The Human Body

The body consists of several integrated systems. Making up these systems are organs and tissues that work together to carry out a specific body function, such as digestion. The different types of tissue that make up organs and other body parts are specialized. For example, the stomach has muscular walls for churning food and a mucosa lining that secretes gastric juices and protective mucus. The interconnected cells that make up these tissues each contain genes that programme cell activities.

Body with all systems

Each major body system has a particular function. In a healthy body, all the systems work efficiently and in synchrony so that we are able to live and reproduce.

Body system

Each of the body’s systems carries out an important function. The organs and tubes that make up the digestive system break down food into nutrients and process waste.


Organs have key roles in each body system. The stomach churns, stores, and partially digests food.


Each body tissue has a distinct function. Mucosa lines the stomach and has glands that secrete enzymes and acid for digestion and mucus for protection.


Collections of cells make up tissues. The cell is the smallest functional body unit capable of life processes.


The nucleus of each cell (except red blood cells, eggs, and sperm) contains 46 chromosomes, which are coiled molecules of DNA. Genes are tiny regions of DNA that dictate cell activity and inherited traits.

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.

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