Unit 2 / Chapter 5 / Integumentary System

Question 1

Describe the basic structure of the skin:

Answer 1

Epidermis: 5 layers of keratinocytes

keratin: hard protein linked by desmosomes

Question 2

What are the 5 basic functions of the skin?

Answer 2

Protection
Sensation
Thermoregulation
Excretion
Vitamin D Synthesis

Question 3

How is the skin used for protection?

Answer 3

– mechanical trauma; pathogens (skin pH, antimicrobial substances, immune cells), environment (UV)

Question 4

How is the skin used for sensation?

Answer 4

– sensors to nervous system

Question 5

How is the skin used for thermoregulation?

Answer 5

– feedback loops for increasing or decreasing temperature (blood vessels constrict or dilate; sweat
glands for heat)

Question 6

How is the skin used for excretion?

Answer 6

– lactic acid, urea, metals

Question 7

How is the skin used for Vitamin D?

Answer 7

Vitamin D synthesis (Vitamin D precursor in skin + UV light – Cholecalciferol (D3)

Question 8

Describe how the cells of the epidermis are arranged into layers:

Answer 8

• stratum corneum
• stratum lucidum
• stratum granulosum
• stratum spinosum
• stratum basale

Question 9

Describe the cells of the stratum corneum:

Answer 9

• top/outermost layer, 20-30 layers of dead keratinocytes

Question 10

Describe the cells of the stratum lucidum:

Answer 10

• Only in thick skin—narrow clear layer of dead keratinocytes

Question 11

Describe the cells of the stratum granulosum:

Answer 11

• 3-5 rows of cells. Granules contain keratin bundles or lipid based lamellar granules

Question 12

Describe the cells of the stratum spinosum:

Answer 12

• “prickle cells” Keratinocytes + desmosomes filaments + pre-keratin (several layers)

Question 13

Describe the cells of the stratum basale:

Answer 13

• single layer of metabolically active stem cells (may appear cuboidal/columnar)

Question 14

Differentiate between thick and thin skin:

Answer 14

1. Thick skin: palms and soles
   All 5 strata (including lucidum)
   Has sweat glands, but no hair
2. Thin skin: everywhere else
   No stratum lucidum
   Hair, sebaceous and sweat glands
   (eccrine and apocrine)