Digestive Systems

Physical Digestion:

The mechanical break down of food into smaller pieces to improve efficiency of chemical digestion. Occurs before chemical digestion and increases surface area to volume ratio. Teeth responsible for the cutting, tearing, chewing and/or grinding of the food.

Chemical Digestion:

The action of acids and enzymes in the break down of complex compounds into simple compounds used in the metabolism of an organism. Digestive enzymes are manufactured in the salivary glands, pancreas and gut wall.

There are three main types of digestive enzymes:

• Amylases - breakdown carbohydrates

• Proteases - breakdown proteins

• Lipases - breakdown lipids

Digestive Systems in Mammals

Carnivores:

• Strong jaws and sharp teeth designed for tearing meat

• Digestion is quicker and more efficient as there is a higher proportion of extractable energy in the diet

• Short and simple digestive system

• Enzymes responsible for the breakdown of food

• Caecum is absent

Herbivores:

• Large amount of physical digestion to breakdown cell walls and increase surface area to volume ratio

• Flat teeth and specialised enzymes for breakdown of cellulose

• Longer digestive system to increase surface area for absorption of nutrients

• Larger reliance on symbiotic gut bacteria

• In foregut fermenters (ruminants) fermentation occurs before stomach

• In hindgut fermenters (non-ruminants) fermentation occurs in the caecum and first section of the large intestine.

Omnivores: