Analytical model for the temperature dependence of the circulation pattern in upper extremities

Area of Science:

• Physiology
• Biophysics
• Thermoregulation

Background:

• Human hand circulation is crucial for thermoregulation.
• Understanding blood flow dynamics in response to thermal stress is vital for physiological studies.

Purpose of the Study:

• To develop an analytical model of upper extremity circulation in response to varying water temperatures.
• To qualitatively describe the temperature-dependent heat loss from the hand based on blood flow rates and water temperature.

Main Methods:

• An analytical model representing the arterial and venous systems (one artery, two veins: deep and cutaneous) was employed.
• The model analyzed the influence of water temperature on blood flow distribution and heat loss.
• Counter-current heat exchange between the artery and deep vein was investigated.

Main Results:

• Blood flow distribution significantly shifts with water temperature: ~10% via deep veins at >25°C, ~80% at <13°C.
• A gradual change in circulation patterns occurs between these temperature extremes.
• The model qualitatively describes the dependence of heat loss on blood flow and water temperature.

Conclusions:

• The analytical model provides insights into the physiological mechanisms of hand thermoregulation.
• Blood flow partitioning between deep and cutaneous veins is a key factor in managing heat loss in cold and warm environments.
• The counter-current heat exchange mechanism plays a role in the overall thermal regulation of the hand.