This document provides an introduction to neurophysiology. It discusses the classification of the nervous system into the central nervous system (CNS) and peripheral nervous system. Within the CNS, it is classified into grey matter and white matter. The basic structural and functional unit of the nervous system, the neuron, is described in detail. The structure and function of the synapse is also explained. Different types of neurons are classified. The composition of the nervous system includes neurons and supporting neuroglia cells. Various receptors and sensory systems are outlined. Important neurotransmitters are identified.

1. Introduction to
NEUROPHYSIOLOGY
BY
DR FAISAL SALEEM KHAN

2. We will study
Classification of nervous system.
Neuron and its details.
Details of synapse.
Classification of neurons.
Composition of nervous system.
Receptors and their details.

3. Classification of CNS
Made up of grey & white matter
Classification
Anatomical Functional l
Central Peripheral Autonomic Somatic
Brain Nerves Involuntary Voluntary
Spinal cord Cranial nerves
Spinal nerves
Ganglion
Sympathetic
Parasympathetic
Dorsal Root.Gang

4. Classification of CNS

5. Neuron
Basic structural & functional unit of the nervous system
PARTS OF
A NEURON
SOMA OR
PROCESSES
CELL BODY
Cell membrane Neuroplasm Axons Dendrites
Carry impulses Carry impulses
Central nucleus Nissel bodies Away from Towards the
Cell body Cell body
Neurofibrils Mitochondria
Golgi apparatus Axon hillock

6. Neuron
Basic structural & functional unit of the nervous system

7. Neuron
Basic structural & functional unit of the nervous system

8. Neuron
Basic structural & functional unit of the nervous system

9. A B C D
E F G H

10. Structure of neuron
A  Dendrite
B  Soma
C  Node of Ranvier
D  Axon terminal
E  Nucleus
F  Axon
G  Myelin sheath
-Faster conduction.
-High insulation.
H  Schwann cell
are responsible for
myelination in PNS.
They are absent in
CNS.

11. Impulse transmission

12. PHYSIOLOGIC ANATOMY OF
SYNAPSE

13. Wave of depolarization causes
release of neurotransmitter
Depolarization of
Presynaptic terminal
Opening of calcium
Channels in the membrane
Ca2 influx into
Presynaptic neuron
Ca2 binds to release site
On inside of cell membrane
Transmitter vesicles fuses
With the release site
Exocytosis&
Neurotransmitter released

14. Action of neurotransmitter on
postsynaptic membrane (function of
receptor proteins)
Receptor proteins of
Postsynaptic membrane
An Ionophore component
A binding component
(passes all the way through
(Protrude outward from
Membrane into interior of
Membrane into cleft)
Postsynaptic neuron)
Second messenger
Ion channel
activator

15. Ion Channels
Ion channels of
Postsynaptic membrane
Cation channels Anion channels
(Lined with negativity) (Lined with positivity)
Conduct Na ions Conduct Cl ions
Opened by excitatory Opened by inhibitory
neurotransmitter neurotransmitter

16. Second messenger system
2nd messenger
system
G protein
Attached to interior
of receptor protein
Alpha Beta Gamma
component component component
The activator

17. Second messenger system
Nerve impulse causes
Neurotransmitter release
Activation of G-protein
Associated receptor
Alpha portion separates
From other components
Opening of specific Activation of
Ion channel cAMP
Activation of Activation of gene
Intracellular enzyme transcription

18. Second messenger system

19. Receptors of postsynaptic
membrane
Postsynaptic
receptors
Excitatory Inhibitory
Opening of Opening of
Na channels Cl channels
Decrease conduction
Increase conduction of
Through Cl or K
K ions
channels
Increase in numbers of
Increase in number of
excitatory Or dec in
Inhibitory or dec in
inhibitory receptors
Excitatory receptors

20. Chemical substances that function
as synaptic transmitters
Synaptic
transmitters
Rapidly acting
Slowly acting
(Small molecule)
Class I Class II Class III Class IV

21. Small molecule, rapidly acting
transmitters

22. Neuropeptide, slowly acting
transmitters

23. Acetylcholine
Terminals of large pyramidal cells
from the motor cortex.
Neurons in the basal ganglia
Motor neurons that innervate skeletal
muscle
Preganglionic neurons of ANS.
Post ganglionic neurons of
sympathetic nervous system.

24. Norepinephrine
Widespread areas of brain.
Locus ceruleus in the pons.
Post ganglionic neurons of
sympathetic nervous system.

25. Dopamine
In substantia nigra.
In the strial region of basal ganglia
Action is usually inhibitory.

26. GABA
Inhibitory neurotransmitter.
Secreted in nerve terminals in
-cerebellum
-spinal cord
-basal ganglia
-many areas of cerebral cortex

27. Glutamate
Excitatory neurotransmitter.
Secreted in
-presynaptic nerve terminal of
sensory pathways entering CNS
-many areas of cerebral cortex.

28. Classification of neurons
Basis of
Classification
On the basis On the basis On the basis of
Of poles Of function Length of axon
Unipolar Motor Sensory Golgi typeI Golgi typeII
Bipolar
neurons neurons Long axon Short axon
Multipolar

29. Classification of neurons
-Unipolar neurons,
Single pole for
axons & dendrites
Mesencephalic
nucleus of V
cranial nerve.
A  BIPOLAR
Two poles, one for
axons, one for
dendrites.
Retina, inner ear
Olfactory mucosa.
B  MULTIPOLAR
Multi poles, one for
axons, other for
dendrites.
Most neurons of
CNS

30. Classification of neurons
A  BIPOLAR
Two poles, one for
axons, one for
dendrites.
Retina, inner ear
Olfactory mucosa.
B  MULTIPOLAR
Multi poles, one for
axons, other for
dendrites.
Most neurons of CNS.

31. Composition of CNS:
In cereberal cortex and cerebellum, grey matter is outside & white
matter is inside.
In spinal cord, grey matter is inside & white matter is outside.
CNS
-Neurons and
-Supporting cells
neuroglia
GREY White
Matter Matter
Nerve cell bodies Nerve fibers
Embeded in Axons, neuroglia
neuroglia -White-myelin sheath

32. NEUROGLIA-Non excitable cells forming interstitial
supporting tissues of CNS. They are present in both grey & white matter.
NEUROGLIA
-Support
-Insulation
Astrocytes Oligodendrocytes Microglia Ependyma
Formation
Myelination in Formation of
of blood Phagocytosis
CNS CSF
Brain barrier

33. Sensory receptors
Sensory
Receptors s
Mechanoreceptors Thermoreceptors
Electromagnetic
Nociceptors
receptors
Chemoreceptors

34. LABELED LINE PRINCIPLE
Each of principal type of sensation
that we can experience- pain, touch,
sight, sound, and so forth is called a
modality of sensation.
The specificity of nerve fibers for
transmitting only one modality of
sensation is called the labeled line
principle.

35. Classification of receptors

36. Classification of receptors

37. Classification of receptors

38. PACINIAN
CORPUSCLE
Deeply located receptors
e.g Periosteum, ligaments
& joint capsules
Carry light touch, pressure
& vibration sensations

39. Free nerve endings
Present superficially in the
Epidermis & dermis
Carry touch, pain &
Temperature sensations

40. Golgi tendon organ
Present in the muscle tendons
Carry information related to
Muscle contractions&
Proprioceptions.

41. Muscle spindles
Present in belly of the muscle
Related to stretch reflex &
Proprioception

42. Meissner’s
corpuscles
Present superficially in fingers, lips
Nipples & external genitalia
Carry fine touch sensations

43. Tactile hair
Present on skin
Carry touch, pressure,
Vibration & pain sensations

44. Properties of receptors
Receptors
properties
Modality of Receptor Receptor
receptors potential adaptation

45. Modality of receptors
Modality of
receptors
Each type of
Receptor is sensitive
To each type of stimulus
Pain Touch
Sight Sound

46. Receptor potential
Effect of application of stimulus is to change the potential across receptor
membrane, this change is called receptor potential.
Mechanisms
Mechanical Application Change in temp Effects of
deformation Of chemical Of membrane electromagnetics
Stretch of receptor Opening of Alters the memb. Light on
membrane Ion channel permeability Visual receptors
Opening of Ion flow across
Ion channel membrane

47. Action potential of pacinian
corpuscle

48. Receptor potential & action potential
when receptor potential rises above the threshold for eliciting action
potential.

49. Stimulus intensity & receptor
potential

50. Adaptation of receptors
When a stimulus is continuously applied, receptors becomes less sensitive to the
stimulus and ignore it, this is called adaptation.
Receptors
Adaptation
Slowly adapting Rapidly adapting
receptors receptors
Detect continuous Detect change in
Stimulus strength Stimulus strength
Recp In vestibular
Pain receptors Pacinian corpuscle
apparatus
Barroreceptors of Chemoreceptors of
Arterial tree Carotid & aortic bodies

51. Adaptation of receptors

52. NERVE FIBERS
CLASSIFICATION
OF NERVE FIBERS
GENERAL SENSORY NERVE
CLASSIFICATION CLASSIFICATION

53. GENERAL
CLASSIFICATION
TYPE A FIBERS TYPE C FIBERS
ALPHA BETA
GAMMA DELTA

54. SENSORY NERVE
CLASSIFICATION
TYPE I TYPE II TYPE III TYPE IV
IA fibers IB fibers