2 - Biochemical Mechanisms Associated With Injury (Exam 1) Flashcards
Is ATP necessary for anabolic processes?
Yes, and if there are not adequate levels of ATP, these processes will be reduced.
What are 4 examples of anabolic processes?
- Protein and nucleic acid synthesis
- Membrane transport mechanisms
- Maintenance of cellular osmolarity
- Intracellular homeostatic mechanisms
What is 1 example of a Reactive Oxygen Species?
Free radicals
Briefly explain free radicals
They are highly reactive and damaging to cells
What are the generally normal concentrations for calcium inside the body?
Higher concentrations in the extracellular space, stored in specific intracellular structures when present in the cell.
How does injury change calcium concentrations?
Calcium ions can freely enter the cell and can also release calcium from intracellular stores.
What 2 changes can result from a changes in plasma membrane permeability?
- Loss of concentration gradients
2. Abnormal movement of solute and water
What changes can occur as a result of mitochondral damage?
Formation of high conductance channels of the inner mitochondrial membrane causes damage to proton gradient across mitochondrial membranes. This results in decreased oxidative phosphorylation and therefore decreased ATP production.
What are 3 common forms of cell injury?
- Ischemic
- Hypoxic
- Free-radical induced
Ischemic and hypoxic are very similar
What is the most common type of cell injury?
Ischemia
Which injures tissues faster, ischemia or hypoxia?
Ischemia
How does ischemia differ from hypoxia?
Less blood leaves the tissue resulting in less removal of metabolic byproducts.
What is hypoxia?
Reduced delivery of oxygen, below the demands of the tissue.
What are 4 effects of both ischemia and hypoxia?
- Cellular Swelling
- Increase in anaerobic glycolysis
- Decrease in pH as a result of lactic acid production
- Detachment of ribosomes from rough ER - because of decreased pH and ATP
What are free radicals?
Chemical species that have a single unpaired electron in the outer orbit, extremely reactive and unstable.
What are 3 sources of free radicals?
- Absorption of extreme energy by the cell, such as ionizing radiation.
- Endogenous reactions associated with reduction of oxygen to water (normal, but excess is bad).
- Enzymatic metabolism of exogenous chemicals/ drugs.
How does the body eliminate free radicals?
The cell’s scavenger system (associated with ER) picks up/ releases electrons.
What are 3 examples of scavenging system compounds?
- Catalases
- Superoxide dismutase
- Glutathione peroxidase
What are 7 examples of antioxidant chemicals that can either block formation of or inactivate free radicals?
- Vitamin C
- Vitamin E
- Cysteine
- Glutathione
- Albumin
- Ceruloplasmin
- Transferrin
What is 1 example of cellular injury caused by free radicals?
Lipid Peroxidation
What is a brief summary of lipid peroxidation?
Destruction of polyunsaturated lipids
This leads to membrane damage and increased permeability and can increase the formation of free fatty acids (precursors to inflammatory molecules).
Damage can be caused to critical proteins, DNA, and mitochondria.
What are 7 types of accumulations associated with cell injury?
- Water
- Proteins
- Lipids
- Cholesterol
- Glycogen
- Pigments
- Minerals
What occurs when water accumulates in the cell?
Results in “cloudy swelling” or hydropic degeneration.
Usually associated with damage to the plasma membrane.
What is steatosis, and what is it a sign of?
The abnormal accumulation of triglycerides within cells.
Usually a sign of reversible damage, may occur in cells adjacent to necrotic cells.