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.
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
3.
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
7.
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
9.
10. What is the composition of nervous tissue?
1. Neuron ( nerve cell ) 2. Neuroglia
Nerve cell body 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.
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
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
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.
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
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
42.
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
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.