The need for Food
There are 3 main types of food: carbohydrates, proteins and fats. * Carbohydrates and fats are both required for sources of energy. * Proteins are needed for growth and for repair or worn out tissues. Digestion is the process of breaking down large, insoluble food particles into smaller, soluble particles. This means they are small enough to pass through the wall of the small intestine and to dissolve into the blood. Different mammals eat different types of foods: * Herbivores eat only plant material; sheep and cattle are herbivores. * Carnivores eat only animal materials; dogs and tigers are carnivores. * Omnivores eat both plant and animal material ; humans are omnivores. Herbivore teeth function.
Incisors: These are not present on the top jaw of sheep. Lower incisors have sharp edges which cut grass against the horny pad on the top jaw. Canines: These are not present on the top jaw. The lower canines look and act like incisors. Premolars and molars: These have ridges which fit close together to grind grass.
Carnivore teeth function.
Incisors: These are small sharp teeth which pull and scrape meat from bones. Canines: These are long and pointed to kill prey. They are then used to grip and tear flesh. Premolars and molars: These have sharp edges which slice flesh.
Omnivore teeth function.
Incisors: These have sharp straight edges for cutting food.
Canines: These are pointed and used to grip tough food.
Premolars and molars: These are wide teeth which crush food between them.
Enzymes are chemicals which speed up biological reactions. Digestion involves several enzymes involved in the breakdown food: * Protease are enzymes used to break down protein.
* Amylase are enzymes used to break down carbohydrates.
* Lipase are enzymes used to break down fat.
The small intestine is long and its inner surface is covered with...