Biology 1225 Chapter Notes - Chapter 19: Positive Feedback, Urinary System, Blood Sugar
23 Sep 2013
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Existing structures become modified over generations to better adapt their bearers to their environment: evolutionary remodeling of existing structures for new purposes often results in body plan that are less than optimal. Animal bodies are structurally and functionally organized on several levels: a tissue is a group of ***one or more specific cell types that assemble and interact to perform a common task or a specific function. Examples are the integumentary (skin) and the circulatory system. Tissues consist of ***one or more cell types- and often an extracellular matrix- that collectively perform a specific task or tasks. ***connective tissue are the body"s most abundant tissues. Neurons serve as communication lines in nervous tissue. They relay electrical signals along their plasma membrane and send and receive chemical signals. For example, the skin is an organ with a deep dermis layer covered by epidermis.
