Expert: Walter Hintz - 7/7/2006

Question
Ambient temp    Body temp    Oxygen consumption
0         37          2500
10         37        1500
20         37          500
30         37          450
40         37          900

I still do not understand about endotherm.
Question 1
Why oxygen consumption decrease from 2500 to 450. Then, increase from 450 to 900.Metabolic rate increases as temperature increases, isn't it?

Question2 (Multiple choice):
Which of the following statements about the way endothermic animals regulate their body temperature is incorrect?
A. Metabolic rate decreases during period of inactivity.
B. The metabolic rate decreases in warm condition.
C. The metabolic rate increases in cool conditions.
D. the metabolic rate increases during period of activity.

The answer is B. But why?
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Followup To

Question -
Dear Sir,
I got some enquiry about endotherms.
Suppose that the constant body temperature of endotherm is 37 degree Celcius.
Now the ambient temperature increases from 20 degree celcius to 40 degree celcius.

I would like to ask why the oxygen consumption of endotherm decrease as the temperature increase until 37 degree celcius. However, oxygen consumption increase after 37 degree celcius.

Answer -
A constant body temperature is controlled in part by the metabolic rate and metabolic processes depend upon O2. An external temperature increase raises the body temperature and along with homeostatic mechanisms like sweating the metabolic rate slows down requiring less O2. With a decrease in temperature the reverse is true.  More heat must be generated and an increase in O2 is required  

Answer
AS to question 1.  I looked at the data and noticed that the O2 consumption doubled when the temperature increased from 30 to 40..  This would mean an increase in metabolic rate and does not make sense to me. It sounds like a positive feedback. Are you sure this data is correct?  Prior to that as the temperature increases from 0 to 30 there is a drop in O2  and this does make sense.  As temperature increases less heat has to be generated by the body to maintain the 37 degrees.  Metabolism decreases.  This answers question #2.