Heterotrophs

Animals need constant energy to organize cells, tissues, organs.

Heterotrophic All Animals

Require organic molecules.

Harvest energy by breaking bonds in food.

• Lipids are for long-term energy storage.

• Carbs are for short-term energy release.

• Proteins are necessary for the building blocks.

Three Types of Heterotrophic Feeding

• Predation
• Suspension feeding
• Symbiosis

Energy

Essential

Can't make your own

Required to obtain via your diet

Amino Acids (8 of 20 are essential)

Organic Atoms

Fatty Acids

Nutrients

Elements

Food energy values measured by amount of heat food produces when burned in the presence of O2.

Animals burn food and give off CO₂ and H₂O.

Calorie

Heat to raise 1 gram of water by 1C.

1 kilocalorie = 1000 Calories

Basil Metabolic Rate BMR

The amount of O₂ consumed per gram of body mass per hour.

Thermoregulation

Endotherms Homeotherms

Warm-blooded

Regulates body temp.

Body temp stays the same.

Costs energy to maintain.

Ectotherms Poikilotherms

Cold-blooded

Can tolerate extreme temperatures.

Body temp 'conforms'.

Body temp matches external environment.

Behavior can still regulate body temp.

Endotherm basil metabolic rate is affected by external temperature.

• BMR is lowest at ideal environment temperatures.

Thermal-Neutral Zone

Low metabolic rate at ideal temperatures.

• Warm-blooded animals hibernate into cold-blooded animals - slows metabolism.

Mechanisms for Thermoregulation

Shivering Shivering Thermogenesis

Muscles contract and convert ATP to heat.

Non-Shivering Thermogenesis Brown Adipose Fat Tissue

Performs oxidative phosphorylation in the mitochondria that converts glucose into heat instead of ATP.

• Regulation of blood glucose levels contribute to thermoregulation.

Countercurrent Heat Exchange

Blood to and from appendages lie next to each other so heat going to the appendages can bleed into heat going into the body core so its not lost to the environment.

Study Guide

• What is the definition of a ‘heterotroph.’
• What is an “organic” molecule, or “organic” materials – what atoms are in those molecules?
• Why do heterotrophs require organic molecules – what are these used for.
• Entropy is a state of disorganization, chaos, disarray … for a thing to move toward entropy, that does not require energy, in face may cause energy loss: What examples to you see in animals that is the opposite of entropy – that requires energy? (hint: see page 680, where it discusses the 2nd law of thermodynamics, and view Figure 28.1 (B) …)
• Name three broad categories of food molecules.
• Where is the energy physically found in a food molecule?
• What is the difference between essential and non-essential nutrients? Why are 8 of the twenty amino acid building blocks for proteins, called “essential” in the human diet?
• What are the other essential nutrients that human heterotrophs get from the diet?
• What does it mean to ‘burn’ food, what are the three products created when burning energy?
• My popcorn has 250 calories. What does that really mean?
• How is metabolic rate measured, and why use that measure?
  • Oxygen consumed per gram of body weight per hour. For comparison amongst different-sized organisms.
• Why do we say that mice need more food than elephants?
  • Because the basil metabolic rate is higher in mice than in elephants.
• What animals regulate internal body temperature, and which ones are conformers?
  • Mammals regulate their body temperature; reptiles generally conform.
• What are terms now used for ‘endotherm’ and ‘ectotherm’ animals?
  • Endo- means inner, meaning body temp is regulated, and was replaced with homeotherm.
  • Ect- means outer, meaning body temp is not regulated, and was replaced with poikilotherm.
• What is a homeotherm? Which reptiles are homeotherms?
  • Homeotherms are able to regulate their internal body temp. Most reptiles are not homeotherms.
• What is a poikilotherm? How do they differ from homeotherms? How do they regulate temperature?
• Why are bees hard to categorize regarding body temp?
• What is the difference between brown fat and white fat in mammals?
• Why is hibernation special in homeotherms?
• What are two ways animals thermoregulate? Which one is ATP-dependent, and which one is ATP-independent?
• How does blood flow affect body temp – whey are arteries and veins close together and not far apart?
• What are some other temp control systems in animals?