Human Anatomy & Physiology Summer Work

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Levels of Structural Organization

The chemical level is the lowest and most simple level of the structural hierarchy. Atoms combine to form molecules, which form various organelles of which cells are comprised.

At the cellular level, cells are the smallest units of life. All cells have some common features, but can vary in shape, size and function.

The tissue level is where cells of similar type that do the same thing. The four types of tissues are epithelium, muscle, connective, and nervous.

At the organ level, two or more, usually four, types of tissue work together in order to perform more complex functions.

The organ system level is comprised of multiple organs working together to make specific things happen. The various organ systems include cardiovascular, integumentary, skeletal, muscular, nervous, endocrine, respiratory, digestive, lymphatic, urinary, and reproductive.

At the organismal level, all of the previous body systems work together to maintain life.

Each structural level is comprised of the level prior to it and performs a more complex function than the last.

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