Metabolism and Body Temperature Regulation
Supplementary Readings:
• Textbook (5th Edition, Chapter 39, pages 1043-1053
Body Energy – Supply & Demand
• For a normal human, daily energy is spent on
o 70% in basic organ function
o 20% on physical activity
o 10% percent is necessary for thermoregulation.
• As organic substrates are absorbed from the digestive system into the blood, they are delivered to
tissues for:
o Immediate conversion to ATP (&heat)
o Synthesis into structural molecules
o Or storage for later conversion to ATP
Heterotrophs derived energy from other organisms (food)
• Metabolism: body processes that used or produce energy; occurs at multiple scales
• Metabolic Rate: the rate at which body energy is used to metabolism.
Metabolism & Metabolic Rate
• Body metabolism is adjusted to meet specific needs
• Seen as changes in metabolic rate
o More body activity = higher overall energy use (metabolic rate)
• Regulated by the CNS and various hormones in mammals
o Motor NS increases skeletal muscle activity
o Autonomic NS switches metabolism
o Epinephrine increases metabolism
o 𝐓𝟑 directly stimulates cellular ATP & heat production indirectly through various other chemical
signals (e.g. cortisol, leptin, etc.)
A change in metabolic rate results from changes in ATP used by individual cells
• However, at the whole-body level, this is seen as:
o Altered 𝐎𝟐 consumption
o Altered 𝐂𝐎𝟐 production
o altered production of 𝐇 # & other by-products
o altered heat production
• some animals have evolved a high rate of metabolism just to maintain an elevated body temperature.
, •
Supplementary Readings:
• Textbook (5th Edition, Chapter 39, pages 1043-1053
Body Energy – Supply & Demand
• For a normal human, daily energy is spent on
o 70% in basic organ function
o 20% on physical activity
o 10% percent is necessary for thermoregulation.
• As organic substrates are absorbed from the digestive system into the blood, they are delivered to
tissues for:
o Immediate conversion to ATP (&heat)
o Synthesis into structural molecules
o Or storage for later conversion to ATP
Heterotrophs derived energy from other organisms (food)
• Metabolism: body processes that used or produce energy; occurs at multiple scales
• Metabolic Rate: the rate at which body energy is used to metabolism.
Metabolism & Metabolic Rate
• Body metabolism is adjusted to meet specific needs
• Seen as changes in metabolic rate
o More body activity = higher overall energy use (metabolic rate)
• Regulated by the CNS and various hormones in mammals
o Motor NS increases skeletal muscle activity
o Autonomic NS switches metabolism
o Epinephrine increases metabolism
o 𝐓𝟑 directly stimulates cellular ATP & heat production indirectly through various other chemical
signals (e.g. cortisol, leptin, etc.)
A change in metabolic rate results from changes in ATP used by individual cells
• However, at the whole-body level, this is seen as:
o Altered 𝐎𝟐 consumption
o Altered 𝐂𝐎𝟐 production
o altered production of 𝐇 # & other by-products
o altered heat production
• some animals have evolved a high rate of metabolism just to maintain an elevated body temperature.
, •
