Cells Under Arrest
Why does cellular death begin within minutes of cardiac arrest?
Loss of oxygen halts ATP production
What ion is most responsible for establishing resting membrane potential?
Potassium
What is the primary role of oxygen at the cellular level?
ATP production
What does pH measure in the body?
Hydrogen ion concentration
Epinephrine primarily stimulates which receptor type?
Alpha and beta adrenergic receptors
Failure of ATP production first disrupts what essential cellular function?
Ion pumps across the cell membrane
How does hyperkalemia affect cardiac cell membranes?
Reduces membrane excitability → conduction delays and arrest
What byproduct of anaerobic metabolism contributes to acidosis during arrest?
Lactic Acid
What acid–base disturbance is most common during prolonged cardiac arrest?
Metabolic acidosis
Why are antiarrhythmics effective in refractory VF/pVT?
They alter ion movement across cardiac cell membranes
Which organelle is responsible for ATP production using oxygen?
Mitochondria
During prolonged arrest, failure of the sodium–potassium pump causes what ECG change?
Widened QRS complexes
Why does poor CPR quality worsen metabolic acidosis?
Inadequate perfusion limits oxygen delivery and waste removal
What happens to pH as CO₂ rises?
pH decreases
Why does magnesium help treat torsades de pointes?
It stabilizes myocardial cell membranes
Why does reperfusion after arrest sometimes worsen cellular injury?
Free radical formation and calcium influx
What does a prolonged QT interval represent at the cellular level?
Delayed repolarization
Why do myocardial cells switch to anaerobic metabolism faster than skeletal muscle during arrest?
Higher constant ATP demand
What buffer system is most important in the blood?
Bicarbonate–carbonic acid system
Why do ACLS medications fail if oxygenation and perfusion are inadequate?
Drugs require circulation to reach target cells
Why does cellular swelling occur early in ischemia?
Failure of ATP-dependent ion pumps
Why does acidosis reduce myocardial contractility?
Hydrogen ions interfere with calcium binding
What cellular process consumes the majority of ATP in cardiac muscle cells?
Ion transport (especially Na⁺/K⁺ pumps)
How does metabolic acidosis affect cardiac contractility?
It decreases myocardial contractility
Why does high-quality CPR matter more than any single medication during cardiac arrest?
Because CPR preserves oxygen delivery, ATP production, membrane stability, and drug circulation, delaying irreversible cellular death.