Nutrition and Transport System in Animals, Biology tutorial


The food which animals eat is comprised of many substances that are usually grouped as carbohydrates, lipids, proteins, minerals, vitamins and water. Such food substances should be eaten, digested by different enzymes and absorbed before it can be helpful to the animal body. Animal nutrition comprises the study of such food substances, digestive enzymes, balanced diet, and absorption of digested food through the villi.

From the villi, the absorbed food will be taken to different parts of the body where they are needed. Different materials are transported in animals; these comprise digested food substances, oxygen, water, nutrients and excretory products like urea, water, carbon-dioxide and hormones. Such materials are transported as aqueous solution. In animals, the cytoplasm and water acts as the transport media. While in higher animals, blood is the means of transportation. Intercellular lymph and fluid are as well part of blood which is as well significant in transporting different materials. The blood consists of various components which flow in the vessels (that is, arteries, veins and capillaries) and are kept flowing through vascularised pumping organ termed as the heart.

Food substances: Classless and sources

The food materials consumed by an animal are proteins, carbohydrates, lipids (fats & oils), mineral salts, vitamins, water and roughage. Food is employed to:

a) To generate energy for the activities of body.

b) To build up body for appropriate growth and development.

c) To form special substances like hormones and enzymes.

The classes of food, sources and their functions are described below:


Carbohydrates are the polyhydroxy organic compounds build-up of carbon, hydrogen and oxygen in which the ratio of hydrogen and oxygen is around 2:1.

The major sources of carbohydrates are plants, example: starch, sugars, potatoes, cereals, millets, legumes, roots and other vegetables.


In accordance to the number of structural units, all carbohydrates are categorized into monosaccharide, oligosaccharides and polysaccharides.

a) Monosaccharide: It is a carbohydrates which can't further be hydrolyzed to simpler units having the fundamental formula Cn(H20)n, where n = 3 or more.

b) Oligosaccharides: Formed of 2 to 10 monosaccharide units covalently bonded to one other by glycosidic bonds. They are categorized according to the number of units of sugar into disaccharides, trisaccharides and so forth.

c) Polysaccharides: They are made of more than 10 molecules of monosaccharide. They might be either linear or branched polymers and might have hundreds or even thousands of units of monosaccharide.


They are comprised of amino acids, which are joined through peptide bonds. They have Carbon, Hydrogen, Oxygen and Nitrogen. Several amino acids have in addition to such sulphur, others encompass phosphorous. There are twenty five kinds of amino acids.

Amino acids make polypeptides which are proteins. Sources of proteins comprise eggs, meat, fish and beans.

Functions of proteins:

a) They are needed for growth and fixing of the body parts.

b) They are required to produce hormones and enzymes.

c) They build antibodies which prevents diseases.

d) They give energy.


These are the fats (which are solid at room temperature) and oils (that are fluidic or liquid). They are made up of fatty acids and glycerol. They as well include Carbon, Hydrogen and Oxygen. The main sources of lipids comprise butter, margarine, vegetable oils, beef fat and milk.

Functions of Lipids:

a) They provide a huge amount of energy.

b) They are stored beneath the skin and around organs like kidneys, intestines, heart and eyes

c) They protect many delicate organs of the body.

d) They assist to maintain the body temperature.

e) They form a significant structural material in the cell and nuclear membranes.

Mineral salts:

The minerals are inorganic substances which serve a diversity of functions like cofactors in enzyme-catalyzed reactions, in nerve conduction and muscle irritability, in the regulation of acid-base balance, and as structural elements in the body. Each and every mineral is requisite in particular amounts. Some important minerals comprise: phosphorus, calcium, sodium, potassium and iron.

Kinds of Minerals:

The minerals might be classified arbitrarily into two groups as:

Macro minerals: The minerals that are needed in amounts more than 100 mg per day.

Micro minerals: The minerals that are needed in amounts less than 100 mg per day.


Vitamins might be stated as organic compounds taking in small amounts in different natural foods and essential for the growth and maintenance of good health in human beings.

They can't be synthesized in the body however supplied by the diet to the human body. Plants generate all vitamins however animal (human) stores them. Some are generated in the body example:  Pro-vitamin carotene is transformed into Vitamin A in the body and Vitamin D is generated in the body in the presence of ultraviolet radiation.

Vitamins are categorized into two groups.

a) Fat-soluble vitamins: These vitamins are soluble in fats and fat solvents. But they are insoluble in water. Therefore these are used only when there is adequate fat in the body example: Vitamin A, D, E and K.

b) Water-soluble vitamins: These vitamins are (heterogeneous group) soluble in water and therefore they can't be stored in the body. Eleven kinds of vitamins are comprised in this class.


Around, 70% of the body is water chemical reaction occurs in water and it is as well means of transport. Substances like excretory products hormones, enzymes and digested food are transported in water and it play a significant role in regulating the body temperature. It is significant in digestion of food and excretion of the waste product.

Transport in Animals:

The major materials to be transported in animals comprise digested food, water and nutrients, oxygen, excretory products like carbon-dioxide, water, urea and hormones. These materials are transported in solution. In simple organisms such as paramecium and amoeba, water and cytoplasm both act as transport media. In animals, the blood is a medium of transportation. Intercellular fluid and lymph are the parts of blood.

Transportation is needed to:

a) It regulates body temperature by distributing the heat.

b) Maintain water balance in the animals.

c) Send food substances to areas of active cell division, development and growth.

d) Take hormones from ductless glands to the target organs.

Transport system is as well termed as circulatory system. Circulatory systems encompass the following features:

  • The blood (that is a circulating fluid).
  • The heart that is a 'pump' which send the fluid to all portions of the body.
  • Vessels or tubes which carry the fluid to various parts of the body.

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