Inflammation And Repair Flashcards
A vascular reaction to injury of tissue
Inflammation
-provides defense against micro organisms
Replacement of damaged tissue
Repair
What are some common causes of inflammation?
Physical injury
Immune reaction
Infection
What is the function of inflammation to damaged tissue?
Prepare the damaged site for repair
Inflammation is characterized by what suffix?
“-itis”
What type of inflammation is characterized by circulatory, cellular, humoral and neurogenic responses with an outpouring of fluid and cells (exudation)?
Acute inflammation
Also characterized by a rapid course and accumulated neutrophils (PMNs)
What kind of inflammation is generally prolonged and characterized by scar tissue formation?
Chronic inflammation
Clinical signs are consistent and predictable in _______ inflammation and variable and less predictable in _______ inflammation
Acute: chronic
What are the benefits of inflammation?
Defense
- localize and dilute damaging agents
- transports antibiotics and therapeutic drugs to the injury site
- promotes fibrin deposit formation
- stimulates immune response
- mobilizes phagocytes
- brings oxygen and nutrients to area for resolution and repair
What are the potentially harmful effects of inflammation?
- leukocyte products injure tissue by releasing enzymes indiscriminately
- prolonged vascular pooling can cause hypoxia and thrombosis
- excessive swelling (myofascial compartment, cranial cavity)
- can increase injury, promote scarring and delay repair
What are the cardinal signs of acute inflammation?
- heat (calor) - due to vasodilation and increased blood flow
- redness (rubor) vasodilation with hyperemia
- swelling (edema) - due to vasodilation and accumulated fluid
- pain (dolor)
- loss of function (functio laesa)
What are the circulatory responses to acute inflammation?
- vasodilation, increased blood flow and increased vascular permeability due to structural changes
- leukocytes, fluid and plasma proteins accumulate
What is the triple response of Lewis?
Mild, reversible vascular response to blunt stroking of skin:
- white line: from momentary arteriolar constriction (insignificant and transient)
- red line (flush): local vasodilation due to release of histamine
- flare (spread): neurogenic mechanisms and chemical factors dilate adjacent vessels and enlarge “red zone”
Wheal: pale swelling due to edema
What is stasis?
Pooling of blood as the result of vasodilation and slowed rate of flow
Blood pooling and dilation of venules leads to what?
Congestion, hemoconcentration and sludging
What is hemoconcentration?
When blood becomes thicker following pooling and dilation of venules due to plasma fluid escaping into surrounding tissue. This concentrates the blood.
What is sludging in relation to alternations in blood flow associated with inflammation?
Clumping of RBCs due to decreased blood flow, hemoconcentration and actions of inflammatory products that make RBCs sticky
What is an ESR?
Erythrocytes sedimentation rate - the rate at which RBCs sediment is influenced by inflammation and therefore can be measured to confirm systemic inflammatory response (ex: Giant Cell Arteritis)
Increased vascular permeability associated with acute inflammation will result in _______.
Exudates - consists of fluids, plasma proteins, debris and leukocytes
What are the reversible mechanisms of increased permeability of vessels (especially venules) in acute inflammation?
- endothelial cells contract and open gaps (regulated by chemical mediators)
- opening of trans cytoplasmic channels
If there is direct injury to the endothelia of vessels in acute inflammation, what will happen?
Detachment and necrosis of injured endothelial cells that will leave gaps until repaired
What is the permeability of new blood vessels that form during repair from acute inflammation?
They are very permeable (leaky) to plasma elements and therefore contribute to edema
THe pattern of exudation in acute inflammation reflects ______.
The severity of vascular injury
What pattern of exudation is generally associated with milder forms of injury with opening of inter-endothelial cell junctions?
Serous exudates
What pattern of exudation gives rise to an albuminous straw-colored fluid?
Serous exudates
In appearance, sxudates are ______ while transudates are ______.
Cloudy : clear
A blister is an example of what pattern of exudation?
Serous exudates
What pattern of exudation is associated with more severe injury to endothelium and larger gaps are formed leading to escape of fibrinogen?
Fibrinous exudates
When extensive, fibrin deposits promote the infiltration of ______ cells and contribute to the formation of _______
Fibroblast : collagenous scar tissue
What pattern of exudation is associated with extensive and severe endothelial damage that contributes to leakage of all blood components?
Hemorrhagic exudates
What are some causes of hemorrhagic exudates?
Bacterial meningitis and acute radiation injury
What are the steps of cell (leukocyte) response in acute inflammation?
- margination (and rolling)
- pavement in (adhesion)
- emigration (diapedesis)
- migration (chemotaxis)
- aggregation
- phagocytosis
What is margination in the cell response?
Leukocytes move from the center to the periphery of vessels in response to adhesive mechanisms and decreased blood flow associated with inflammation. They begin to stick to endothelium
What is pavementing in the cell response?
Leukocytes adhere to the vessel wall and line-up (like cobble stones)
What is emigration in the cell response?
Diapedesis- following adhesion of leukocytes to vessel walls, they actively squeeze through gaps in the vessels and into the tissue
What is migration in cell response?
Chemotaxis - the directed movement of leukocytes toward chemical attractants (bacterial products, complement, arachidonic acid metabolites, etc) released at the site of injury
What is aggregation in the cell response?
Leukocytes accumulate at site of inflammation
What are the steps of phagocytosis?
Adhesion
Ingestion
Killing
Digestion
What is involved in the adhesion step of phagocytosis?
Recognition and attachment
- it is mediated by leukocyte membrane receptor
- aided by opsonins that that coat the foreign cell and bind specific receptors on leukocytes (examples of opsonins: IgG and complement)
What is involved in the ingestion step of phagocytosis?
Engulfment
- pseudopodia extend around foreign particle and form phagocytic vesicle
- lysosomes and other cytoplasmic vesicles fuse with phagocytic vesicles and discharge contents to form phagolysosomes
What is involved in the killing step of phagocytosis?
Leukocytes produce noxious microbicidal (cytotoxic) agents
Some of this is done by oxygen dependent mechanisms, so it can give rise to oxygen derived free radicals
Some of this is done by oxygen independent mechanisms (lysosomal enzymes)
Products formed by leukocytes during phagocytosis can can injury to surrounding tissues. How?
- Regurgitation through feeding
- incomplete (frustrated) phagocytosis
- cytotoxic release from dying leukocyte
What is involved in the digestion step of phagocytosis?
Degradation
- acid hydrolases (lysosomal enzymes) digest ingested materials within phagolysosomes
What is another name for neutrophils?
PMNs - polymorphonuclear leukocytes
Who are the first responders in inflammation?
Neutrophils
Which leukocytes dominate in acute inflammation?
Neutrophils
Neutrophils survive in the tissue for only a few days. Why?
- lack the capacity for mitosis
- sensitive to pHs that are common in inflammatory response
- undergo apoptosis when “finished”
What cells are efficient phagocytes of bacteria?
Neutrophils
Which leukocyte cells contribute to the “first line of defense”
Neutrophils
Which leukocytes are associated with all phases of inflammation but respond more slowly and dominate in chronic inflammation?
Monocytes/macrophages
Monocytes/macrophages have prolonged survival in the tissue. WHy?
- capable of mitosis and can therefore be sustained by proliferation
What is the primary function of monocytes/macrophages?
- Phagocytosis of bacteria and debris (cell clean up)
- produce cytokines and other active agents (IL-1, TNF, NO, components of complement, etc)
What are the functions of the cytokines and other active agents (IL-1, TNF, NO, components of complement, etc) that are secreted by monocytes/macrophages?
- activate inflammation
- recruit other leukocytes
- activate fibroblast and promote collagen formation
What cells often appear in response to viral infections and increased response to allergies?
Lymphocytes and plasma cells
What cells are chiefly seen in hypersensitivity conditions such as allergies
basophils
WHat cells are chiefly seen in parasitic infections?
Eosinophils
PHagocytic leukocytes that produce MBP (major basic protein) which is a cytotoxic agent designed to destroy parasites but also injures tissue in the process?
Eosinophils
“Circulating mast cells” whose numbers are increased in peripheral blood in allergies?
Basophils
What is the main actions of chemical mediators in inflammation?
- Initiate and regulate inflammation (both vascular and cellular steps)
- modify actions of other mediators
- contribute to systemic manifestation of pain and fever
- bind to specific receptors on target cells
What is the origin of chemical mediators involved in inflammation?
- Locally from cells such as leukocytes and endothelium at the side of injury: They can be preformed elements that are released (histamine) or synthesized on demand (prostaglandins)
- components present in the blood such as plasma proteases (require activation)
Where do plasma factors used as chemical mediators in inflammation come from?
They are synthesized and activated in the liver and then transported to the tissue via the blood.
What are some examples of plasma factors used as chemical mediators in inflammation?
- coagulation proteins (thrombin, fibrin, etc)
- kinins
- components of complement
WHat are some preformed mediators that are present in secretory vessels of local cells involved in inflammation?
Histamine
Serotonin
Lysosomal enzymes
Serotonin is formed from ____
Platelets
Vasoactive amines include ____ and _____
Histamine : serotonin
Histamine and serotonin mediate what in the inflammatory response?
Immediate increased vascular permeability and vasodilation
Histamine is synthesized and stored in
Mast cells, basophils and platelets.
What factors stimulate histamine release?
- trauma
- thermal factors
- IgE mediated reactions with sensitized mast cells
- C3a and C5a (components of complement)
- lysosomal proteases
- interleukin-1
What are the derivative of arachadonic acid in the inflammatory process?
Prostaglandins, thrombocytes and leukotrienes
The derivatives of arachadonic acid participate in every step of ______
Acute inflammation
Where is arachadonic acid found?
In the phospholipid bilayer of most cell types (endothelium, platelets, leukocytes)
How is arachadonic acid released due to cell injury?
Cell injury activates phospholipase A2 which releases arachidonic acid which in turn is used in synthesis of biologically active agents bu the cyclooxygenase and lipoxygenase pathways
The cyclooxygenase pathway of arachadonic acid produces what?
Prostaglandins, Prostacyclins and thromboxanes
What does NSAIDs inhibit?
Cyclooxygenase, so prostaglandins. Prostacyclins and thromboxanes are not produced
The lipoxygenase pathway of arachadonic acid produces what?
Leukotrienes
What do steroids inhibit?
Phospholipase A2, so arachadonic acid is not released from the cell membrane and therefore leukotrienes, prostaglandins, prostacyclins and thromboxanes are not produced
What is the function of leukotrienes?
They are chemotactic for neutrophils.
They also increased vascular permeability and vasoconstriction
What is the function of thromboxane A2? And where is it derived from?
Platelet aggregation and constriction of blood vessels
Promotes hemostasis
Derived from platelets
What is the function of prostacyclin and where is it formed?
Formed in endothelium
Prevent platelet aggregation and is a vasodilator
Beneficial when hemostasis is not required
What is the function of prostaglandin E?
Potent vasodilator
Potentiates the affect of bradykinin to cause pain
Mediator of fever by acting on thermoregulatory centers of the hypothalamus
Aspirin and most NSAIDs inhibit ______ and therefore synthesis of all ______ which functions as treatment for pain and fever
Cyclooxygenase : prostaglandin
There are 2 forms of cyclooxygenase inhibitors. What are they and how do they work?
COX1 - expressed in gastric mucosa so while they do diminish inflammation, they also contribute to increased gastric ulcerations
COX2 - selectively decrease inflammation but minimize stomach affects. Pulled from market due to cardiovascular side effects
SRS or slow reacting substance is another name for what arachadonic acid derivative?
Leukotrienes
How does Fish Oil inhibit inflammation?
They inhibit the production of leukotrienes (and to a lesser extent, prostaglandins), because it is structurally similar to arachadonic acid and will be metabolized by cyclooxygenase and lipoxygenase to less biologically active products
The other cell derived mediators of inflammation include:
- lysosomal agents
- oxygen derived radicals
- cytokines
- substance P (neurokinin)
- nitric oxide
A group of circulating molecules that are converted to inflammatory mediators by a series of sequential enzymatic reactions
Plasma factors (proteases)
What are some examples of plasma factors?
- the kinin system
- components of the complement system
- components of the clotting system