10/01/19
Dr Dunja Aksentijevic
Thermoregulation
• Maintenance of the core temperature
• Core body temperature is the temperature of the body around the main organs
o The size of the core and size and temperature of the shell around it varies
o Heat is exchanged between core and shell by blood
• Poikilotherm – environmental dependent
• Homeotherm – core temperature maintained, no matter what outside is like
Variations
Core – 37.8ᵒC
• Controlled by central nervous system
• Abdominal and thoracic cavities
• Highest temperature in body
• Precisely regulated
Shell
• Skin and subcutaneous fat
• Cooler than core
• Fluctuates between 20ᵒC and 40ᵒC
These both vary with diurnal activities, menstrual cycle, exercise, age and surrounding temperature
Hierarchy of importance – some physiological variables matter more than others
Measuring Core Temperature
Type Factors Estimation of Temperature
Oral Simple Underestimate
Non-invasive
Aural Fast Underestimate
Uncomfortable
Rectal Continuous Close estimate
Slow
Oesophageal Continuous Close estimate
Slow
Affected by food and drink
GI tract Continuous Close estimate
Varies along tract
“radio transmitter pill”
Must be retrieved
Dr Dunja Aksentijevic
Thermoregulation
• Maintenance of the core temperature
• Core body temperature is the temperature of the body around the main organs
o The size of the core and size and temperature of the shell around it varies
o Heat is exchanged between core and shell by blood
• Poikilotherm – environmental dependent
• Homeotherm – core temperature maintained, no matter what outside is like
Variations
Core – 37.8ᵒC
• Controlled by central nervous system
• Abdominal and thoracic cavities
• Highest temperature in body
• Precisely regulated
Shell
• Skin and subcutaneous fat
• Cooler than core
• Fluctuates between 20ᵒC and 40ᵒC
These both vary with diurnal activities, menstrual cycle, exercise, age and surrounding temperature
Hierarchy of importance – some physiological variables matter more than others
Measuring Core Temperature
Type Factors Estimation of Temperature
Oral Simple Underestimate
Non-invasive
Aural Fast Underestimate
Uncomfortable
Rectal Continuous Close estimate
Slow
Oesophageal Continuous Close estimate
Slow
Affected by food and drink
GI tract Continuous Close estimate
Varies along tract
“radio transmitter pill”
Must be retrieved
