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

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 1600-2000 Calories/day Examples of endotherms: Birds & Mammals

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.

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.

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