Chp 40: Basic Principles of Animal Form and Function
•
Physical requirements constrain what natural selection can invent, including size
and shape of animals
•
Convergent Evolution- ex: speedy swimmers have similar shapes; because of
natural selection
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Two layered sacs (hydra) and flat shapes- put large surface area in contact with
environment
•
Tissues- groups of cells with a common structure and function. Different types
have different structures that are suited to their function
Epithelial Tissue
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Sheets of tightly packed cells
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Covers the outside of the body and lines organs and cavities within the body
•
Cells of epithelium are closely joined with little material between them. Often
riveted together by tight junctions
o
Tight packing enables it to function as a barrier against mechanical injury,
microbes, and fluid loss
o
Glandular epithelia- absorb or secrete chemical solutions. The glandular
epithelia that line the lumen of the digestive and respiratory tracts form a
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- Spring '08
- Campbell
- Biology, Evolution, Epithelial cells, tightly packed cells, epithelium- single layer, Basement membrane- cells
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