0514 Ischaemia

Question 1

What is the difference between hypoxia and ischaemia

Answer 1

Hypoxia is decreased availability of oxygen to tissues. Ischaemia is a generally reduction in blood suppply to tissues (due to acute arterial cause or decreased venous drainage). Ischaemia results in a decrease of system supply of all solute/compounds (including oxygen).

Question 2

What are some factors that can influences the severity of an insult to a patiet

Answer 2

Site, mechanism of action, condition at the time, magnitude, and rapiditiy/duration of application

Question 3

What are the characteristics of reversible cell injury

Answer 3

Removal of agent resulting in cell recovery or damage to cell which is still viable but appearance or function is altered

Question 4

What are the characteristics of irreversible cell injury

Answer 4

Damage beyond the point of no return resulting in necrosis or apoptosis

Question 5

List 3 potential causes of hypoxia

Answer 5

Decrease in partial pressure of oxygen in blood, constriction or obstruction of artery and pumonary disease (poor gas transfer)

Question 6

What some potential bodily adaptations to hypoxia

Answer 6

Increase breathing effort, increase in red cell mass and use of anaerobic pathways and metabolic processes

Question 7

Describe the Common elements of cellular inury

Answer 7

Mitochondrial damage, loss of calcium homeostassis, reduced ATP, Free radical production, pH drops, permeability of membrane is compromised

(think Maimed Cells Always Follow Predictable Patterns)

Question 8

What is risk of reintroduction of oxygen to a hypoxic cell (what is the mechanism)

Answer 8

Ichaemic reperfusion injury = damage from absence of oxygen + nutrietns creates conditions in cell where restoration of circulation causes inflammation and oxidative damage

Question 9

List some characteristics of Apoptosis that are different to necrosis

Answer 9

Condensation chromtain, DNA fragmentation, Membrane is intact, inflammation is absent and shrinkage of cell

(think Apoptotic Cells Don’t Make Inflammatory Signals)

Question 10

What are the common elements of cellular injury (briefly describe each and in the order they happen)

Answer 10

1. Depletion of ATP
2. Production of activated oxygen species and free radicals
3. ↑ intracellular [calcium] →loss of homeostasis of cells
4. ↑ membrane permeability
5. Mitochondrial damage – mitochondria has enormous surface area, it is particularly vulnerable (makes but is also dependant on ATP)