Skin, Hair, and Nails (Chapter 9) Flashcards
What are some functions of the skin? (7)
- Protects the body against microorganism invaders
- Excretes urea, sweat, and lactic acid
- Helps with injury healing via exaggerated cell replacement
- Prevents excessive water loss
- Helps regulate body temperature
- Produces vitamin D
- Helps with sensory perception
Where is the epidermis? What are its layers? What are it’s primary functions?
The epidermis is the outermost layer of the skin. It is composed of the stratum basale, stratum granulosum, stratum corneum. Thicker parts of the skin (soles of the feet and palms of the hands) contain an extra layer for protection known as the stratum lucidum. Mucus membranes lack the stratum corneum layer.
The epidermis primary functions are protection from invading organisms and restriction of water loss.
Stratum corneum
Stratum lucidum
Stratum granulosum
Stratum basale
Stratum corneum is the outer most layer of the epidermis and the skin in general. It’s composed of dead squamous cells packed full of keratin.
Stratum lucidum is an extra layer of protection found on the palms of the hands and soles of the feet.
Stratum granulosum is a middle layer
Stratum basale is the lowest layer and contains stem cells that allow for the regenerative properties of the skin.
How long does it take skin cells to progress through the layers of the epidermis?
28 days
What is the dermis? Where is it? What is its main functions? How does it differ from the epidermis?
The dermis is the middle layer of the skin. It is connective tissue and is highly vascular and contains nerves.
What is the hypodermis? What is it otherwise known as? What is it’s functions?
The hypodermis is also known as the subcutaneous layer. It is comprised of adipose tissue that provides insulation and shock absorption.
What are the appendages of the skin?
- Eccrine sweat glands
- Apocrine sweat glands
- Hair
- Nails
- Sebaceous glands
Eccrine Vs Apocrine sweat glands
Eccrine sweat glands open directly onto the surface of the majority of the skin. Secrete sweat which helps regulate body temperature.
Apocrine sweat glands are sweat glands that are only found in the armpits, nipples, areolae, and anogenital region. They secrete a clear, odorless sweat that is more oily than that of the eccrine sweat glands. It help lubricate movement
What is the function of sebum?
Sebum is a lipid rich substance secreted by the sebaceous glands and acts as a lubricant, moisturizer for the skin
Infant skin:
- What is vernix caseosa?
- What is lanugo?
- Why are infants at risk for hypothermia?
- Eccrine and Apocrine functioning
Vernix caseosa - a mixture of sebum and cornified epidermis that covers the babies body at birth.
Lanugo - fine, silky hair that covers the newborns body. More prominent at the shoulders and back
Infants are at increased risk for hypothermia due to their lack of adipose tissue and inability to shiver to create heat
Eccrine sweat glands begin functioning after 1 month
Apocrine glands do not start working until puberty, which explains the lack of smell from a sweaty child
What changes of the skin are seen with puberty?
- Apocrine glands begin secreting their oily, lipid filled substances which accounts for the new found body odor in this population.
- Hormonal changes, in particular androgen, cause an increase in sebum secretion via the sebaceous glands. This gives adolescents the oily appearance and predisposes them to acne.
- Coarse hair grows in the armpits and pubic region in both males and females. Males begin growing coarse hair on their face.
Nevi
Moles
What skin changes are seen in older adults?
- Dry skin - decrease in sebaceous and sweat gland activity. Epidermis thins which allows increased amounts of moisture to escape.
- Wrinkles - loss of collagen in the dermis and exposure to sun rays cause the epidermis to fold inward.
- Decreased subcutaneous tissue
- Gray hair - decreased melanocytes
- Facial hair in women, baldness
Carotenemia
Common in infants who are eating baby food or whole foods that are high in beta-carotene. Foods that are high in this are sweet potatoes, carrots, squash. This is a harmless condition that is self-limiting once the consumption of the offending food is eliminated.
What are the risk factors for melanoma? (8)
How does a nevi concerning for melanoma appear?
- Sun exposure or tanning beds
- Increased exposure to UV radiation (high altitude living)
- Personal history of melanoma
- Family history of melanoma
- Atypical nevi (mole)
- Large nevi
- Immunosuppression
- Skin type, relative inability to tan
Think of the ABCDEs. Asymmetrical, borders are irregular, not the same color throughout the nevi, larger in diameter than 6mm, and evolving.
What are the risk factors for basal and squamous cell carcinoma?
- Age - 50+ increases risk
- Exposure to sunlight or UV radiation
- Chronic and cumulative - squamous
- Intermittent exposure to sunlight - basal
-Petroleum products - Over exposure to radiation (x-rays)
- Large scars
Compare the color features of a normal nevi (mole) vs an atypical one
Normal - uniformly tan or brown. All moles on one individual seem to look alike
Atypical - mixture of tan, brown, black, red, or pink. The moles on the individual do not resemble each other
Compare the shape features of a normal nevi vs an atypical one
Normal - round or oval with a clearly defined border that separates the nevi from surrounding skin
Atypical - irregular borders that may include notches. May fade into surrounding skin.
Compare the surface features of a normal nevi vs an atypical one
Normal - Begins as flat, smooth spot on skin; becomes raised; smooth bump
Atypical - smooth, slightly scaly, or have a rough irregular appearance
Compare the size features of normal vs atypical nevi
Normal - Usually less than 6mm
Atypical - often larger than 6 mm
Compare the number feature of normal vs atypical nevi
Normal - 40 or less
Atypical - whole bunch
Compare the location features of normal vs atypical nevi
Normal - above the waist on sun exposed surfaces. Scalp, breast, and buttocks rarely have normal moles.
Atypical - occur anyway on the body. Most commonly appear on the back but can also be seen on the scalp, breast, and buttock
Purpura
Red, purple nonblanchable. Similar to bruising but smaller in size and has different causes.
Causes - platelet dysfunction, infections
Petechiae
Red-purple nonblanchable. Tiny dots.
Causes - platelet dysfunction, infection