AP BIOLOGY

Detailed explanation-1: -The epidermis, the outermost layer of the skin, is subdivided into the stratum corneum, stratum lucidum, stratum granulosum, and stratum basale. The stratum corneum contains corneocytes, which are terminally differentiated keratinocytes.

Detailed explanation-2: -Vitamins, pigment, touch. Our skin is a vital organ with many functions. Perhaps most importantly, it protects us against viruses and bacteria.

Detailed explanation-3: -The skin acts as an external barrier to bacteria, preventing infection and protecting the internal organs. The skin also protects the body from ultraviolet radiation using the pigment barrier formed from melanocyte cells found in the top of the papillary dermis and a protein layer found in the epidermis.

Detailed explanation-4: -Skin is a barrier that serves as one of the body’s first lines of defense against harmful microbes. Specialized immune cells within skin tissue help to fight invading organisms. Yet the skin hosts diverse communities of beneficial bacteria, collectively known as the skin microbiota.

Detailed explanation-5: -Skin, tears and mucus form the first line of defence of the body against microbial invasion. These are called so because they are the first barriers which the pathogens encounter when they enter a body during an infection.