an easy introduction of nervous system. Detail theoretical information purposefully avoided. At the beginning of medical course, also biology student need to know about nervous system. Within short time this presentation give a simple overview of NS.

1. • General anatomy of nervous system

2. Nervous system
• Nervous system
integrates these
sensory information,
store information as
memory
Nervous system receives sensory
information
•From external environment
(temperature, vision, sound etc.)
•From body (touch, pressure, pain etc.)
Nervous system makes an appropriate
response, ex: movement of muscles

4. Simple flowchart of nervous system function
Skin > touch
> nerve (sensory nerve/afferent
fibre/ascending tract)
Brain
 nerve(motor nerve/efferent
fibres/descending tract)
 muscle> movement

5. CNS : PRINCIPLES ROLES
• Integrate and coordinate
incoming and outgoing neural
signals
• Carry out higher mental
functions such as thinking and
learning

6. Division of nervous system
• Structurally,
• Central nervous
system
Brain Spinal cord
• Peripheral nervous
system
Cranial nerves, Spinal
nerves, Autonomic
nerves

8. Functional division
Somatic nervous system,
is the part of
nervous
system which
control voluntary
activities
Autonomic nervous system,
is the part of nervous
system concerned with
the innervation of
involuntary structures,
such as the heart,
smooth muscle, and
glands within the body

10. What is the composition of nervous tissue?
1. Neuron ( nerve cell ) 2. Neuroglia
Nerve cell body Processes
Dendrite Axon

11. Nerve cell body
Nerve cell processes
Dendrite
Axon

12. Histological feature of neuron
nerve cell body
A centrally placed
spherical, unusually
large , euchromatic
(pale-staining)
nucleus with a
prominent
nucleolus,

13. Nissl body unique feature of neuron
Nissl bodies are
basophilic granular
areas formed by
the rER , iron &
free ribosomes.

14. Golgi complex
arranged
around the
periphery of
the nucleus.

15. Mitochondria are found through out of the cell body,
dendrites, and axons. They are spherical or rod shaped.

16. Axon hillock :
it is the area of
cell body which is
free of large
cytoplasmic
organelles. It is a
landmark to
distinguish
between axons
and dendrites in
both light & TEM
microscopes.

17. • Dendrites are
receptor processes that
receive stimuli from
other neurons or from
the external
environment
• Axon are effector
processes that transmit
stimuli to other
neurons or effector
cells

18. What is gray matter and
white matter?

19. Grey matter
Nerve cell body
Neuroglia
Blood vessel
White matter
Nerve processes
Neuroglia
Blood vessels
Neuroglia
Blood vessels

20. • Gray matter: Neuron cell bodies
Neuroglial cells
Blood vessels
• White matter: Processes of neuron
Neuroglial cells
Blood vessels

21. Location of gray & white matter in the CNS
• Cerebrum and
cerebellum ,
• Outer gray matter
• Inner white matter
• Spinal cord,
• outer part white
matter
• Inner gray matter

22. Gray matter matter

25. Classification of neuron
According to the polarity

26. According to function
Sensory neuron
Motor neuron

27. Neuroglia
• The neuron of the central nervous system are
supported by several varieties of non excitable
cells, which together are called neuroglia.
• They are smaller than the neuron
• Number of them 5-10 times greater than the
neuron

28. There are four types of neuroglial cells in CNS &
two types in PNS:
CNS
1. Astrocytes
(a) fibrous
(b) protoplasmic
2. Oligodendrocytes
3. Microglia
4. Ependyma
• PNS
1. Schwann cells
2. Satellite cells.

30. Protoplasmic Astrocytes Fibrous Astrocytes

31. Oligodendrocytes Microglia

32. Ependyma

33. Schwann cells:
It have the same
function as
oligodendrocytes but
are located around
axons in the peripheral
NS.
Axon

34. Functions of neuroglia
Name of the neuroglia Functions
Astrocytes Formation of blood brain barrier
Oligodendrocyte Myelination of nerve fibers in the CNS
Ependymal cells secrete, circulate and absorbed CSF
Microglia Phagocytic function in inflamed
brain (They are inactive in normal
brain)
Schwann cells Myelination of nerve fibers in the PNS

35. Development of neuroglia
Name of the
neuroglia
Functions
Astrocytes Neuroectoderm
Oligodendrocyte Neuroectoderm
Ependymal cells Neuroectoderm
Microglia Mesodermal in origin
Schwann cells Neural crest

36. What is myelin sheath?
• Axon of neuron is covered by
sheaths which are modified cell
membranes of schwann cells in PNS
and oligodendrocytes in CNS

37. Schwann
cells
Axon
Schwann cells undergo
spiraling around the axon

39. Myelination in the CNS by oligodendrocyte

40. Function of myelination
• It acts as an insulator
• Helps in impulse conduction

41. Ganglia
a collection of nerve cell bodies out side the
CNS
1. sensory ganglia of spinal nerves
(posterior root ganglia) and
cranial nerves
2. autonomic ganglia

43. Nucleus: a collection of nerve cell bodies of
neuron in the CNS is called nucleus
Example:
Dorsal nucleus of vagus
nucleus ambiguous,
nucleus of tractus solitarius

44. Grey matter
White matter
Nucleus

46. What is synapse?
• The synapse is the specialised
junctions between two or
more adjacent neurons.

47. How impulse go from one neuron to
another ?

49. What are the types of synapses?
According to the location of synapse in the post
synaptic neurons

50. • How nervous system is
worked ?

51. Simple reflex arc

53. Reflex arc
• A reflex may be define as an involuntary response
to a stimulus. It depends on the integrity of the
reflex arc .
A reflex arc consists of the following anatomical
structures:
Location
1) a receptor organ Skin, muscle, or tendon
2) an afferent neuron Posterior root ganglion
3) an effector neuron Example: Lower motor
neuron located in the
ventral horn of spinal
cord
4) an effector organ Example: Skeletal muscle

54. Structural organization of reflex may be two
types
•Monosynaptic reflex
Incoming axons of
the unipolar
primary sensory
neurons synapse
directly on a motor
neuron.
Example: tendon jerks
•Polysynaptic reflex
In these reflex one
or more
interneurons,
excitatory or
inhibitory,
intervene between
sensory and motor
neurons.

55. Polysynaptic reflex

56. Types of reflex
• Reflex may be divided into 4 groups:
1) superficial (or skin and mucous membrane) reflexes
Corneal reflexes, gag reflexes
2) deep (or myotatic) reflexes
Jaw jerk, knee jerk
3) visceral ( or organic) reflexes
Pupillary reflex
4) pathological (or abnormal) reflexes
Ankle clonus, Babinski’s sign