BIOL355 Lecture Notes - Lecture 25: Loose Connective Tissue, Basement Membrane, Diffusion Barrier
21 Apr 2017
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Document Summary
Binds epidermis to underlying tissues, provides support to skin. Dense c. t. (collagen fibers, some elastin provides skin tone) Rich in nerve endings (pain, pressure and touch), sebaceous (oil glands), sweat glands + hair follicles. Regulates body temperature with blood vessels and sweat glands: hypodermis: deepest layer. Basal layer relies on nutrients, growth factors, oxygen passed through the basement membrane for growth. Regulates cell growth of the epidermal layer. Thinning of the layers (more fragile), decreased elasticity. Roughness and dryness, reduced skin pigment, paler skin. Decreased blood flow (fewer nutrients reach the epidermis) Decrease in basal layer cell division effects turnover rate of epithelial cells resulting in: decreased ability to repair the skin when damaged. Baby skin new cells reach top in 2 weeks. By the age of 40 new cells reach the top in 6 weeks. Disorganized cell arrangement (shape and size change) Loss of sebaceous glands in the dermis makes the skin, hair dry (less oil production)
