BIOSC 1200 Study Guide - Midterm Guide: Stratum Basale, Stratum Corneum, Enamel Organ
23 Nov 2017
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Integument study guide: compare and contrast epidermis and dermis with respect to their embryonic origin and tissue structure. Epidermis is a component of skin that originates from the somatic ectoderm. It"s stratified epithelium and has a basal layer called stratum germinativum. Dermis is a component of skin that originates from the dermatome. It"s a fibrous connective tissue, containing many components typical of connective tissue: define and contrast: epidermis, epithelium, ectoderm. The stratum corneum is flattened dead keratinized cells embedded in an extracellular matrix of keratin. It"s of adaptive value for life on land b/c it prevents drying out (desiccation) of organs in terrestrial environments. It"s thin in amphibians b/c they breathe through skin; thick in amniotes b/c they live in terrestrial environment: describe the process of keratinization, as discussed in lecture. Keratinization: process where free surface cells constantly wear away and are replaced by cells from stratum germinativum. Before they die, vacuoles release keratin via exocytosis & cells flatten.
