GEL 12 Lecture Notes - Lecture 14: Basal Metabolic Rate, Homeothermy, Poikilotherm
1. What is the metabolic rate?
a. Metabolic rate: energy expenditure per unit time
i. Usually measured by how much oxygen is responded per unit time and
sometimes converted to J/s
b. Basal Metabolic rate (endotherms)
i. Standard Metabolic Rate (ectotherms - fish)
ii. Energy expenditure per unit time at rest
1. Minimum amount of energy you need to spend to do nothing
iii. Basal metabolic rate is less than exercise metabolic rate
2. How does the metabolic rate change with temperature in reptiles?
a. Daily temperatures changes throughout the day
i. 15-20 degrees celsius
ii. Body temperature is controlled by the outside temperature
b. Use external heat to warm up
c. Minimize heat loss (blood flow pattern change, additional insulation)
i. Catch some wind to cool them down
d. Metabolic rates go up in the daytime where the temperature is higher
e. Metabolic rate depends on temperature
3. What does “warm-blooded” mean?
a. Combination of homeothermy and endothermy and stenothermy (mostly first 2)
b. Homeothermy
i. Body temperature is constant, despite the outside temperature
ii. Poikilothermy
1. Body temperature changes with the outside temperature
iii. Constant body temperature is based off of the core temperature
1. Where the main organs are so they can continue to function
iv. Daily fluctuation of core temperature is a few degrees celsius
v. Exists in mammals and birds, but not all have the same body temperatures
c. Endothermy
i. Where the heat is coming from?
ii. The heat comes from internal organs and only a quarter comes from the
skins and muscles
iii. High heat generation inside the body
1. Ectothermy – reptiles, get body heat from the outside environment
iv. Warm-blooded: maintain high body temperature (> 30 degrees Celsius)
with endothermy – mammals and birds
d. Stenothermy
i. How our chemicals work inside our body
ii. Our body is tuned to work under a certain body temperature
iii. Chemicals in our body work best in that body temperature range
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