Acute and Chronic Inflammation Flashcards
What are the two functions of inflammation?
Destroy/contain the harmful agent and prepare for the occurence of healing/repair
What are the four cardinal signs of inflammation?
Heat, redness, swelling, pain (and loss of function)
What are the features of acute inflammation?
- fast onset (min-hr)
- mainly neutrophil infiltrate
- usually mild/self-limiting tissue injury
- prominent local and systemic signs
What are the features of chronic inflammation?
- slow onset (days)
- monocyte/macrophage and lymphocyte infiltrate
- often severe/progressive tissue injury
- less prominent local and systemic signs
**chronic inflammation may follow acute or arise de novo
What are the common causes of inflammation?
- Infections/microbial toxins (bacteria, viruses, fungi, parasites)
- Tissue necrosis (ischemia, trauma, etc)
- Foreign bodies (splinters, sutures, etc)
- Immune/hypersensitvity reactions
- environmental substances
- self antigens
What 3 ways are abnormal stimuli recognized by the body?
- Cells with receptors to detect infectious pathogens (epithelial, DCs, phagocytes, TLRs)
- Cell receptors that recognize molecular structures present with cell damage (e.g. inflammasomes recognize parts of dead cells in cytoplasm such as uric acid/DNA/ATP and activate caspase-1/IL-1 to recruit leukocytes)
- Circulating proteins (i.e. complement)
What are the three components of acute inflammation?
- Small vessel dilation (induced by histamine and nitric oxide… affects arterioles then capillary beds)
- Increased permeability of small vessels (induced by histamine and bradykinin… affects mainly venules)
- Margination/emigration of leukocytes from circulation, leukocyte activation
What causes the erythema and warmth associated with inflammation?
Stasis of blood flow/congestion due to the vasodilation of small vessels
**Think wider river= slow flowing, fast little stream
Define exudate
Inflammatory extravascular fluid with high protein content that may contain some white and red cells
*High specific gravity >1.020
**More serious inflammation process than the leakage of transudate, caused by alteration in normal vessel permeability
Define transudate
Non-inflammatory extravascular fluid with low protein content and few cells (ultrafiltrate of plasma)
*Low specific gravity <1.012
**Leakage due to increased hydrostatic pressure/decreased colloid osmotic pressure… more mild than exudate leakage
Define pus
Purulent thick exudate rich in leukocytes
Define edema
Excess fluid in interstitium or serosal cavities
Describe how histamine is released and its effect on vessels
- Released from mast cells in connective tissue in response to cytokines (IL1), trauma, complement, etc
- Causes vasodilation and increased vascular permeability
Describe how nitric oxide is released and its effect on vessels
- Many functions/origins
- In inflammation; released by endothelial cells in response to injury and causes vasodilation
Describe what bradykinin is and its effect on vessels
- Plasma protein resulting from kinin system activation (exposure to site of endothelial injury)
- Causes vasodilation, increased permeability, and pain
What is the origin of neutrophils? macrophages?
Neutrophils are from hematopoietic stem cells in marrow
Macrophages are from hematopoietic stem cells in marrow in inflammatory reactions AND many tissue-resident macrophages come from stem cells in development
What is the life span of neutrophils? macrophages?
Neutrophils= 1-2 days (short)
Inflammatory Macrophages= days-weeks (long)
Tissue-resident Macrophages= years (long)
What is the response of neutrophils to stimuli? of macrophages?
Neutrophils= rapid, short-lived response
Macrophages= more prolonged, slower, dependent on new gene transcription
Define leukocyte margination
Movement closer to vessel wall (due to vasodilation and stasis)