Utilization Of Food


Nutrition in Animals

The nutritional requirements of most animals are relatively complex compared with the simple requirements of plants. Animals require carbohydrates, lipids, nucleic acids, proteins, minerals, and vitamins.

Plants prepare their own food but animals depend on plants for their food.

Animals derive their nutrition either by eating plants directly; herbivores, or indirectly by eating animals which have consumed plants; carnivores. Some animals feed on both plants and animals; these animals are termed as omnivores.  All organisms require food for their survival and growth.

Food has different components, called nutrients, like carbohydrates, fats, minerals, proteins, and vitamins, which are required for maintenance of the body. These components are complex and cannot be used as it is for nutrition in animals; so they break down the food into simpler components by the process of digestion.

Ahaa!! Now that’s why your mother is very careful about you eating good food that keeps your digestion system healthy.

Differences between Nutrition in simple organism like amoeba and human beings:

  1. Digestion in Amoeba: Mouth and digestive system are absent in mmoeba. It ingests food through pseudopodia. Humans have a mouth and a complex digestive system. A human ingests food through the mouth.
  2. In mmoeba, digestive juices are secreted in the food vacuole. In humans, digestive juices are secreted in the stomach and small intestine.
  3. In amoeba, all the food components are digested in the food vacuole, whereas in humans, digestion of carbohydrates, proteins starts in separate regions.

Balanced Diet for Us

Nutrients are the substances in food that maintain the body and make it work.  As discussed before most of what one eats is carbohydrates, proteins, and fats.  Nutrients needed in smaller amounts, but still vital, are vitamins and minerals.  Also on the list are fiber and water.  Our diet should comprise a mix of foods that supply all necessary nutrients in the right amounts. Such a diet is called a balanced diet.


Digestion in humans happens through a stepwise process which is common to all organisms. The order in which it occurs in human beings is described below:

  1. Ingestion: It is the process of us ingesting the food by actually eating it. In the mouth, the food material is subject to cutting, tearing, chewing, and a little bit of pre-digestion using the salivary juice and finally swallowing.
  2. Digestion: It is the breakdown of the ingested food into microscopic and finally molecular fragments. Most of the digestion happens in the stomach and a small part of it also occurs in the small intestine.
  3. Absorption: This is a critical stage where nutrients are taken up from digestive organs and distributed to the body’s tissues. This process is where food ingested is converted to actual energy to be used by our bodies.
  4. Excretion: This is the final process where waste material is excreted from our bodies.

Digestive system

Our digestive system is uniquely designed to turn the food you eat into nutrients, which the body uses for energy, growth and cell repair. Here's how it works.

We can remember the parts of digestive system by remembering  the acronym:

LARGE S&S – {Large Intestine, Anus, Rectum , Gall Bladder , Esophagus} {Stomach, Small Intestine)


The mouth is the beginning of the digestive tract. In fact, digestion starts here as soon as you take the first bite of a meal. Chewing breaks the food into pieces that are more easily digested, while saliva mixes with food to begin the process of breaking it down into a form your body can absorb and use.


Throat is also called the pharynx. Food travels from mouth to throat, further it travels to the esophagus or the swallowing tube.


The esophagus is a muscular tube extending from the pharynx to the stomach. By means of a series of contractions, the esophagus delivers food to the stomach.


The stomach is a sac-like organ with strong muscular walls. In addition to holding the food, it's also a mixer and grinder. The stomach secretes acid and powerful enzymes that continue the process of breaking down the food. When it leaves the stomach, food is the consistency of a liquid or paste. From there the food moves to the small intestine.

Small Intestine

The small intestine is a long tube loosely coiled in the abdomen (spread out, it would be more than 20 feet long). The small intestine continues the process of breaking down food by using enzymes released by the pancreas and bile from the liver. Bile is a compound that aids in the digestion of fat and eliminates waste products from the blood.

Digestion in Ruminants

Ruminants are plant-eating animals like sheep, elk, cows, that have four stomachs for their digestion instead of one like how humans have. They obtain nutrition from plant material by adopting a certain process called rumination. Through rumination, they ferment the food and regurgitate and chew their food before the principal digestion.

For humans, the food goes from the mouth to the food pipe to the stomach to intestines and onward but it’s just a little bit different for the ruminants. That’s why when you see cows on the roads sometimes we think that they are always chewing away to glory. And most often than not, they don’t even have food near them.

Types of teeth:

There are four main types of teeth, and each one has a different shape and function.

Incisors - Your incisors are eight teeth in the front center of your mouth (four on both bottom and top).

Canines - Your canines are the next teeth that develop in your mouth.

Premolars - Premolars are used for tearing and crushing food.

Molars - Your molars are your largest teeth.

Many people take their teeth for granted. Your teeth help you chew food, which makes it easier to digest.