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):

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


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.


Describe the 3 layers of the skin. 

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


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.


Name 3 epidermal cell types. 

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


Describe the role of melanocytes. 

Synthesises melanosomes and transfers them to basal keratinocytes through long dendrites


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


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 


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

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


Why is the dermal-epidermal border often wavy?

To resist shear forces - rubbing sideways


Which cells make and maintain collagen?



The dermis consists of which 2 connective tissue fibres?

Collagen and elastic fibres


What is the cause of skin wrinkles?

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


What is the function of the hypodermis?

Provides insulation, cushioning and energy storage


Where are hair follicles and sweat glands found? 



What do sebaceous glands make?

Oily sebum


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


What causes acne? 

Hair follicles become blocked, can get infected


What are the nails made of?

Hard keratin


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