Basic Principles of Animal Form and Function

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Heat production is increased by muscle activity such as moving or shivering.

Some ectotherms can also shiver to increase body temperature.

Slide 50

RESULTS

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O2 consumption (mL O2/hr) per kg

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A Burmese python generates heat while incubating eggs.

Slide 51

Acclimatization in Thermoregulation

Birds and mammals can vary their insulation to acclimatize to seasonal temperature changes.

When temperatures are subzero, some ectotherms produce “antifreeze” compounds to prevent ice formation in their cells.

Thermoregulation is controlled by a region of the brain called the hypothalamus. The hypothalamus triggers heat loss or heat generating mechanisms.

Fever is the result of a change to the set point for a biological thermostat.

Slide 52

Hypothalamus: thermoregulation

Sweat glands secrete sweat, which evaporates, cooling the body.

Thermostat in hypothalamus activates cooling mechanisms.

Blood vessels in skin dilate: capillaries fill; heat radiates from skin.

Increased body temperature

Decreased body temperature

Thermostat in hypothalamus activates warming mechanisms.

Blood vessels in skin constrict, reducing heat loss.

Skeletal muscles contract; shivering generates heat.

Body temperature increases; thermostat shuts off warming mechanisms.

Homeostasis: Internal temperature of 36–38°C

Body temperature decreases; thermostat shuts off cooling mechanisms.

Slide 53

Energy requirements are related to animal size, activity, and environment

Bioenergetics is the overall flow and transformation of energy in an animal.

It determines how much food an animal needs and relates to an animal’s size, activity, and environment.

Slide 54

Energy Allocation and Use

Animals harvest chemical energy from food.

Energy-containing molecules from food are usually used to make ATP, which powers cellular work.

After the needs of staying alive are met, remaining food molecules can be used in biosynthesis.

Biosynthesis includes body growth and repair, synthesis of storage material such as fat, and production of gametes.

Slide 55

Bioenergetics of an animal

Organic molecules

in food

External

environment

Animal

body

Digestion and

absorption

Nutrient molecules