(Solved): In a second-degree burn, the epidermis and part of the dermis are damaged. This condition is more s ...

In a second-degree burn, the epidermis and part of the dermis are damaged. This condition is more serious than a first-degree burn. With proper care, skin regeneration may take place in three to four weeks, and scarring may be avoided. What are the effects on skin functions if the blood vessels, sweat glands, and oil glands are seriously damaged? A third-degree burn penetrates past the dermis; a first-degree burn affects only the epidermis. What additional skin functions are lost from a thirddegree burn as compared to a first-degree burn? Structure of the Epidermis The epidermis is composed of two major cell types. Keratinocytes are cells that produce the protein keratin, which is a strong gluelike material that also helps prevent water loss through our skin. Melanocytes are cells that produce melanin, a brown pigment that protects the nucleus of the skin cells from the ultraviolet rays of the sun. The epidermis consists of four to five layers, called strata, that vary in thickness. There are five strata in thick skin, which covers the palms, the fingertips, and the soles of the feet. Thin skin, which covers the remainder of the body, consists of only four strata, which are thinner than those found in thick skin. The five strata of epidermis, from the outermost stratum to the deepest, are as follows: 1. Stratum corneum: most superficial portion, 25-30 layers of cells in thick skin; considerably fewer in thin skin. - This is also called the cornified layer. - It consists of dead, dried-out keratinocytes. - No nucleus is evident. 2. Stratum lucidum: 3-5 layers of cells. - This is also called the translucent layer. - It consists of dying keratinocytes. - No nucleus is evident. - This layer, which is not found as a distinct layer in thin skin, is mainly found on palms and soles and provides additional protection for these heavy-traffic skin areas. 3. Stratum granulosum: 3-5 layera of cella. - This is also called the granular layer. - It consists of living keratinocytes, which are becoming flatter. - The nucleus is barely evident. 4. Stratum apinosum: 8-15 layers of cells. - This is alao called the apiny layer. - It conalata of living kerabinocytes, which are atill rounded or euboidal. - The nuelei are evident. - The cella are protected by melanin granules produced by melanceytes and concentrated in the layer above. 5. Stratum basales deepest portion, 1 layer of cells only. - This is also called the base layer. - It consists of living keratinocytes and melanocytes. - The nuclei are evident, and cell division in in progress. - A basement membrane attaches this layer to the dermis. ACTIVITY 2 Identifying the Layers of the Epidermis Materials for This Activity Skin models with epidermal layers Skin models of scalp, body skin, and palm or sole Magnifying glass or hand lens 1. Obtain a skin model with epidermal layers, and compare it to Figure 7.2. Analyze the cells that make up each stratum in the epidermis. For each stratum, compare these points: number of layers, shape of the cells, shape of the nucleus, and any special features of the stratum: stratum corneum stratum lucidum stratum granulosum stratum spinosum stratum basale