Practice question · Multiple choice
A perfectly regular heartbeat sounds healthy and is a warning sign. Why does clinical medicine treat variability in heart rate as the good news?
Hints
- The resting heart sits under continuous opposing drive. Ask what its output looks like when both sides are actively adjusting.
- A system that never varies is not stable, it is unresponsive.
Show the answer
B. Because the beat-to-beat variation IS the two branches adjusting
Why
The wobble is the regulation showing through: sympathetic and parasympathetic trimming the rate breath by breath. Lose it and you are seeing a heart no longer being steered, which is why reduced heart rate variability predicts poor cardiac outcomes and tracks chronic stress.
Practise The Nervous System
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