Name the tissue types composing the epidermis and dermis; major layers of each & describe functions of each layer
- Epidermis: kerantized stratified squamous epithelium. Layers:
- * Stratum basale, deepest epidermal layer, is the site of mitosis
- * Stratum spinosum, serval cll layers thick and contains keratincytes, melanin granules, and the highest concentration of epidermal dendritic cells.
- * Stratum granulosum, contains keratinocytes that are undergoing physical changes, turning them into the tough outer cells of the epidermis
- * Stratum lucidum, found only in thick skin and is composed of dead keratinocytes
- * Stratum corneum, outermost protective layer of the epidermis composed of a thick layer of dead keratinocytes
Dermis: has 2 layers: the thin, superficil papillary layer , highly vascularized areolar connective tissue containing a woven mat of collegen and elastin fibers. And the reticular layer, 80% of the thickness of dermis, dense irregular connective tissue.
Compare and contrast eccrine and apocrine glands
- They are both sweat glands.
- Eccrine: sweat glands produce true sweat, the most numerous of sweat glands, particularly abundant on the palms of hands, soles of feet, and forehead.
- Apocrine: sweat glands confined to axillary and anogential areas, produce true sweat witht he addition of fatty substances and proteins.
How does the skin accomplish five different functions
- 1) protection: secretions, melanin, chemical, physical, and mechanically barriers
- 2) Body temp. regulation, using sweat glands of skin to cool body
- 3) Cutaneous sensation, made possible by placement of cutaneous sensory receptors
- 4) Skin, protect metabolic functions of making Vit D when exposed to sunlight
- 5) Skin acts as a blood reservior, holding up to 5% of body's blood supply
- 6) Limited amounts of nitrogenous wastes are excreted through the skin