Chapter 13 - Skin, Hair, And Nails Flashcards
1
Q
Skin
A
- Largest organ system in the body (20 square ft surface area)
- guard the body against environmental stresses (trauma, pathogens, dirt)
- adapts to other environmental influences (heat, cold)
- 2 layers (Epidermis and Dermis)
- the subcutaneous layer of adipose tissue under the dermis
2
Q
Epidermis
A
- top layer
- thin but tough
- avascular (nourished by blood vessels in the dermis below)
- cells are bound tightly together to form a rugged protective barrier
- stratified into several zones
- completely replaced every 4 weeks.
3
Q
Epidermis zones
A
stratum corneum stratum lucidum stratum granulosum stratum spinosum stratum basale
4
Q
Basal cell layer
A
- forms new skin
- keratin is the major tough ingredient
5
Q
Keratin
A
- the fibrous protein made by keratinocyte as the new cell gets closer to the surface of the skin,
6
Q
Melanin
A
- produced by melanocytes
- gives brown tones to the skin and hair
- people of all skin colors have the same number of melanocytes
- The amount produced varies with genetic, hormonal, and environmental influences.
7
Q
Horny cell layer
A
- the outer layer formed by flattened cells migrating upwards
- consists of dead keratinized cells that are interwoven and closely packed.
- cells are constantly being shed or desquamated and replace with new cells from below
- the epidermis is completely replaced every 4 weeks.
8
Q
Palms and soles
A
- thicker because of work and weight-bearing
9
Q
Skin Color
A
- Mainly from the brown pigment Melanin
- from the yellow-orange tones of Carotene
- from red-purple tones in the underlying Vascular bed
- All people have a skin of varying shades of brown, yellow, and red
it is modified by the thickness of the skin and the presence of edema.
10
Q
Demis
A
- the inner supportive layer
- consisting of mostly connective tissue or collagen
- tough, fibrous protein that allows the skin to resist tearing
- resilient elastic tissue that allows the skin to stretch with body movements
- nerves, sensory receptors, blood vessels, and lymphatics lie in the dermis
- Appendages (hair follicles, sebaceous glands, and sweat glands are embedded in the dermis
11
Q
Subcutaneous Layer
A
- is adipose tissue (lobules of fat cells)
- Stores fat for energy, provides insulation for temperature control, aids in protecting by its soft cushioning effect
- loose layer gives skin its increased mobility over structure underneath
12
Q
Hair
A
- threads of keratin
- the hair shaft is visible projecting part
- the hair root is below the surface embedded in a hair follicle
- bulb matrix - where new cells are produced
- growth is cyclical
- Active and Resting phases for hir follicle
- Hair follicle functions separately
- Arrector pili muscle contract and elevate the hair
- “goose flesh” - exposed to cold or in emotional states
- 2 types of hair (Vellus hair and terminal hair)
13
Q
Vellus hair
A
- fine, faint
- ## covers most of the body (except palms and shoes, dorsa or distal parts of the fingers, the umbilicus, the glans penis, and inside the labia)
14
Q
Terminal hair
A
- the darker, thicker hair
- grows on the scalp and eyebrows, and after puberty, on the axillae, pubic area, face, and chest in the male.
15
Q
Sebaceous Glands
A
- produce a protective lipid substance (sebum)
- Sebum is secreted through the hair follice
- lubricates the skin and hair and forms an emulsion with water that retards water loss from skin
- they are everywhere except on the palms and soles
- abundant in the scalp, forehead, face, and chin
