Intro to Inflammation and Infection

Question 1

describe the 4 purposes of inflammation

Answer 1

1. to destroy the pathogen or noxious stimulant
2. to destroy infected cells
3. to expel noxious or foreign material and remove cellular debris
4. to help aid in the healing of tissues

Question 2

list the 3 types of stimuli that can initiate and inflammatory response and recognize examples of each

Answer 2

1. microbes: PAMPs like peptidoglycan, LPS, dsRNA
2. injured cells of the body: DAMPs can be intracellular (like when cells rupture) or extracellular
3. foreign material

Question 3

describe the role of PRRs in inflammatory responses

Answer 3

bind their respective PAMP, initiate a signaling cascade, activate transcription factors, and lead to expression of genes like pro-inflammatory cytokines, chemokines, adhesion molecules, and co-stimulatory molecules

Question 4

list basic categories of inflammatory mediators; briefly describe their targets and effects at the tissue or cellular level

Answer 4

cellular:
1. released by macrophages: pro-inflam cytokines, chemokines, and eicosanoids
2. released by mast cells: histamine
3. released by other cells: chemokines and cytokines
4. released by cell membranes: lipid mediators, arachadonic acid

plasma:
complement, kinins, plasmin, clotting cascade

effects/steps of extravasation:
1. vasoactive mediators cause vasodilation, which slows down blood flow, making it easier for inflammatory cells to exit vessels
2. vascular permeability increases: endothelial walls of small vessel walls are less tightly bound to each other, making it easier for inflammatory cells to get to the tissue
3. neutrophils migrate to site of infection via diapedesis/extravasation

Question 5

describe the 5 cardinal signs of inflammation

Answer 5

1. redness: due to vasodilation
2. heat: due to vasodilation
3. swelling: due to vasodilation, increased vascular permeability, and immune cell influx
4. pain: due to nocioceptor stimulation (physical and chemical) and immune cell influx
5. loss of function: due to physical disruption of tissues, immune cell influx, and remodeling of tissues over time

Question 6

describe the blood vessel changes that occur during inflammation

Answer 6

1. small blood vessels dilate
2. vascular permeability increases
3. neutrophils migrate to site of infection

Question 7

describe the basic steps of extravasation and chemotaxis of leukocytes

Answer 7

1. rolling
2. adhesion to endothelial cells
3. crawling, firm adhesion, and patrolling
4. transendothelial migration (extravasation): after approaching the site of inflammation, neutrophils find a small gap between pericytes, migrating through the space by forming a protuding uropod that allows neutrophils to access the inflamed area
5. leukocytes follow a chemical gradient to reach the site of inflammation in tissues