Definitions Flashcards
Abscess
Cavity lined by granulation tissue containing pus (alive & dead bacteria, alive & dead neutrophils, tissue debris, serum)
Pus
alive & dead bacteria, alive & dead neutrophils, tissue debris, serum
Cyst
collection of fluid in a sac lined by endothelium or epithelium which usually secretes the fluid.
• True cysts are lined by endo- or epithelium.
• False cysts are the result of exudation or degeneration, e.g.
pseudocyst of pancreas, cystic degeneration in a tumour.
Classification of cysts
True: lined by endo/epithelium
False: from exudation/degeneration- eg pancreatic pseudocyst, cystic degeneration of tumour
Congenital: dermoid cyst, branchial cyst, hyatidid of Morgagni
Acquired: sebacous, thyroid/ovarian, parasitic, pseudocysts
Sinus
blind epithelial track, lined by granulation tissue which extends from a free surface into the tissues, e.g. pilonidal sinus.
Fistula
abnormal communication between two epithelial
surfaces. It is lined by granulation tissue and colonized by bacteria, e.g. fistula-in-ano, pancreaticocutaneous, colovesical, vesicovaginal.
Ulcer
breach in an epithelial surface.
Diverticulum
Outpouching of a hollow viscous (true = includes all tissue layers), false= only mucosa & muscularis mucosae
eg bowel, bladder, oesophagus
Atherosclerosis
Degenerative disease of large and medium-sized arteries characterized by lipid deposition and fibrosis.
Thrombus
solid mass of blood constituents formed within the vascular system.
Embolism
mobile mass of material in the vascular system capable of blocking its lumen.
Clot
Solid collection of blood cells in a fibrin network
Ischaemia
Tissue effect from insufficient oxygen
Infarction
Tissue death from insufficient oxygen
Gangrene
Ischaemic tissue necrosis with desiccation (dry) or putrefaction (wet)
Can be secondary to thrombosis (eg appendicular artery)/ embolism eg in PVD/extrinsic compression eg in facture or tourniquet use
Metaplasia
Reversible transformation of one type of terminally differentiated cell into another fully differentiated cell type.
Eg Baratt’s oesophagus (squamous to columnar)
Adaptive response of a tissue to environmental stress. It is mediated by changes in expression of genes involved in cellular differ- entiation. It does not progress to malignancy: if the environmental changes persist, dysplasia may result and progress to malignancy
Dysplasia
Potentially premalignant condition characterized
by increased cell growth, atypical morphology, and altered differentiation.
May be a response to chronic inflam- mation or exposure to carcinogens. Early forms may be reversible: severe dysplasia has a high risk of progression to malignancy,
Neoplasia
Autonomous abnormal growth of cells which persists
after the initiating stimulus has been removed.
Inflammation
local physiological response to tissue injury. It can be acute or chronic.
Granuloma
Aggregate of epitheloid histiocytes to isolate infection or foreign body
Necrosis
Abnormal tissue death with inflammatory changes- not energy depedant
Apoptosis
Physiological process
Cell degradation via intracellular enzyme activation
Energy dependant with no inflammatory response
Coagulative necrosis
Preserved tissue architecture
Coagulation of proteins to preserve architecture eg kidney/heart/spleen
Eg when tissue placed in boiling water
Colliquative necrosis
Liquefactive necrosis occurring in lipid-rich tissue
Lysosomal enzymes active to break down fat to denature it resulting in liquefaction eg in brain
Caseous necrosis
Unstructured necrosis where tissue architecture cannot be identified secondary to necrosis eg in TB
Contains amorphous proteins and degenerate lipids
Wet gangrene
From venous & arterial occlusion
Necrosis and putrefaction by gram negative bacteria- bacterioides & clostridia
Dry gangrene
Tissue desiccation with no infection and often autoamputates eg in diabetic foot
Gas gangrene
infection with gas-forming anaerobic bacteria resulting in surgical emphysema & crepitus
