Chapter 5(1).docx

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26 Apr 2012
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Chapter 5 Aging of The Skin and Musculoskeletal System
Skin
Basic Anatomy and Physiology
The skin is the front line of defence against harmful environmental influences and is an important part of our
immunologic and endocrine systems
Critical in temp maintenance and aids in homeostasis
Sensory nerves in the skin allow us to monitor the environment but also warn us of danger through pain
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
The skin is that largest and most visible organ of the body
Outermost layer of the skin is called the epidermis , and the second layer is the dermis
- Beneath the epidermis and dermis is a layer of subcutaneous fat; hair follicles, nail beds and nails, and sweat and
sebaceous glands are embedded in the various layers
- Epidermis consists mostly of keratinocytes- cells that protect the skin from outside harm and help it heal if it is
injured; found deep in the epidermis
- They slowly move to the surface of the epidermis as they age, a process that takes about 30 days
- If the skin is injured, the keratinocytes will reproduce and turn over at a more rapid rate, allowing the damage to
be repaired
Melanocytes (2% of cells in epidermis) produce melanin for keratinocytes and give colour to the skin
Exposure to the sun results in an increase in melanin production but these cells, which helps to protect the skin from
damage
Langerhans cells (1% of cells in epidermis) are an important part of the immune system as along w/ the mast cells
found in the dermal layer, they respond to toxic allergic stimuli
Dermis consists largely of collagen and elastin tissue, which provide strength and elasticity to the skin
- Cells in the dermis layer include mast cells that are responsible for the skin’s ability to respond to allergens
Under the epidermis and dermis is a layer of subcutaneous fat, which consists mostly of adipocytes (fat cells)
- Subcutaneous fat gives shape and form to the body and provides protection and insulation
Age-Related Changes
Wrinkles are partially due to a decrease in the subcutaneous fat layer and in the collagen and elastin found in the
dermal layer
Fig 5.1 (pg. 100)- Aging of the Skin
A decrease in the size and number of keratinocytes limits the skin’s ability to help the body produce vitamin D
A decrease in melanocytes affects the skin’s ability to protect itself from the sun and some of the remaining
melanocytes clump together, leaving blotchy unpigmented areas of the skin
The Langerhans cells decrease by as much as 40% reducing the ability of the skin to respond to allergic stimuli
There is a flattening of the junction b/w the epidermis and dermis, which decreases the adhesion b/w the two layers
an b/c of these changes, the skin is much more likely to bruise and tear if an injury occurs, and less likely to heal
- The decrease in blood vessel availability predisposes the older person to both hypothermia and hyperthermia
- 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 w/ age
- This thinning not only makes the skin more fragile, but the loss of insulation also increases the risk of an older
person’s developing hypothermia
- The loss of sweat glands in the skin affects thermal regulation, decreasing the ability to sweat, which is why elders
are more vulnerable to high temps than younger people
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- Loss of subcutaneous fat changes the appearance of the older person, as the protruding angles of the jaw and
elbows become more obvious
- Thus, changes in the integumentary system not only decrease the skin’s protective functions but also its
appearance
Disease- Related Processes
Xerosis
Characterized by red, scaly, and itchy skin on the legs, back and arms found in older people
Cause- unknown but it may be associated w/ the slowing of the keratinocyte turnover rate
Troublesome during the winter months when people tend to spend a lot of time indoors in a warm and dry
environment
Treatment- application of skin creams after bathing to slow the loss of water from the epidermis
Seborrheic Keratoses
Also known as old-age spots, are benign (non-malignant) lesions commonly found in older people
Usually brown to black in colour and have irregular edges; theses can occur in young adulthood but appear more
frequently w/ age
B/c they are slightly raised, people frequently remark that they appear to be stuck on top of the skin
Sun exposure is a risk factor but some people probably have a hereditary predisposition to develop them
Important that they be evaluated, and possibly removed, to differentiate them from malignant growths
Skin Cancer
Two most common forms are: basal-cell and squamous-cell carcinomas
Basal-cell carcinoma
- Appears as a small, fleshy bump or nodule that’s usually on the head or neck
- The greatest risk factor- exposure to the sun
- Although it is very slow growing and metastases are rare, the lesions are generally removed in an early stage of
growth to minimize further damage to the skin
- Common for people w/ this type to have a 2nd primary growth
Squamous-cell carcinoma
- Usually found on the face or the back of the hand
- They have the appearance of a red, scaly, and hard patch, although they may become ulcerated and crusty w/
time
- Exposure to the sun is a significant cant risk factor, but other risks include chronic irritations
- They can be unattractive, and many older people wish to have them removed
- Basal-cell and squamous-cell carcinomas are less likely to be found in younger people than are malignant
melanomas
Malignant melanomas are the most dangerous of the skin cancers as they are cancers of melanocytes and the cells
are normally found in the epidermis of the skin
- A melanoma is a red, white, blue, or black growth w/ an irregular border
- These growths are painless, although they may ulcerate and bleed in later stages of development
- Risk factors- very light skin and blond or red hair, a family history of melanoma, and a history of severe
intermittent sunburns, especially when young
- May metastasize to the lymph nodes and then to other parts of the body, like the liver or brain
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