BIO 109 - Exam 2 Questions and Answers 100% Pass

BIO 109 - Exam 2 Questions and Answers 100% Pass Keratin (define) - a fibrous protein Dermacidin (What is it) - known as proteolysis inducing factor (PIF), is a protein that is encoded by the DCD gene it is an anti-microbial peptide secreted by human eccrine sweat glands onto the skin as apart of the unnate host defense of the immune system Defensisns (Define) - are small cysteine-rich cationic protein found in both vertebrates and invertebrates. They are, and function as, host defense peptides. They are acute against bacteria, fungi, and many enveloped and nonenveloped viruses Epidermis - stratified squamous epithelium What are the functions of the skin? - resistance to trauma and infection, barrier function, vitamin D synthesis, sensation, thermoregulation, nonverbal communication. What are the layers of the epidermis? - stratum basale deepest epidermal layer, stratum spinosum, statym granulosum, stratum lucidum, statym corneum surface layer Statum granulosum contains? - cells contain dark-staining kerotohyalin granules Statum lucudum contains? - thin, pale layer found only in thick skin, keratinocytes packed with clear protein eledin 2© EMILY CHARLENE YEAR , ALL RIGHTS RESERVED Eledin - is clear intracellular protein which is present in the stratum lucidum of the skin. Statum corneym (surface layer) - several layers (up to 30) of dead, scaly, keratinized cells, Resists abrasion, penetration, water loss Five epidermal cell types? - stem cells undifferentiated cells that give rise to keratinocytes, melanocytes - synthesize pigment melanin that shields DNA from ultraviolet radiation, tactile cells - associated with dermal nerve fibers, dentritic cell - macrophages found in stratum spinosum, keratinocytes great majority of epidermal cells synthesize keratin Dermis - connective tissue layer beneath epidermis. Areolar and dense irregular connective tissue, well supplied with blood vessels, sweat glands, sebaceous glands, and nerve endings, houses hair follicles and nail roots Papillary layer - superficial zone of dermis. Thin zone of areolar connective tissue in and near the dermal papilla. Allows for mobility of leukocytes and other defense cells, rich in small blood vessels. Dermal papillae - are upward, finger-like extensions of dermis Recticular layer - deeper and thicker layer of dermis. Consists of dense irregular connective tissue Hypodermis - subcutaneous tissue, has more areolar and adipose than dermis has, pads body and binds skin to underlying tissues, common site of drug injection since it has many blood vessels. Subcutaneous fat - energy reservoir, thermal insulation, thicker in women Melanin - most significant factor in skin color. Produced by melonocytes, accumulates in keratinocytes. There are two forms eumelanin, pheomelanin 3© EMILY CHARLENE YEAR , ALL RIGHTS RESERVED Eumelanin - brownish black Pheomelanin - reddish yellow People of different skin colors have the ________? - same number of melanocytes Exposure to UV light stimulates? - melanin secretion and darkens skin. This color fades as melanin is degraded and old cells are exfoliated. What are other pigments that can influence skin color? - hemoglobin, carotene, bilirubin hemoglobin - pigment in red blood cells. Adds reddish to pinkish hue to skin. carotene - yellow pigment acquired from egg yolks and yellow/orange vegetables. Concentrates in stratum corneum and subcutaneous fat