Level of Structural Organization of the Body

The human body has different structural levels of organization, starting with atoms molecules and compounds and increasing in size and complexity to cells, tissues, organs and the systems that make up the complete organism.

Atoms molecules and compounds

At its simplest level, the body is composed of atoms. The most common elements in living organism are carbon, hydrogen, oxygen, nitrogen phosphorus and sulfur.

 

Atoms → Molecule → Compounds.

 

Cell

The smallest independent units of life. All life depends on the many chemical activities of cells. Some of the basic functions of cell are: growth, metabolism, irritability and reproduction.

 

Tissue

Tissue is made up of many similar cells that perform a specific function. The various tissues of the body are divided in to four groups. These are epithelial, connective, and nervous and muscle tissue.

 

Epithelial tissue

Found in the outer layer of skin, lining of organs, blood and lymph vessels and body cavities. Connective tissue: - Connects and supports most part of the body. They constitute most part of skin, bone and tendons.

Muscle tissue

Produces movement through its ability to contract. This constitutes skeletal, smooth and cardiac muscles.

Nerve tissue

Found in the brain, spinal cord and nerves. It responds to various types of stimuli and transmits nerve impulses.

Organ

Is an integrated collection of two or more kinds of tissue that works together to perform specific function. For example: Stomach is made of all type of tissues

System

Is a group of organs that work together to perform major function? For example: Respiratory system contains several organs.

Organism Level

The various organs of the body form the entire organism.