Definitions Flashcards
(53 cards)
Define proliferation
Cell proliferation is the process that results in an increase of the number of cells, and is defined by the balance between cell divisions and cell loss through cell death or differentiation.
Pathological proliferation is seen following tissue damage
Define apoptosis
(4)
Programmed cell death is termed apoptosis
It is a complicated process in which nuclei condense and fragmentation of the cell occurs forming apoptotic bodies.
The cytoplasmic organelles remain intact during these events.
Apoptosis is a physiological event but may be induced by pathological conditions e.g. malignancy, infection
Define necrosis
(2)
Accidental cell death - necrosis - occurs when a cell is damaged as a consequence of some injurious stimulus e.g. when it is derived of oxygen
The cell and cytoplasmic organelles swell and rupture, spilling their contents into the surrounding environment
Define hyperplasia
Increase int he number of cells in response to increased functional demands
Define neoplasia
When inappropriate or excessive cellular growth persists in the absence of any continuing stimulus the resulting tissue mass is termed a neoplasm
Define hyperplasia
Increase in the number of cells in response to increased functional demands
Define neoplasia
When inappropriate or excessive cellular growth persists in the absence of any continuing stimulus the resulting tissue mass is termed a neoplasm
Define hypertrophy
Increase in the size of cell because of extra functional demands, e.g. skeletal muscle following exercise
Define atrophy
Decrease in cell size due to decreased demanded on the cell or tissue
Define metaplasia
Alteration in cell morphology due to changes in cell differentiation. This results in a change to another cell type (usually associated with trauma or irritation)
Define dyplasia
Abnormal growth of a tissue or organ, cells present may signify the stage preceding the development of cancer
Define inclusions
Inclusions are stored nutrients, secretory products, and pigment granules
e.g. bile, iron, copper, fat
Define fibrosis
The formation of excess fibrous connective tissue in an organ or tissue in a reparative or reactive process
This can be a reactive, benign, or pathological state
In response to injury, this is called scarring, and if fibrosis arises from a single cell line, this is called a fibroma
Define amyloid
An abnormal extracellular protein, which is derived from many precursor proteins and gives rise to a condition called Amyloidosis
It is deposited extracellularly as a homogenous acellular substance and is most commonly found in the walls of blood vessels, beneath the endothelial linings
The progressive nature of deposition may result in occlusion of vessels and destruction of parenchyma with loss or organ function
The condition may be systemic or localised. In systemic conditions, amyloid is deposited in a wide variety of tissues and organs such as kidneys, spleen, liver, adrenal glands and heart
In localised form it is present only in the organ involved
Define foam cells
A type of macrophage that localise to fatty deposits on blood vessel walls, where they ingest low-density lipoproteins and become laden with lipids, giving them a foamy appearance
Define cirrhosis
Defined histologically as diffuse hepatic process characterised by fibrosis and conversion of the normal liver architecture into structurally abnormal nodules
Define cirrhosis
a diffuse hepatic process characterised by fibrosis and conversion of the normal liver architecture into structurally abnormal nodules
Define inflammation
A process by which the body attempts to deal with injury to the tissues
Such damage may be caused by a variety of physical, chemical or biological agents
In the inflammatory response the body attempts to eliminate or neutralise injurious agents and repair the tissues
Define acute inflammation
The initial series of events following injury to a tissue, directed towards neutralizing the injurious agents and restoring the tissues to useful function
Define resolution
When tissue damage is minimal, the exudate is reabsorbed into local vessels and no evidence of injury remains
Define inflammatory exudate
Composed of serum, leucocytes (mostly PMLs? and fibrin
Define chronic inflammation
Results from persistence of injurious stimulus over a long period of time causing continuing tissue damage
It most commonly follows acute inflammation where the process has failed to eradicate the causative agent
Define granulomas
An organised collection of inflammatory cells including activated macrophages (epitheliod histiocytes), Langhand’s giant cells (multinucleated macrophages) and lymphocytes
Granulomas are associated with M. tuberculosis infections where organism is resistant to destruction by neutrophils and fail to excite a strong acute reaction
Define exudate
Acute inflammation exudate can be:
- purulent: Neutrophils dominate
- Fibrinous: fibrin abundant
- Serous: fluid is major component
