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.