Lecture 2 Flashcards
3 Lines of Defense
- Skin and Mucous Membranes (tears, saliva, gut flora, stomach acid)
- Inflammatory Response (nonspecific and acute)
- Immune Response
What are the 7 etiologies that can cause inflammation?
Microorganisms, Hypoxia/Ischemia, Nutritional Deficiencies (low B12,iron), Trauma/Surgery, Radiation, Caustic Chemicals, and Extreme Heat/Cold
2 Main Components of the Vascular Response
Increased Blood Flow to injury site
Increased blood vessel permeability at the injury site
Major component of the cellular response
removal of offending agent and damaged tissue
3 Major Components of Acute Inflammation
Vascular Response, Cellular Response, and Inflammatory Mediators
What are the 2 major anatomical changes that occur during the vascular response?
Increased blood vessel dilation
Increased blood vessel permeability
What are the steps of the vascular response?
- Transient vasoconstriction
- Local blood vessels dilate (vasodilation) to increase blood flow to area and enhance the transport of blood and cells.
- Endothelial cells lining the vessels contract to open up gaps in the intracellular junctions, which is increased permeability.
- Increased vessel permeability allows for plasma and cells to travel to the injured tissue.
This results in dilution of the pathogen via exudation of fluid, stagnated blood flow in the vessel at that location, slowing the spread of the offending agent, and clotting elements can move into the injury site.
What are the 3 types of capillaries?
Continuous, Fenestrated, and Sinusoids (discontinuous)
Where do I find fenestrated capillaries?
Endocrine organs, small intestine, and the choroid plexus.
Where do I find continuous capillaries?
CNS (blood-brain barriers) and lungs.
Where do I find sinusoidal capillaries?
Bone marrow, spleen, and liver.
What are the 3 major patterns of vascular response?
Immediate Transient: post minor injury
Immediate Sustained: post major injury (most common)
Delayed Hemodynamic: 4-24 hrs post injury. (ie sunburn/radiation)
What is the cellular response and its 4 steps?
Movement of phagocytic WBCs into area of injury.
- Margination/Adhesion
- Migration/Diapedesis
- Chemotaxis
- Phagocytosis
Main phagocytic WBCs that move into injury area
Granulocytes
Monocytes
What are the steps of margination/adhesion?
- An injury causes cytokine release. (chemical mediator)
- Cytokines (IL-1 and TNF-alpha) increased expression of adhesion molecules, specifically selectin.
- Leukocytes have slowed migration and begin marginating/pavementing along the periphery of vessels.
- Adhesion to the vessel walls.
What is migration/diapedesis?
It is when WBCs extend their pseudopods and pass through the capillary wall via ameboid movement.
What is chemotaxis and the components of it?
Chemotaxis is when leukocytes travel throughout the tissue to the site of injury.
It is signaled by cytokines and complements (C3a and C5a)
What is phagocytosis and opsonization?
Phagocytosis is the engulfment of cells.
Opsonization is the recognition and attachment of a cell, done usually by C3b.
Leukocyte response
Stick to selectin in order to roll along vessel and find place to pass through to tissue, only move through veins, not arteries.
What is a Neutrophil?
AKA a polymorphonuclear neutrophil (PMNs) or segmented neutrophil (segs)
It is the primary phagocyte to arrive early to the injury site and arrives in ~90 minutes with a duration of 10 hrs.
Presence of bands or left-shift means there is a lot of inflammation and immature neutrophils may be released from marrow.
What is leukocytosis?
The increased production/presence of WBCs. Usually neutrophils.
Eosinophils
For allergic and primarily parasitic infections.
Basophils
For inflammation and allergic reactions
Can release histamine
Bonds with IgE
Mast Cells
Similar to basophils but reside in portals of entry (connective tissue) and act as sentinel position cells on mucosal surfaces (lung, GI tract, dermis)
Also commonly seen in allergic and parasitic infections with IgE. Not direct injury to tissue, but recognize something and start response.
Monocyte (macrophage when in tissue)
Largest WBC (engulf larger stuff than neutrophils)
Arrives ~24 hrs post injury, majority cell type after 48 hrs.
Play a role in adaptive immune response
Erythrocytes (RBC)
transport of oxygen to tissues
Platelets/Thrombocytes
Helps mediate vascular response
Involved in hemostasis and thrombosis
Releases inflammatory mediators
Endothelial cells
Involved in vascular response
Synthesizes and releases inflammatory mediators
What are the general effects of an inflammatory mediator?
Affects vasodilation, chemotaxis, platelet aggregation, endothelial cell stickiness, pain, and vascular permeability.
What are the inflammatory mediators?
Plasma proteins, Histamine, Cytokines, Platelet Activating Factor, Prostaglandins, and Leukotrienes
What are the 3 Plasma Proteins?
Kinins, Complements, and the clotting system
What are Kinins?
A plasma protein that causes vasodilation, increased vascular permeability, smooth muscle contraction and is involved in the pain response. Most common is bradykinin. They are broken down by Kininases and ACEs.
What is the clotting system?
Plasma proteins involved in clotting. Generally, fibrinopeptides are formed along with a thrombus.
Thrombin is the key protease enzyme.
Functions include expression of endothelial adhesion molecules and production of prostaglandins, PAF, and chemokines.
What is the complement system?
Inactive plasma proteins that become activated in a cascade to degrade subsequent complements.
Functions include vasodilation and increased vascular permeability, smooth muscle contraction, leukocyte activation, adhesion, and chemotaxis, augmentation of phagocytosis, and mast cell degranulation.
Most common are C3a and C5a.
Histamine
An inflammatory mediator released by mast cells, basophils, and platelets.
Plays a major role in vascular response via H1 receptor, causing vasodilation and increased vascular permeability.
It is one of the first mediators of inflammation.
Cytokines
Signal inflammatory mediators made up of 5 categories: chemokines, lymphokines, interleukins, interferons, and tumor necrosis factors.
IL-1 and TNF-alpha
early and major mediators of the inflammatory response.
They are responsible for inducing fever, adhesion of leukocytes to the endothelium, chemotaxis, general acute-phase response, and in the pain response.
Arachidonic Acid
The precursor to both leukotrienes and prostaglandins. It is formed from cell membrane phospholipids.
Inhibited by corticosteroids, which prevent its formation.