Flashcards in MOD 3 Deck (63):
What clinical signs of acute inflammation remain in chronic inflammation?
Swelling and pain persist but redness and heat resolve.
Acute inflammation and chronic inflammation often overlap. How else can these processes more accurately be termed?
Stereotyped inflammation and modulated inflammation.
Acute inflammation is a response to what types of injury?
It is an instant reaction to ANY type of injury
What is the purpose of acute inflammation?
To phagocytose and kill bacteria, with or without the help of plasma proteins, before they can establish a foothold.
What are the three ways in which chronic inflammation can occur?
1. Takes over from acute inflammation - most common way
2. Begins without proceeding acute inflammation e.g. in chronic infections
3. Develops alongside and superimposed on acute inflammation
What is the dominant cell type in acute inflammation vs chronic inflammation?
Acute - neutrophils
Chronic - macrophages
What can the persistent injurious agent in chronic inflammation be?
1. microbe e.g. bacteria
2. sterile but irritating substance e.g. necrotic tissue, a foreign body or a crystalline substance
3. Antigen e.g. in an autoimmune disease
What is the most common way in which chronic inflammation occurs?
Takes over from acute inflammation.
Give examples of triggers for chronic infections that are not caused by a proceeding acute inflammation, or alongside existing acute inflammation
1. TB infections
2. Some autoimmune conditions e.g. RA
3. Prolonged exposure to some toxic agents e.g. silica
What can cause chronic inflammation to occur alongside and superimposed on acute inflammation?
on-going bacterial infectiosn
What does chronic infection look like under the microscope?
1. Mononuclear cells (macrophages and lumphocytes) are now the predominant cell type rather than neutrophils
2. Granulation tissue begins to form as healing simultaneously gets underway
What cell types are seen in chronic inflammation (though with varying numbers and mix)?
2. T and B lymphocytes
4. Fibroblasts and myofibroblasts
5. Giant cells
Where are moncytes made? How long can they circulate in the blood before they enter tissues and become dormant?
Bone marrow. About six days.
How long can macrophages live for? Are they capable of replication?
Many months. Yes
Are neutrophils capable of replication?
Macrophages are a very versatile cell. They mastermind chronic inflammation and the immune response. List their functions:
2. Secretion of chemokines/cytokines which summon and activate other cells (order of 100)
3. Antigen-presenting to the immune system, to activate an immune response
4. Stimulate angiogenesis - important in wound healing
5. Induce fibrosis
6. Induce fever, acute phase response and cachexia
What are the predominant cells of the immune system?
If lymphocytes are present in tissues where they are normally absent, what is this a sign of?
That some antigenic material is or has been there.
What are the functions of T and B lymphocytes?
DO NOT phagocytose. They:
1. Process antigens
2. Secrete antibodies (B lymphocytes that have differentiated into plasma cells)
3. Secrete cytokines that influence other inflammatory cells
4. Killing cells (natural killer cells attack virus-infected cells and sometimes tumour cells)
Where are eosinophils normally found?
Scattered throughout the tissues of the body
Which cells - macrophages or neutrophils - are better at phagocytosis?
Normally neutrophils, though macophages are better at phagocytosing some difficult to kill bacteria, such as Myobacterium tuberculosis.
When are eosinophils present in high numbers?
Large parasitic infections and in some immune responses(allergic reactions) (bronchi in asthma and in some tumours e.g. Hodgkin's lymphoma).
How do fibroblast alter their location to arrive at sites where they are needed?
They respond to chemotactic stimuli (like leucocytes).
What is the function of fibroblasts?
They produce connective tissue substances such as collagen, elastin and glucosaminoglycans. This is important in wound healing.
What are myofibroblasts? What is their function?
Fibroblasts can differentiate into myofibroblasts. These cells can contract - important in wound healing.
What are giant cells?
A single 'giant' cell created by the fusion of macrophages under particular circumstances. They can be very large and contain dozens to hundreds of nuclei.
When are Langhans Giant cells seen?
Often (but not exclusively) in Tuberculosis
When are Foreign body giant cells seen?
Often (but not exclusively) when a hard to digest foreign body is present. If the foreign body is small it can be phagocytosed by the giant cell, if it is large the giant cell sticks to its surface.
When are Touton giant cells seen?
They form in lesions where there is a high lipid content, such as fat necrosis and xanthomas. These lesion will also contain foam cells which are just macrophages whose cytoplasm appears frothy as they have phagocytosed a lot of lipid.
List some situations in which chronic inflammation typically arises?
1. After or alongside acute inflammation
2. Chronic persistent infections
3. Autoimmune conditions
4. Prolonged exposure to toxic agents
List 4 possible complications of chronic infection:
1. Tissue destruction
2. Excessive fibrosis
3. Impaired function
Describe the chronic inflammation seen in rheumatoid arthritis:
Describe the chronic inflammation seen in ulcerative colitis:
Describe the chronic inflammation seen in Crohn's disease:
Describe the chronic inflammation seen in chronic cholecystitis:
Describe the chronic inflammation seen in chronic gastritis:
Describe the chronic inflammation seen in cirrhosis:
Define a granuloma:
A granuloma is the body's way of dealing with poorly soluble or difficult to eliminate particles. A granuloma forms around the particle, which can be free of phagocytosed within the centre of the granuloma, and walls it off whilst concentrating mononuclear cells within its centre with which it hopes to destroy the particle
When does granulomatous inflammation occur?
Major causes: foreign material, infections, unknown causes
Name some infections that cause granulomatous inflammation:
TB, leprosy and syphilis
Name some diseases which show granulomatous inflammations of unknown cause:
Sarcoidosis, Crohn's disease.
When are giant cells present?
In certain circumstance e.g. when foreign bodies or infections with certain bacteria are present. They are seen in granulomatous inflammation.
What do Langhans giant cells look like?
Nuclei are arranged around the periphery in a horse-shoe shape.
What do Foreign body giant cells look like?
The nuclei are arranged randomly within the cell. They may contain phagocytosed small foreign bodies or be stuck to the outside of large foreign bodies.
What do Touton giant cells look like?
They have nuclei that are arranged in a ring towards the centre of the cell.
What is fibrosis?
An excess of fibrous tissues.
When does fibrosis occur?
It occurs when fibroblasts are stimulated by cytokines to produce excess collagen and is typically seen in chronic inflammation.
What are the useful functions of fibrosis?
1. Helps to wall of infected areas
2. It is essential in the production of fibrous scars which replace damaged tissue in wound healing.
When does fibrosis cause problems?
1. If it replaces normal parenchymal tissue and impairs the function of an organ
2. If the area of fibrosis contains enough myofibroblasts this can slowly contract causing further problems
Give an example of when inappropriate fibrosis of parenchymal tissue occurs, impairing the function of an organ.
Interstitial fibrosis of the lung.
Give an example of the problems that can occur if an area of fibrosis contains enough myofibroblasts to slowly contract.
Contraction in a cirrhotic liver will impair the flow of portal blood resulting in ascites.
How does the immune system utilise inflammation?
It uses inflammation as a non-specific weaoib too destroy its targets. When cells and antibodies of the immune system bind with their specific targets they release mediators that cause inflammation.
Give two examples of types of inappropriate immune responses
1. To innocuous targets - e.g. hay fever
2. To body's normal tissue - autoimmune diseases
What is granulomatous inflammation?
A type of chronic inflammation in which granulomas are seen.
Provide some examples of particles that might cause granulomas:
Foreign bodies - thorns, splinters
'tough bacteria' - Myobacterium tuberculosis and M. leprae
Describe the histology of a granuloma.
They usually measure 0.5-1mm in diameter. They contains epitheliod cells which are macrophages that have become modified to look like epithelial cells in that they are elongated, have esoinophilic cytoplasm and appear tightly packed together, as epthelial cells do.
What are the two general types of granulomas?
1. Foreign body granulomas
2. Hypersensitivity of immune type granulomas
Describe the appearance of a foreign body granuloma.
They contain macrophages, foreign body giant cells, epitherloid cells and some fibroblasts (at the periphery) but very few, if any, lymphocytes. They develop around the material that is antigenic e.g. surgical thread.
What is the main differences in appearance between foreign body and hypersensitivity/ immune-type granulomas?
Immune type granulomas have lymphocytes, unlike the few, if any, seen in foreign body granulomas. Their epitheloid cells are also usually more prominent and you may see Langans type giant cells instead of foreign body giant cells as you see in foreign body granulomas. Immune-type granulomas may also undergo central necrosis (particularly in those associated with tuberculosis).
Why do hypersensitivity/immune type granulomas develop?
They develop around insoluble antigenic particels that cause cell-mediated immunity.
What organisms may cause hypersensitivity/immune type granulomas to develop?
1. Syphilis-causing organisms (Treponema pallidum)
2. Tuberculosis (Mycobacterium tuberculosis)
3. Leprosy (Mycobacterium leprae)
4. Cat-scratch disease ( Bartonella henselae or Bartonella quintana)
Name some diseases in which hypersensitivity granulomas are seen - with an unknown cause.
Sarcoidosis - seen thoughout body