Animal nutrition 1

ANIMAL NUTRITION 

39.2. Nutrition and Diet

Energy balance is a form of homeostasis 

• The energy balance of an organism is often maintained at a constant level. 

  • An animal in energy balance takes in = calories from food that it uses over time to meet its metabolic needs. 

  • Energy balance can be thought of as a form of homeostasis. 

  • Factors determine energy balance: sources of energy, energy intake, energy use 

1. Relate oxygen consumption to metabolic rate. Compare how animal cells meet short term and long term ATP needs. 

Oxygen consumption and metabolism 

• If you want to increase the ATP production, oxygen consumption must be increased. 

  • More frequent, deeper inhales for humans. 

• If there is insufficient oxygen, ATP production can be done via faster, less efficient process- fermentation. 

Glucose is not the only thing that can be broken down to release energy

• Lipids in food can be broken down into pieces that can then enter glycolysis or the citric acid cycle (e.g. triacyglycerol) 

• Proteins can also be broken down and, via chemical reactions be used as a source of energy/ ATP production. 

Metabolic rate

• Overall rate of energy use. 

• Varies depending on how much ATP is needed. 

• How much ATP is needed depends on what the organism is doing

  • For sustained, constant activity, the cell can usually meet its atp needs via oxidative phosphorylation - aerobic respiration in the mitochondria. 

  • For brief but FAST activity, some cells will switch to using anaerobic ATP production methods. 

B) Contrast metabolic activity in endotherms vs endotherms. 

Endotherms and ectotherms 

• Metabolisms produces some heat 

• Some animals rely mostly on this heat generated by metabolism - ENDOTHERMS 

  • Maintain a relatively constant body temp. 

  • Can live in a variety of environments. 

• Some animals rely more on the heat of the environment - ECTOTHERMS 

  • Need to move to different areas where heat is available. 

  • Tend to have much lower metabolic rates. 

Why does body temperature matter? 

• protein integrity 

• membrane fluidity 

• body temperature is important —> body systems coordinate to regulate it: homeostasis. 

Energy storage

• if fuel molecules like carbohydrates and lipids are consumed beyond the animal’s current needs —> stored for future use. 

  • E.g: glucose can be polymerized in the liver to form glycogen. Glycogen then broken down when metabolic activity increases and there is a need for glucose. 

C) Define essential nutrient and dietary minerals 

• A nutrient is essential if it is required for life but cannot be synthesized by the organism. 

  • Essential nutrient: vitamins, some amino acids (9 for humans), fatty acids. 

    • vitamins: organic molecules that are required in very small amounts in the diet. 

      • Fat soluble 

      • water soluble 

      • storage abilities vary between fat and water soluble vitamins 

  • Human: 13 essential vitamins. 

  • vitamin deficiency can have serious consequences

  • vitamin C: necessary for building connective tissue. Humans who do not ingest enough of this vitamin develop scurvy. Green vegetables and fruit supply vitamin C. 

  • vitamins B1, B2, B12: can cause nervous system disorders and various forms of anemia 

  • vitamin D: essential for absorption of Ca in the diet, skeletal growth and health. Adequate exposure to UV solar radiation, skin cells synthesize enough vitamin D to sustain a growing body. 

    • People inhibiting northern regions of the world do not get a lot of sunlight —> they produce low levels of vitamin D and require more of it in their diet. 

    • Lack of vitamin D can lead to rickets.

  • Dietary minerals: inorganic elements needed for life (other than C, H, O, N) 

  • Including: Na, Cl, Mg, P, K, Ca, Fe, Zn

    • Mg and Zn: associated with enzymes as cofactors. 

    • Ca: required for neuron function, muscle function, building skeletons. 

    • Fe: hemoglobin binds O and transports it in the blood. 

    • Na and K: nerve function, supporting the Na-K pumps characteristic of all cells.

      •  Humans obtain the minerals Na and Cl through table salt

      • Animals seek exposed rock that they lick to obtain minerals and salts. 

D) Describe examples of specialized structures for feeding found in mammals. 

• suspension filter feeding - aquatic organisms only 

• suction feeding  - fish, mosquitoes, little mammal babies.

HUMANS 

• Among vertebrates, mammals evolved a specialized jaw joint, the temporomandibular joint and great diversity forms of teeth. 

  • Teeth: cutting and crushing surfaces, enable mammals to break down a variety of foods mechanically before swallowing those foods. 

    • Incisors: teeth in the front of the mouth, specialized for biting. 

    • Canines: dogs, cats, and other carnivores, are specialized for piercing the body of their prey. 

    • Premolars and molars: teeth in the back of the mouth that are well adapted for crushing and shredding tougher foods. 

      • Herbivorous animals have specialized premolars and molars with prominent surface ridges  —> these teeth can shred tough plant material before it is swallowed and digested. 

      • Mammalian herbivores use their front incisors and canines to bite grasses and leaves —> move the food to the back of the mouth (where it is ground and crushed between their ridged premolars and molars.) 

      • Arthropods (insects, crustaceans, lack jaws, teeth) are able to capture, manipulate, and break down food. 

        • Some of them use paired mouthparts called mandibles (xương hàm dưới - replaced that of incisors and canine teeth in the mammals.) In contrast to the teeth of vertebrates, mandibles are located outside and in front of the mouth. 

          • Purpose: used to capture and physically break down food before it enters the mouth and then the gut. 

        • Arthropod mandibles have evolved a great diversity of structures and are well adapted to different sources of food