1. Homeostasis is defined as the body's internal environment being within a certain physiological state. There are seven major factors that need to be homeostaticly maintained. They are: concentration of oxygen and carbon dioxide, nutrition of cells, concentration of wastes, concentration of sugars, salts, and other electrolytes, temperature, and volume and pressure. An example of the body maintaining homeostasis is blood pressure. When the hear begins to pump faster, it sends more blood into the arteries which increases blood pressure. Pressure sensitive nerve cells detect the higher pressure and respond by sending the brain nerve impulses. The brain then sends impulses to the heart and certain blood vessels to slow the heart rate. If any of the seven factors and not correctly maintained, illness or death may occur.
2. Tissues are groups of cells and i
3. Both shape and arrangement of layers of cells can classify epithelial tissues. There are four basic shapes of connective tissue cells. Squamous cells are flat and connect to each other like tiles. Cuboidal cells are thicker and can be described as cubed or hexagonal shape. Columnar cells are cylindrical and tall. Transitional cells range in shape. They can change shape du to stretching or movement of body parts. Epithelial tissue can also be classified by layers of cells. A single epithelium is just a single layer of cells, which is found in areas where passive and active movement of molecules is needed. Stratified epithelium consists of two or more layers and is used for protection of underlying tissues. Pseudostratified columnar epithelium tissue looks multilayered, but is actually only a single layer. Not all cells reach the surface and tho
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