A sportsman spontaneously held breath for 40 seconds, which resulted in an increase in heart rate and systemic arterial pressure. Changes of these indicators are due to activation of the following regulatory mechanisms:

Answer options

1. -
2. Unconditioned sympathetic reflexes
3. Unconditioned parasympathetic reflexes
4. Conditioned sympathetic reflexes
5. Conditioned parasympathetic reflexes

Explanation

Changes in heart rate and blood pressure are unconditioned responses. The ‘increase’ here is due to the action of the sympathetic nervous system through the production of epinephrine (flight or fight reflex). Parasympathetic NS reduces HR and BP via acetylcholine.