WEEK 4 - INTEGUMENTARY

Question 1

Skin

Answer 1

• Largest and heaviest organ
• Replaced every 7 years

Question 2

What are the 3 major region of the skin?

Answer 2

1) Epidermis: above / upon dermis, outer
2) Dermis: middle
3) Hypodermis: below / under dermis, deepest

Question 3

What is epidermis?

Answer 3

• Stratified squamous epithelium
• 5 cell types and 4 cell layers (5 on palms and soles of foot)
• Replaced every 2-4 weeks
• Avascular (diffusion)

Question 4

What are stem cells in the epidermis?

Answer 4

• Undifferentiated.
• Generates keratinocytes

Question 5

What are keratinocytes in the epidermis?

Answer 5

• Main cell
• Produce fibrous protein KERATIN (double-helix), structure, flexibility, water resistance

Question 6

What are dendritic cells in the epidermis?

Answer 6

• Phagocytic, activate immune system (800 per mm2)
• Damaged by ultraviolet light (UV)

Question 7

What are tactile cells or disc in the epidermis?

Answer 7

Touch receptors in association with dermal sensory nerve endings

Question 8

What are melanocytes in the epidermis?

Answer 8

• Produce MELANIN (pigment)
• Long extensions (spider-like)
• Transfers melanin (exocytosis) to keratinocytes (endocytosis)
• Protects nucleus DNA from UV light (melanoma

Question 9

Stratum Basale

Answer 9

• Simple cuboidal epithelium
• Attached to dermis (via basement membrane)
• Stem cells undergo cell division (Mitosis)
• Generate new keratinocytes.
• Accelerated with injury and mechanical stress

Question 10

Stratum Spinosum

Answer 10

• Stratified epithelium
• Keratinocytes linked by desmosomes
• KERATIN fibres (cytoskeleton) linked to desmosomes

Question 11

Stratum Granulosum

Answer 11

• 3-5 layers of keratinocytes
• Organelles degenerate, cells flatten and die
• Accumulate granules that secrete a Protein that binds keratin filaments together
  Glycolipid that waterproofs against water loss and gain (and nutrient diffusion)

Question 12

Stratum Lucidum

Answer 12

• Few rows of DEAD keratinocytes superficial to stratum granulosum
• Where friction present. Fingertips, palms and soles

Question 13

Stratum Corneum

Answer 13

• Outermost. 5 to 50 layers of very keratinized DEAD cells
• Dead cells (shed 18 kg / year, dust)

Question 14

Thickness in the epidermis

Answer 14

• Thin epidermis covers most of the body (0.08 mm, plastic sandwich bag)
• Thicker epidermis on palms and soles (0.5 mm, paper towel)

Question 15

What is dermis?

Answer 15

• Holds body together
• Thicker than epidermis (0.2 to 6 mm)
• Strong, flexible connective tissue, mostly collagen (triple-helix)
• Vascular

Question 16

What are nursing actions for dermis?

Answer 16

Transdermal drugs:
- Absorbed through skin
- Lipid-soluble
Thermoregulation:
- Vasoconstriction (warming)
- Vasodilation (cooling)
- Sweating

Question 17

What is thermoregulation?

Answer 17

• Body’s thermostat in hypothalamus (brain)
• Hypothalamus receives input from:
  
  • Peripheral thermoreceptors (skin)
  • Central thermoreceptors (hypothalamus)
• Initiates, heat-loss or -promoting mechanisms

Question 18

What are the 2 layers of dermis?

Answer 18

1. Papillary layer
2. Reticular (net-like) layer

Question 19

What is the papillary layer?

Answer 19

• Loose connective tissue
  
  • Collagen, elastic fibers = Spaces for blood vessels, nerves
• Dermal papillae project into epidermis
  - Interlock = strong bond (blister)
• Increase surface area for grip and sites for
  
  • Tactile (Meissner) corpuscles (light pressure receptors).
  • Free nerve endings (temperature, itching etc.). Lips and genitals

Question 20

What is the reticular layer?

Answer 20

• Dense irregular connective tissue
  
  • 80% of skin thickness
  • Fibroblasts, Macrophages, Lamellated corpuscles (deep pressure receptors)
• Collagen and elastin fibers in parallel bundles
• Bundles orientated to resist multi-directional stresses (cleavage / tension lines)
• Cut / tear parallel to cleavage line = better healing, less scarring

Question 21

What is hypodermis (subcutaneous)?

Answer 21

• Loose connective tissue with adipocytes (50% of bodies fat)
• Collagen fibres interwoven with those of dermis
  
  • Binds skin to underlying muscle
• Shock absorber, insulator, energy source

Question 22

What are nursing actions related to hypodermis?

Answer 22

Subcutaneous (SC) injections
▪ Adipose. Vascular
▪ Constant turnover
▪ No pain receptors