Life Processes

The digestion process of food begins in the mouth by the enzymes present in the saliva. The functions of saliva include moistening food, and helping to create a food bolus, which can be swallowed easily. Salivary amylase is an enzyme in saliva that breaks down complex molecules such as starch into simpler molecules. Hence, digestion process begins from the mouth.

Diffusion is the movement of a substance from an area of higher concentration to an area of lower concentration. The air in alveoli contains higher concentration of oxygen. The alveoli are very close to capillaries, which has low oxygen concentration and high carbon dioxide as compared to alveolar air. Oxygen diffuses from the alveoli, into the blood in the capillaries. Similarly, carbon dioxide from the blood moves out of the capillaries into the alveoli.

Alveoli or air sacs are formed at the end of bronchioles. They provide a surface where the exchange of gases can take place. The walls of the alveoli contain an extensive network of blood vessels. The blood brings carbon dioxide from the rest of the body and releases it into the alveoli. The oxygen in the alveolar air is taken up by the blood in the alveolar blood vessels and is transported to all cells in the body.

Respiration involves breakdown of glucose. It produces carbon, water and releases energy in the form of ATP. It is a biochemical process and takes place inside the cell. The released energy is utilized for various metabolic activities.

The process of obtaining food to meet the energy demands of the body is known as nutrition. It is the most important step because without nutrition there will be no energy available for any other life processes. In simple words, it’s the fuel which enables the car to run.