This document provides an overview of the nervous system, including its main components and functions. It discusses the central nervous system (CNS) which includes the brain and spinal cord, and the peripheral nervous system (PNS) which includes nerves connecting the CNS to other parts of the body. It describes the types of cells in the nervous system including neurons and neuroglia. Key topics like nerve conduction, synapses, neurotransmitters and the autonomic nervous system are summarized. The regeneration potential of the PNS is also briefly covered.

3.  INTRODUCTION
 TERMINOLOGIES
 NEURON
 NERVE FIBER AND FACIAL NERVE FIBERS
 NERVE CONDUCTION PROCESS
 SYNAPSE
 NEUROTRANSMITTER
 NEUROMUSCULAR JUNCTION
 AUTONOMIC NERVOUS SYSTEM
 REGENERATION POTENTIAL

4.  Nervous system controls all the activity of the
body.
 It is quicker than other control system in the
body which is endocrine system.
 Primarily, the nervous system is divided into the
two parts
Central nervous system
Peripheral nervous system

5.  Central nervous system
-brain and spinal cord
(Integrating/command centre)
 Peripheral nervous system
-Nerves from brain and spinal cord

6.  Brain tissue is made up of the large number
of the neurons which can be called as
functional unit i.e. one neuron can function
itself
 Neuron consist of three part
Cell body
Axon
Dendrite
 Collection of cytons together forms gray
matter
 Collection of peripherial process together
forms white matter

7. Neuron
Cell Body ( cytons )
Axon
Dendrite

8. Protein‐lipid filled cytoplasm of Schwann cells
– Neurilemma
– Myelin sheath
• Protects/insulates AXON

9.  NUCLEUS: Collection of cytons in side CNS is known
as nucleus.
 GANGLION: Collection of cytons out side the CNS is
known as ganglion.
 TRACT: Collection of axon in side CNS is know as
tract.
 NERVE: Collection of axon outside CNS is known as
nerve.
cranial nerve
spinal nerve
Facial nerve is seventh cranial nerve arising from
second branchial arch.

10. CENTRAL NERVOUS SYSTEM:brain and spinal cord
PERIPHERAL NERVOUS SYSTEM
sensory division motor division
Sympathetic division parasympathetic division
Visceral
sensory
division
Visceral
motor
division
Somatic
motor
division
somatic
sensory
division

12. TYPES OF CELLS FOUND INTHE NERVOUS
SYSTEM
• Neurons : excitable cells
motor neuron
sensory neuron
• Neuroglia: supporting cells (glial cells)
non excitable cells
GLIAL CELLS IN PNS
 Satellite cells -regulate o2 ,co2,neutrients and
neurotransmitter around ganglia
 Schwann cells-myelin sheaths formation

13. GLIAL CELLS IN CNS
 Astrocyte-most abundant, blood brain barrier
 Microglia-removes the debris (phagocytosis)
 Ependymal cells-produce CSF
 Oligodendrocytes-myelin sheath formation

15.  Depending upon structure
- myelinated nerve fibre
-non myelinated nerve fibre
 Depending upon distribution
- somatic nerve fibre
-visceral or autonomic nerve fibre
 Depending upon source
-cranial nerve
-spinal nerve

16.  Depending upon function
-motor nerve fibre
-sensory nerve fibre
 Depending upon chemical neurotransmitter
-adrenergic nerve fibre(nor-adrenalin)
-cholinergic nerve fibre(acetylcholine)
 Depending upon the thickness
thickness = conduction velocity
type 1 -A alpha fibre (12 to 24 micron)
type 2 -A beta fibre (6 to 12 micron)
type 3 -A delta fibre (2 to 5 micron)
type 4 - C fibre (1.5 micron)

17.  SpecialVisceral Efferent (Branchial Motor fiber)
 GeneralVisceral Efferent (Parasympathetic fibers)
 SpecialVisceral Afferent (Taste)
 General Sensory

19. motor cortex  bilateral facial motor nuclei (pons)
 facial muscles
supply the facial muscles and stapedius muscle

20.  Superior salivatory nucleus(pons)  nervus intermedius
greater/superficial petrosal nerve 
spheno /pterygopalatine ganglion 
postganglionic parasympathetic fibers 
lacrimal gland & seromucinous glands of nasal
and oral cavity
 Superior salivatory nucleus  nervus intermedius 
chorda tympani  joins lingual nerve 
submandibular ganglion – postganglionic
parasympathetic fibers  submandibular and
sublingual glands

22.  nucleus solitaries –> tractus solitarius –>
nervus intermedius –>
geniculate ganglion –>
chorda tympani 
joins lingual nerve  anterior 2/3 tongue, soft
and hard palate

23.  These fibers innervate a part of the skin and ear.
Its fibre communicate with the vegus nerve fibre.

24. • Function
– Sensory (afferent neurons)
– Motor (efferent neurons)
– Interneurons
(association neurons)
Facial nerve is mixed nerve mainly motor and
partly sensory

25.  Nerve impulse is transmitted through a nerve fibre
(axon) electrochemically.
 it is not a flow of electrons as in electric current but it
travel as wave of depolarization.
EXCITABILITY: excitability is defined as the
physiochemical changes in a tissue when stimulus is
applied
 Stimulus two type of response accure
Action potential(nerve impulse)
Electronic potential(local response)
(firing level below15mv)

27.  ACTION POTENTIAL:
Strength of the stimulus must be adequate to
produce the action potential
this is known as threshold or minimal stimulus
Resting potential=-70MV
Firing level=-55MV
Depolarization
end at =+35MV

28. Resiting membrane potential in nerve fibre is
- MV.
When stimulus is applied to nerve membrane this
potential increase this is known as depolarization.
In normal (resting) condition nerve is in polarized
state
This is maintained by,
1. Na+ - K+ pump (three Na+ pumped out for every K+
inside)
2. more permeability to K+ than Na+.
3. Immobile (-) vely charged protein ions occur inside.

30. When an axon receives stimulus
A wave of depolarization passes through it. It
reverses the membrane potential with inner surface
becoming positive and outer surface electronegative due
to
1. membrane becoming 10 times more permeable to Na+
(than K+) and
Na+ from extra cellular fluid the neuron interior .
2. stoppage of Na+ - K+ pump
Repetition of this process produces a wave of
stimulation along the axon

31.  Action potential transmitted through the nerve fiber
as nerve impulse.
 Depolarization accure at first spot cause the
depolarization of neighbour area.
 This depolarization travel through nerve fiber.
 Conduction from myelinated nerve fiber is 50 time
more faster then non myelinated nerve fiber
 Because meyelin seath forms an effective insulator
and action potential jump from
one node of renvier to another
so conduction is faster.

32.  The Junction between the two neuron is called
synapse. It is physiologic continuation.
 As there is a gap between the junctions we have
to explain how the nerve impulse generated in
one nerve is passed to the other nerve through
this synaptic junction.

33. 1. Cholinergic transmission i.e. those nerves which
on stimulation secrete
acetylcholine at the nerve ending.They are
a. Parasympathetic nerves of autonomic nervous
system
b. Somatic nerves i.e. nerves supplying the skeletal
muscles.

34. 2. Adrenergic transmission that means those
nerves which will be
secreting adrenaline at the nerve ending when
stimulated.
The fiber of this category is only one i.e.
sympathetic fiber of A.N.S.

35. 1.A.P Arrival of the stimulus at the synaptic junction.
2.This stimulus will release Ca.
3.This Ca will break the vesicle releasing acetylcholine.
4.This acetylcholine can easily pass through the
synaptic junction.
5.This acetylcholine will depolarize the membrane
thereby forming the nerve impulse again.
6.This nerve impulse passes to the next node.

37.  Chemical mediator substances responsible for
the transmission of impulse through synapse.
 Small molecules -acetylcholine
- nor adrenalin, dopamine
serotonin, histamine(amines)
-Amino acid- GABA, glycine
glutamate
 Large molecules- substance p

38.  Synthesized in presynaptic neuron.
 Stored in synaptic vesicle.
 Some neurotransmitters causes excitation of
post synaptic neuron other causes inhibition.
 EXCITATORY-Acetylcholine, Nor adrenalin
 INHIBITORY-GABA, Dopamine

39.  Nerve impulse stimulates the release
of a neurotransmitter (acetylcholine) from
synaptic vesicles into synaptic cleft
 Stimulates muscle impulse (MAP)
 Impulse spreads across sarcolemma and into
fiber along theT-tubules .
 This impulse causes an increase in the cisternae's
permeability to calcium ions.

40.  The sarcoplasmic reticulum has a high conc. of
Ca++.
 Calcium ions diffuse into the sarcoplasm ' the
Ca++ causes the formation of "cross
bridges" between the actin and myosin filaments
' the filaments slide between each other.
 This shortens the myofibrils which in turn
shorten the muscle fibers, which shortens the
muscles

42.  PAIN :- It is defined as unpleasant sensations and emotional
experience with or without actual tissue damage.
 GATE CONTROLTHEORY:-
 Nerve fibers with smaller diameter carry the pain stimuli
through the gate mechanism present in spinal cord
 Nerve fiber with large diameter carry the other stimuli like
touch and pressure passes through the same gate.
 Large nerve inhibits transmission of the pain signals by smaller
nerves through gate.

43.  Autonomic nervous system concern with
regulation of function, which are beyond
voluntary control. By controlling various
vegetative functions.
 It helps in maintenance of constant internal
environment (homeostasis)
 All visceral components are supplied by the
sympathetic or parasympathetic division of ANS

44.  Two division produce and antagonistic effect on
each organ.
 When fibers from one devision supplying organ is
sectioned or affected by lesion, the effect from
fibers from other division on the organ become
more prominent.

45.  Degenerated nerve may be regenerated.
Regeneration mainly accure in PNS due to
presence of myelin sheath.
 It accur only in favorable condition.
Following criteria are necessary
 Gap between the cut should less than 3 mm.
 Neurilemma should be present.As it is absent in
CNS regeneration does not accur in CNS.
 Nucleus must be intact.
 Two cut end should be in same line.

46.  Cells of Schwann from proximal and distal cut
end grow in all direction and form pseudopodia
like fibrils
 Fibril from one end join with fibril of another end.
 Filling the gap lead to development of continuity
of Neurilemmal tube.
 myelin seath is formed by Schwann cell
myelination is completed in one year.
 Nissl granules appear followed by Golgi
apparatus.
 Functional recovery accur after long period.