horns of thoracic and first two lumbar
segments of Spinal cord.
~ Sympathetic division supplies smooth muscle fibres of all the visceral organs
such as blood vessels,heart, lungs, glands, gastrointestinal organs etc,.
~ Allow body to function under stress.
~Flight or fight.
~ Primes body for intense skeletal muscle activity.

18. PARASYMPATHETIC DIVISION:
~It is otherwise called Craniosacral outflow because, the fibres of this division
arise from the brain sacral segments of Spinal cord.
~Maintains functions
~Rest and digest.
~Counterbalances sympathetic functions.

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