156879
| Question | Answer |
| Define cell injury. | Normal cells are in a state of homeostasis (i.e., an equilibrium with their environment). Injury is defined as a set of biochemical and/or morphologic changes that occur when the state of homeostasis is perturbed by adverse influences. It can be reversible (sublethal) or irreversible (lethal). |
| What is the most common cause of cell injury? | Hypoxia |
| Hypoxia | Lack of O2 in cells - relative deficiency of O2 - disproportion between the need for O2 and its availability - which leads to the inability of the cell to synthesize sufficient ATP by aerobic oxidation (=not enough oxygen for oxidative phosphorylation in cells) |
| Anoxia | An extreme form of hypoxia - complete block in the oxygen supply |
| What is the most common cause of hypoxia? | Ischaemia |
| Ischaemia | Loss of arterial blood flow and/or reduced venous drainage of tissues, causing a shortage of oxygen and glucose needed for cellular metabolism. (from Greek ischaimía; isch= restriction, hema or haema = blood) |
| Ischaemia (2) | is a restriction in blood supply to tissues, causing a shortage of oxygen and glucose needed for cellular metabolism |
| Ischaemia (3) | Loss of blood supply in a tissue due to impeded arterial flow or reduced venous drainage |
| Ischaemia (4) | Ischemia, defined as interruption of blood flow, results in cell injury or cell death by necrosis or apoptosis, or both. |
| Hypoxemia | Decrease in PaO2 measured in an arterial blood gas, that results from inadequate oxygenation of the blood ↓PaO2 - partial pressure of oxygen in art. |
| What are free radicals? | Free radicals are atoms or molecules with an unpaired electron in the outermost orbital. As such they are unstable and therefore highly reactive. |
| Hypoxia (2) | Inadequate oxygenation of tissue. It may result from a reduced supply or increased demand that cannot be satisfied. |
| What is the most common cause of ischemia? | Thrombosis in a muscular artery overlying an atherosclerotic plaque is the most common cause of ischemia. |
| Ischaemia (final def) | Decreased arterial blood flow to tissue or venous outflow of blood from tissue, > causing a shortage of oxygen and glucose needed for cellular metabolism, > results in cell injury or cell death |
| normal PaO2 | 80-100 Hgmm |
| normal PvO2 | 30-50 Hgmm |
| Hb oxygen saturation (artery) | 95-98% |
| Hb oxygen saturation (vein) | approx. 75% |
| PaCO2 | 35-45 Hgmm |
| PvCO2 | 41-53 Hgmm |
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