Definitions Flashcards
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
Define granulation tissue
When tissue damage is extensive, the exudate undergoes a process called organisation and repair
In this process the dead tissue is phagocytosed and the necrotic area is replaced with granulation tissue composed of a vascularised connective tissue laid down by fibroblasts
Define hyperaemia
An increase in the amount of blood in the tissue
Typically seen in acute inflammation due to the release of histamine which stimulated blood flow to the area
Define granuloma
Some microorganisms are resistant to destruction by neutrophils and
fail to excite a strong acute reaction. The initial neutrophil response is usually sparse
and is quickly followed by a macrophage response. This local accumulation of
macrophages produces a discrete lesion called a granuloma
Define giant cell
Activated macrophages enlarge and sometimes fuse to form multinucleated giant cells (Langhan’s giant cells)
Define a koilocyte
A squamous epithelial cell that has undergone a number of structural changes, which occur as a result of infection of the cell by human papillomavirus
What is neoplasia
(2)
When inappropriate or excessive cellular
growth persists in the absence of any
continuing stimulus the resulting tissue mass
is termed a neoplasm
In neoplasia, the mechanisms regulating cell
division fail and this lack of regulation
characteristic is transmitted to each new
generation of cells
What are benign neoplasms
These may grow large but do not spread into, or invade nearby tissues or other parts of the body
Contained within epithelium or connective tissue capsule/sheath
What are malignant neoplasms?
Can display aggressive characteristics, spread into, or invade nearby tissues
Can spread to other parts of the body through the blood and lymph systems
Cancer is a term that is associated with malignant neoplasms
What is dysplasia
Abnormal cells within a tissue or organ
Morphologically the cells look abnormal however they are not classified as cancerous
Can be graded as mild, moderate, or severe depending on how abnormal the cells look under a microscope and how much of the tissue or organ is affected
May be a stage of abnormality preceding development of malignancy in some tissues
Define intraepithelial neoplasia
(5)
Development of benign neoplasm or high grade dysplasia in an epithelium
The neoplastic cells are still contained within (intra) the epithelium and have not yet invaded through the basement membrane of the epithelium or gland
The epithelial cell of origin can be either:
- squamous - CIN/VAIN/VIN
- Glandular - CGIN/PIN
Define carcinoma in-situ
Abnormal cells presenting as ‘non-invasive’ malignancy
The morphology of the cells meets the criteria of malignancy but they have not yet invaded surrounding tissue
While still localized, CIS have a high probability of progressing to become invasive
Give three examples of Carcinoma in situ
Ductal carcinoma in-situ of breast
Lobular carcinoma in-situ of breast
Bladder carcinoma in-situ
Define a haemangioma
Benign neoplasm of blood vessels. Increased number of blood vessels surrounded by connective tissue
Define phaeochromocytoma
Pheochromocytoma is a rare tumor of the adrenal medulla composed of chromaffin cells, also known as pheochromocytes
Define well differentiated
Phenotypically similar to cell of origin. Look the same, expresses same antigens
Squamous carcinomas - may have keratinization
Adenocarcinomas - form glands, may produce
Define moderately differentiated
Similar to cell of origin, but not fully structurally similar
Define poorly differentiated
Some similarities, but not forming structural components
Define undifferentiated (anaplastic)
No resemblance to cell of origin, often immuno-negative for biomarker found on cell of origin
Define differentiation
Refers to tumour grading system based on how much the cells have matured and look like the normal cells in the tissue from which it arose
How much the cells have phenotypically developed to look like terminally differentiated cells
Differentiation is important as a prognostic indicator and often well differentiated tumours have a better prognosis that poorly or undifferentiated tumours
Define microinvasion
Tumour is invading through the basement membrane, but can only be seen microscopically
Define micrometastases
Small microscopic foci of clumps of tumour cells
Define occult metastases
Metastases are hidden or not easily seen
Define distant metastases
(2)
Tumour has spread to another distant organ through lymphatic or vascular spread
Common sites are lung, liver, bone, brain
Define invasion
Refers to the direct extension and penetration by cancer cells into neighbouring tissues
Define metastasis
Refers to the spread of cancer cells to other parts of the body via the blood or lymph system
This is a multistep process
What is an adenocarcinoma
malignancy of glandular epithelium
What is a squamous cell carcinoma
Malignancy of squamous cells
growth of blood vessels
Haemangioma
Adrenal medulla malignancy
Phaeochromocytoma
