| Oxygen conservation for aerobic tissues is paramount! | Lung, blood, tissue oxygen used; results in decreased saturation of hemoglobin, and hypercapnia (respiratory acidosis) |
| Apnea/face immersion; facial./glottal receptors initiate response, intensified by peripheral chemo-receptors | Decrease in overall metabolism, heat production, decrease in body temperature |
| Increased peripheral resistance and arterial B.P. due to intense peripheral sympathetic tone; directs blood to most critical organs | Increase in insulation due to peripheral vasoconstriction |
| Bradycardia due to intense vagal tone (withdrawal of sympathetic tone?); hypertensive response may contribute; abolished with atropine, intensified by cold water; sinus arrhythmia | Anaerobic metabolism in skeletal muscle and other peripheral tissues, release of lactate and development of metabolic acidosis (oxygen debt) |