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Cell injury
| Question | Answer |
|---|---|
| What is cell injury ? | CEll injury occurs when the stress exceeds its natural ability to adapt. |
| what are factors of cell injury?(ie.. what determines if the cell is goign to be able to adapt or not) | 1.type of stress(trauma vs nutritional def.) 2.its severity (Slow ischemia (eg:renal artery atherosclerosis) atrophy, whereas, acute ischemia (e.g. renal artery embolus) results in injury 3. cell type affected.(Neurons(more effected) vs skeletal muscle |
| Common causes of cellular injury are? | inflammation, nutritional deficiency or excess, hypoxia, trauma, and genetic mutations |
| What is hypoxia? | hypo= low oxia = oxygen Low oxygen delievery to tissues leading to cell injury. Tissue in there cellular cycle requires oxygen to be the final electron acceptor for the generation of ATP. low oxygen then low ATP then high injury |
| What are the causes of hypoxia? | ischemia, hypoxemia, and decreased 0 2 - c a r r y i n g capacity of blood |
| describe how hypoxia is caused from ischemia? | Ischemia is decreased blood FLOW THRU an organ.. if low oxygen There might be a block in the arterial flow(artherosclerosis) There might a block in the venous flow Shock—generalized hypotension resulting in poor tissue perfusion |
| What is Hypoxemia? | Low partial pressure of o2 w/n the blood. o2 pressure in air -> o2 pressure in alveoli-> o2 pressure in arteries-> o2 on heme. if o2 pressure in the artery is low then its low in alveoli & air->high alt, hypoventilation, V/Q mismatch, diffusion defect |
| How do high altitudes cause hypoxemia? | Decreased barometric pressure results in decreased Pao,. o2 pressure in air -> o2 pressure in alveoli-> o2 pressure in arteries-> o2 on heme. if o2 pressure in the artery is low then its low in alveoli & air |
| How does Hypoventilation causes hypoxemia? | Increased Paco, results in decreased Pao.. lesser gradient so less oxygen is absorbed into the blood stream |
| How does diffusion defect causes hypoxemia? | Pressure of oxygen in the alveoli, not able to push as much O, into Lhe blood due to a thicker diffusion barrier (e.g., interstitial pulmonary fibrosis) |
| How does V/Q mismatch causes hypoxemia? | v/q mismatch-top of lung( ventilation low perfusion(gravity))- bottom of lung( ventilation high perfusion). Artery block causes(high ventilation low perfusion) blood shunted to other arteries(so normal ventilation but high perfusion) low Pa of o2. |
| How does lowering o2 carrying capacity causes hypoxia?three of them | Anemia- loss of RBC and heme- normal partial pressures CO poisoning-CO binds hemoglobin more rapidly PaO2 = normal; Sao3=decreased Caused by smoke.-- cherry-red skin. Methemoglobinemia-Iron heme oxidized to Fe2+ thus less o2 — Pao normal; Sao,decreased |
| What is methemoglobinemia? | i. Iron in heme is oxidized to Fe2+ which cannot bind oxygen — Pao normal; Sao,decreased iii. Classic finding is cyanosis with chocolate-colored blood. iv. Treatment is intravenous methylene blue, which helps reduce FeJ' back to Fe1+ state. |
| How does hypoxia lead to reversible cell injury? | bad oxidative phosphorylation-> low ATP-> low cell function(Na K pump,Ca pump) anaerobic glycolysis->Lactic acid-> low ph->denatures proteins and precipitates DNA. NOTE cellular swelling- injury reversible ER swelling->loss ribosomes and low protein sy |
| How does hypoxia lead to irreversible cell injury? | NOTE membrane damage- irreversible injury Plasma damage-> Cytosol enzymes leak into serum Mitochondrial damage-> Loss of ETC & Cytochrome c leaking into cytosol(activates apoptosis) Lysosome membrane damage->hydrolytic enzymes leaking into the cytosol |
Created by:
atayal
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