5 major functions of Integument are protection, temperature maintenance, synthesis and storage of nutrients, sensory reception, excretion and secretion
cell layers- strata
In order, from the basement membrane toward the free surface, are the stratum germinativum, three intermediate layers, (the stratum spinosum, the stratum granulosum, and the stratum lucidum) and the stratum corneum
Stratum Germinativum- the deepest epidermal layer, forms epidermal ridges (which extend to the dermis), contains melanocytes, cells whose cytoplasmic procsses extend between epithelial cells,and receptors that provide information. Epidermal cells must obtain nutrients delivered by dermal blood vessels.
Large stem cells- germinative cells
Intermediate Strata- cells are displaced from the basal layer
Keratin- extremely durable and water resistant
Stratum lucidum (clear layer) covers the stratum granulosum
Stratum corneum- most superficial layer of epidermis, consists of 15-30 layers
Cells are said to be keratinized