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Tissues > 10. Skin > Flashcards

10. Skin Flashcards

1
Q

What are the 8 functions of skin?

A 
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
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2
Q

Describe the structure of skin

A 
Stratum cornea 
Epidermis
Papillary dermis
Reticular dermis 
Hypodermis
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3
Q

Appendageal structures

A 
Pilo-sebaceous unit (follicle, hair shaft, sebaceous gland and pilo erecti muscle)
Sweat glands (apocrine and eccrine).
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4
Q

Describe the structure of the epidermis

A

Consists of keratinocytes arranged in 4 layers

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5
Q

What are the 4 layers of the epidermis?

A

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

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6
Q

Name 3 cell types found in the epidermis and their functions

A

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

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7
Q

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

A

Barrier

Much of the barrier is formed by Keratin

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8
Q

What happens as a keratinocyte progresses up through the epidermis?

A

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

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9
Q

Structure of stratum corneum

A

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

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10
Q

What is the result of a mutation in filagrin gene?

A

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

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11
Q

What are the dendritic cells within the epidermis?

A

Langerhans

Melanocytes

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12
Q

Where are melanocytes found?

A

Basement membrane of epidermis

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13
Q

In which organelle is the pigment melanin produced?

A

Melanosomes

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14
Q

How are melanosomes packaged?

A

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

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15
Q

What do melanin granules do?

A

Form a protective cap around the keratinocyte nuclei

Protect DNA within nucleus from UV induced damage and lead to skin pigmentation

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16
Q

What stimulates melanocytes to produce more melanin?

A

UV radiation (mainly within 290-320 nm spectrum)

17
Q

What causes variation in racial pigmentation?

A

Number and size of melanosomes produced

18
Q

What is Vitamin D deficiency in children called?

A

Rickets

19
Q

When is Vitamin D produced in skin?

A

After sun exposure

20
Q

What may rickets lead to?

A

Problems with immune system

Predisposition to certain cancers

21
Q

What is Vitamin D deficiency in adults called?

A

Osteomalacia

22
Q

What is the basement membrane zone?

A

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

23
Q

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

A

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

24
Q

What does the dermis contain?

A 
Collagen
Elastin
Glycosaminoglycans (GAGs)
Fibroblasts 
Immune cells
25
Q

What is the function of fibroblasts in the dermis?

A

To synthesise:
Collagen
Elastin
Glycosaminoglycans

26
Q

Give examples proving variation in thickness of dermis

A

0.1mm Eyelids

3mm Back

27
Q

What does the subcutaneous layer consist of?

A

Connective tissue

Fat

28
Q

How is a body temperature of 36.8 maintained?

A

Regulation of skin blood flow
Sweating
Shivering
Behaviour

29
Q

Discuss regulation of skin blood flow

A

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

30
Q

Discuss sweating

A

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

31
Q

2 types of sweat glands

A 
Eccrine = all over body, salty sweat 
Apocrine = under hair follicle, viscous sweat can be metabolised by bacteria
32
Q

Embryology of epidermis, dermis and melanocytes

A 
Epidermis = ectoderm 
Dermis = mesoderm
Melanocytes = neural crest

Tissues (11 decks)

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