Tissue

Of multicelled organisms, a group of cells and intercellular substances that function together in one or more specialized tasks.

Tight Junctions

Cell junction where strands of fibrous proteins oriented in parallel with a tissue's free surface collectively block leaks between the adjoining cells.

Smooth Muscle Tissue

Nonstriated contractile tissue found in soft internal organs.

Skeletical Muscle Tissue

Striated contractile tissue that is the functional partner of bone.

Organ System

Organs interacting chemically, physically, or both in a common task.

Organ

Body structure with definite form and function that consists of more than one tissue.