Introductory path Flashcards
What is Metaplasia?
When one adult cell type is replaced by another adult cell type.
What Is Hyperplasia?
An increase in the number of Cells in a tissue/organ
What is Dysplasia?
Alteration in the size/shape or organisation of a tissue.
Describe Reversible Cell Injury
Reduced ATP levels - switch to anaerobic metabolism - depletion of glycogen and accumulation of lactate and inorganic phosphates - inhibition of membrane sodium/potassium pumps and water moves into the cell.
Describe coagulative necrosis
Basic cell outlines are preserved due to delayed proteolysis. acute. e.g renal infarct.
Describe Caseous Necrosis
Friable cheese like appearance, a chronic lesion. May develop dystrophic calcification.
Describe Liquefactive necrosis
Cavity/cavities filled with liquefied debris. e.g in the CNS due to little fibrous tissue framework to support dead cells, and in abscesses: caused by pyogenic bacteria.
Describe Gangrenous Necrosis
Follows on from some cases of coagulative necrosis. Can be moist, dry, gas. Eg saprophytes invade dead tissue (moist and gas), mummification (dry)
What is Fat necrosis?
Specific necrosis of Fat, e.g pancreatic fat necrosis, traumatic necrosis
Define Pyknosis
A small shrunken densely staining nuclei
Define karyorrhexis
Nucleus has fragmented into small pieces
Define karyolysis
The nucleus has lysed (fades into the background in histology)
What is the difference between dystrophic and metastatic calcification?
In dystrophic calcification serum calcium levels are normal but the calcium is deposited in tissue that is already dead or dying due to cellular damage interfering with cells ability to regulate calcium. In metastatic calcification - the primary problem is Hypercalcaemia.
Describe Suppurative Exudate
Has many neutrophils (dead and alive) plus dead host cells. It is often bacterial in origin.
Describe Fibrinous Excudate
Histologically, a thin eosinophilic meshwork which sometimes coagulates. Increased vascular permeability - escape of plasma protein including fibrinogen. This then forms fibrin and can be seen in some inflammatory reactions as a coagulum of yellow tinged irregular soft material.
Describe Serous Exudate
Occurs early in most inflammatory lesions, it is made up of fluid albumen and other plasma proteins eg serous rhinitis.
Describe Mucous/ catarrhal Exudate
It is present in the respiratory and GI tract where mucous secreting cells contribute. Hypersecretion accompanying an inflammatory reaction.
Describe the PM changes associated with barbiturates
1.Local reaction, 2.barbiturate crystals, 3. splenomegaly - most prominent in dogs and horses following either barbiturate euthanasia or anaesthesia. spleen can be massively enlarged making the capsule fragile.
Describe the PM changes associated with steroids.
Long term steroid use can lead to steroid induced hepatopathy. Pathogenesis: glucocorticoids induce the enzyme glycogen synthetase leading to increased storage of glycogen within hepatocytes. The hepatocytes in midzonal areas are often preferentially affected and can be up to 10x normal size.
The typical anteroventral distribution of lesions seen in association with bronchopneuomia is consistent with what?
Aerogenous portal of entry into the lungs as oopposed to haematogenous spread.
Why are benign tumours often well demarcated?
They grow by expansion, this may or may not be the case for malignant tumours. With regard to inflammatory lesions, well demarcated inflammatory lesions are often surrounded by fibrosis whereas poorly demarcated inflammatory lesions are more acute.
What is Algor mortis?
The cooling of the body after death (can aid in estimating time of death)
What is Rigor mortis?
Rigidity of skeletal muscles. A burst of metabolic activity as substrates are depleted on cessation of circulation, causes a progressive decrease in muscle pH, oxygen and ATP. There is a calcium efflux from the SR of muscle cell and shortening of muscle fibres. The head and neck affected first. Disappears as putrefaction begins. (1-2 days)
What is Autolysis?
The process whereby the release of intracellular lytic enzymes from lysosomes results in self digestion of tissues. The process of autolysis results in changes in the cytoplasm and nucleus of the cells which resembles those seen in necrosis. The mucosa of the stomach and intestine autolyse very rapidly as does the pancreas and renal tubules.
What is Putrefaction?
Occurs when dead tissue is invaded by anaerobic organisms such as clostridia. Tissue turns green/brown due to combination of haemoglobin breakdown and formation of hydrogen sulphide.
What is Hypostatic congestion?
The effect of gravity - often evident in the lungs and kidneys. Causing pooling of blood in dependant sites (resulting in asymmetric congestion)
What is Pseudomelanosis?
Green/black discolouration due to conversion of iron to iron sulphide by GI bacteria.
What is Emphysema?
Invasion of tissue by gas producing bacteria.
What is Nodular Hyperplasia?
Nodular hyperplasia occurs when hyper plastic nodules of tissue develop in organs (most notably the liver, spleen, adrenal and pancreas of older dogs).. The lesions comprise multiple n odules of well-differentiated cells within the tissue and are important as they may be mistaken for genuine neoplasms.
What is splenic Siderofibrosis?
Yellow dry encrustations on the capsule of the spleen thought to represent sites of previous local haemorrhage with subsequent deposits of Fe, Ca and fibrosis.
Describe Anthracosis
In polluted areas, inhaled carbon particles phagocytosed by alveolar macrophages. Can become visible as multiple small black foci in lung tissue. In addition as the macrophages then travel to the tracheobronchial lymph nodes, the medulla of these nodes can become black.
What is Steroid induced hepatopathy?
Pathogenesis: glucocorticoids induce the enzyme glycogen synthetase leading to increased storage of glycogen within hepatocytes. The hepatocytes in midzonal areas are often preferentially affected and can be up to 10x normal size.
What would commonly cause multifocal raised lesions in sheep lungs?
Muellerius capillaris.
