Presentation

1. Cells and tissues of the
nervous system
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2. Nervous System
Central Nervous
System (CNS)
Consists of :
1. Brain
2. Spinal Cord
Peripheral Nervous
System (PNS)
Somatic Nervous System
Carries out mostly Voluntary
functions like Skeletal muscle
movement.
Autonomic Nervous System
(ANS)
Functions are mostly autonomic
(involuntary)
Sympathetic
Nervous System
Parasympathetic
Nervous System
Classification of the Nervous System

3. Neurons
 The entire nervous
system is made up
of Neurons
(Functional units)
 Each neuron consist
of a cell body and its
processes, one axon
and many dendrites.
 Bundles of axons
bound together =
Nerves
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4.  Neurons generate and transmit electrical
impulses called action potential.
 Some neurons initiate nerve impulses while
others act as ‘relay stations’ where
impulses are passed on.
 Transmission of nerve signals is both
electrical and chemical.
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5. Neuron
 Cell body
 Axons and dendrites
 Cell body : Cell bodies form the grey matter of
the nervous system. Grey matter is found at
the periphery of the brain and in the centre of
the spinal cord.
 Groups of cell bodies in CNS = nuclei
 Group of cell bodies in PNS = ganglia
 Important exception: basal ganglia is situated
within cerebrum
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6.  Axons and dendrites are extensions of
cell bodies and form the white matter of
nervous system.
 Within the brain, groups of axon = tracts
 Groups of axon outside brain and spinal
cord are called nerves or nerve fibres.
 Each nerve cell has only one axon which
begins from an area called axon hillock.
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7. Structure of Axon
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8. Action potential
Node or
Ranvier
Schwann cell
a. Non-myelinated neuron, b. Myelinated neuron
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11. After an action potential arrives at an axon terminal and
calcium ions enter the cell, synaptic vessicles fuse with the
presynaptic membrane.
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12. Neurotransmitter molecules are released and
bind to on the postsynaptic membrane.
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13. When a stimulatory neurotransmitter binds to a receptor,
Na+ diffuses into the postsynaptic neuron.
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14. Nerves
 Within brain and spinal cord (CNS) = Tracts
 Outside CNS = Nerves or nerve fibres
 A nerve consists of numerous neurones
collected into bundles and each bundle has
several coverings of protective connective
tissue.
 Endoneurium
 Perineurium
 Epineurium
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15. Transverse section of a peripheral
nerve showing the protective
covering
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16. Sensory or Afferent nerves
 They carry information from the body to the
spinal cord and the brain.
 Sensory receptors: They respond to
changes inside & outside the body.
o Somatic, cutaneous or common senses
o Propriorceptor senses
o Special senses
o Autonomic afferent nerves. Originate from
internal organs, glands & tissues. e.g.
baroreceptors & chemoreceptors
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17. Motor or efferent nerves
 Originate from the brain, spinal cord and
the autonomic ganglia and transmit
impulses to the effector organs.
 There are two types:
o Somatic nerves
o Autonomic nerves (sympathetic and
parasympathetic)
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18. Neuroglia
 Neurons of CNS is supported by four
non-excitable glial cells which
continue to replicate throughout life.
o Astrocytes – constitute the BBB
o Oligodendrocytes
o Ependymal cells
o Microglia – derived from monocytes
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