Tissues

The human body is a complex machine made up of many parts.  Although diverse in structure and function, all body parts are constructed of four basic tissue types: 1) epithelia, 2) connective, 3) muscle, and 4) nervous tissues.  Consider these basic tissue types as the "lego building blocks" of the human body.  During development, these building blocks are put together in many different ways to build the anatomical elements of the body.

Anatomy always relates to physiology or more concisely, structure relates to function.  Remember this as you learn about these tissue types.  The differences between tissues and how they might appear under the microscope always relates to the particular functions they provide.

Let us begin our understanding of tissues by introducing ourselves to the four basic tissue types and the broad functions they provide:

Tissue Type

Broad Function

Epithelia Act as protective linings and coverings.  In some locales, absorption and secretion are important functions of these lining and covering cells.  As secretory cells, epithelia form most glandular structures of the body.
Connective Serve as connective and supportive tissues that bind and hold body structures together.  Specialized fluid connective tissue types serve as liquid media important in transport, exchange, and body defense.  
Muscle Tissues with the unique capability to contract or shorten.  This enables muscle types to be involved in functions of support and movement.
Nervous Nerve cells are specialized for conduction.  Nervous tissues therefore serve as the complex telecommunications network of the body.  These tissues act in a sensory capacity, to receive, disseminate, and store information collected from receptors. In a motor capacity, nervous tissues  provide response potential by controlling effectors such as muscles or glands.

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