Inflammation Flashcards
What are the two different types of autopsies?
Hospital autopsy- audit, teaching, governance, research
Medico-legal autopsy- coronial and forensic autopsies (main type- 90% of autopsies)
What is the role of an autopsy? 4 questions they ask
Who is the deceased?
When did they die?
How did they die?
Where did they die?
Definition: Inflammation
A local physiological response to tissue injury
6 Causes of inflammation
- Microbial infections
- Hypersensitivity reactions
- Physical agents (burns, trauma etc.)
- Corrosive and irritant chemicals
- Tissue necrosis (e.g. from a lack of oxygen)
- Bacterial toxins
What is the characteristic cell recruited to tissue during inflammation?
Neutrophil polymorphs
What are the 4 outcomes of acute inflammation?
- Suppuration (pus/abscess)- excessive exudate
- Organisation- excessive necrosis causes scarring
- Resolution (best outcome)
- Progession to chronic inflammation- persistent acute
What is the macroscopic appearance of acute inflammation?
- Redness (rubor)- dilation of small blood vessels
- Heat (calor)- due to increased blood flow to region
- Swelling (tumor)- due to oedema
- Pain (dolor)- due to stretching of tissues and pus under pressure in cavity
4 Cells involved in acute inflammation
- Neutrophil polymorphs (phagocytosis)
- Endothelial cells (allows migration of neutrophils to tissue)
- Lymphocytes (produces chemicals to attract other cells)
- Tissue macrophages (derived from monocytes)
4 Cells involved in chronic inflammation
- Lymphocytes (B+T)
- Plasma cells
- Fibroblasts (form collagen in areas of repair)
- Macrophages
4 causes of chronic inflammation
- Primary chronic inflammation
- Transplant rejection
- Progression from acute inflammation
- Recurrent episodes of acute inflammation
Examples of chronic inflammation
Crohn’s, Leprosy, Chronic inflammatory bowel disease
What is a granuloma?
An aggregate of epithelioid histiocytes (may contain lymphocytes and other large cells)
3 different types of skin wound healing
- Abrasion- epithelium divides to replace lost cells- scab
- Healing by first intention- surfaces are close so can join back together, area filled with fibrin (e.g. needle injection
- Healing by second intention- when surfaces are separate so can’t rejoin, loss of tissue (e.g. stab wound)
When does repair occur instead of resolution?
When the cells involved can’t regenerate, or initiating factor is still present
List cells that can regenerate, and can’t regenerate
Can: hepatocytes, pneumocytes, blood cells, gut epithelium, skin epithelium, osteocytes
Can’t: neurones, myocardial cells
Definition: Thrombosis
Solid mass of blood constituents formed within intact vascular system during life
Causes of a thrombosis (think triad…)
- Change in vessel wall- epithelial cell injury (smoking)
- Change in blood flow- from laminar to turbulent
- Change in blood constituents- e.g. a disease which increases the number of platelets
Once a thombus is formed, it can do 1 of 4 things:
- Resolution (good)
- Organisation (scar)
- Recanalise (capillaries grow through clot)
- Embolise
Definition: embolism
The process of a solid mass in the blood being carried through circulation to a place where is gets stuck and blocks the vessel
Definition: ischaemia
reduction in blood flow to a tissue without any other implications
How does re-perfusion injury occur?
when normal blood flow is restored after ischaemia, and oxygen is restored too quickly, mass influx of reactive oxygen species into cells which kills them
Definition: infarction
Reduction in blood flow to a tissue that is so reduced that it cannot support cell maintenance so the cells die
Definition: watershed areas
Areas of dual artery supply that receive little supply from either as they are right in the middle