Acute inflammation vascular phase: vasodilation by Hageman factor and bradykinin Flashcards
What is the main mediator of acute inflammation that causes vasodilation?
Hageman factor/Factor XII
What is Hageman factor/Factor XII, and where is is located?
Clotting factor circulating in blood which is produced by liver
What 2 substances activate Hageman factor/Factor XII when they come into contact?
Microbe, collagen
What layers of the skin are pierced to initiate the vascular phase of acute inflammation?
Skin epidermis then papillary dermis (upper vascular layer of dermis)
How is hageman factor/factor XII activated after the skin is pierced in acute inflammation?
Hageman factor comes into contact with collagen in dermis
What 3 mechanisms does hageman factor activate after coming into contact with collagen in acute inflammation?
Complement system
Clotting cascade
Kinin system
In the kinin system, what molecule does hageman factor cleave?
Hageman factor cleaves kallikrein (plasma protein)
In the kinin system, what does kallikrein cleave and what is the resulting molecule?
Kallikrein cleaves High Molecular Weight kininogen to form bradykinin
How does bradykinin cause vasodilation in the vascular phase of acute inflammation?
Stimulates smooth muscle in arteriole walls to relax so that there is increased blood flow in the vessel
What 2 cardinal features does vasodilation create in acute inflammation and why?
Rubor (redness) and calor (heat) due to increased blood flow that is also more superficial to skin surface
What are the 3 functions of bradykinin in the vascular phase of acute inflammation?
Vasodilation
Increased vascular permeability
Sensitisation of nerve endings
How does bradykinin increase vascular permeability in the vascular phase of acute inflammation?
Stimulates endothelial cells in blood vessel walls to contract which increases space between the individual cells
How does vasodilation present in acute cellulitis?
Leg is red and hot to touch
When endothelial cells are damaged due to necrosis, what happens to the fluid in the blood vessels?
Fluid leakage into interstitium due to increased vascular permeability
How does bradykinin cause dolor in acute inflammation?
Nerve endings are sensitised, which causes more pain (dolor)
