Pathological processes Flashcards
What are the two types of cell death?
Apoptosis and necrosis
Which cell components are most susceptible to injury?
Mitochondria, proteins, nucleus (DNA) and cell membranes
What is hypoxia?
Hypoxia is a deficiency of oxygen that can result in a reduction in aerobic oxidative respiration
What characteristics do hypoxic tumours show?
- Increased aggressiveness
- Resistance to therapy
- Increased metastasis
- Poor patient prognosis
What is hypoxaemic hypoxia?
Low arterial oxygen content
What is anaemic hypoxia?
Decreased ability of haemoglobin to carry oxygen
What is ischaemic hypoxia?
Interruption to blood supply
What is histiocytic hypoxia?
Inability to utilise oxygen in cells due to disabled oxidative phosphorylation enzymes
What is a hypersensitivity reaction?
When host tissue is injured secondary to an overly vigorous immune reaction
What are the main free radicals?
hydroxyl, superoxide and hydrogen peroxide
When are free radicals produced?
- Metabolic reactions - Oxidative phosphorylation
- Inflammation - Oxidative burst of neutrophils
- Radiation
- Contact with unbound metals within the body - iron
- Drugs and chemicals - in the liver during the metabolism of paracetamol
Which three vitamins are antioxidants?
A, C and E
Which enzymes neutralise free radicals?
Superoxide dismutase, Catalase
What do free radicals do to lipids in cell membranes?
Lipid peroxidation
Proteins that mend misfolded proteins and maintain cell viability are called…
Heat shock proteins (unfoldases or chaperonins)
What is a method of diagnosing cell death based on increased permeability of the cell membrane?
Dye exclusion assays
What is oncosis?
Cell death with swelling
What are the two main types of necrosis?
Coagulative and liquefactive (colliquitive)
When does coagulative necrosis occur?
When there is more protein denaturation than the release of active proteases e.g. ischaemia of solid organs, free radical damage
When does liquefactive necrosis occur?
When enzyme degradation is substantially greater than denaturation e.g. ischaemia in loose tissues, the presence of many neutrophils, release of reactive oxygen species
What is caseous necrosis?
A type of coagulative necrosis. The tissue contains amorphous debris.
Which type of necrosis is associated with tuberculosis?
Caseous necrosis
What is fat necrosis?
It results from the action of lipases released into adipose tissue. Free fatty acids accumulate and precipitate as calcium soaps (saponification)
What is gangrene?
Necrosis visible to the naked eye
