The document discusses the nervous system and its components. It is divided into the central nervous system and peripheral nervous system. The central nervous system comprises the brain and spinal cord. The brain is made up of the cerebrum, cerebellum, and brain stem. Neurons are the basic functional units that transmit nerve impulses. The peripheral nervous system includes the somatic, sensory, and autonomic nervous systems. The autonomic nervous system regulates involuntary body functions and is divided into the sympathetic and parasympathetic systems. Common disorders of the brain include cerebral hypoxia and dementia.

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