1. Introduction and overview


2. Heat stress and orthostatic tolerance
2.1 Heat stress defined
2.2 Heat stress impairs orthostatic tolerance


3. Autonomic control of cardiovascular function
3.1 Measuring the activity of the autonomic nervous system in humans


4. Thermoregulation during heat stress
4.1 Human temperature regulation
4.2 Sensors of body temperature
4.2.1 Central thermosensors
4.2.2 Peripheral thermosensors
4.3 Central nervous system integration
4.4 Heat balance and thermoregulatory responses during heat stress
4.4.1 Skin blood flow: cutaneous vasodilation
4.4.2 Sweating


5. The arterial baroreflexes in humans
5.1 Measurement approaches


6. Cardiac output and blood flow redistribution during heat stress
6.1 Cardiac output during heat stress
6.1.1 Heart rate
6.1.2 Stroke volume
6.1.3 The Frank-Starling relationship during heat stress
6.1.4 Cardiac contractility during heat stress
6.2 Cardiac output redistribution during heat stress
6.2.1 Splanchnic and renal blood flow
6.2.2 Muscle blood flow


7. Neurovascular control during heat stress
7.1 Venoarteriolar response


8. Control of cerebral perfusion during heat stress
8.1 Heat stress decreases brain blood flow
8.2 Mechanisms of heat stress-induced reductions in cerebral perfusion
8.2.1 Perfusion pressure
8.2.2 Partial pressure of arterial carbon dioxide
8.2.3 sympathetic activation
8.3 Regional cerebral perfusion during heat stress
8.4 Cerebral perfusion and orthostatic tolerance during heat stress


9. Effects of dehydration on autonomic and cardiovascular responses to heat stress


10. Countermeasures for improving orthostatic tolerance during heat stress


11. Summary and conclusions
Author biographies.