Ex3 L10 - Integument

Question 1

What are the layers of the skin and what composes each layer?

Answer 1

epidermis - epithelial tissue
dermis - connective tissue, hair follicles and sweat glands
hypodermis - adipose tissue

Question 2

Describe the composition of the epidermis

Answer 2

• keratinized stratified squamous epithelium
• avascular
• keratinocytes that produce keratin
• epidermal stem cells in the stratum basale
• melanocytes that produce melanin

Question 3

What does keratin do?

Answer 3

toughens and waterproofs the skin
some telomerase activity

Question 4

Epidermal stem cells in the stratum basale have…

Answer 4

high telomerase activity

Question 5

What does melanin do?

Answer 5

protect from UV exposure, involved in skin color

Question 6

What do Langerhans cells do?

Answer 6

immune cells for the epidermis

Question 7

What do Merkel cells do?

Answer 7

touch receptors for the epidermis

Question 8

Describe the composition of the dermis

Answer 8

• connective tissue (collagen and elastin)
• rich vasculature (providing nutrients to epidermis)
• few cells, mostly ECM
• dermal-epidermal junction (DEJ)

Question 9

What is the function of the dermal-epidermal junction (DEJ)

Answer 9

• anchor epidermis to the dermis
• interface for nutrient exchange and signaling between layers

Question 10

What happens to the dermal-epidermal junction (DEJ) with age?

Answer 10

gets flatter, less surface area for nutrient exchange, contributes to changes with age

Question 11

What are characteristics of aging skin?

Answer 11

dullness
dryness
thinning
visible pores
increased redness
uneven pigmentation
dark spots
wrinkles
fine lines
tissue ptosis
loss of elasticity

Question 12

Wrinkles are a result of…

Answer 12

loss of collagen

Question 13

What is tissue ptosis?

Answer 13

sagging

Question 14

Changes in aging skin result from…

Answer 14

• modifications to epidermis
• degradation of dermal ECM
• altered dermal-epidermal junction (DEJ)

Question 15

What is intrinsic aging vs extrinsic aging (of the skin)?

Answer 15

intrinsic - naturally occuring
extrinsic - earlier deterioration from exposure to sunlight (photoaging) or pollution, lifestyle, etc.

Question 16

How does collagen/wrinkles change with age (due to intrinsic and extrinsic factors)?

Answer 16

young skin - high collagen, no lines or furrows

intrinsic aging only - low collagen, moderate lines and furrows

intrinsic and extrinsic - very low collagen, deep lines and furrows

Question 17

Dullness of aging skin is a result of…

Answer 17

slower cell turnover rate - as cell turnover rate slows, the cells that remain on the top layer of skin are older and older and therefore are more dull appearing

Question 18

Describe collagen production/function/change with age

Answer 18

produced: fibroblasts in the dermis
function: structural network for support, tensile strength and firmness
with age: collagenase increases (more degradation) and fibroblast synthesis decreases (less production)
- leads to wrinkles and fragile skin

Question 19

Describe elastin production/function/change with age

Answer 19

produced: fibroblasts in the dermis
function: stretch and resilience, keep skin pulled tight
with age: develop crosslinks that prevent them from functioning appropriately, become frayed/fragmented, and become thickened and disorganized
- age is also associated with pseudoelastin, which is an intermediate composition of elastic and collagen that is less effective

Question 20

What are age spots/sun spots?

Answer 20

dysregulated production and processing of melanin

Question 21

What things contribute to facial appearance and therefore facial aging?

Answer 21

skin, fat, muscle, and bone
- loss of subcutaneous fat and redeposition (under the chin)
- repeated muscle contractions for facial expression lead to wrinkles

Question 22

Intrinsic aging of the skin occurs at —– rate depending on ——

Answer 22

variable rates
depending on genetic factors and skin type

Question 23

What stimulates collagenase (other than age)?

Answer 23

cortisol

Question 24

Skin dryness with age is caused by…

Answer 24

reduced keratin and hyaluronic acid secretion by the fibroblasts of the dermis

Question 25

With age, skin becomes thinner as…

Answer 25

the dermis and epidermis individually become thinner

Question 26

What are the main extrinsic factors of skin aging?

Answer 26

• UV light exposure causes photoaging (increases telomerase activity, leading to neoplastic lesions aka skin cancer)
• repeated sun damage can penetrate tot eh dermal layer, especially in thinner aged skin

Question 27

Sun damage often does not cause problems for young people because…

Answer 27

epidermal cell turnover is fast

Question 28

What happens to sweat and oil glands with age?

Answer 28

• less sweat production (suderiferous glands)
• less oil production (sebaceous glands) leads to dry flaky skin and brittle hair

Question 29

What happens to nails with age?

Answer 29

• slowed nail growth
• increased calcium deposition causes yellowing
• disappearance of the lunula
• appearance of longitudinal ridges

Question 30

Describe the structure of hair

Answer 30

hair is made of dead, keratinized epithelial cells

the hair follicle surrounds the root, and has active telomerase

Question 31

What is the term for hair graying?

Answer 31

canities

Question 32

When is hair graying correlated or not correlated with age?

Answer 32

graying of axillary hair - correlated
graying of scalp/facial hair - not always correlated

Question 33

What are McSCs?

Answer 33

melanocyte stem cells
- give rise to melanocytes
- fail earlier than hair follicle stem cells
- need to move in the hair to function, so if they get stuck the hair becomes gray
- but failed McSCs are not the only cause of gray hair

Question 34

What are the phases of hair growth?

Answer 34

anagen - growth
catagen - transition
telogen - resting

Question 35

How do the phases of hair change with age?

Answer 35

in younger age the anagen phase is dominant, but with age the telogen phase lengthens and eventually contributes to hair loss