NO words to describe...just download and watch yourself.... very informative and beautiful presentation about sensory system and receptors of our body,,,,will surely help to understand in a better and easy way... best viewed only when downloaded

3. SENSORY RECEPTOR
 Organs which receive
information from
outside or within the
body and send it to the
central nervous system
for processing.
 Can be activated by
various forms of energy:
light, heat mechanical
chemical etc.

4. HOW

5.  They convert stimulation energy into electrochemical
energy.
 Process is called Sensory Transduction.

6. Sensory Transduction
1. The Stimulus energy produces changes in the
electrical state of the receptor membrane.
2. Energy of stimulation is transformed into process of
excitation by metabolism of receptors.
3. Effect of stimulus on receptor produces a type of
local potential(Local Response).
4. Mechanism of excitation depends on structure of
receptor.
Secondary Sensory ReceptorPrimary Sensory Receptors

7. Primary Sensitive
receptor
Irritant acts to the receptor
Changes in ionic channels of
receptor membrane
Increase of its membrane
permeability for different ions
Local depolarization of
receptor membrane
Receptor Potential
Secondary sensitive
receptor
Irritant acts to receptor
Changes in ionic channels of
receptor membrane
Receptor releases
neurotransmitter
Neurotransmitters acts with post-
synaptic membrane of 1st order
neuron of conductive department
Local depolarization of receptor
membrane
Generator potential

8. • Receptors transform
an external signal
into a membrane
potential.
• Receptor Potential
- separate receptor
• Generator Potential
- a specialized
ending of an afferent
neuron

9.  When receptor potential reaches a critical level of
depolarization, it triggers the discharge of nerve impulse in
the nerve fiber connected with the receptor.
 The frequency of impulse is directly proportional to receptor
potential.

11. Pain receptors are absent in BRAIN
Begins after
1 sec & slowly
increases
Deep
Organs
Pain along
coarse of
nerves
Pain of
about 0.1
sec
Superficial
SCRATCH HERE TO REVEAL INTERESTING FACT

12. No pain
receptor in
brain???
Migrane???
Headache???

14. Peripheral Part-Receptive Part
Types of
Receptor
Nerve Fiber Function Location Peculiarities
Mechano And
Mechano-
Thermal
nociceptor
A δ fibres
(Myelinated)
 React to
strong &
thermal
stimuli
 Fast
adaptation
 Superficial
layer of skin
 In certain
internal
organs
(Periosteum,
arterial walls
 Have high
threshold of
excitation
Polymodal
nociceptors
C-fibres
(Unmyelinated)
 React to
mechanical
thermal &
chemical
stimuli.
 Slow
adaptation
& joint
surfaces, flax
& tentorium
in cranial
vault).
 Adapt very
little &
sometimes
not at all

15. Conducting Part
Neospinothalamic
Tract Paleospinothalamic
Tract
Lateral
Spinothalamic
Tract

18. Significance of Pain Pathways
PaleospinothalamicNeospinothalamic
a) Continuously inform the
C.N.S about the presence of
tissue damage → direct the
person to remove the
injurious agents.
a) Rapidly inform the
C.N.S about the injurious
agent → initiate rapid
protective reflexes as
flexion withdrawal reflex.
b) Strong arousal state.
c) Initiation of the emotional
& autonomic reactions,
through RF.
b) Determines accurately
the site “locality” of the
painful stimuli.

19. Comparisons Between Slow and Fast Pain
Chronic (Slow)Acute (Fast)
Skin, deep tissues, and
viscera
Skin onlySource
BurningPrickingQuality
One or more seconds
after stimulation
Within 0.1 sec after
stimulation
Onset
Long (few minutes)Short (one second)Duration
DiffuseWell –localizedLocalization
CA-deltaAfferent
Paleospinothalamic
tract
Neospinothalamic tractTract
ThalamusCerebral cortexCentre
Substance PGlutamateChemical
transmitters

20. Cortical
Areas of
Pain
Sensation
Primary
Area S I
Limbic
System
Frontal
Cortex
Primary
Area S
II
Perception of fast
sharp pain & its
localization
Controls emotional
component of pain,
vegetative, motor &
behavioral
responses.
Self appraisal of pain
to form purposeful
behavious
Has strong double
sided connection
with nuclei of
thalamus & can
enhance or reduce
pain

23. Analgesic System-
Anti-nociceptive
System