This document provides an overview of neurophysiology and the nervous system. It discusses the following key points in 3 sentences or less: The central nervous system is made up of the brain and spinal cord. The brain controls all body functions and is divided into areas that control thinking, memory, movement, and other tasks. The peripheral nervous system connects the central nervous system to the rest of the body and is made up of nerves and sensory organs.

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Prof. DR.Rashid Mahmood

2. Review of Neurophysiology
(Sensory System)
2
Introductory Lecture
Courtesy: Prof. Dr. Abid Hussain,
Vice Principal,
Northwest School of Medicine ,
Peshawar
Prof..Rashid Mahmood

3. NeurophysiologyNeurophysiology
What is Neurophysiology?What is Neurophysiology?
Neurophysiology is the study of
nervous system function

4. Control of body functionsControl of body functions
 Nervous systemNervous system
 HormonesHormones
Skeletal muscles
Visceral functions
Somatic NS
Autonom
ic NS

5. Organization of
Nervous System

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A system that controls all of the
activities of the body.
The nervous system is made of:
The brain The spinal cord
The nerves The senses
Prof..Rashid Mahmood

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The Central Nervous System is made
of the brain and the spinal cord.
Prof..Rashid Mahmood

8. CNSCNS
 Spinal CordSpinal Cord
 Brain StemBrain Stem
 Medulla, pons, and midbrainMedulla, pons, and midbrain
 CerebellumCerebellum
 DiencephalonDiencephalon
 Thalamus and hypothalamusThalamus and hypothalamus
 Cerebral HemispheresCerebral Hemispheres
 Cerebral cortex, basal ganglia, hippocampus, andCerebral cortex, basal ganglia, hippocampus, and
amygdalaamygdala

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An organ that controls your
emotions, your thoughts, and every
movement you make.
Prof..Rashid Mahmood

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* The brain controls everything in the
body.
* The brain is made of more than 10
billion nerves!
* The brain is divided into three
parts and is protected by the skull.
Prof..Rashid Mahmood

11. Brain Stem

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Major Levels of Central Nervous
System Function
(1) the spinal cord level,
(2) the lower brain or subcortical level:
medulla,
pons,
mesencephalon,
hypothalamus,
thalamus,
cerebellum, and
basal ganglia
(3) the higher brain or cortical level

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* The Cerebrum is the largest part of
the brain. It controls:
1. thinking.
2. memory.
3. speaking.
4. movements
5. Receives/ identifies /processes sensory information
and integrates motor functions
Prof..Rashid Mahmood

15. Cerebral Hemispheres
• 3 deep nuclei within hemispheres:
• Basal Ganglia
– Receives input from cerebral cortex and project
to frontal cortex
– Regulates movement
• Hippocampus
– Involved in memory
• Amygdala
– Involved with emotions

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Functions of Different
Areas of brain

17. CerebellumCerebellum

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* The cerebellum is below and to the
back of the cerebrum.
1. controls balance.
2. controls posture.
Prof..Rashid Mahmood

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* The spinal cord sends messages to the
brain.
* The spinal cord is the part of the
nervous system that connects the brain
to the rest of the nervous system.Prof..Rashid Mahmood

20. Prof..Rashid Mahmood
20
8
12
5
5
1
Spinal
Segments
Spinal Nerves
(Contain both sensory
and motor nerves)

21. Spinal Cord
• Ascending pathways
– Carry sensory info from periphery to higher levels of
CNS
• Descending pathways
– Carry motor info from higher levels to motor nerves
that innervate periphery

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* The outer nervous system is made of
the nerves and the sense organs.
Ear
Eye
Skin
Nerves
Tongue
Prof..Rashid Mahmood
It carries messages between the central
nervous system and the rest of the body
Nose

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Peripheral Nervous System
• Two subdivisions
– Sensory or afferent
– Motor or efferent
• Divisions
• Somatic nervous system
• Autonomic nervous
system (ANS)
» Sympathetic
» Parasympathetic
» Enteric

24. Sensory Pathway
Motor Pathway
Interneuron
(Integration)
CNSPNS
Receptors
Effector
Tissue
1. Sensory Neuron
3. Motor Neuron
2.Interneuron

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Functional classification
of Neurons
– Sensory or afferent: Action potentials
toward
CNS
– Motor or efferent: Action potentials
away from CNS
– Interneuron : Within CNS from one
neuron to another

26. Other Classifications of Neurons
• Based on Myelin Sheath
1. Myelinated
2. Unmyelinated
• Based on Structure Self-Study
1. Unipolar
2. Multipolar,
3. Bipolar,
4. Pseudo-unipolar
Dr. Rashid Mahmood 26

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* An automatic reaction that
happens without thinking about it.
* A reflex happens quickly in
less than a second.
Prof..Rashid Mahmood

28. 28Prof..Rashid Mahmood

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The Synapse
• Junctional point
between two neurons
that
transmits impulse
from first to the
second Neuron.
(Junction between muscle+
neuron=
Synapse?)

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Classification of Synapses
• Anatomical Classification
• (on the Basis of Communication )
– 1. Axo-Dendritic
– 2. Axo-Somatic
– 3. Axo-Axonic
– 4. Dendro-dendritic (amacrine cells in Eye)
PHYSIOLOGICAL Classification: (According to Nature)
1. Electrical
2. Chemical

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1. Axo-
Dendritic
2. Axo-Somatic
3. Axo-Axonic
4. Dendro-
dendritic

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Electrical Synapse
Gap Junctions in
Cardiac & Smooth
Muscle

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Chemical Synapses

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Properties of Synapses
1. One Way Conduction
2. Synaptic Delay
3. Excitation (EPSP)
4. Inhibition
1. Presynaptic Inhibition
2. Postsynaptic Inhibition
3. Reciprocal Inhibition
5. Synaptic fatigue
6. Summation
1. Spatial summation
2. Temporal summation
7. Facilitation
8. Occlusion& Subliminal
Fringe
9. Convergence
10. Divergence
11. Recruitment
12. Afterdischarge
13. Posttetanic Potentiation
14. Habituation
15. Effect of Acidosis &
Alkalosis
16. Effect of Hypoxia on
Synaptic Transmission
17. Effect of Drugs on Synaptic
Transmission

36. Classification of Senses
Conscious
– Somatic senses
• Touch / pressure
• Temperature
• Pain
• Proprioception
– Special senses
• Vision
• Hearing
• Taste
• Smell
• Equilibrium
Subconscious
– Somatic stimuli
– Muscle length and
tension
– Visceral stimuli
– Blood pressure
– pH / oxygen content in
blood
– pH of cerebrospinal fluid
– Lung inflation / Deflation
– Osmolarity of body fluids
– Blood glucose level
Dec 10, 2016 Dr. Rashid Mahmood 36

37. Dec 10, 2016 Dr. Rashid Mahmood 37
Receptors
• Receptors are transducers which detect the
Change in the environment (stimulus)& converts
it into Propagated action Potential ( impulse).
• The complexity of sensory receptors ranges
from
free nerve endings to
specialized nerve endings
and receptor organ.

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Classification of Receptors
5 types of classification
1. On the basis of Modality of sensations Carried by Receptors
( Five Major Groups )
I. .Mechanoreceptors – ( Mechanical Change )
i. skin tactile – Free Nerve Endings, Hair end organs etc
ii. Deep tissues - ( Pacinian Corpuscles )
iii. Muscles / Tendons (Muscle spindles & Golgi tendons Organs
iv. Hearing - ( Organ of Corti )
v. Equilibrium – ( Vestibular apparatus)
vi. B.P. ( Baroreceptors )
II. Thermoreceptors - Cold & Warm Receptors
III. Nociceptors (pain) - Free Nerve Endings

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Classification of Receptors- contd
• IV. Electromagnetic Receptors (Vision)- Rods &
Cones.
• V. CHEMORECPTORS;
- Taste- Taste Buds
- Smell – Olfactory Epithelium.
- Arterial PO2- Aortic & Carotid Bodies
- PCO2 - Central Chemoreceptors
- Osmolality - Neurons in Supraoptic Nucleus of
Hypothalamus, and
- Blood Glucose, A.A & F.A- Receptors in
Hypothalamus

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Classification of Receptors…contd
2. On the Basis of Distribution in the Body i.e
Somatic (Somesthetic) &
Special Senses
3. On the basis of Origin of Stimuli:
Interoceptors
Proprioceptors
Exteroceptors
4. Structural Classification
Non Encapsulated
Encapsulated
5. On the Basis of Adaptation:
Phasic ( Rapidly Adapting)- Pacinian Corpuscles
Tonic ( Slowly Adapting)- Pain (free Nerve endings)

41. Classification of Somatic Senses
Somatic Senses
• Mechanoreceptive
Somatic Sensations
– Tactile
– Position
• Thermoreceptive Senses
– Heat
– Cold
• Pain Senses
Special senses
• Vision
• Hearing
• Smell
• Taste
• Equilibrium
Dec 10, 2016 Dr. Rashid Mahmood 41
Based on Modality of sensation

42. Classification of Somatic Senses
• Exteroceptive Sensations
• Interoceptive sensations
– Proprioceptive sensations
• Position
• Muscle, tendon
– Visceral sensations
• Viscera
– Deep sensations
• Bone, fasciae
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Based on Origin of sensation

43. Functions of Thalamus
1. Relay center for somatic sensory information to
cerebral cortex
2. Perception of group tactile sensations
3. Perception of Pain sensation
4. Perception of temperature sensation
5. Center for integration & modification of sensory signals
6. Capacity to determine whether a sensation is pleasant
or unpleasant and agreeable or disagreeable
7. Center for sexual sensation
8. Arousal and alertness reaction (connection with
reticular nuclei)
9. Center for reflex activities
10. Center for integration of motor function (cerebellum +
Basal ganglia)

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Sensory
Pathways

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Transmission of Somatic Sensations
• All sensory information enter the spinal cord through
dorsal route (Bell Magendie Law) from where they are
carried through any of the following
Ascending Pathways:
1. Dorsal column-medial Laminiscal System.
1. Fasciculus Gracilus (Medial)
2. Fasciculus Cuneatus (Lateral)
2. Antero-lateral system (Spino-thalamic).
1. Anterior Spinothalamic Tract
2. Lateral Spinothalamic tract
1. Spinocerebellar tracts
1. Dorsal
2. ventral
4. Spinotectal, Spino olivary, Spino Vestibular

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Dorsal Column-Medial
Laminiscal system
• Ist Order N. From Receptor Enter the
spinal cord & divide into Lateral & Medial
Branches.
- The medial Branch goes to the Medulla
(Gracile or Cuneate Nucleus).
- The lateral branch divide & relay in the
Ventral horn to serve as:
1. Local spinal Reflex action
2. for formation of Spino-Cerebellar Tract
3. May accompany dorsal column Tract
• 2nd. Order N. From Gracile or Cuneate N
in the Medulla to the VPL nucleus of the
Thalamus (Ventrobasal Complex)

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Antero-Lateral
Path
2nd
Order N. From Laminae I,IV,V & VI
Cross to opposite side obliquely,
Ascend up & relay in Anterior & Lat.
White columns of the spinal cord
1. Reticular formation of Brain stem.
2. VPL N & Intralaminar Nuclei of the
Thalamus
3rd
Order N. From Thalamus – Pass
through Internal capsule to the
Primary Sensory Cortex

48. 48 Figure 15.8a, b
Dorsal Column & Anterolateral

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Somatosensory Cortex I & II
I II

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Representation of different areas of the Body
in the Somatosensory Cortex-I
Humunculous

51. Prof..RashidProf..Rashid
MahmoodMahmood 5151
Recommended BooksRecommended Books
TextbooksTextbooks::
1.1. Textbook of MedicalTextbook of Medical
Physiology,Physiology, GuytonGuyton
& Hall, 13& Hall, 13thth
EditionEdition
2.2. Ganong’sGanong’s Review ofReview of
Medical Physiology,Medical Physiology,
2424thth
EditionEdition
3.3. Neurophysiology byNeurophysiology by
Prof. Dr. MasoodProf. Dr. Masood (3(3rdrd
InternationalInternational
Edition)Edition)
4.4. Lecture Notes ofLecture Notes of
NeurophysiologyNeurophysiology byby
Prof. Dr. M. TariqProf. Dr. M. Tariq
(2(2ndnd
Edition)Edition)
Reference booksReference books
 SherwoodSherwood HumanHuman
Physiology from cells to systemsPhysiology from cells to systems
8th edition8th edition
 SherwoodSherwood Principals ofPrincipals of
Human Physiology 9th editionHuman Physiology 9th edition

K.K. SembulingamSembulingam
Essentials of Medical PhysiologyEssentials of Medical Physiology
6th Edition6th Edition
 StuartStuart IraIra FoxFox HumanHuman
PhysiologyPhysiology 13th Edition13th Edition
 Vander,sVander,s Human PhysiologyHuman Physiology
(The Mechanism of Body(The Mechanism of Body
function) 11th Editionfunction) 11th Edition
 Guyton & Hall PhysiologyGuyton & Hall Physiology
ReviewReview (2nd Edition)(2nd Edition)

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The End
Thank You