BIO E121 Lecture Notes - Lecture 13: Keratin, Melanoma, Basal-Cell Carcinoma
Document Summary
Protects against bacteria/harmful particles, uv radiation, and physical/chemical stress. Prevents excessive water loss due to protein keratin in its outermost cell layer. Receives stimuli the skin has multiple layers. Dermis: thicker inner layer containing nerves, blood vessels, hair follicles, & glands. Hypodermis or subcutaneous layer: layer of loose connective tissue beneath dermis (not a part of the integument) The epidermis consists of several layers of epithelial cells. Outer surface made of dead skin cells. Deepest later consists of rapidly diving cells. Cells get nourishment from dermis, but flatten & die as they move towards the surface. The dermis consists of primarily of connective tissue. Has blood vessels, sensory structures/receptors, nerve endings glands, and hair follicles. Dense connective tissue with collagen & elastic fibers are found in the lower layer which allows the skin to stretch. Collagen fibers supports base tissue as people age, the fibers get stiffer meaning the collagen fibers are losing elasticity.
