BIO 112 Notes: Animal Nutrition

Categories of nutrition that animals fall under

• Food is ==taken in, taken apart, and taken up== in the process of animal nutrition.

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In general, animals fall into three categories.

1. ==Herbivores==, which eat mainly plants and algae.
2. ==Carnivores==, which eat other animals.
3. And ==omnivores==, which regularly consume animals as well as plants or algae.

Overall, most animals are also ==opportunistic== feeders.

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Essential nutrients

Essential nutrients are ==required by cells== and ==must be obtained from dietary sources==.

There are four classes of essential nutrients:

1. ==essential amino acids==
2. ==essential fatty acids==
3. ==vitamins==
4. ==minerals==

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An example of an essential amino acid is ==methionine==. An essential fatty acid is ==linoleic acid== (LA), which is an omega-6 fatty acid. An example of a vitamin is ==Vitamin C,== which is found in fruits. An example of a mineral is ==calcium==, which is found in bones.

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Stages of food processing

Food processing can be divided into four distinct stages

1. ==Ingestion==
2. ==Digestion==
3. ==Absorption==
4. ==Elimination==

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Ingestion is the act of ==eating or feeding==. Digestion is the process of ==breaking down food== into molecules small enough to absorb. Absorption is the ==uptake of nutrients== by body cells. Elimination is the ==passage of undigested material out of the digestive system.==

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Food processing: ingestion, digestion, absorption, elimination

Difference between intracellular and extracellular digestion

In ==intracellular== digestion, food particles are engulfed by ==phagocytosis==.

==Extracellular== digestion is the ==breakdown of food particles outside of cells.==

• Intracellular digestion takes place in ==unicellular== organisms such as protozoans while extracellular digestion occurs in ==animals and fungi.==

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Types of digestive compartments found in animals using extracellular digestion

Animals with ==simple== body plans have a ==gastrovascular cavity== that functions in both digestion and distribution of nutrients.

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More ==complex== animals have a complete digestive tract or an ==alimentary canal== with a mouth and an anus. The alimentary canal can have specialized regions that carry out digestion and absorption in a stepwise fashion.

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==Simple body plan: gastrovascular cavity. Complex body plan: alimentary canal (specialized)==

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Evolutionary adaptations of the vertebrate digestive system

• ==Dentition==, an animal’s assortment of teeth, is one example of structural variation reflecting diet. The success of mammals is due in part to their dentition, which is specialized for different diets.
• Vertebrates also have ==stomach and intestinal adaptations==. Herbivores and omnivores generally have longer alimentary canals than carnivores, reflecting the longer time needed to digest vegetation.
• ==Mutualistic adaptations== in humans have also been formed to correlate with diet. Some intestinal bacteria produce vitamins; others regulate the development of intestinal epithelium and the function of the innate immune system.

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Many vertebrates also host mutualistic bacteria and protists in the ==fermentation chambers== of their alimentary canals. These microorganisms can ==digest cellulose== to simple sugars and other compounds.

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Dentition: an animal’s assortment of teeth

Herbivores and omnivores: have longer alimentary canals

Intestinal bacteria: produce vitamins

Mutualistic bacteria: digest cellulose in some animals