Upload
tanika
View
216
Download
1
Tags:
Embed Size (px)
DESCRIPTION
Lewis Triple Response. Described by sir Thomas Lewis in 1924. Lewis triple response is the characteristic 3 part response that develops when a line is made by a pointed object (a key) on the skin. It is produced due to the release of histamine from the mast cells. - PowerPoint PPT Presentation
Citation preview
Lewis Triple Response• Described by sir Thomas Lewis in 1924.
• Lewis triple response is the characteristic 3 part response that develops when a line is made by a pointed object (a key) on the skin. It is produced due to the release of histamine from the mast cells.
• Trauma may release an antigen that interacts with the membrane-bound immunoglobulin E of mast cells, which release inflammatory mediators, particularly histamine, into the tissues. This causes small blood vessels to leak, allowing fluid to accumulate in the skin.
Inflammatory Response
Components of the Triple Response
1.Red reaction: red line (transient local vasodilation due to histamine), appears in few seconds.
2.Wheal: localized edema in the region of the redline (increased capillary permeability and exudation of fluid from capillaries and venules due to histamine release), appears in 1 min.
3.Flare: spreading redness extending beyond the red line (due to axon reflex), appears slowly.
- Three cell types – smooth muscle in the microcirculation – endothelium: capillary or venule – sensory nerve endings
Receptor types
Type Location Function
H1 Smooth m., endothelium, CNS
Bronchoconstriction, Contraction of GIT, VasodilatationIncreased capillary permeability leading to edemaPain and itch
H2 Parietal cells, vascular smooth m.
Vasodilatation, gastric acid secretion
H3 CNS Modulate the release of other neurotransmitters
H4 Basophils, BM, Thymus, spleen
Chemotaxis
Subgroups of Histamine Receptor Blockers
What will occur with
Antihistamine OR
Local Anesthetics?