Life Processes

The activities by which living organisms take in food, derive energy, remove waste from their body and respond to changes in the environment are called life processes.

Nutrition is a process by which living beings procure food or synthesize it and change it into simple absorbable form by a series of biochemical processes in the body. The photosynthesis provides food for all. It is the ultimate source of energy for all living organisms. It is essential for sustaining life.

Conversion of complex food material into smaller substances so that it can be absorbed by the cells is called digestion. The digestive system enables conversion of ingested food into its simpler form. The process of digestion requires a number of enzymes.

The distribution of food and oxygen to all parts of the body as well as the removal of body wastes is performed by a transport system within the body of all living organisms. Our body also secretes many hormones, which have to be carried to their target organs. The flow of fluid (blood or lymph) within the body for transport purposes is termed circulation and the organs for circulation constitute circulatory system.

Breathing is the physical process of respiratory gaseous exchange between the organism and the environment by diffusion. On the other hand, respiration involves oxidation of food and release of energy along with respiratory gaseous exchange.

In human beings, excretion is carried out by an organ system known as the urinary system or the excretory system. A nephron is the structural and functional unit of the kidney.