Pathology: Cellular and Tissue Responses Flashcards
What is hypertrophy?
An increase in the size of cells (by producing more organelles)
What causes hypertrophy?
Increased functional demand (eg Muscle) or stimulation by hormones or growth factors
What could be a problem with hypertrophy?
The blood supply may not increase adequately to serve the increased mass
What is hyperplasia?
An increase in the number of cells
What causes hyperplasia?
Physiologic: Hormonal hyperplasia or compensatory hyperplasia
Pathologic: Diffuse (whole organ enlarged) or localised (nodular hyperplasia)
What is atrophy?
Decrease in cell size and number
What causes pathologic atrophy?
Decreased workload Lossof innervation Diminished blood supply inadequate nutrition Loss of endocrine stimulation Pressure
What is metaplasia?
Where one cell type is replaced by another eg. columnar epithelium becomes squamous epithelium
What causes metaplasia?
Caused by chronic irritation, deficiencies (eg. vitamin A) as a result of cell/tissue injury or oestrogen toxicity
Why does columnar epithelium transition to squamous epithelium in metaplasia?
Because sq. epithelium is able to serve in conditions where fragile columnar epithelium would have succumbed
Hyperplasia can only occur under what conditions?
The cells must be dividing in the organ
labile cells> stable cells> permanent cells
What are labile cells?
Cells that routinely proliferate
Eg. Epidermis, intestinal epithelium, bone marrow cells
What are stable cells?
Intermediate in their ability to regenerate/divide
Eg. bone, cartilage and smooth muscle
What are permanent cells?
Have very little capacity to regenerate
Eg. skeletal muscle and cardiac muscle
what is agenesis?
Complete failure of an organ to develop during embryonic growth due to the absence of primordial tissue
What is aplasia?
Lack of development of an organ (but its precursor did exist)
What is atresia?
The absence or closure of a body orifice or tubular passage
What is hypoplasia?
Incomplete development of an organ
What is dysplasia?
Disordered growth of cells
What is lipidosis?
Accumulation of triglycerides and other lipid metabolites (neutral fats and cholesterol) within parenchymal cells (often in the liver)
What causes an accumulation of glycogen in cells?
Variable amounts of glycogen are stored in hepatocytes and myocytes but excessive amounts of glycogen are present in animals with an abnormal glucose metabolism eg. Diabetes mellitus, corticosteroid therapy
What does hyaline mean?
A descriptive term for homogenous, eosinophilic glassy looking tissue
What is gout?
Deposition of sodium rate crystals or urges in tissue
In birds and reptiles and humans
Can be articular or viceral
Where do uric acid and crate come from?
End products of purine metabolism
Where do cholesterol crystals come from?
By-products of haemorrhage and necrosis
How do cholesterol crystals appear on histology?
Clefts, as the cholesterol dissolves during processing
What is a cholesteatoma?
A cholesterol granuloma
Commonly found in the choroid plexus of the lateral ventricles of older horses
What is dystrophic calcification?
Locally in dying/dead tissue
What is metastatic calcification?
In normal tissue secondary to hypercalcaemia
What disease processes can cause calcification?
Renal failure
Vitamin D toxicosis
Parathyroid hormone and PTH related protein produced by certain types of neoplasia
Destruction of bone from primary or metastatic neoplasia
Name three ways exogenous pigmentation can occur
Carbon- inhalation and accumulation in the lung (anthracosis) turns it black
Carotenoid pigments are fat soluble pigments from plants (including the vitamin A precursor beta carotene) which turn yellow/orange
Tetracycline stains teeth and bones yellow/brown
Where are lipofuscin and ceroid (endogenous pigments) produced and what colour to they turn tissue?
Lipofuscin: In aged cells (non-pathologic)
Ceroid: pathologic pigment, often in vitamin E deficiency
Brown
What colour is oxygenated haemoglobin?
Red
What colour is deoxygenated haemoglobin?
Blue
What colour staining does bilirubin cause?
From the breakdown of erythrocytes (porphyrin ring is broken down to bilirubin) it causes icterus, yellow staining
