1. Bioenergetics: Metabolic Rate: Measured by: Affected by:
“The study of the dynamic balance of energy intake & loss.”
Metabolic Rate:
Total energy an animal uses per unit time
Measured by:
ATP produced
Heat generated
O2 Consumed
CO2 exhaled
Affected by:
Age, sex, size
Environmental Temperatures
Food quality / quantity
Activity level
Time of day

2. ENDOTHERMS Animals that generate their own heat.
“warm-blooded” (but don’t call them that!!)
We measure their
Basal Metabolic Rate (BMR)
Measured at resting, fasting, stress free
Human BMR is about Calories/day
Examples of endotherms:
Birds & Mammals

3. EctOTHERMS Animals that acquire most of their heat
from their environment.
“Cold-blooded” (but don’t call them that!!)
We measure their:
Standard Metabolic Rate (SMR)
Still measured at resting, fasting, stress free…but:
…at a controlled temperature!
And, of course it can vary widely with temperature.
Examples of ectotherms:
Fish, Amphibians, reptiles, and all invertebrates.

4. Metabolic Rate & Body Size:
An inverse relationship
Holds true for BOTH endotherms and ectotherms
Small Animals have higher:
Calorie consumption per gram of body weight
Breathing rate
Blood volume per gram of body weight
Larger animals, of course, the opposite.

5. Homeostasis: Maintained by 3 control systems: Animation Weblink
Keeping internal conditions relatively stable.
“a steady state”
Maintained by 3 control systems:
1. Receptor-
Detects internal change
2. Control Center-
Processes information and directs
the effecter to respond.
3. Effecter-
Provides the response
Negative feedback -
The most common homeostatic mechanism.
Stops or reduces the intensity of the original stimulus.
Example: Hypothalamus- detects high blood temperature and
causes increased sweating to cause evaporative cooling.
Positive feedback-
Less common… enhances initial response
Examples: Uterine contractions, blood clotting