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.