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Flashcards in 10. Skin Deck (32)
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1

What are the 8 functions of skin?

Protection against injury
Protection against pathogenic organisms
Waterproofing and fluid conservation
Thermoregulation
Protection against radiation, absorption of ultra violet radiation and vitamin D production
Surface for grip
Sensory organ
Cosmetic

2

Describe the structure of skin

Stratum cornea
Epidermis
Papillary dermis
Reticular dermis
Hypodermis

3

Appendageal structures

Pilo-sebaceous unit (follicle, hair shaft, sebaceous gland and pilo erecti muscle)
Sweat glands (apocrine and eccrine).

4

Describe the structure of the epidermis

Consists of keratinocytes arranged in 4 layers

5

What are the 4 layers of the epidermis?

Stratum basale
Stratum spinosum
Stratum granulosum (cells have keratin granules)
Stratus corneum (cells have no nucleus)

6

Name 3 cell types found in the epidermis and their functions

Melanocytes: produce melanin
Langerhans cells: antigen presenting cells
Merkel cells: sensation

7

What is the main purpose of the epidermis and what forms this?

Barrier
Much of the barrier is formed by Keratin

8

What happens as a keratinocyte progresses up through the epidermis?

It transforms at stratum granulosum into a nonviable corneocyte before being shed in the normal epidermal turnover process

9

Structure of stratum corneum

Corneocytes/keratinocytes produce layers of skin, stuck together by lipids to create a seal
Protective
No nucleus as dead

10

What is the result of a mutation in filagrin gene?

"Glue" between corneocytes in epidermis is not normal
Leads to eczema
Palmar hyper-linearity is a sign

11

What are the dendritic cells within the epidermis?

Langerhans
Melanocytes

12

Where are melanocytes found?

Basement membrane of epidermis

13

In which organelle is the pigment melanin produced?

Melanosomes

14

How are melanosomes packaged?

Into granules which move down dendritic processes and are transferred by phagocytosis to adjacent keratinocytes

15

What do melanin granules do?

Form a protective cap around the keratinocyte nuclei
Protect DNA within nucleus from UV induced damage and lead to skin pigmentation

16

What stimulates melanocytes to produce more melanin?

UV radiation (mainly within 290-320 nm spectrum)

17

What causes variation in racial pigmentation?

Number and size of melanosomes produced

18

What is Vitamin D deficiency in children called?

Rickets

19

When is Vitamin D produced in skin?

After sun exposure

20

What may rickets lead to?

Problems with immune system
Predisposition to certain cancers

21

What is Vitamin D deficiency in adults called?

Osteomalacia

22

What is the basement membrane zone?

Region where epidermis is attached to dermis via semi-desmosomes, anchoring plaques and a multitude of proteins

23

What happens if there is a mutation in a protein in the basement membrane zone?

Layers aren’t connected properly
Gives rise to blisters
Epidermolysis bullosa (Bullous Pemphigoid)

24

What does the dermis contain?

Collagen
Elastin
Glycosaminoglycans (GAGs)
Fibroblasts
Immune cells

25

What is the function of fibroblasts in the dermis?

To synthesise:
Collagen
Elastin
Glycosaminoglycans

26

Give examples proving variation in thickness of dermis

0.1mm Eyelids
3mm Back

27

What does the subcutaneous layer consist of?

Connective tissue
Fat

28

How is a body temperature of 36.8 maintained?

Regulation of skin blood flow
Sweating
Shivering
Behaviour

29

Discuss regulation of skin blood flow

Skin temp responsive to blood flow (vasoconstriction and vasodilation)
1 – 100ml / min per 100g skin
Under sympathetic control

30

Discuss sweating

Cools skin through evaporation
Minimum 0.5L per day
Max 10L per day
Produced by eccrine and apocrine sweat glands

31

2 types of sweat glands

Eccrine = all over body, salty sweat
Apocrine = under hair follicle, viscous sweat can be metabolised by bacteria

32

Embryology of epidermis, dermis and melanocytes

Epidermis = ectoderm
Dermis = mesoderm
Melanocytes = neural crest