Classes 3-4 Flashcards
What are the possible outcomes of chronic inflammation?
Tissue destruction, fibrosis
When does acute inflammation usually stop?
When injurious stimulus is removed, walled off, or broken down.
Outcomes: resolution, abscess formation, chronic inflammation.
What are the 7 morphotypes of inflammation?
Serous Fibrinous Purulent Ulcerative Pseudo membranous Chronic Granulomatous
Serous inflammation
Mildest form of inflammation
Characterized by clear fluid
Occurs in early stage; typical in viral infections, burns, arthritis
Exudate mostly albumin and immunoglobulin
Self limiting
Generally resolves easily.
Fibrinous inflammation
Exudate rich in fibrin
Bacterial infections (strep throat, bacterial pneumonia, bacterial pericarditis).
Does not resolve easily. Often requires antibiotics.
Leads to growth of fibrous tissue (scarring) in parenchyma –> loss of function.
Purulent inflammation
Typically formed by pus-forming bacteria. (Staph and strep)can accumulate on mucosa or in internal organs. May form abscess.
Abscess
Localized collection of pus within an organ or tissue
Does not heal spontaneously; must be surgically excised.
May lead to fistula or sinus.
Sinus
Cavity, usually occupied previously by an abscess that has ruptured, that drains through a tract to the surface of the body.
Fistula
A channel between preexisting cavities and/or hollow organs and/or surface of the body.
Empyema
Accumulation of pus in a preformed cavity (ex. gallbladder)
Ulcerative Inflammation
Inflammation do body surfaces or mucosa.
Leads to ulceration or necrosis of epithelial lining.
Ulcer
Defect involving the epithelium, which can also extend into connective tissue.
Pseudomembranous inflammation
Combination of ulcerative, fibrinous and purulent inflammation.
Ulcerative with fibronopurulent exudate (with mucus and cellular debris) which forms a pseudomembrane on surface of ulcer.
Diphtheria (pseudomembranes form on throat); C. Difficile in large intestines (secondary to antibiotic use)
Chronic inflammation
Because of length of inflammation, produces more tissue destruction, heals less readily and associated with more serious functional deficiencies.
Exudate contains monocytes, lymphocytes, macrophages, plasma cells.
Secretory products stimulate proliferation of fibroblasts (–> scarring –> loss of function) and recruit new inflammatory cells (perpetuating inflammation)
Sm
Granulomatous inflammation
Not preceded by acute inflammation.
Not neutrophil driven.
T-lymphocytes and macrophages accumulate at site of injury.
Lymphocytes release cytokines, which transform macrophages into epithelioid cells.
Epithelial cells fuse with each other and form multinucleated giant cells.
Multinucleated giant cells, epithelium cells and lymphocytes form granulomas, which destroy cells and last long time.
Caseous and non caseous
TB, fungal infections, syphillis.
Clinical correlations of inflammation
Fever 37 degrees +
Leukocytosis
Constitutional symptoms (fatigue, weakness, depression)
What causes fever?
Pyrogenes cytokines (Tumour Necrosis Factor -- TNF -- and IL-1) -- stimulate production of prostaglandins in hypothalamus
Cell categories based on ability to proliferate
- Continuously dividing/labile/mitotic
- Quiescent/facultative mitotic/stable
- Non-dividing/post-mitotic/permanent
Continuously Dividing Cell
Labile, mitotic, stem cells
Typically found in basal layer of skin or mucosa of internal organs.
Outcome: minimal tissue damage, short recovery time
Quiescent Cells
Facultative mitotic, stable
Do not divide regularly but can be stimulated to divide if necessary.
Form the parenchymal organs. (Eg liver, kidneys).
Outcome: regeneration, although may be limited.
Non-dividing Cells
Post-mitotic, permanent.
No capacity to divide period. Ex: neurons.
Outcome: replacement of parenchymal tissue with connective tissue leads to loss of function.
Healing by First Intention.
When wound is clean, free of foreign material and necrotic tissue, and edge are close together.
Scab
PMNs scavenge debris
2-4 days later granulation tissue develops.
3-6 weeks scar develops
Healing by Second Intention
Large break in tissue, inflammation, longer healing and more scarring.
Granulation tissue
Vascularized connective tissue rich in macrophages, myofibroblasts and angioblasts.
Part of wound healing. Develops in 2-4 days.
PMN’s role in wound healing
Scavenge briefly at injury site
The role of connective tissue cells in wound healing
Produce scar tissue.
Include myofibroblasts, angioblasts, fibroblasts
Epithelial cells and wound healing
Undergo mitosis and extend across wound.
Macrophages and wound healing
Stay at site and produce cytokines and growth factors.
Myofibroblasts and wound healing
Hybrids – have properties of smooth muscle and fibroblasts.
In first few days, contract reduces defect and holds margins together.
Secrete matrix substances like fibroblasts.
Angioblasts and wound healing
Precursors of blood vessels
Appear 2-3 days after incision and new blood vessels permeate site by 5-6th day.
New vessels provide route for scavenger cells to remove scab and debris and allow influx of nutrients and O2