ICS - PATHOLOGY Flashcards
Define inflammation
TEst
It’s hard to define, but its a reaction to a tissue injury or infection.
Involves cells such as neutrophils and macrophages
It is not a disease but instead usually a manifestation of the disease
How is inflammation classified?
Acute or chronic.
Outline qualities of acute inflammation. give an example
Sudden onset
Short duration
Usually resolves
It is the intial and short lived tissue reactions that occur due to injury
Appendicitis is an example
Outline qualities of chronic inflammation.
Slow onset or comes after acute inflammation
Long duration
May never resolve
When is inflammation good?
It is able to destroy invading microorganisms
Walling off of an abscess cavity can prevent the spread of infection.
When is inflammation bad?
Bad in autoimmunity
Also bad when it over-reacts to the stimulus.
Can cause diesase - eg an abscess in the brain will act as a space pccupying lesion and COMPRESS VITAL STRUCTURES
Fibrosis from chronic inflammation may disort tissues and permanently alter function
Name some cells that are involved in inflammation.
Neurtophils Polymorphs
Macrophages
Endothelial Cells
Lymphocytes
Fibrolasts
Outline what Neutrophils Polymorphs are.
THEY ARE GRANUOLCYTES!!!!
Short lived cells, that are FIRST ON THE SCENE OF ACUTE INFLAMMATION
They contain cytoplasmic granules that are full of enzymes that kill bacteria
They normally die at the scene of inflammation
They RELEASE CHEMICALS that attract other inflammatory cells eg Macrophages.
Outline what Macrophages are
LONG LIVED CELLS, (weeks to months)
They have PHAGOCYTIC PROPERITES
They INGEST bacteria and debris, and may carry them away
present antigen to lymphocytes
How long to Lymphocytes live for? What do they do? What is special about them?
They are long lived cells (YEARS)
They produce chemicals which attract in other inflammatory cells
They have an IMMUNOLOGICAL MEMORY for past infections and anitgens
What are endothelial cells?
They line the capillary blood vessels in areas of inflammation
What do endothelial cells do in inflammation? How do they help inflammatory cells? 3
They BECOME STICKY in areas of inflammation so inflammatory cells can adhere to them
They BECOME POROUS to allow for inflammatory cells to pass into tissues
The GROW into areas of damage to form new capillary vessels
Are fibrobalsts long or short lived? What do they do?
They are long lived. They form collagen in areas of chronic inflammation
What are the 5 main features of Acute Inflammation?
- Rubor (Redness)
- Tumour (Swelling
- Calor (Heat)
- Dolar (Pain)
- Functio Laesa (Loss of function)
What happens to vessel walls in acute inflammation?
Precapillary sphincters open (which are regulated by arteriolar walls)
thereby increasing the blood flow
thorough the capillaries contributing to redness and heat
Endothelial cell walls separate, as a response to mediators.
Inflammation can be triggered by internal or external factors- give examples of external factors
External are either
Non microbial (eg Allergens, Irritants, Toxic Compounds)
Or Microbial Factors
Outline two main microbial factors
What are PAMPs?
Virulence Factors - Help pathogens colonise tissues and cause infections
Pathogenic associated molecular Patterns (PAMPs) = General molecular features common to many types of pathogen - the body recognises to trigger inflammaroty response
Outline what DAMPs Are
DAMPs are Damage Associated Molecular Patterns, and are INTRACELLULAR PROTEINS that get released when a cells plasma membrane is injured, or when the cell dies - THEY TRIGGER INFLAMMATION, AN INTERNAL FACTOR
the inflammatory process: Name 3 things Macrophages and Mast Cells release, and what does it do to blood vessels?
1 Macrophage and Mast cells release inflammatory mediators like Histamine, Serotonin, Cytokines, and Eicosanoids like prostaglandins.
- These mediators act on the endothelial cell wall, causing the cells to separate.
- These mediators cause the capillaries to swell/dilate, and the separation of the cells lead to INCREASED VASCULAR PERMEABILITY
Nitric oxide also makes the capillaries more permeable.
Macrophages will start to eat pathogens
What happens to the hydrostatic pressure in capillaries during acute inflammation? why is this? What happens as a consequence?
Capillary hydrostatic pressure increased. As mediators cause blood vessels to SWELL/VASODILATE and the cells in the capillary endothelium separate, increasing VASCULAR PERMEABILITY
As a consequence, plasma proteins leave the capillary.
Define Exudation. What is fluid exudate
The net escape of protein rich fluid into the exravascular space.
This protein rich fluid is called Fluid exudate.
What are the 5 main causes of acute inflammation?
Microbial Infections
Irritant and corrosive chemicals
Physical agents
Tissue necrosis
Hypersensitivity reactions
MIPTH
Briefly outline how microbial infections cause acute inflammation
Bacteria release exotoxins, which are chemicals that specifically iniate inflammation,
or ENDOTOXINS, associated with their cell walls
What are the 3 key things that accumulate in extracellular spaces in acute inflammation?
oedema fluid (exudate), fibrin and neutrophil polymorphs
accumulate in the extracellular spaces
Fibrin is deposited on the extravascular tissues, hence they are said to be covered in fibrinous exudate
What is said to be the key diagnostic histological feature of acute inflammation?
The accumulation of neutrophil polymorphs with the extracellular space
Define pavementing. Why does this not happen in healthy states?
pavementing is the adhesion of neutrophils to the vascular endothelium.
In healthy states, leukocytes only flow in the central/axial part of the vessel - not near the edges. They also wouldn’t usually adhere to the vessels.
Where does pavementing occur
only in venules. Hence leucocytes will leave/migrate form the walls of venules and small veins, but not normally from capillaries
What are the 4 outcomes of inflammation?
- Resolution.
- Suppuration.
- Organisation (scar tissue formation).
- Progression onto chronic inflammation.
Give 3 endogenous chemical mediators of acute inflammation. Where do they come from?
- Bradykinin.
- Histamine.
- Nitric Oxide.
They are released from the injured tissue, and spread outwards to uninjured areas
What do histamine and thrombin do early on in acute inflammation?
Histamine and thrombin cause up regulation of adhesions molecules to endothelial walls - so leukocytes can adhere to it.
Outline some of the broader things that endogenous chemical mediators lead to
They lead to vasodilation,
Emigration of neutophils
Increased vascular permemability
itiching and pain
chemotaxis
Define chemotaxis
(the attraction of neutrophil polymorphs towards certain
chemicals e.g at the site of inflammation)
What do macrophages release in acute inflammation and what does this do?
They release the cytokines That attracts Neutrophil Polymorphs
interleukin-1 (IL-1) and tumour necrosis factor alpha (TNF-alpha)
When do macrophages appear, and when do they predominate?
start to appear within a few hours of the commencement of
inflammation, but do not predominate until the later stages when the
neutrophils have diminished
What are macrophages responsible for?
clearing away tissue debris and damaged
cells
How is exudate cleared?
By lysosomal enzymes, released by both neutrophils and macrophages
What are the outcomes of acute inflammation?
Resolution (everythings ok)
Suppuration (formation of pus)
Organisation of tissue
Progression to chronic inflammation
In organisation, what replaces old tissue?
Granulation tissue, contains new blood vessels and lots of fibroblasts = can lead to scar formation
When will chronic inflammation happen?
If the agent causing acute inflammation is not removed
What cell can form when several macrophages try to ingest the same particle?
Multinucleate giant cell.
What cells are involved in chronic inflammation?
Macrophages and plasma cells (B and T lymphocytes)
These replace the neutrophils
What are 4 systemic effects of acute inflammation?
- Fever.
- Feeling unwell.
- Weight loss. (negative nitrgoen balance due to immune response)
- Reactive hyperplasia of the reticuloendothelial system.
Give 4 causes of chronic inflammation.
What is the most common?
- Primary chronic inflammation. - most common
- Transplant rejection.
- Recurrent acute inflammation.
- Progression from acute inflammation.
Give examples of primary chronic inflammation.
- Infective substances having resistance to phagocytosis e.g. TB, leprosy.
- Endogenous materials e.g. uric acid crystals.
- Exogenous materials e.g. asbestos.
- Autoimmune diseases e.g. chronic gastritis, rheumatoid arthritis etc.
- Other chronic inflammatory diseases e.g. chronic inflammatory bowel disease.
What are some macroscopic features of chronic inflammation?
- Chronic ulcer.
- Chronic abscess cavity.
- Granulomatous inflammation.
- Fibrosis.
What is granulation tissue?
Granulation tissue is new connective tissue and microscopic blood vessels that form on the surfaces of a wound during the healing process
Is composed of small blood vessels in a connective tissue matrix with myofibroblasts. It is important in healing and repair.
What is the difference between a granuloma and granulation tissue?
granulation tissue = new connective tissue and tiny blood vessels that form on the surface of a wound, during healing process
granuloma is an organized collection of macrophages that forms in response to persistent inflammation.
Granulation tissue - result of would healing process
Grannuloma - result of inflammation
What is the actual function of a
granuloma
and
Granulation tissue
Grannulation tissue - replaces ded/necrotic tissue, fills the wound and protects wound surface from microbes
Granuloma - to surround/destruct antigens
Define chronic inflammation. what things predominate?
The subsequent and often prolonged tissue reactions to injury following the initial
response
lymphocytes, plasma cells and
macrophages predominate
What is the most common way acute inflammation becomes chronic?
The Supparitive type - the pus forms an abscess that is deep seated or doesn’t drain properly, so the walls of the abscess cavity fail to come together, leading to scaring
Give some microscopic features of chronic inflammation.
of lymphocytes, plasma cells &
macrophages
- A few eosinophil polymorphs may be present but neutrophil polymorphs are
scarce
- Some of the macrophages may form multinucleate giant cells
Define granuloma.
An aggregate of epithelioid histocytes.
Give an example of a granulomatous disease
TB, leprosy, Crohn’s disease and sarcoidosis.
Outline what epithelioid histocytes are. What is their function?
Appear vaguely histologically similar to epithelial cells
* Have large vesicular nuclei
Appear in clusters
Have little phagocytic activity, but secrete angiotensin converting enzyme
The activity of what enzyme in the blood can act as a marker for granulomatous disease?
Angiotensin converting enzyme.
Name 5 types of cells capable of regeneration.
- Hepatocytes.
- Osteocytes.
- Pneumocytes.
- Blood cells.
- Gut and skin epithelial cells.
Name 2 types of cells that are incapable of regeneration.
- Myocardial cells.
- Neuronal cells.
Define abscess.
Acute inflammation WITH A FIBROTIC WALL (CONTAINS INFLAMMATORY RESPONSE) but can compress
Define thrombosis.
Formation of a solid mass from blood constituents WITHIN AN intact vessel in the living.
How is a thrombosis different to a clot?
A clot is blood coagulated OUTSIDE OF THE VASCULAR SYSTEM, or after death
Give 2 reasons why thrombosis formation is uncommon.
- Laminar flow. (Cells flow down the centre of vessels)
- Non sticky endothelial cells. (when heatlhy)
What are the 3 factors that can lead to thrombosis formation?
- Change in vessel wall.
- Change in blood constituents.
- Change in blood flow.
What are platelets derived from?
Megakaryocytes, cells from the bone marrow. They have no nucleus
When are platelets activated? What do they release?
They they come into contact with COLLAGEN
Release ALPHA GRANULES (help paltelets adhere to damaged vessel walls eg fibrinogen)
and DENSE GRANULES (Help platelets aggregate eg ADP)
What are the different types of thrombosis and what causes them?
Arterial thrombosis - atherogenesis
Venous thrombosis - venous stasis
How do Arterial Thrombus form?
- starts with Vasospasm, and is Most commonly superimposed on an atheroma
- Platelets bind to collagen via VWF factor, activating them
- Releasing granules which lead to lead to postive feedback platelet plug
a. Then after a cascade of reactions fibrinogen becomes activated to fibrin, binding platelets together - ===> so RBCs become entrapped.
How do venous thrombosis commonly form?
VENOUS THROMBOSIS - MOST LIKELY TO OCCUR AROUND VALVES, DURING SURGURY OR PERIODS OF POOR MOBILISATION. ===> BLOOD SITS IN VEINS, LEADING TO CLOT FORAMTION. ===> STASIS
Made up mainly of coagulation factors
How do you treat venous thrombosis?
known as a RED THROMBUS
treat with ANTI COAGULANTS
eg Warafin, Heparin
How do you treat an arterial thrombosis?
Think - White Thrombus, made of platelets
So give ANTIPLATELETS , eg Aspirin, Clopidogerel
Define embolus.
A mass of material ( blood clot, air bubble, piece of fatty deposit, or thrombus or other object) which has been carried in the bloodstream to lodge in and block a vessel and cause an embolism.
Define ischaemia.
Decreased blood flow.
Define infarction.
Decreased blood flow with subsequent cell death.
Why are tissues with an end arterial supply more susceptible to infarction?
They only have a single arterial supply and so if this vessel is interrupted infarction is likely.
Give 3 examples of organs with a dual arterial supply.
- Lungs (bronchial arteries and pulmonary veins).
- Liver (hepatic arteries and portal veins).
- Some areas of the brain around the circle of willis.
What things make up Virchow’s triad?
Endothelial injury (Trauma Surgery, MI)
change in blood constituents (Sepsis
Change in blood flow (laminar to turbulent) (AF)
Not all three factors are needed for
thrombosis to occur; any one of them
may result in thrombosis
- However, most usually its a combination of two or three of these,
What are the two types of thrombosis?
Arterial and venous
How do arterial thrombosis form?
Through ARTHEROGENESIS - CLOT FORMATION:
- Leads to turbulence
- Turbulence exposes collagen
- Platelets bind to collagen, fibrin mesh
Turbulence is greatest down stream of the aterial thrombosis, as blood passes over the thrombus, disrupting laminar flow
Propagation - Thrombi growing in the direction of blood flow
Name some conditions assocociated with arterial thrombosis
MI , Ischaemic heart disease, stroke, periperhal vascular disease
Where does the greatest degree of tubulence happen in arterial thrombosis?
Downstream of an arterial thrombosis, as
the blood passes over the thrombus, disrputing laminar flow
Platelet plug: what do e dense granules do? Give an example of a substance found in them
Helps platelets adhere to one another. A substance released is ADP
Platelet plug: what do alpha granules do? Give an example of a substance found in them
Alpha granules help platelets adhere to the damaged vessel wall
Fibrinogen is found here, which when activated becomes fibrin via enzyme Thrombin
Define Propagation
Thrombi growing in the direction of blood flow