Pain And Analgesia

PAIN AND ANALGESIA

Q. 1 Which of the following types of nerve fibres carry fast pain:
 A A alpha
 B A beta
 C A gamma
 D A delta
Q. 1 Which of the following types of nerve fibres carry fast pain:
 A A alpha
 B A beta
 C A gamma
 D A delta
Ans. D

Explanation:

A delta


Q. 2

Activation of which of the following fiber result in first pain which help to localize the site and intensity of the noxious stimulus:

 A

A beta fiber

 B

A delta fiber

 C

B fiber

 D

C fiber

Q. 2

Activation of which of the following fiber result in first pain which help to localize the site and intensity of the noxious stimulus:

 A

A beta fiber

 B

A delta fiber

 C

B fiber

 D

C fiber

Ans. B

Explanation:

Activation of A delta  fiber releases glutamate, and is responsible for first pain (also called fast pain or epicritic pain) which is a rapid response and mediates the discriminative aspect of pain or the ability to localize the site and intensity of the noxious stimulus. Adelta fibers are thinly myelinated, 2-5 microns in diameter and conduct at rates of 12–35 m/s.
 
Activation of C fibers releases a combination of glutamate and substance P, and is responsible for the delayed second pain (also called slow pain or protopathic pain) which is the dull, intense, diffuse, and unpleasant feeling associated with a noxious stimulus. Unmyelinated C fibers are 0.4 –1.2 m in diameter and they conduct at low rates of 0.5–2 m/s.
 
Ref: Barrett K.E., Barman S.M., Boitano S., Brooks H.L. (2012). Chapter 8. Somatosensory Neurotransmission: Touch, Pain, and Temperature. In K.E. Barrett, S.M. Barman, S. Boitano, H.L. Brooks (Eds), Ganong’s Review of Medical Physiology, 24e. 

Q. 3

Perception of normal sensory stimuli as painful is called

 A

Hyperalgesia

 B

Allodynia

 C

Hyperpathia

 D

Causalgia

Q. 3

Perception of normal sensory stimuli as painful is called

 A

Hyperalgesia

 B

Allodynia

 C

Hyperpathia

 D

Causalgia

Ans. B

Explanation:

B i.e. Allodynia


Q. 4

True about Visceral pain:

 A

It is poorly localized

 B

Resembles “fast pain” produced by noxious stimulation of the skin

 C

Mediated by B fibers in the dorsal roots of the spinal nerves

 D

Causes relaxation of nearby skeletal muscles

Q. 4

True about Visceral pain:

 A

It is poorly localized

 B

Resembles “fast pain” produced by noxious stimulation of the skin

 C

Mediated by B fibers in the dorsal roots of the spinal nerves

 D

Causes relaxation of nearby skeletal muscles

Ans. A

Explanation:

A i.e. It is poorly localized

– Vanilloid receptors – VR1 are activated not only by pain causing agents capsaicinQ but also by protons & temperatures above 43°02.

Pain receptors are absent in liver parenchyma, lung alveoli, brain parenchyma, arachnoidmater, piamater, pial veins, & choroids plexusQ

– Perception of normal innocuous sensory stumuli (eg touch) as painfulQ is known as allodynia or different pain; whereas hyperalgesia is a hypesensitization of pain receptorsQ, thus lowering their threshold and causing exaggerated response on minor pain producing stumiliQ.

– Visceral pain (of thoracic & abdominal cavities) is transmitted through small type C fibers and so can only be of chronic aching-suffering type showing slow adaptationQ. Due to relative deficiency of A8 nerve fibers in deep (visceral) structures there is only very little rapid, bright, fast pain. Visceral pain is poorly localized(2 (often referred & radiating), nauseating & a/w autonomous symptoms and spasm (reflex contraction of nearby skeletal muscle)Q.

Pain – Nociception

Pain is defined as an unpleasant sensory and emotional experience a/w actual or potential tissue damage, or described in terms of such damage. Whereas nociception is unconscious activity induced by a harmful stimulus applied to sense receptors.

Acute or physiological pain is considered as good pain as it serves an important protective mechanism like withdrawl reflex. Whereas chronic or pathological pain like inflammatory & neuropathic (eg causalgia) pain can be considered bad pain.


Q. 5

Which of the following is not characteristic of visceral pain –

 A

Poor localisation

 B

Diffuse in nature

 C

High threshold

 D

Very rapid adaptation

Q. 5

Which of the following is not characteristic of visceral pain –

 A

Poor localisation

 B

Diffuse in nature

 C

High threshold

 D

Very rapid adaptation

Ans. D

Explanation:

Ans. is ‘d’ i.e., Very rapid adaptation 


Q. 6

Non-noxious stimuli perceived as pain is termed as:

 A

Allodynia

 B

Hyperalgesia

 C

Hyperesthesia

 D

Hyperpathia

Q. 6

Non-noxious stimuli perceived as pain is termed as:

 A

Allodynia

 B

Hyperalgesia

 C

Hyperesthesia

 D

Hyperpathia

Ans. A

Explanation:

Answer is A (Allodynia) :

Perception of a non painful stimulus (non-noxious stimulus) as ‘pain’ is termed as `allodynia’.

Terminology

Sensory Disturbance

Allodynia

Situation in which a non painful (non-noxious) stimulus once perceived is experienced as

painful.( example is elicitation of a painful sensation by application of a vibrating tuning fork)

Hyperalgesia

Situation in which a mildly painful (mildly noxious) stimulus once perceived is experienced as

severely painful, often excruciating

Hyperesthesia

Increased sensitivity or pain in response to touch

Hyperpathia

Broad term that encompasses all above phenomenon, namely, Allodynia, Hyperalgesia and

Hyperesthesia


Q. 7

Free nerve endings carrying nociceptive fibers are seen in:

 A

Intestine

 B

Spleen

 C

Liver

 D

Mesentery

Q. 7

Free nerve endings carrying nociceptive fibers are seen in:

 A

Intestine

 B

Spleen

 C

Liver

 D

Mesentery

Ans. D

Explanation:

Ans. d. Mesentery

Free nerve endings carrying nociceptive fibers are seen in mesentery.

`Visceral nociceptors are thought to be free nerve endings which occur in the walls of most hollow viscera and mesenteries.’-Applied Basic Science for Basic Surgical training by Andrew T Puffery (2008)/211

`The afferent innervations of serosa and mesentery are provided by spinal afferent fibres which are mostly bare nerve endings. By contrast most nerve fibre endings in the muscle layer of the gut comprise two specialized endings — IGLEs and Intramuscular arrays (IMA) with only a small population of free nerve endings reported in the intestines. ‘- Physiology of the Gastrointestinal Tract by Kim E. Barrett, Fayez K. Ghishan, Juanita L. Merchant, Hamid M. Said, Jackie D. Wood p690

‘Physiologic determinants of pain (nociception) include the nature of the stimulus, the type of receptor involved, the organization of the neural pathways from the site of injury to the central nervous system, and a complex interaction of moding influences on the transmission, interpretation, and reaction to pain messages. Sensory neuroreceptors in abdominal organs are located in the mucosa and muscularis of hollow viscera, on serosal structures such as the peritoneum, and within the mesentery. Visceral pain is transmitted by C fibers that are found in muscle, periosteum, mesentery, peritoneum, and viscera. ‘- Feldman: Sleisenger and Fordtran’s Gastrointestinal and Liver Disease, 9/e



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