The Skin

Question 1

What three layers make up the skin?

Answer 1

Epidermis- superficial layer
Dermis- underlying connective tissues
Hypodermis- subcutaneous layer

Question 2

What are the functions of the skin?

Answer 2

• Protection- covers underlying tissues
  
  • Excretion- sweating ensuring maintence of body temperature
  • Production of melanin
  • Production of keratin
  • Synthesis of vitamin D3- converted into calcitriol (calcium synthesis)
  • Storage of lipids- heat receptors and stimuli or sharp, hot and cold (acts as protection)
  • Coordination of immune response

Question 3

What is the structure of the epidermis?

Answer 3

Stratified squamous epithelium
* Avascular- no blood supply gets oxygen, carbon dioxide vitimans and glucoose etc from the dermis and they diffuse into the epidermis
* Keratinocytes dominate epidermis – form several strata and provide it with its water resistant qualities
* Contain large amounts of keratin
* Layers closest to dermis have the highest metabolic demands
* Superficial cells are dead

Question 4

Name the five layers of the epidermis?

Answer 4

Stratum Basale
Stratum Spinosum
Stratum Granulosum
Stratum Lucidum
Stratum Corneum

Question 5

What are the three types of skin cancer?

Answer 5

Basal cell carcinoma
Squamous cell carcinomas
Malignant melanoma

Question 6

Information on Basal cell carcinoma

Answer 6

• most common form of skin cancer
  
  • 2/3 cases due to chronic UV exposure but there is also a genetic predisposition

Question 7

Information on squamous cell carcinoma

Answer 7

• less common
  
  • Only caused by UV exposure
  • Metastasis (tumour moving from one place to another) uncommon if treated

Question 8

Information on malignant melanomas

Answer 8

• rapid proliferation and metastasis
  Survival dependent on early diagnosis

Question 9

What two pigments are in the epidermis?

Answer 9

Melanin (protects from UV) and carotene (is converted into vitamin A)

Question 10

What is the structure of the dermis?

Answer 10

• Contains capillaries, lymphatic vessels and sensory neurons
  
  • Collagen and elastin fibres present, extend into hypodermis
  • Provide strength and elasticity
  • Accessory structures extend into dermis
  • Infection/inflammation painful due to abundance of sensory neurones
  • Dermatitis- inflation of dermis painful because of the nerves in the dermis
  • Arteries in hypodermis branch into dermis

Question 11

What is the result of increase in body temperature?

Answer 11

vasodilation, heat loss, reddened skin

Question 12

What is the result of decrease in body temperature?

Answer 12

vasoconstriction, heat preservation, pale skin

Question 13

What is cyanosis?

Answer 13

reduced O2 bound to haemoglobin, bluish colouration of lips, nail beds

Question 14

What is the structure of the hypodermis?

Answer 14

• Subcutaneous layer
  
  • Elastic
  • Stabilises the position of the skin in relation to underlying tissues
  • Contains numerous adipose cells – 80% body fat stored here
  • Highly vascularised
  • Excellent route for administration of drugs- as it has a really good blood supply

Question 15

information on hair as an accessory structure?

Answer 15

Produced in hair follicles – extend into dermis & hypodermis
Protect scalp from UV, cushion light impacts, insulate the skull
Keep out foreign particles
Keep sweat from eyes (eyebrows)
Also sensory receptors (hairs in the ear)

Question 16

Information on sweat glands as an accessory structure?

Answer 16

Produce sweat
Cools surface of skin to reduce body temperature
Excretion of water and electrolytes
Protection from environmental hazards

Question 17

Information on Sebaceous glands as an accessory structure?

Answer 17

Secrete an oil product called sebum into hair follicle
Lubricates the skin and hair and makes skin water resistant

Question 18

Information on nails as an accessory structure?

Answer 18

Keratinised epidermal cells that protect dorsal surfaces of fingers/toes
Limit distortion of the digits from mechanical forces when picking up objects
Enhances sensitivity of fingertip
Function as a tool – extended precision grip
Fingernails can provide clues to overall health
Nails serve to enhance precise delicate movements of the distal digits through counter-pressure exerted on the pulp of the finger. The nail then acts as a counterforce when the end of the finger touches an object, thereby enhancing the sensitivity of the fingertip
extended precision grip” e.g. pulling out a splinter in one’s finger

Question 19

What are the effects of ageing on skin?

Answer 19

· Epidermis thins as basal cell activity declines this causes skin to tear more easily
· Connection between epidermis and dermis weakens
· Number of Langerhans cells decrease, this reduces the effect of the immune system, can lead to skin infection
· Vitamin D3 production declines-reduced Ca and PO4 absorption causing muscle weakness and reduction in bone density
· Melanocyte activity declines- skin becomes paler, more sensitive to uv light
· Glandular activity declines- skin becomes drier
· Blood supply to dermis reduced prevents tears from healing- skin cools and person feels colder
· Dermis thins- elastic fibres decrease making skin less resilient, wrinkled, sagging