Structure and function of skin Flashcards Preview

Sem 3: Integ > Structure and function of skin > Flashcards

Flashcards in Structure and function of skin Deck (20):
1

Name the 5 main functions of skin.

  1. Barrier protection - dehydration, infection, injury, solar radiation - all epidermis
  2. Thermoregulation - hypodermis (insulation)
  3. Sensation - mainly dermis, hypodermis
  4. Repair - epidermis, dermis - fibroblasts
  5. Vitamin D production - epidermis

2

What is the integument?

The skin, hair and nails. 

The skin is the largest and heaviest organ of the body, making up 15% of adult body weight.

3

Describe the 3 layers of the skin. 

  • Epidermis - outer epithelial layer
  • Dermis - middle collagen layer
  • Hypodermis - inner fatty layer - often thickest

4

Describe the 4 main layers of the epidermis from the most basal upwards. 

  1. Stratum basale - stem cells attached to dermis constantly proliferate. 

  2. Stratum spinosum - cells have many desmosomes, visible as “spines” between cells. 

  3. Stratum granulosum - 1-4 layers of cells containing granules of keratohyalin. Also contain lamellar bodies containing lipids. 

  4. Stratum corneum - squamous de-nucleated cells, cornified due to keratin.

5

Name 3 epidermal cell types. 

  • Melanocytes - pigment
  • Langerhans cells - defence
  • Merkel cells - sensation

6

Describe the role of melanocytes. 

Synthesises melanosomes and transfers them to basal keratinocytes through long dendrites

7

What is the difference in prevalence of skin cancers between black and white-skinned people?

Black-skinned people with the same lifestyle tend to have only 10% as many skin cancers as white-skinned people

8

Describe vitamin D production in the skin and how it is converted to its active form. 

  • Epidermis: mostly produced in stratum basale, some production in stratum spinosum
  • Requires UV light, and more in darker skin
  • Converted to active form in liver and kidney: 1,25-dihydroxyvitamin D(calcitriol) 
  • Commonly deficient in UK 

9

Which layer of the skin has a rich blood and nerve supply?

  • The dermis
  • Carries blood and nerve supply for itself and the epidermis 

10

Why is the dermal-epidermal border often wavy?

To resist shear forces - rubbing sideways

11

Which cells make and maintain collagen?

Fibroblasts

12

The dermis consists of which 2 connective tissue fibres?

Collagen and elastic fibres

13

What is the cause of skin wrinkles?

Damage to elastic fibres of the dermis by UV light - resulting in loss of elasticity

14

What is the function of the hypodermis?

Provides insulation, cushioning and energy storage

15

Where are hair follicles and sweat glands found? 

Hypodermis

16

What do sebaceous glands make?

Oily sebum

17

Describe the function of eccrine and apocrine sweat glands. 

  • Eccrine - normal sweat glands, watery secretion onto skin surface cools body by evaporation
  • Apocrine - oily fluid secreted into follicles, function unclear, source of body odour, found in armpits and anogenital region (after puberty), less in Asian people

18

What causes acne? 

Hair follicles become blocked, can get infected

19

What are the nails made of?

Hard keratin

20

Describe where different sense organs are found in the skin. 

  • Dermis: thermoreceptors, Meissner's corpuscles (touch), nociceptors
  • Hypodermis: Pacinian corpuscles - presssure
  • Basal epidermis: Merkel's cells - detect light touch