Session 3 Flashcards
How does chronic inflammation arise?
It can take over from acute inflammation (most common)
It can arise de novo - as in some autoimmune conditions (eg RA) and chronic infections.
It can develop alongside acute inflammation in severe persistent or repeated irritation
Lost the cells principally involved in chronic inflammation and their functions
Macrophages - phagocytosis, presentation of antigens to immune system, stimulate angiogenesis, induce fibrosis and control of other cells via cytokines
Lymphocytes - B plasma cells produce antibodies, T cells control cytotoxic functions and NK cells kill cells
Eosinophils - allergic reactions, parasite infestations
Fibroblasts/myofibroblasts - produce collagen
What are giant cells and what are the different types?
Multinucleate cells formed by the fusion of macrophages.
Langhans giant cell - nuclei arranged around the periphery. Seen in TB.
Foreign body giant cells - nuclei arranged randomly. Seen where a hard to digest foreign body is present.
Touton giant cell - nuclei arranged in a ring towards the centre. Form in lesions with a high fat content.
What are unwanted effects of chronic inflammation?
Fibrosis and impaired function - collagen (produced when fibroblasts are stimulated by cytokines) is initially useful as it walls off infection. In excess it can replace normal parenchymal tissue, impairing the function of the organ. Contracting myofibroblasts can also cause problems.
Involvement in inappropriate immune responses - attacks harmless cells (eg pollen in hay fever) or self tissue.
Atrophy
Why do granulomas form and what do they contain?
They form around particles that are difficult to digest (eg mycobacterium or thorns) and walls it off whilst concentrating mononuclear cells in the centre to try and destroy it. They often contain epitheliod cells (modified macrophages), fibroblasts, giant cells and lymphocytes.
What are the two types of granuloma and when are they seen?
Foreign body granuloma - develop around non-antigenic material. Very few lymphocytes.
Hypersensitivity/immune type granulomas - undergo central necrosis, particularly with TB. Develop around antigenic particles - e.g. Syphillis, TB, leprosy. Also seen in sarcoidosis, Crohn’s disease and Wegeners granulomatosis
What is chronic cholecystitis?
Occurs when there is repeated obstruction of the gall bladder with gall stones.
What causes gastric ulceration?
An imbalance between acid production and mucosal defence. Acute gastritis due to alcohol/drugs. Chronic gastritis due to helicobacter pylori.
What is inflammatory bowel disease and what are the two types?
Idiopathic inflammatory disease affecting large and small bowel. Patient present with diarrhoea and rectal bleeding amongst other symptoms.
Ulcerative colitis is superficial and comes with diarrhoea and bleeding.
Mostly present in distal colon.
Crohn’s disease is transmural and comes with strictures (narrowing) and fistula (abnormal connection between two epithelium lined organs. Discontinuous and can affect any part of the GI tract.
What is liver cirrhosis and what can cause it?
Chronic inflammation with fibrosis leading to disorganisation of architecture and attempted regeneration. Caused by alcohol (most common), drugs, infection.
