1) Pain physiology involves transduction, transmission, perception, and modulation of nociceptive signals from the periphery to the brain.
2) Pain signals are transmitted via Aδ and C nerve fibers to the spinal cord and then to the brain. Aδ fibers transmit fast, sharp pain while C fibers transmit slow, dull pain.
3) Central modulation occurs in the spinal cord and brain and can either facilitate or inhibit pain transmission and perception through mechanisms like windup, sensitization, and the release of neurotransmitters.
Pain pathway gate control theory
Pain management
An unpleasant emotional experience usually initiated by noxious stimulus and transmitted over a specialized neural network to CNS where it is interpreted as such.
1. Exteroceptors: arising from receptors from skin & mucosa. sensed at conscious level
E.g. Merkel corpuscles : Tactile receptors.
Free Nerve ending :Perceive superficial pain.
2. Proprioceptors : From musculoskeletal structures.
The presence , positions & movement of body. below conscious levels.
E.g. 1) Muscle spindles : Skeletal muscle fibers. Mechanoreceptors.
2) Free nerve ending : Perceive deep somatic pain & other sensations.
3. Interoceptors : From viscera of body below conscious level.
E.g. Pacinian corpuscles : perception of touch-pressure.
Free nerve ending : Perceive visceral pain & other sensations.
Pain is the common symptom in many chronic conditions such as cancers, neuropathies, and chronic disease. It is also experienced in trauma varying from mild to severe based on the location and degree of trauma. This presentation is a brief outline on types of pain, classification of pain, pain pathways and management of pain
Pain pathway gate control theory
Pain management
An unpleasant emotional experience usually initiated by noxious stimulus and transmitted over a specialized neural network to CNS where it is interpreted as such.
1. Exteroceptors: arising from receptors from skin & mucosa. sensed at conscious level
E.g. Merkel corpuscles : Tactile receptors.
Free Nerve ending :Perceive superficial pain.
2. Proprioceptors : From musculoskeletal structures.
The presence , positions & movement of body. below conscious levels.
E.g. 1) Muscle spindles : Skeletal muscle fibers. Mechanoreceptors.
2) Free nerve ending : Perceive deep somatic pain & other sensations.
3. Interoceptors : From viscera of body below conscious level.
E.g. Pacinian corpuscles : perception of touch-pressure.
Free nerve ending : Perceive visceral pain & other sensations.
Pain is the common symptom in many chronic conditions such as cancers, neuropathies, and chronic disease. It is also experienced in trauma varying from mild to severe based on the location and degree of trauma. This presentation is a brief outline on types of pain, classification of pain, pain pathways and management of pain
Physiology of Pain, Characteristic of pain, Basic consideration of nervous system, Pain receptor, Mechanism of pain causation, Theories of pain, Pathways of pain, Pain Receptors
Pain is defined as an “unpleasant emotional experience usually initiated by a noxious stimulus and transmitted over a specialized neural network to the central nervous system where it is interpreted as such”.
Free nerve endings – responsible for carrying noxious stimulus from both superficial as well as deep somatic and visceral pain sensations therefore reffered as nociceptors
According to type of impulses they carry second order neuron can be classified as –
LOW THRESHOLD MECHANOSENSORY( ligth touch, pressure and Proprioception)
NOCIOCEPTIVE SPECIFIC ( Noxious stimulation)
WIDE DYNAMIC RANGE ( wide range of stimulus intensities from nonnoxious to noxious.
SILENT NOCICEPTORS (It is an afferent neuron that appear to remain or silent to any mechanical stimulation .These neuron become active with tissue injury and add to the nociceptive input entering the CNS.
Physiology of Pain (PPT) Nervous System PhysiologyShaista Jabeen
https://www.youtube.com/channel/UCrrAABI7QDRCJ1yMrQCip_w/videos
https://www.facebook.com/ShaistaJabeeen/
https://www.facebook.com/Human-Physiology-Lectures-100702741804409/
Physiology of Pain (PPT)
Nervous System Physiology
INTRODUCTION
BENEFITS OF PAIN SENSATION
COMPONENTS OF PAIN SENSATION
PATHWAYS OF PAIN SENSATION
FROM SKIN AND DEEPER STRUCTURES
FROM FACE
FROM VISCERA
FROM PELVIC REGION
VISCERAL PAIN
CAUSES OF VISCERAL PAIN
REFERRED PAIN
DEFINITION
EXAMPLES OF REFERRED PAIN
MECHANISM OF REFERRED PAIN
NEUROTRANSMITTERS INVOLVED IN PAIN SENSATION
ANALGESIA SYSTEM
ANALGESIC PATHWAY
GATE CONTROL THEORY
APPLIED PHYSIOLOGY
Short Notes
pdf ppt
Physiology of Pain, Characteristic of pain, Basic consideration of nervous system, Pain receptor, Mechanism of pain causation, Theories of pain, Pathways of pain, Pain Receptors
Pain is defined as an “unpleasant emotional experience usually initiated by a noxious stimulus and transmitted over a specialized neural network to the central nervous system where it is interpreted as such”.
Free nerve endings – responsible for carrying noxious stimulus from both superficial as well as deep somatic and visceral pain sensations therefore reffered as nociceptors
According to type of impulses they carry second order neuron can be classified as –
LOW THRESHOLD MECHANOSENSORY( ligth touch, pressure and Proprioception)
NOCIOCEPTIVE SPECIFIC ( Noxious stimulation)
WIDE DYNAMIC RANGE ( wide range of stimulus intensities from nonnoxious to noxious.
SILENT NOCICEPTORS (It is an afferent neuron that appear to remain or silent to any mechanical stimulation .These neuron become active with tissue injury and add to the nociceptive input entering the CNS.
Physiology of Pain (PPT) Nervous System PhysiologyShaista Jabeen
https://www.youtube.com/channel/UCrrAABI7QDRCJ1yMrQCip_w/videos
https://www.facebook.com/ShaistaJabeeen/
https://www.facebook.com/Human-Physiology-Lectures-100702741804409/
Physiology of Pain (PPT)
Nervous System Physiology
INTRODUCTION
BENEFITS OF PAIN SENSATION
COMPONENTS OF PAIN SENSATION
PATHWAYS OF PAIN SENSATION
FROM SKIN AND DEEPER STRUCTURES
FROM FACE
FROM VISCERA
FROM PELVIC REGION
VISCERAL PAIN
CAUSES OF VISCERAL PAIN
REFERRED PAIN
DEFINITION
EXAMPLES OF REFERRED PAIN
MECHANISM OF REFERRED PAIN
NEUROTRANSMITTERS INVOLVED IN PAIN SENSATION
ANALGESIA SYSTEM
ANALGESIC PATHWAY
GATE CONTROL THEORY
APPLIED PHYSIOLOGY
Short Notes
pdf ppt
Pain Physiology Presented At St Thomases Hospital 2.3.07London Pain Clinic
Pain Physiology.
Presented At St Thomases Hospital for trainee Anaesthetists as part of their FRCA (Fellow of the Royal College of Anaesthetists) examination preparations.
2nd March 2007
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
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In this ppt I mentioned all the imp point related to pain pathway and pain pathophysiology. refrence: essentials of interventional techniques in managing chronic pain (laxmaiah manchikanti)
Mechanism of odontogenic and non odontogenic painiflahshah
Mechanism of Odontogenic and Non-Odontogenic Pain
CONTENTS:
DEFINITION
TRIGEMINAL PAIN SYSTEM
PERIPHERAL PAIN MECHANISM
CENTRAL PAIN MECHANISM
NEUROPHYSIOLOGY OF PAIN
REFFERED PAIN
THEORIES OF PAIN
ASSESSMENT OF PAIN
PAIN CLASSIFICATION
ODONTOGENIC PAIN
NON-ODONTOGENIC PAIN
HISTORY OF PAIN
PHYSICAL EXAMINATION
DIAGNOSIS OF PAIN
CONCLUSION
Perioperative management of a patient with diabetes mellitusrajkumarsrihari
Anesthetic implications in a patient with Diabetes Mellitis with latest updates taken from british journal of anesthesia on perioperative glycemic control (2013)
micro teaching on communication m.sc nursing.pdfAnurag Sharma
Microteaching is a unique model of practice teaching. It is a viable instrument for the. desired change in the teaching behavior or the behavior potential which, in specified types of real. classroom situations, tends to facilitate the achievement of specified types of objectives.
- Video recording of this lecture in English language: https://youtu.be/lK81BzxMqdo
- Video recording of this lecture in Arabic language: https://youtu.be/Ve4P0COk9OI
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
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Ozempic: Preoperative Management of Patients on GLP-1 Receptor Agonists Saeid Safari
Preoperative Management of Patients on GLP-1 Receptor Agonists like Ozempic and Semiglutide
ASA GUIDELINE
NYSORA Guideline
2 Case Reports of Gastric Ultrasound
Report Back from SGO 2024: What’s the Latest in Cervical Cancer?bkling
Are you curious about what’s new in cervical cancer research or unsure what the findings mean? Join Dr. Emily Ko, a gynecologic oncologist at Penn Medicine, to learn about the latest updates from the Society of Gynecologic Oncology (SGO) 2024 Annual Meeting on Women’s Cancer. Dr. Ko will discuss what the research presented at the conference means for you and answer your questions about the new developments.
The prostate is an exocrine gland of the male mammalian reproductive system
It is a walnut-sized gland that forms part of the male reproductive system and is located in front of the rectum and just below the urinary bladder
Function is to store and secrete a clear, slightly alkaline fluid that constitutes 10-30% of the volume of the seminal fluid that along with the spermatozoa, constitutes semen
A healthy human prostate measures (4cm-vertical, by 3cm-horizontal, 2cm ant-post ).
It surrounds the urethra just below the urinary bladder. It has anterior, median, posterior and two lateral lobes
It’s work is regulated by androgens which are responsible for male sex characteristics
Generalised disease of the prostate due to hormonal derangement which leads to non malignant enlargement of the gland (increase in the number of epithelial cells and stromal tissue)to cause compression of the urethra leading to symptoms (LUTS
Title: Sense of Smell
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the primary categories of smells and the concept of odor blindness.
Explain the structure and location of the olfactory membrane and mucosa, including the types and roles of cells involved in olfaction.
Describe the pathway and mechanisms of olfactory signal transmission from the olfactory receptors to the brain.
Illustrate the biochemical cascade triggered by odorant binding to olfactory receptors, including the role of G-proteins and second messengers in generating an action potential.
Identify different types of olfactory disorders such as anosmia, hyposmia, hyperosmia, and dysosmia, including their potential causes.
Key Topics:
Olfactory Genes:
3% of the human genome accounts for olfactory genes.
400 genes for odorant receptors.
Olfactory Membrane:
Located in the superior part of the nasal cavity.
Medially: Folds downward along the superior septum.
Laterally: Folds over the superior turbinate and upper surface of the middle turbinate.
Total surface area: 5-10 square centimeters.
Olfactory Mucosa:
Olfactory Cells: Bipolar nerve cells derived from the CNS (100 million), with 4-25 olfactory cilia per cell.
Sustentacular Cells: Produce mucus and maintain ionic and molecular environment.
Basal Cells: Replace worn-out olfactory cells with an average lifespan of 1-2 months.
Bowman’s Gland: Secretes mucus.
Stimulation of Olfactory Cells:
Odorant dissolves in mucus and attaches to receptors on olfactory cilia.
Involves a cascade effect through G-proteins and second messengers, leading to depolarization and action potential generation in the olfactory nerve.
Quality of a Good Odorant:
Small (3-20 Carbon atoms), volatile, water-soluble, and lipid-soluble.
Facilitated by odorant-binding proteins in mucus.
Membrane Potential and Action Potential:
Resting membrane potential: -55mV.
Action potential frequency in the olfactory nerve increases with odorant strength.
Adaptation Towards the Sense of Smell:
Rapid adaptation within the first second, with further slow adaptation.
Psychological adaptation greater than receptor adaptation, involving feedback inhibition from the central nervous system.
Primary Sensations of Smell:
Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.
Odor Detection Threshold:
Examples: Hydrogen sulfide (0.0005 ppm), Methyl-mercaptan (0.002 ppm).
Some toxic substances are odorless at lethal concentrations.
Characteristics of Smell:
Odor blindness for single substances due to lack of appropriate receptor protein.
Behavioral and emotional influences of smell.
Transmission of Olfactory Signals:
From olfactory cells to glomeruli in the olfactory bulb, involving lateral inhibition.
Primitive, less old, and new olfactory systems with different path
Pulmonary Thromboembolism - etilogy, types, medical- Surgical and nursing man...VarunMahajani
Disruption of blood supply to lung alveoli due to blockage of one or more pulmonary blood vessels is called as Pulmonary thromboembolism. In this presentation we will discuss its causes, types and its management in depth.
Title: Sense of Taste
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
Prix Galien International 2024 Forum ProgramLevi Shapiro
June 20, 2024, Prix Galien International and Jerusalem Ethics Forum in ROME. Detailed agenda including panels:
- ADVANCES IN CARDIOLOGY: A NEW PARADIGM IS COMING
- WOMEN’S HEALTH: FERTILITY PRESERVATION
- WHAT’S NEW IN THE TREATMENT OF INFECTIOUS,
ONCOLOGICAL AND INFLAMMATORY SKIN DISEASES?
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- GENE THERAPY
- BEYOND BORDERS: GLOBAL INITIATIVES FOR DEMOCRATIZING LIFE SCIENCE TECHNOLOGIES AND PROMOTING ACCESS TO HEALTHCARE
- ETHICAL CHALLENGES IN LIFE SCIENCES
- Prix Galien International Awards Ceremony
2. Topics for discussion
• Definitions
• Physiology of pain
• Pain pathway
• Important terminologies
3. Definition
• Pain:
– An unpleasant sensory or emotional experience
associated with actual or potential tissue damage
or described in terms of such damage
• Nociception:
– neural response related to potentially tissue
damaging stimuli
4. Terminologies for pain
• dysthesia – experience of abnormal noxious
sensation
– paraesthesia - abnormal nonpainful sensation;
– hyperpathia- exaggerated pain response to
noxious or nonoxious stimuli)
• allodynia - perception of nonoxious stimuli as
painful
5. • Hyperalgesia: increased pain response to
painful stimuli
• Hypoalgesia: decreased sensitivity to noxious
stimuli
• Hyperesthesia and Hypoesthesia :increase or
decrease, respectively, in sensitivity to
nonnoxious stimuli
6. Physiology of Pain
• Pain transmission:
– A good way to understand physiology of pain is to
follow nociceptive signal pathways from the
periphery to the brain,
– with emphasis on integration and modulation of
nociceptive signal at different steps in the CNS
7. • Transmission of pain occurs by :
– Transduction
– Transmission
– Perception
– Modulation
• For understanding, it can be divided into
peripheral transmission and central
transmission
8.
9. • Peripheral Transmission:
– Peripheral transmission of pain consists
production of electrical signals at the pain nerve
endings (Transduction) followed by propagation of
those signals through the peripheral nervous
system (Transmission)
• Central Transmission:
– Includes transmission and perception whereby
signals are transmitted from spinal cord to the
brain
10. • Transduction:
– Primary sensory structure that accomplishes
transduction –nociceptor (free nerve endings sensing
heat, mechanical and chemical tissue damage)
– Several types are described:
• Mechanoceptors – sense pinch and pin prick
• Silent nociceptors- sense pain only during inflammation
• Polymodal mechanothermal receptors- most prevalent and
respond to excess pressure, temperature and algogens
11. • Transmission:
– Pain impulses transmitted by 2 fibre systems
– The presence of 2 pain pathways-explains
existence of 2 components of pain: Fast pain(Ad)
and Slow pain (C )
– Ultimately synapse in spinal cord with second
order neurons which send impulse to CNS
12. • Perception:
– From thalamus to somatosensory areas of
cerebral cortex( in the post central gyrus) and
superior wall of the sylvian fissure
– Fibres are also projected to limbic system- anterior
cingulate gyrus and insula
13. • Modulation:
– Occurs at different sites:
• Nociceptor
• Spinal cord
• Supraspinal structures
– This modulation can either inhibit or facilitate pain
14. • Peripheral Modulation:
– Nociceptors and their neurons display sensitization
following repeated stimulation
– Sensitization of nociceptors result in
• decrease in threshold
• Increase in frequency response
• Decrease in response latency
• Spontaneous firing even after cessation of stimulus
– Primary hyperalgesia mediated by algogens like
histamine, bradykinin, PGE2 and leukotrienes from
damaged tissues
15. • Secondary hyperalgesia or neurogenic inflammation-
longterm tissue hypersensitivity beyond area of
original injury within the CNS
– Repeated recruitment of C-fibres following an injury will cause change
in response properties of membranes of secondary neurons
– Over a period – can cause increase in perceived pain even if intensity
of stimulation remains constant
– This spinal sensitization can persist for minutes, but can also present
for hours or even days
– The prolonged activation of NMDA receptors will induce transcription
of rapidly expressed genes (c-fos, c-jun), resulting in sensitization of
nociceptors
– This neuronal plasticity of the secondary neuron will result in reduced
recruitment threshold of secondary neurons in the spinal cord
hyperalgesia and allodynia that persist even after healing of injury
16. • Central Sensitization: refers to phenomenon where
second neuron membrane permeability changes and
responds at higher frequency when recruited by nociceptive
and non-nociceptive primary input
– This can facilitate or inhibit pain. The mechanisms of
facilitation are as follows:
• Windup and sensitization of second order neurons
• Receptive field expansion
• Hyper excitability of flexion responses
– Neurochemical mediators of central sensitization
• sP , CGRP, VIP, Cholecystokinin, angiotensin, galantin, L-
aspartate and L-glutamate
17. – These substances trigger changes in membrane excitability by
interacting with G-protein coupled receptors
– Activating intracellular second messengers
– Phorsphorylate substance proteins
– Leading to increased intracellular calcium concentration
– Stimulate Nitric oxide synthase and production of NO
– NO diffuses action of neuron and by action on guanylyl cyclase,
NO stimulates formation of cGMP in neighbouring neurons
– Depending on the expression cGMP- controlled ion channels in
target neurons, NO may be excitatory or inhibitory- most cases
implicated in development of hyperalgesia and allodynia
18. • Inhibitory mechanisms can be either Spinal or
Supraspinal
– Segmental inhibition –consists of activation of large
afferent fibres of inhibitory WDR neurons and
spinothalamic activity
– Glycine and GABA –inhibitory neurotransmitters
– Segmental inhibtion mediated by GABA receptor
activity increases K+ conductance across cell
membrane
19. – Supraspinal inhibition – occurs whereby several
supraspinal structures send fibres down the spinal cord to
inhibit pain at the level of the dorsal horn
• Includes –Periaqueductal Gray, Nucleus Raphe Magnus and
Reticular formation
– Axons from these structures act pre-synaptically on the
primary afferent neurons and post synaptically on the
second order neurons(interneurones)
– These axons utilise monoamines (NA and Serotonin) as
neurotransmitters and terminate on nociceptive neurons
in spinal cord + spinal inhibitory interneurones (store and
release opioids)
– Noradrenaline mediates action via alpha 2 receptors
– Endogeneous opioids via enkephalins and B-endorphins–
mainly act presynaptically whereas opiates act
postsynaptically
20. – Cognitive Modulation:
• Involves patient’s ability to relate a painful experience
to another event
25. Important terminologies
• Physical characteristics of nerve fibres:
Ab Ad C
Diameter 6-12 microns
Myelinated
1-5 microns
Myelinated
0.2-1 microns
Unmyelinated
Conduction 33–75 m/s 3–30 m/s 0.5-2.0 m/s
Role Light touch
Proprioception
Temperature
Nociception
(mechanical,thermal)
Nociception
(mechanical,
thermal, chemical)
26. • Ab fibres:
– Besides conduction of non-nociceptive signal, stimulation
of Ab fibres will recruit inhibitory interneurones in the
substantia gelatinosa of dorsal horn inhibition
nociceptive input at same spinal segment (innocuous
stimulus)
• Ad fibres:
– Responsible for the first pain sensation, rapid pinprick,
sharp and transient sensation
• C fibres:
– Represent 3 quarters of the sensory afferent input and are
mostly recruited by nociceptive stimulation
– Responsible for dull aching pain
27. • First and Second pain:
– Conduction velocity between Ad and C fibres can be
appreciated when isolating sensation of 1st and 2nd
pain
– Following brief nociceptive stimulation- Ad fibres will
transmit brief and acute pin-prick like sensation,
perceived to be precisely located at he point of
stimulation results in nociceptive withdrawal reflex
– Following this activity, C fibres will transmit their
information with long delay (100ms to 1 s) depending
on stimulus location
28.
29. • Secondary neurons : can be classified as
– Nociceptive specific neurons:
• Respond only to nociceptive stimulation
• Can be divided into 2 subclasses depending on their recruitment
by Ad alone or combination of Ad and C fibres
– Wide dynamic range neurons:
• Respond gradually to stimuli from innocuous to nociceptive
• Their capacity to respond to both nociceptive and innocous stimuli
is related to the fact that they have received input from Ad, C and
Ab fibres
• Receptive field is dynamic
• Changes in receptive field, membrane permeability to ion
exchange and discharge frequency of these neurons all suggest
substantial role in chronicity of pain
30. • Temporal Summation:
– Good illustration of importance of signal conduction in Ad
and C fibres
– Here, pain perception is compared with repeated
stimulations at same intensity but different rates
– High frequency of stimulation will produce temporal
summation of C-fibre activity as a result of relatively slow
conductance of these fibres
– Resulting in increased perceived intensity of second pain
31. • Spatial Summation:
– Stimulation of a large territory will recruit more
nociceptors than when a small area is stimulated
– Results in more intense pain perception
– However increasing surface area that is stimulated
recruits both excitatory and inhibitory
mechanisms