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1. GROUP THREE
 AHORGBA CONSTANT XORLALI
 BOATENG MERCY
 TEI PADDY
 LEPOAH K.KUMATOR

2. OUTLINES
 Nervous system
 Composition of the nervous system
 Explanation of the compositions
 Disorder of the central nervous system
 References

3. NERVOUS SYSTEM`
It is a complex network of nerves
and cells that carry messages to
and from the brain and spinal cord
to various part of the body.
It is made up of; central nervous
system and peripheral nervous
system.

4. CENTRAL NERVOUS SYSTEM
 It comprises the brain and the spinal cord
THE BRAIN
 This is the part of the central nervous system
which lies within the cranium.
 It weighs about 1.3 to 1.4 kg.
 The components are;
• Cerebrum(fore brain)
• Cerebellum(hind brain)
• Brain stem comprises the mid brain, the Pons varolii and
Medulla oblongata

5. COMPONENTS OF THE BRAIN
FORE BRAIN
 It is dominated by cerebral hemisphere(cerebrum).
 It is the region where thalamus and hypothalamus are
found.
CEREBRUM
 It is the largest part of the brain.
 It fills the cavity of the cranium.
 It is divided into two hemispheres.i.e right and left cerebral
hemisphere.
 Each hemisphere is divided into 4
parts.i.e.front,parietal,temporal and occipital

6. CEREBRUM

7. FUNCTIONS OF THE CEREBRUM
 It controls all voluntary actions such as thinking.
 It contains motor centers which initiates and
controls all movements of the body.
 It is the center of intelligence, imagination and
memory.
 It contains the centers for sight, hearing, taste,
smell and speech.

8. HYPOTHALAMUS
 It is located just below the thalamus hence the name.
 It controls some involuntary actions.
 It is concerned with a number of homeostatic mechanism
such as temperature control, water balance and CO2 levels
in the blood.
THALAMUS
 it is situated just below the corpus callosum
 It serves as the major relay station for sensory impulses
such as pain, temperature, pressure and touch from the
periphery of the body.

9. THALAMUS

10. PONS
 It serves as a relay station between cerebellum, spinal
cord and the rest of the brain.
 It consist mainly on nerve fibres [white matter] that forms
a bridge between the two hemispheres of the cerebellum.
MEDULLA OBLONGATA
 It is the posterior part of the brain.
 It is responsible for most involuntary actions such as
heartbeat, sneezing, coughing, vomiting and swallowing.
 It is located between the spinal cord and Pons.
 It is only about one inch long.

11. CEREBELLUM
 It is situated behind the Pons and
immediately below the posterior portion
of the cerebrum.
 It is made up of two hemisphere namely;
 Left and Right cerebellar hemispheres
 It is responsible for maintenance of
balance, locomotion and positioning of
the body
 It regulates and coordinates muscular
movement especially skeletal muscles

12. NEURONES
 The nervous system is made up of units
called neurones or nerve cells, which are
highly specialized for their functions of
receiving and conducting impulses.
 It consist of parts such as,
• Cell body which consist of a large nucleus
and dense, granulated cytoplasm.
• Dendrites which receive and carry incoming
impulses towards cell bodies.

13. CONT..
• The Axon which carries impulses away from
the cell body.
TYPES OF NEURONS
 Sensory neurones; it transmit impulses from
sensory cells to the central nervous system.
 Motor neurones; it carries impulses from the
central nervous system to the effector
organs(muscles and glands)
 Relay neuron; it connects the sensory neuron
to the motor neurones

14. NEURONS

15. MENINGES
 It is the layers that cover the brain and the spinal cord
completely.
 The layers are;
• Dura mater; is the outer layer of the brain and spinal cord.
• Arachnoid mater; is the middle layer of fibrous tissue
between the Dura and Pia matter.
 Pia matter; it is a delicate inner layer of connective tissue
containing many minute blood vessel.
 Between the Pia mater and Arachnoid mater is a fluid
called CEREBROSPINAL FLUID.
 The fluid support and nourish the spinal cord.

16. MENINGES

17. SPINAL CORD
 It is elongated, almost cylindrical part of the
central nervous system.
 It has meninges and cerebrospinal fluid
surrounding it.
 It is about 45cm long in adult and about the
thickness of the little finger.
 It serves as a tissue link between brain and the
rest of the body
 It also serve as pathway through which
impulses are conveyed from the brain.

19. REFLEX ACTION AND REFLEX ARC
 Reflex action is a quick, automatic response to
stimuli.
 Reflex arc is the nervous pathway taken by
nerve impulses in a simple reflex action.
voluntary and involuntary action
 Voluntary actions are actions that are under the
control of the will or actions initiated consciously.
Unlike reflex actions,which involves the brain.
Eg walking, talking, clapping and singing.
 Involuntary actions are actions that are not
under the control of the will. Eg sneezing,
breathing etc

20. PERIPHERAL NERVOUS SYSTEM
 It compose of sensory nerve fibres
transmitting afferent impulses from sensory
organs to the brain, motor nerve fibres
transmitting efferent from the brain to the
effector organs.
 It is divided into three;
 Somatic nervous system
 Sensory nervous system
 Autonomic nervous system

21. SOMATIC NERVOUS SYSTEM
 It is under voluntary control and transmit signals
from the brain to end organs.
 It associated with the skeletal muscle voluntary
control of the body movement.
 It consists of;
• Afferent nerves which are responsible for
relaying sensation from the body to the CNS.
• Efferent nerves which are responsible for
sending out commands from the CNS to the
body

22. SENSORY NERVOUS SYSTEM
 It is the NS that transmit signals.
 It detects stimuli from outside the body
 It includes the eyes,ears,nose,tongue and
skin

23. SNS

24. AUTONOMIC NERVOUS SYSTEM
 It is a division of PNS that influences the
functions of internal organs.
 It control system that act largely
unconsciously and regulate body function.
 It is the main primary mechanism in control
of the fight-or-flight response.
 It is regulated by the hypothalamus.
 It is branch into; sympathetic and
parasympathetic

25. AUTONOMOUS

26. SYMPATHETIC NERVOUS SYSTEM
 It activity tends to predominate in stressful
situation.
 It functions opposite to parasympathetic NS in
order to maintain balance.
 It mobilizes the body for fight or flight.
 Its effect on stimulation on the heart, blood
vessel and lungs enable the body to respond by
preparing it for exercise.
 It stimulation prepare the body to deal with
exciting and stressful situation.

27. SYMPATHETIC

28. PARASYMPATHETIC NS
 It has the tendency to slow down body
processes except digestion and absorption of
food.
 It function in opposing manner to maintain
balance.
 Its general effect is that of a ‘peace-maker’

29. PARASYMPATHETIC

30. EFFECT OF AUTONOMIC STIMULATION
1. Cardiovascular system
 Sympathetic stimulation’;
 Increase the rate and force of heart beat
 Dilates coronary arteries
 Parasympathetic stimulation;
 Decreases the rate and force of heartbeat
 Constricts the coronary arteries

31. CONT..
 Eye;
Sympathetic stimulation;
• Dilating of the pupil
Parasympathetic stimulation;
• Constriction of the pupil
 Digestive and urinary system
Sympathetic stimulation;
• The liver increases conversion of glycogen to
glucose
Parasympathetic stimulation;
• The secretion of bile is increased

32. DISORDER OF THE BRAIN
 Cerebral hypoxia; disturbance in the auto
regulation of blood supply to the brain.
 Condition affecting the cerebral blood vessel
 Dementia; it is caused by progressive
irreversible of degenerating of cerebral
cortex and result in mental deteriorating

33. INFECTIONS OF CNS
 Bacterial infections.e.g
Bacterial meningitis refers to the
inflammation of the sub-arachnoids space
and is most commonly transmitted through
contact with an infected person

34. REFERENCES
 Ross and Wilson
 www.google.com
 wikipedia