Module 2: Inflammation Flashcards
What are the two types of immune defenses?
1) innate– fast but non-specific and is both the 1st and 2nd line of defense
2) adaptive– slow but very specific and is the 3rd line of defense
Describe the innate immune response
fast, non-specific to particular antigens, ex. mucous production
Describe the adaptive immune response
very specific response to a very specific antigen– this response is developing between 6 months and 2 years of age
What causes acute inflammation?
any breach of body defenses results in an immediate, localized response to damage (acute inflammation)
if the issue is not resolved then it may result in chronic inflammation
What is the difference between first line of defense and second line of defense?
first line– physical barriers, biochemical barriers, and normal microbiome
second line– antimicrobial substances (ex. cytokines), and immune cellular defenses (innate WBC functions such as apoptosis), inflammatory response, and fever
Describe the third line of defense (adaptive immunity)
2 lymphocyte types with difference mechanisms of destroying the antigen
1) humoral (antibody mediated) immunity (B lymphocytes)
2) cell mediated immunity (T lymphocytes)
What is humoral immunity?
also called antibody mediated immunity, part of the third line of defense
B lymphocytes–> differentiate into plasma cells–> production of specific antibody/immunoglobulin which binds to and results in destruction of antigen
What is cell mediated immunity
part of the third line of defense
T lymphocytes–> production of antigen specific helper T cells (stimulate other T and B cells) and cytotoxic T cells–> bind to and stimulate apoptotic destruction of antigen containing cell
What are the two key features of adaptive immunity?
1) specificity– each B or T cell responds to one specific type of antigen
2) immunological memory– each B or T cell remembers the antigen and subsequent re-exposure elicits a rapid response (so fast that no symptoms of illness should appear)
What is included in the microscopic blood vessels?
arterioles, capillaries, and venules
Describe the arterioles
they vasoconstrict and vasodilate to control local capillary bed blood flow to tissues
contain smooth muscle
Describe the capillaries
sit of nutrient and gas exchange
do NOT contain smooth muscle
Describe the venules
direct blood flow away from capillary bed
contain smooth muscle
What do precapillary sphincters do?
they are rings of smooth muscle that contract and relax to regulate blood flow into the capillary bed
What are cytokines?
the nervous system of the WBCs
What are chemokines?
the attract WBCs to a site
What happens if too much histamine is released? not enough?
too much causes hypersensitivity and not enough causes immunodeficiency
What are the 5 signs of inflammation?
redness, heat, swelling, pain, and loss of function
Define inflammation
the tissue response to injury or infection– occurs in vascularized tissue
Define inflammatory response
describes how various tissues react to injury or infection that causes tissue damage– non-specific, rapid response of injured tissue to any causative (etiological) agent of tissue damage
What are the purposes of the inflammatory response?
-limit further tissue damage
-prevent spread of injurious agent/infection
-stimulate adaptive immune response
-begin wound healing process
What effect does stromal tissue have on tissue damage?
-triggers the inflammatory response
-increases vascular permeability
-vasodilation
-fibroblasts secrete protein fibers called collagen
-mast cells secrete histamine and heparin
What does heparin do?
prevents blood clotting
What effect does parenchymal tissue have at the tissue damage site?
-may be damaged and need to be replaced
-do not directly cause the inflammatory response
What are the two patterns of inflammatory response and what determine which one it is?
1) acute inflammatory response
2) chronic inflammatory response
based on the duration of the response and the specific WBCs present in the lesion
Describe acute inflammation
-innate, immediate tissue response to injury
-main chemical mediator is histamine
-tries to limit the damage and prevent scarring
-promotes wound healing by bringing in nutrients and removing debris
-predominant immune cells: mast cells, neutrophils and macrophages (order is important)
Describe chronic inflammation
-innate and adaptive, prolonged tissue reaction to continued injury or persistent infection
-main chemical mediator is histamine
-still trying to limit the damage and promote wound healing, but scarring is probable
-predominant immune cells: macrophages, lymphocytes, and mast cells (order is important)
What are the 3 possible results of wound healing?
1) resolution– damaged cells recover
2) regeneration– replacement by same type of cell
3) repair– scarring occurs
What are the major WBCs involved in the acute inflammatory response and what do they do?
Mast cells– secrete histamine (major proinflammatory chemical mediator)
Neutrophils– phagocytic; first responders to tissue distress
Macrophages– phagocytic; clean up cellular debris (slow to get to the site)
What are the 3 types of plasma protein systems responses for the acute inflammatory response?
1) complement
2) coagulation
3) kinin cascades
These promote inflammation and blood clotting when needed
What are the 3 major components of the acute inflammatory response?
1) the vascular response
2) the cellular response
3) the plasma protein systems response
These are caused by the release of histamine and are all proinflammatory!
Describe the vascular response of the acute inflammatory response
the immediate histamine-mediated response by the microvascular endothelial and smooth muscle cells within the wound site; it will increase blood flow into the injured tissue and increase vascular permeability
Describe the cellular response of the acute inflammatory response
includes all 3 types of blood cells– WBCs, platelets, and RBCs as they respond to injured tissue and increase vascular permeability
Describe the plasma protein systems response of the acute inflammatory response
includes a variety of biochemical responses to injury; these proinflammatory proteins are part of the acute phase proteins, they are transported in the blood plasma to the injury site, where they act as proinflammatory mediators (complement system, coagulation system, and kinin system)
Where are mast cells located?
in the connective tissue surrounding the microvasculature
Where are histamine receptors located?
endothelial cells and smooth muscle cells
What are the effects of histamine release on the microvasculature during an inflammatory response?
(very long answer)
tissue damage stimulates mast cells to rapidly “degranulate” ie. release histamine from storage in cytoplasmic vesicles. Histamine bind to histamine receptors on vascular endothelial and smooth muscle cells causing specific independent responses and 3 things happen:
1) the arteriolar and precapillary sphincter smooth muscle cells-> histamine stimulates vascular smooth muscle cells to relax-> arteriole vasodilation and opens precapillary sphincters-> increased rate of blood flow to cap. bed
2) venular endothelium-> histamine stimulates endothelial cells to contract-> ‘myo’endothelial contraction creates inter-endothelial cell gaps-> increased vascular permeability
3) venular endothelium-> histamine also stimulates endothelial cells to decrease production of anti-endothelial cells and infiltrate the wound site-> promotes leukocyte infiltration and clot formation
What type of cells produce histamine?
Mast cells– innate tissue immune cells that recognize and respond to tissue ‘distress’ signals by secreting histamine and other proinflammatory mediators, including heparin
What are the cell characteristics of mast cells?
-derived from pluripotent stem cells in red bone marrow
-reside in connective tissue (stromal immune surveillance cells)
-recognize tissue damage, microbial invasion
Describe the 2 mechanisms in which mast cells release proinflammatory mediators
1) mast cell degranulation
-immediate release of mediators
-the mediators are made in advance and stored in vesicles within the mast cell (look granular)
-histamine
-other proinflammatory mediators (chemotactic factors and cytokines)
2) mast cell synthesis
-slower release of newly synthesized mediators
-includes cell membrane components of damaged mast cells
-chemokines (made by any cell that is dying)
Does histamine cause pain?
not directly, it can stimulate the edema that pushed on nerve endings causing them to be compressed or irritated, it is said to elicit all 5 signs, even if one is an indirect effect