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Phase 1 Medicine > Week 1 - Structure and function of the skin > Flashcards

Week 1 - Structure and function of the skin Flashcards

1
Q

What are the 3 main functions of the skin

A

Protection (both physically and immunologically)
Physiological regulation (body temperature, fluid balance, vitamin D production)
Sensation

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2
Q

What are the 3 main layers of the skin

A

Epidermis
Dermis
Hypodermis

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3
Q

What is the name of the muscle which attaches to the hair follicle

A

Arrector pilli

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4
Q

Describe the mechanism by which the arrestor pili warms the body in response to being cold

A

The muscle contracts to cause the hair to stand on end which traps air and warms the body

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5
Q

Describe the structure of the epidermal epithelial cells

A

Keratinised stratified squamous epithelium

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6
Q

What are the epithelial cells that make up the epidermis

A

Keratinocytes

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7
Q

How is the stratum basale layer connected to the basement membrane

A

By hemidesmosomes (intermediate filament –>extracellular matrix)

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8
Q

How are the epithelial cells joined together in the epidermis

A

Joined together by desmosome cell–>cell junctions

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9
Q

Name all the layers of epidermis from top to bottom

A

Stratum Corneum
Stratum Lucidum (areas of thick skin)
Stratum Granulosum
Stratum Spinosum
Stratum basale

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10
Q

What type of cells make up the epidermis

A

Keratinocytes

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11
Q

What do keratinocytes sit on

A

The basement membrane

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12
Q

What type of cells do you find in the stratum basale

A

Stem cells

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13
Q

What is the cell junction between the stem cells and the basement membrane

A

Hemi-desmasomes

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14
Q

What joins together the epithelial cells

A

Desmosome cell junctions

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15
Q

Describe the cells in the stratum corneum

A

Flat, anucleate cells, filled with keratin and lipids, producing a hydrophobic barrier for the skin

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16
Q

What is the extra layer of skin cells found in the epidermis and what is it’s function

A

The stratum lucidum and it’s role is to reduce abrasion between the stratum corneum and stratum granulosum

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17
Q

Describe the way in which the daughter cells move up the layers of skin

A

The daughter cells move up from the basale layer and differentiate on their way upwards. 2 weeks to get to the stratum granulosin and 2 weeks to make it up to the top of the stratum corneum?

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18
Q

What type of epithelial tissue is epidermis tissue

A

Keratinised stratified squamous epithelium

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19
Q

What is the function of the keratinocyte and where found

A

Provides protection, a barrier and is the site of vitamin D production. Found in the epidermis

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20
Q

What is the function of the stem cells in epidermis and where found

A

Self renewal and repopulation of epidermal layers
Found in the stratum basale

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21
Q

Function and location of Merkel cell

A

Found in epidermis and involved in sensation

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22
Q

Function and location of Langerhans cell

A

Dendritic cell
Antigen presentation phagocytosis. Mainly found in the stratum spinosum

23
Q

Function and location of the melanocyte

A

Protection from radiation
Found in the basal layer

24
Q

Where is melanin made

A

In melanocyte cells in the melanosomes

25
Q

How does melanin protect cell from UV

A

They form a protective layer over the nucleus, thus protecting DNA from damage

26
Q

Function and location of keratins

A

Major structural protein and a type of intermediate filament. Found in all epidermal layers

27
Q

Function and location of profilaggrin granules

A

Converted to filaggrin which aggregrates keratin filaments into tight bundles. Found in keratohyalin granules

28
Q

Function and location of involucrin

A

formation of cell envelope around cells in stratum corneum. Found in keratohyalin granules

29
Q

Function and location of Loricrin

A

Cross links to involucrin
Found in keratohylin granules

30
Q

Function and location of polysaccharides, glycoproteins and lipids

A

Extrude into intercellular space, form the ‘cement’ that holds together the stratum corneum cells

31
Q

What type of tissue is the dermis

A

Connective tissue

32
Q

What are the main 4 components found in the dermis

A

Fibroblasts
Collagen type 1
Elastin
Ground substance tissue

33
Q

What allows the strength in the dermis

A

Collagen

34
Q

What allows the stretch in the dermis

A

Elastin

35
Q

As you go further down the epidermis, what happens to the strength of collagen and elastin

A

Collagen gets stronger
Elastin gets less stretchy

36
Q

Which portion of the dermis has most blood vessels

A

Outer layer

37
Q

What do you call the region between the epidermis and the dermis

A

The dermo-epidermal junction

38
Q

Function of fibroblast cells

A

Involved in the synthesis of collagen, elastin and other extracellular matrix components

39
Q

Function of lymphocytes

A

immunosurveillance

40
Q

Function of dermal dendritic cells (langerhan’s cells)

A

Phagocytosis
Antigen presentation

41
Q

Functions of mast cells and give examples of substances produced

A

Produce inflammatory mediators (e.g histamine and heparin)
Produce chemotactic factors for eosinophils and neutrophils

42
Q

What is the hypodermis composed of

A

Adipose tissue

43
Q

What are the 3 main functions of the hypodermis

A

Energy source
Shock absorption
Insulation

44
Q

Where do most nerve endings finish

A

The dermis

45
Q

When nerve endings finish in the epidermis, into what cells do they extend into

A

Merkel cells

46
Q

What are Meissner’s corpuscles

A

Dermal mechanoreceptors responsible for touch

47
Q

What are pacinian corpuscles

A

Hypo-dermal receptor that detects deep pressure and vibration

48
Q

What are nails composed of

A

Plates of heavily compacted, heavily keratinised epithelial cells

49
Q

Name 3 glands found in the skin and describe where they are mainly found

A

Eccrine glands - found almost everywhere and they excrete sweat

Apocrine gland - armpit sweat?

Sebaceous gland - secrete sebum and are formed from a hair follicle

50
Q

What are the 3 stages of wound healing

A

Inflammation

Proliferation

Remodelling

51
Q

Describe the inflammation stage and for how long this happens

A

Platelets initiate the blood clot and healing cascade
Neutrophils and basophils are recruited towards the site of injury - red swelling
Neurtophils and macrophages phagocytose the dead tissues and organsims

For 24-48 hours

52
Q

Describe the proliferative stage

A

Re-epithelialisation occurs
Within 1/2 days, cell to cell adhesions are loosened and epithelial cells cover the granulation tissue. Granulation tissue forms, mainly made up from type 3 collagen.

Neovascularisation occurs where endothelial cells proliferate

53
Q

Describe the remodelling phase

A
  • The new granulation tissue becomes mature scar tissue through collagen organising itself into extensively cross-linked bundles
  • Collagen type 3 turns into collagen type I
  • Final skin strength 70-80% at 1 year

Phase 1 Medicine (37 decks)

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