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PRESENTER
ROLL NO 119
PARA G2
NEURON
• It is the structural and the functional unit of
nervous system.
• The human nervous system contains
approximate 1...
STRUCTURE OF NEURON
INTRODUCTION ABOUT NERVE
FIBER
• A nerve fiber is a thread like
extension of a nerve cell and
consists of an axon and
myel...
Depending upon STRUCTURE
MYELINSHEATH In peripheral nervous system it is formed by
schwann’s cell. While in case of central nervous
system it is fo...
MYELINSHEATH The places ,where myelin sheath is absent are called
node of ranvier(2-3µm) and these are present once
about ...
 IT PREVENTS LEAKAGE OF IONS BY 5000 FOLDS.
 IT INCREASES VELOCITY OF CONDUCTION BY 5-50 FOLDS DUE TO
SALTATORY CONDUCTI...
Depending upon DISTRIBUTION
SOMATICNERVEFIBERS
 These are α type motor nerve fibers.
 The neurotransmitter released at the neuron endings is
acetylc...
AUTONOMICNERVEFIBERS
 they innervate smooth muscles , cardiac muscles and
glands.
 Their main work is to maintain homeos...
SYMPATHETICAND
PARASYMPATHETICNERVEFIBERS PREGANGLIONIC POSTGANGLIONIC
Release acetylcholine in both. Release acetylcholin...
Depending upon diameter and
velocity of conduction (Erlanger
and Grasser’s classification)
ERLANGER AND GRASSER’S CLASSIFICATION
• Erlanger and Grasser studied the action potential
of mixed nerve trunk by means of...
PROPERTIES CORELATED WITH DIAMETER
AS Diameter increases
• Velocity of conduction increases.
• Magnitude of electrical res...
• A GROUP
• B GROUP
• C GROUP
GROUPS OF NERVE FIBERS
A GROUP
• A group is composed of largest fibers.
• The fibers of this group are myelinated.
• Both sensory and motor in fu...
B GROUP
• The fibers of this group are myelinated.
• The B fibers are found solely in preganglionic
autonomic nerve.
C GROUP
• It is composed of smallest fibers.
• All the fibers of this group are unmyelinated.
• Mostly found in visceral a...
About the nerve fibers
RAJ NIDHI 24
Numerical classification
NUMERICAL CLASSIFICATION OF SENSORY NERVE FIBERS
RAJ NIDHI 27
MULTIPLE SCLEROSIS
• It is autoimmune disorder.
• Causes may be genetic or
environmental.
• Antibodies & white blood cells...
NO TREATMENT of this disease but some
drug like β-INTERFERON suppresses the
immune response, reduce the severity &
slow th...
PERIPHERAL NEUROPATHY
 Peripheral neuropathy is damage to nerves of peripheral nervous
system which may be caused by dise...
POLYNEUROPATHY
 It is pattern of nerve damage which is a quite different from
mononeuropathy and often more serious and a...
REFERENCES
 GUYTON
 GANONG ’S REVIEW OF MEDICAL PHYSIOLOGY
 INTERNET
RAJ NIDHI 32
RAJ NIDHI 33
classification of nerve fibers
classification of nerve fibers
classification of nerve fibers
classification of nerve fibers
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classification of nerve fibers

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about nerve fibers
It is the structural and the functional unit of nervous system.
The human nervous system contains approximate 1012 neurons.
A nerve fiber is a thread like extension of a nerve cell and consists of an axon and myelin sheath (if present) in the nervous system.
In peripheral nervous system it is formed by
schwann’s cell. While in case of central nervous system it is formed by oligodendroglia.
The places ,where myelin sheath is absent are called node of ranvier(2-3µm) and these are present once about 1-3 mm distance along the myelin sheath.
IT PREVENTS LEAKAGE OF IONS BY 5000 FOLDS.
IT INCREASES VELOCITY OF CONDUCTION BY 5-50 FOLDS DUE TO
SALTATORY CONDUCTION i.e. ABOUT 100 m/s IN CASE OF
MYELINATED NERVE FIBERS WHILE IN NONMYELINATED
IT IS ABOUT 0.25 m/s.
SALTATORY CONDUCTION CONSERVES ENERGY BECAUSE ONLY NODES OF RANVIER GET DEPOLARISED.
These are α type motor nerve fibers.
The neurotransmitter released at the neuron endings is acetylcholine(Ach).
It always leads to muscles excitation . Inhibition takes place centrally due to participation of interneurons.
they innervate smooth muscles , cardiac muscles and glands.
Their main work is to maintain homeostasis with the help of autonomic nervous system.
they can lead to either excitation or inhibition of effector organs
Erlanger and Grasser studied the action potential of mixed nerve trunk by means of cathode ray oscilloscope and they obtained the compounded spike. So they divided nerve fibers into 3 groups. They observed that the main cause of difference in nerve fibers is diameter
AS Diameter increases
Velocity of conduction increases.
Magnitude of electrical response increases.
Threshold of excitation decreases.
Duration of response decreases.
Refractory period decreases.

classification of nerve fibers

  1. 1. PRESENTER ROLL NO 119 PARA G2
  2. 2. NEURON • It is the structural and the functional unit of nervous system. • The human nervous system contains approximate 1012 neurons.
  3. 3. STRUCTURE OF NEURON
  4. 4. INTRODUCTION ABOUT NERVE FIBER • A nerve fiber is a thread like extension of a nerve cell and consists of an axon and myelin sheath (if present) in the nervous system.
  5. 5. Depending upon STRUCTURE
  6. 6. MYELINSHEATH In peripheral nervous system it is formed by schwann’s cell. While in case of central nervous system it is formed by oligodendroglia. COMPOSITION PROTEINS LIPIDS(CHOLESTEROL, LECITHIN & SPHINGOMYELIN)
  7. 7. MYELINSHEATH The places ,where myelin sheath is absent are called node of ranvier(2-3µm) and these are present once about 1-3 mm distance along the myelin sheath. FACTS
  8. 8.  IT PREVENTS LEAKAGE OF IONS BY 5000 FOLDS.  IT INCREASES VELOCITY OF CONDUCTION BY 5-50 FOLDS DUE TO SALTATORY CONDUCTION i.e. ABOUT 100 m/s IN CASE OF MYELINATED NERVE FIBERS WHILE IN NONMYELINATED IT IS ABOUT 0.25 m/s.  SALTATORY CONDUCTION CONSERVES ENERGY BECAUSE ONLY NODES OF RANVIER GET DEPOLARISED. About the myelinsheath
  9. 9. Depending upon DISTRIBUTION
  10. 10. SOMATICNERVEFIBERS  These are α type motor nerve fibers.  The neurotransmitter released at the neuron endings is acetylcholine(Ach).  It always leads to muscles excitation . Inhibition takes place centrally due to participation of interneurons.
  11. 11. AUTONOMICNERVEFIBERS  they innervate smooth muscles , cardiac muscles and glands.  Their main work is to maintain homeostasis with the help of autonomic nervous system.  they can lead to either excitation or inhibition of effector organs.
  12. 12. SYMPATHETICAND PARASYMPATHETICNERVEFIBERS PREGANGLIONIC POSTGANGLIONIC Release acetylcholine in both. Release acetylcholine in case of parasympathetic. Release either acetylcholine or norepinephrine in case of sympathetic. Myelinated B fibers. Unmyelinated C fibers are present in the case of sympathetic . Terminate on the postganglionic cyton Terminate on visceral effector. In case of sympathetic it is smaller than postganglionic nerve fiber and vice versa for parasympathetic nerve fiber. In case of parasympathetic it is smaller than preganglionic nerve fiber and vice versa for sympathetic nerve fibre
  13. 13. Depending upon diameter and velocity of conduction (Erlanger and Grasser’s classification)
  14. 14. ERLANGER AND GRASSER’S CLASSIFICATION • Erlanger and Grasser studied the action potential of mixed nerve trunk by means of cathode ray oscilloscope and they obtained the compounded spike. So they divided nerve fibers into 3 groups. They observed that the main cause of difference in nerve fibers is diameter RAJ NIDHI 17
  15. 15. PROPERTIES CORELATED WITH DIAMETER AS Diameter increases • Velocity of conduction increases. • Magnitude of electrical response increases. • Threshold of excitation decreases. • Duration of response decreases. • Refractory period decreases.
  16. 16. • A GROUP • B GROUP • C GROUP GROUPS OF NERVE FIBERS
  17. 17. A GROUP • A group is composed of largest fibers. • The fibers of this group are myelinated. • Both sensory and motor in function. • It is found in somatic nerves as SCIATIC AND SAPHENOUS nerve. It is further classified into 4 sub groups. • Aα (afferent and efferent fibers) • Aβ (afferent and efferent fibers) • Aγ (efferent fibers) • Aδ (afferent fibers)
  18. 18. B GROUP • The fibers of this group are myelinated. • The B fibers are found solely in preganglionic autonomic nerve.
  19. 19. C GROUP • It is composed of smallest fibers. • All the fibers of this group are unmyelinated. • Mostly found in visceral and cutaneous nerve. • They have high threshold i.e. 30 folds that of A group. • Generally they are found in postganglionic sympathetic nerve.
  20. 20. About the nerve fibers RAJ NIDHI 24
  21. 21. Numerical classification
  22. 22. NUMERICAL CLASSIFICATION OF SENSORY NERVE FIBERS
  23. 23. RAJ NIDHI 27
  24. 24. MULTIPLE SCLEROSIS • It is autoimmune disorder. • Causes may be genetic or environmental. • Antibodies & white blood cells in the immune system attack myelin causing inflammation and injury of sheath. • So the loss of myelin leads to leakage of k+ through voltage gated channels, hyperpolarisation and failure to conduct action potential. RAJ NIDHI 28
  25. 25. NO TREATMENT of this disease but some drug like β-INTERFERON suppresses the immune response, reduce the severity & slow the progression of disease. RAJ NIDHI 29
  26. 26. PERIPHERAL NEUROPATHY  Peripheral neuropathy is damage to nerves of peripheral nervous system which may be caused by diseases or trauma.  It is classified according to number of nerves affected or types of nerve cells affected (motor ,sensory, autonomic). MONONEUROPATHY  It is a type of neuropathy that only affects single nerve.  The most common cause of mononeuropathy is physical compression of the nerve known as compression neuropathy. MONONEURITIS MULTIPLEX  It is the simultaneous or sequential involvement of the individual noncontiguous nerve trunk either partially or completely. the pattern of involvement is asymmetric. RAJ NIDHI 30
  27. 27. POLYNEUROPATHY  It is pattern of nerve damage which is a quite different from mononeuropathy and often more serious and affecting more areas of body. The pattern of involvement is symmetric. AUTONOMIC NEUROPATHY  It is a form of polyneuropathy which affects the involuntary system i.e. autonomic nervous system affecting mostly the internal organs. Most commonly it is seen in person with long standing diabetes mellitus type1 and 2. NEURITIS  It is a general term of inflammation of a nerve or the general inflammation of the peripheral nervous system.RAJ NIDHI 31
  28. 28. REFERENCES  GUYTON  GANONG ’S REVIEW OF MEDICAL PHYSIOLOGY  INTERNET RAJ NIDHI 32
  29. 29. RAJ NIDHI 33

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