Pathology 2 - Cell Injury Flashcards Preview

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Flashcards in Pathology 2 - Cell Injury Deck (55)
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What are the three phases of apoptosis?

- initiation
- execution
- degradation and phagocytosis


What are caspases?

Enzymes that control and mediate apoptosis and cause cleavage of DNA and proteins of the cytoskeleton


Give some triggers of the intrinsic pathway of apoptosis

- irreparable DNA damage
- withdrawal of growth factors/hormones


How is the intrinsic pathway of apoptosis carried out?

- p53 protein is activated which results in outer mitochondrial membrane becoming leaky
- cytochrome C is released from the mitochondria which causes activation of caspases


How is the extrinsic pathway of apoptosis carried out?

- triggered by cells that are a danger eg tumour or virus-infected cells
- initiated by extracellular signals eg TNF alpha
- TNP alpha is secreted by T killer cells and binds to the cell membrane receptor, resulting in the activation of caspases


How are apoptotic bodies disposed of?

They express proteins on their surface, so they can be recognised by phagocytes which engulf and degrade them


What is the difference between budding and blebbing?

Budding is when small parts of the cell break off in apoptosis. Blebbing is when parts of the cell swell out of a disruption in the cell membrane in necrosis.


What are the five main groups of intracellular accumulations?

1) water and electrolytes
2) lipids
3) carbohydrates
4) proteins
5) 'pigments'


Why is hydropic swelling a particular problem in the brain?

If the brain swells, there is nowhere for the pressure to go


What is steatosis?

A accumulation of triglycerides in cells (often in liver) due to alcohol/diabetes mellitus/obesity/toxins


How do lipids accumulate in cells?

- Cholesterol cannot be broken down and is insoluble so must be eliminated via the liver.
- Excess is stored in cell in vesicles.
- Also accumulates in smooth muscle and macrophages in atherosclerotic plaques.
- Present in macrophages in skin and tendons of people with hereditary hyperlipidaemias


How does alpha-1 antitrypsin deficiency lead to accumulation of proteins in the cells?

- liver produces incorrectly folded alpha-1 antitrypsin protein
- cannot be packaged by ER, accumulates within ER and is not secreted
- in systemic deficiency, proteases act unchecked in the lung resulting in emphysema


Give examples of exogenous pigments which could accumulate in the skin

- carbon, coal, dust or soot (urban air pollutants)
- tattoos


What is haemosiderin?

Iron storage molecule derived from haemoglobin. It is deposited in organs with a systemic overload of iron


What is hereditary haemochromatosis?

Genetically inherited disorder which results in increased intestinal absorption of dietary iron. It is deposited in skin, liver, pancreas, heart and endocrine organs, with symptoms of liver damage, heart dysfunction and multiple endocrine failures.


How is hereditary haemochromatosis treated?

Repeated bleeding


What causes the yellow colour of jaundice?

Accumulation of yellow bilirubin


How is bilirubin usually removed from the body?

It is conjugated in liver and excreted in bile


What are the four mechanisms of intracellular accumulations?

- abnormal metabolism
- alterations in protein folding and transport
- deficiency of critical enzymes
- inability to degrade phagocytosed particles


What is calcification of tissues?

Abnormal deposition of calcium salts within tissues. Can be localised (dystrophic) or generalised (metastatic).


Why does dystrophic calcification occur?

Local change/disturbance favours nucleation of hydroxyapatite crystals


Why does metastatic calcification occur?

Due to hypercalcaemia secondary to disturbances in calcium metabolism


What causes hypercalcaemia?

- increased secretion of parathyroid hormone resulting in bone resorption
- destruction of bone tissue


Give some causes of destruction of bone tissue

- primary tumours of bone marrow
- diffuse skeletal metastases
- Paget's disease of bone
- immobilisation


Why are germ cells, stem cells and some cancer cells not affected by shortened telomeres?

They contain telomerase, which maintains the telomere length and allows them to replicate multiple times.

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