Cell Injury and Death Flashcards
List 4 factors which contribute to the maintenance of a cellular steady state
- Preservation of genetic integrity 2. Normal enzyme content 3. Intact membranes and transmembrane proteins Adequate supply of substrates and oxygen
Define ‘Cell Injury’
A biochemical and/or morphological change which occurs when the steady state is perturbed by adverse influences
What do each of these prefixes or suffixes mean? Ana- Dys- Hyper- Hypo-
Ana- = ‘without’ Dys- = ‘disordered’ Hyper- = ‘extreme or beyond normal’ Hypo - = ‘Below normal’
What do each of these prefixes or suffixes mean? Meta- -itis -oma -osis
Meta- = ‘change’ -itis = ‘inflamed’ -oma = ‘tumour’ -osis = ‘ condition, disease or increase’
What do these suffixes mean? -oid -penia -cytosis -ectasis -plasia -opathy
-oid = ‘resemblance’ -penia = ‘deficiency’ -cytosis = ‘increase in cell number’ -ectasis = ‘dilatation’ -plasia = ‘formation’ -opathy = ‘denoting disease or disorder’ (governed by the prefix i.e. ‘neuropathy’ - a disease of the peripheral nerves
List 4 common causes of cell injury
Oxygen availability Physical Trauma Chemical Agents Infectious organisms Irradiation Immunological Genetics Ageing
What is the difference between hypoxia and anoxia and what is the common cause of both?
Hypoxia is a reduction in the availability of oxygen Anoxia is the complete loss of oxygen delivered to cells Common cause is ischaemia
What is the danger with radical re-oxygenation of tissues?
Reperfusing tissues can generate oxygen free radicals and further cause damage
Explain the mechanism of cyanide poisoning
Primary effect of cyanide poisoning is impairment of oxidative phosphorylation. This is catalysed by the cytochrome oxidase enzyme system in the mitochondria, and the impairment arises from the inhibition by cyanide of cytochrome oxidase
What are the consequences of mechanical trauma?
Disruption of cell structure Thrombosis leading to ischaemia
Which product is toxic in the breakdown of paracetamol?
NAPQI N-Acetyl-P-Benzo-Quinone Imine
What is the treatment for paracetamol poisoning?
Administer activated charcoal (AC) if the patient is alert and presents, ideally, within 1 hour post ingestion. The IV formulation of NAC (Acetate) is commonly used in many institutions for the treatment of acetaminophen ingestion in more severe cases
What are the two secretions from bacteria which are toxic?
Endo- and Exo- toxins
Briefly describe the mechanism of ionisation to the tissue
Generation of free radicals causing direct damage to macro molecules following exposure to a source such as UV light
Give 3 examples of tissues which have a high sensitivity to ionising radiation
Bone marrow Gonads Intestines
Give 3 examples of tissues which have a low sensitivity to ionising radiation
Uterus Pancreas Adrenal
What makes certain cells more sensitive to ionising radiation than others?
The most sensitive cells are those that are undifferentiated, well nourished, dividing quickly and highly active metabolically.
List the targets of cell injury
Mitochondrial function Membrane integrity and function Protein synthesis Cytoskeleton Genetic apparatus
Describe this flow chart
Diminished oxidative phosphorylation and reduced ATP levels
- Activity of plasma membrane ATP-driven “sodium pump” is reduced, with consequent influx of sodium and calcium, leading to isosmotic gain of water and acute cellular swelling
- Anaerobic glycolysis increases to generate ATP from glycogen, which depletes glycogen stores and results in accumulation of lactic acid thus lowering the intracellular pH
- Decreasing pH and ATP levels cause ribosomes to detach from rough endoplasmic reticulum and reduction in protein synthesis
- Note that all these effects are potentially reversible, and the restoration of blood flow eventually allows the cell to recover normal function.
- Cellular swelling or acute cellular oedema is usually associated with hypoxia, but may also occur with fever or damage due to toxins
What is the treatment for free radical toxicity?
Detoxification by superoxide dismutase and antioxidants like vitamins A, C and E
Name 3 factors can cause membrane defects?
Bacterial toxins
Viral proteins
Complement
Cytolytic Lymphocytes
Various physical and chemical agents
What can an iincrease in calcium into the cell cause?
Activates a number of enzymes with potential deleterious cellular effects:
ATPases
Phospholipases
Proteases
Endonucleases
What is the function of an ATPase enzyme?
ATPases transport a variety of different compounds, like ions and phospholipids, across a membrane using ATP hydrolysis for energy. An increased activation of ATPase would hesten ATP depletion
What is the function of a phospholipase enzyme?
Hydrolyses phospholipds into fatty acids. Increased activation of these enzymes will lead to membrane damage
