Chapter 5 Textbook Notes

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University of Toronto Scarborough
Health Studies
Ingrid L.Stefanovic

HEALTH AND AGING TEXTBOOK NOTES Chapter 5: Aging of the Skin and Musculoskeletal System The skin provides the covering for the body and is the first line of defense against bacteria, viruses, and other type of environmental damage. The bones, ligaments, tendons, and muscles that make up the musculoskeletal system provide shape and support for the body, make movement and adjustments in position possible, and protect the internal vital organs from external trauma. The skin and musculoskeletal system provides the most obvious signs of aging, with both normal changes and disease processes. Basic Anatomy and Physiology The skin, or integumentary, has several major functions. It is our front line of defense against harmful environmental influences and is an important part of our immunological and endocrine systems. The skin is critical in temperature maintenance and, in general, aids in homeostasis. Sensory nerves in the skin allow us to monitor the environment but also warn us of danger through pain. Finally, the integumentary system has important symbolic functions in that it is a key component of our appearance and is a critical source of cues that affect social interaction. JL3J419K08NL3L8430419K024894-;L4:8.O:0894,3L3L;L:,O8,J0. The skin is the largest visible organ of the body. The outermost layer of skin is called the epidermis, and the second layer is the dermis. Beneath the epidermis and dermis is a layer of subcutaneous fat. The epidermis consists mostly of keratinocytes (more than 90% of all epidermis cells) cells that protect the skin from the outside harm and help it heal if it is injured. Keratinocytes slowly move to the surface of the epidermis as they age, a process that takes about 30 days. If the skin is injured, they will reproduce and turn over at a more rapid rate, allowing the damage to be repaired. Melanocytes make up 2% of the cells in the epidermis; it gives colour to the skin. Although only about 1% of the cells in the epidermis, they are an important part of the immune system as they respond to toxic allergic stimuli. The dermis consists largely of collagen and elastin tissue, which provides strength and elasticity to the skin. 0OO8L39K0072L8O,07L3.O:02,88.0OO89K,9,707085438L-O01479K08NL38 ability to respond to allergens. Under the epidermis and the dermis is a layer of subcutaneous fat, which consists mostly of adipocytes (fat cells). Subcutaneous fat fives shape and form to the body and provides protection and insulation. Age Related Changes Changes in hair follicles result in the graying and loss of hair. Wrinkles are partially due to a decrease in the subcutaneous fat layer and in the collagen and elastin found in the dermal layer. The skin over the nose almost always stays smooth, whereas there is usually some wrinkling around the eyes and deepening of the lines around the mouth. 0.70,80L39K08L]0,33:2-0741N07,9L34.908OL2L989K08NL38,-LOL994K0O59K0-4574:.0;L9,2L3 The turnover rate of keratinocytes is reduc0,82:.K,8 OL2L9L3J9K08NL38,-LOL994K0,O The dermis is almost about 20% thinner in an older person, and fewer fibroblasts in the layer make the skin less elastic and not as strong as that of younger people. There is a flattening of the junction between the epidermis and dermis, which decreases the adhesion between two layers. Because of these changes, the skin is much more likely to bruise and tear if an injury occurs and less likely to heal. Decrease in number of sensory nerves also results in decreased sensitivity to touch, injury, and to heat and cold. Thinning of the subcutaneous fat layer also affects the ability of the body to maintain homeostasis with age. This thinning not only makes the skin less fragile, but the loss of insulation also increases the risk of an older 50784380;0O45L3JK549K072L, Xerosis One of the most common dermatological problems of the older person is xerosis, or dry skin. Xerosis is characterized by red, scaly, and itchy skin on the legs, back and arms. The cause of xerosis is not known, although it may be associated with the slowing of keratinocyte turnover rate.
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