Control of respiration · Physiology

During heavy exercise, ventilation increases almost immediately, often before any changes in arterial blood gases are detected. What is the primary cause of this initial increase?

  1. Delayed reflex stimulation of the central chemoreceptors in the medulla
  2. Feed-forward drive from the cerebral cortex and limb and joint proprioceptors
  3. A rapid drop in arterial pH from early lactic acid buildup in working muscle
  4. Rising blood temperature during exercise stimulating the hypothalamic centres
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Correct answer: Feed-forward drive from the cerebral cortex and limb and joint proprioceptors

The initial rapid rise in ventilation during exercise is mediated by neural factors, including motor impulses from the cerebral cortex (anticipatory) and sensory input from proprioceptors in moving limbs. This ensures oxygen delivery and CO2 removal match the increased metabolic demand instantly.

Difficulty: Medium Question 26 of 40

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