Acute Inflammation 1 Flashcards
What is acute inflammation?
It is a series of protective changes in living tissue in response to an injury and is fundamental in maintaining homeostasis.
What are the cardinal signs of acute inflammation?
Rubor Calor Tumor Dolor Loss of function (protective mechanism)
What is the aetiology of acute inflammation?
Pathogenic micro organisms
Mechanical injury to tissue/trauma
Chemicals such as acid/alkali to upset the pH or bile/urine irritate peritoneal cavity
Extreme physical conditions such as heat, cold or ionising radiation
Cell necrosis irritates adjacent tissue
Hypersensitivity causes several reactions
What is the micro circulation?
Capillary beds fed by arterioles and drained by venules. It is the extracellular compartment with fluid and molecules in it. Starling forces control fluid flux across the membrane. There is a dynamic balance between hydrostatic and colloid oncotic pressure.
What happens to the vessels in acute inflammation and what is recruited?
The vessel radius increases and the membrane permeability changes so exudation happens.
Neutrophils move from the vessel to the extravascular compartment.
What is the triple response?
Transient arteriolar construction is protective.
Local arteriolar dilation
Relaxation of vessel smooth muscle.
Flush, flare and wheal.
How does poiseuille’s law affect flow of blood?
The flow is proportional to the arteriolar radius to the power of four so a small change in radius causes big changes in flow.
How is increased permeability caused and what is the effect of this?
An endothelial leak caused by imbalance of starling forces produces local chemical mediators.
This causes the net movement of plasma from capillaries to the extravascular compartment. This is exudation and the exudate is rich in plasma proteins such as immunoglobulin and fibrinogen.
This causes an oedema which means pain so is a protective response. The fluid loss also means increased viscosity which changes the characteristics of the flow of the vessel.
How does the flow change in inflammation?
There is a loss of normal laminar flow. The red cells aggregate in he centre of the lumen and the neutrophils are near the endothelium.
What are the phases of emigration of neutrophils?
Margination involves the neutrophils move to the endothelium of lumen.
Pavementing is when they adhere to it.
Emigration is when they squeeze between endothelial cells to extravascular tissues. (Diapedesis)
What is the ideal outcome for acute inflammation?
Inciting agent is found and destroyed and macrophages come to area and phagocytose debris. The epithelial surfaces regenerate and inflammatory exudate filters away and vascular changes resolve. Homeostasis is regained.
What are the benefits of acute inflammation?
Rapid response to non specific aspect
Cardinal signs and loss of function is transient protection.
Neutrophils destroy organisms and denature antigens for macrophages.
Plasma proteins localise the process.
