BIO 1300 Lecture Notes - Lecture 7: Desmosome, Desiccation, Collagen
11 Feb 2017
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Document Summary
The line that gave rise to mammals. Were not able to live permanently on dry land. Gametes were susceptible to dessication (drying out) Skin is permeable, thus it was challenging for them not to dry out like their gametes. Reptiles evolved and solved the problems that amphibians had, including impermeable skin, egg with shell, eternal genitals to insert gametes in female directly, keratin makes up the scales. Keratin makes the skin and hair of both animals, as well as beaks and nails. The epidermis and dermis are the skin, the hypodermis isn"t as its also called. Erect hairs help keep air trapped between our hair and skin, it was more effective when we had full bodies of hair. Sweat gland used for cooling as it evaporates. Production of cells that will exist in the outermost layer. They are actually dead cells about 20-30 layers thick. Because they are dead and empty they absorb water easily, thus they become wrinkly.
