Lecture 2 Flashcards
Examples of Physical Injury to a cell?
trauma
heat
cold
radiation
electricity
O2 deprivation
Examples of Chemical Injury to a cell?
Carbontetrachloride injuring cells in the liver
pH
extremes free radicals
low or high oxygen concentration
poisons
drugs
Examples of Biological Causes to a cell?
factors arising from microorganisms
damaging factors released during immune responses
nutritional imbalances
lack of growth factors
Examples of Immunological injury Injury to a cell?
autoimmune reactions
autoimmune disease
Examples of Genetic Derangements to a cell?
range from severe cognital malformations
subtle variations in genetic makeup -both influence the susceptibility of cells to injury
- genome sequencing has increased our knowledge of how genetic determinates alter how cells respond
- not very strong determinents
- often large numbers which interact with one another and other aspects of the disease
Examples of Nutritional imbalances to a cell?
range from severe protein-calorie deficiencies in third world
starvation
anorexia nervosa
excess intake of lipids and cholesterol
- predisposing atherosclerosis
- directly injury
- modulate how other factors injure cells
What is the anagram to remember the causes of cell stress and injury?
PiC’N BIG
Physical
Chemical
Nutritional
Biological
Immunological
Genetic derangements
What are 4x things that cause damage to the cell membrane?
- Directly due to Free Radicals
- After Hypoxia (stress induced due to low O2)
- membrane targeting bacterial toxins (a-toxin of Clostridium Perfringens)
- Ca2= plasma membrane pump failure
What is an example of a bacterial toxin that targets the plasma membrane?
a-toxin of Clostridium Perfringens
What 4 things happen when the plasma membrane is damaged?
- loss of cellular contents
- loss of proteins, enzymes, co-enzymes and RNA (ribo-nucleic acids)
- loss of osmotic balance
- influx of fluids and ions
What is the function of transmembrane pumps and how can they be injured?
Transmembrane pumps control the ionic and iso-osmotic balance or cells and organelles
- injured directly
- decreased function due to decreased ATP availability
What is Autolysis?
Lysosomal membranes injured
= enzymes leak into cytoplasm
= digestion (autolysis) of cellular components
What is severe cell injury often associated with and how does this arise?
Severe cell injury = assoc. decreased content of membrane phospholipids
Caused by combination of two factors:
- cell injury activation of phospholipases +
- decreased ATP causing decreased synthesis of phospholipids
What happens when there is decreased Ca2+ membrane pump activity?
- increased Ca2+ influx into cytosol
- activation of destructive Ca2+ dependant enzymes
a) ATPases (faster ATP depletion)
b) Phosopholipases (damages lipid parts of membrane)
c) Proteases (breaks down both membrane and cytoskeletal proteins) - Endonucleases (breaks down both DNA and chromatin into fragments (fragmentation))
What do proteases break down?
both 1. Membrane and 2. Cytoskeletal proteins