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Phase 1 revision > SUGER - SKIN > Flashcards

SUGER - SKIN Flashcards

1
Q

Where does normal proliferation of the skin occur?

A

Normal proliferation of the skin occurs
just in the basal layer.
The epidermis grows from its basal layer up towards the surface. At the surface dead cells are shredded into the environment, these are replaced by new cells growing up from the base.

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2
Q

Functions of the skin

A

1) Barrier to infection
2) Thermo-regulation
3) Protection against trauma
4) Protection against UV
5) Vitamin D synthesis
6) Water-proofing
7) Sensation

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3
Q

What is the largest organ of the body ?

A

The skin

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4
Q

Basic layers of the skin

A
  • Epidermis
  • Dermis
  • Subcutaneous tissue
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5
Q

Layers of the epidermis (inner to outer)

A

1) Stratum basale
2) Stratum spinosum
3) Stratum granulosum
4) Stratum corneum
in soles and palms they have Stratum lucidum aswell.

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6
Q

Startum basale

- what type of cells found here and what do they produce

A

Is the single layer of cells that rest against the basement membrane. Two types of cells are found here:

  • Basal epithelial cells (form the stem cell population)
  • Melanocytes (produce melanin)
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7
Q

Function of melanocytes

A

Synthesis melanin from tyrosine and transfer it to surrounding keratinocytes in melanosomes in repsonse to MSH and ACTH hormones.

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8
Q

Function of melanin

A

Melanin absorbs UV light , protecting us from non-ionising radiation.

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9
Q

What determines a person’s skin colour?

A

THE AMOUNT AND TYPE OF MELANIN SYNTHESISED not amount of melanocytes present.

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10
Q

Stratum spinosum

  • what type of cells?
  • desosomes?
A
  • Plump polygonal kertinocytes
  • prominent inter cellular adhesions called desosomes
  • Langerhan cells that produce antigen recognition
  • Merkel cells- sensory
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11
Q

Stratum granulosum

  • what type of cells
  • function
A
  • kerato-hyaline granules

- it is in this layer that keratin forms.

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12
Q

Stratum corneum :

- What is it made up of?

A
  • Corneocytes
  • Corneo-desosomes
  • Desosomes
  • Corneo-desmosomes (known as adhesion molecules) keep the corneocytes together
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13
Q

What happens to the desosomes in psoriasis?

A

Increased numbers of corneodesmosomes which means there is a thickening of the stratum corneum

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14
Q

What happens to the desosomes in atopic eczema?

A

Decreased numbers of corneodesmosomes which means which there is a thinning of the stratum corneum, meaning there is an increased risk of inflammation

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15
Q

Atopic eczema is an example of what type of disease?

A

Gene-environment interaction disease

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16
Q

Describe a healthy skin barrier

A

1) Filaggrin (derived from profilaggrin) produces natural moisturising factor (NMF).
2) Corneocytes are filled with NMF which help
maintain the skin’s hydration - keeps H2O inside the skin.
3) NMF is also important in maintaining an acidic environment at the outer surface of the stratum corneum.
4) In order to balance the introduction of new cells in the basal layer of the epidermis, mature corneocytes are shed from the surface of the stratum corneum in a process called desquamation.
5) The lipid lamellae keeps the water inside the skin cells
6) Irritants & allergens tend to “bounce off” the surface of the skin due to the presence of the lipid lamellae
7) The normal & intact stratum corneum acts as an efficient barrier to the penetration of irritants and allergens and to the loss of water

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17
Q

Where is profilaggrin found?

A

Structural component in the cornified envelope

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18
Q

Desquamation

A

Desquamation involves the degradation
of the extracellular corneo-desmosomes
under the action of protease enzymes.

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19
Q

What is the normal pH of the skin? Why is this important?

A

The pH of normal skin is 5.5
1) This allows the proteases to remain on the skin
thereby enabling desquamation
2) Helps lipid processing to form the lipid lamallae

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20
Q

Describe the brick model analogy of skin

A

The skin barrier can be explained using the brick wall model; whereby the corneocytes are the bricks, the corneodesmosomes are the iron rods & the lipid lamellae is the cement.

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21
Q

Role of Vitamin D in the skin

A

Vitamin D is essential in producing the anti-microbial peptides necessary to
defend the skin from bacteria & viruses

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22
Q

What do irritants do?

A

Break down healthy skin.

23
Q

What causes skin flare ups?

A

Caused by allergens which are able to penetrate into the skin, where they are met with lymphocytes which release chemicals that induce INFLAMMATION.

24
Q

Adult vs Baby skin

A

1) Baby skin has v. thin brick wall
2) v. little damage can cause allergens to break in
3) Eyelids have the thinnest stratum corneum

25
Q

Gene interactions in AD

A

1) Gene that effects filaggrin gene.
2) Less filaggrin produced
3) Less NMF
4) Increased pH environment

26
Q

Effects of increased pH on the skin

A

1) High pH switches on proteases
2) Corneo-desmosomes are damaged all the way down th skin barrier.
3) Lipid processing is also reduced so lipid lamellae breaks and there is reduced water retention.
4) Allergens can enter as skin barrier broken down.

27
Q

What causes the red skin in skin flare ups?

A

Dilation of blood vessels - due to lymphocyte activity

28
Q

What causes the itchy skin in skin flare ups?

A

Stimulation of nerves.

29
Q

What causes the dry skin in flare ups?

A

Skin cells leaking - due to lymphocyte activity

30
Q

What happens when the allergens enter the skin?

A
  • They interact with the immune system
  • Th0 into Th2 which is a type 1 allergic reaction
  • Causes release of more cytokines like IL-4 and IL-13
  • These can feedback to further impair barrier function and inflammation
  • So a vicious circle started
31
Q

Do babies get allergies by eating foods or by penetration through skin?

A

Route of sensitisation is through the skin.

32
Q

Effects of inflammation on the brain

A

1) Pro-inflammatory cytokines from the skin directly suppress mediators in the brain.
2) E.g. Serotonin, so less serotonin means depression and less melatonin which causes sleep disturbance.
3) Can have effects on development of brain in babies.

33
Q

Reactive treatment

A

Treating a flare up when it’s active

34
Q

Pro-active treatment

A

Trying to prevent flares

35
Q

Prevention

A

Taking a baby at birth that is genetically pre-disposed to AD and you change the way you treat their skin to try prevent AD developing at all.

36
Q

Healthy Barrier

A
  • Swelled corneocytes
  • High levels of NMF
  • Lipid lamallae to prevent trans-epidermal water loss
37
Q

Defective Barrier in AD

A
  • Low NMF—–dry skin and cracks
  • Broken Lipid Lamallae
  • Broken corneo-desmosomes
  • High trans-epidermal water loss
38
Q

Simple “occlusive” emollients + humectants effect on the skin barrier

A
  • Artificial restoration of the barrier above the stratum corneum»> stops allergens entering
  • Doesn’t repair barrier underneath
  • They trap moisture in skin so increase hydration
  • Added humectants help to retain moisture in skin
  • All of this builds up the barrier.
39
Q

What causes acne? PART 1

A

1) In acne, hypercornification of the stratum corneum occurs resulting in adherentcells (corneodesmosomes) blocking the entrance to hair follicles
2) This results in the increased production of sebum by the sebaceous glands
3) Eventually some of the sebum to become trapped in the narrowed hair follicle
4) This means that the sebum STAGNATES at the pit of the follicle where there is NO OXYGEN
5) This provides anaerobic conditions which allow the propionic bacteria acnes (p.acnes) to multiply in the
stagnant sebum
6) The p.acnes breakdown the triglycerides in sebum into free fatty acids resulting in irritation, inflammation
7) The p.acnes release chemicals that attract neutrophils.
8) This then results in pus formation and further inflammation since the no full hair follicle is rapidly filled with attracted neutrophils.

40
Q

Cosmetically induced acne

A

Cosmetics & oily hair gel can trigger acne since they help “plug” the hair follicle and initiate the acne process - acne caused by these products is known as
cosmetically induced acne.

41
Q

At sites of abrasion what layer is thicker?

A

Stratum Corneum.

Sometimes there is another layer between the stratum granulosum and stratum corneum»»STRATUM LUCIDUM

42
Q

Epidermal adnexae

A

Downward growth of the epidermis into the dermis. They have hair follicles, sebaceous glands, eccrine sweat glands and apocrine sweat glands.

43
Q

Sebaceous glands

  • What is the role?
  • What type of secretion?
A

They produce sebaceous secretions which lubricate and waterproof hairs. Holocrine secretion.

44
Q

Holocrine secretions

A

Discharging the contents of entire cells onto the surface of hair follicles.

45
Q

Apocrine glands

  • Where are they found?
  • Type of secretions?
A
  • Armpits, groins, anus and genitals have this specialised sweat glands. In the external auditory canals in the ceruminous glands that produce ear wax
  • Apocrine secretion : this means that the secretion comprises elements of the cytoplasm of these cells which bud off from the lumen surface of these cells.
46
Q

Eccrine glands

  • Where are they found?
  • Type of secretions?
A
  • Found everywhere
  • Coiled tube 2 cell layer thick- inner secretory, outer myoepithelial that contract to force secretions out
  • Eccrine secretion: relies on exocytosis across the luminal membrane of the secretory cells, normally called merocrine secretion but called eccrine when it occurs in these glands.
47
Q

Dermo-epidermal junction

A
  • Epidermis protrudes downwards into the underlying dermis like pegs
  • Papillary dermis is the dermis between the pegs of epidermis
48
Q

Layers of the dermis

A

Papillary dermis

Reticular dermis

49
Q

What does the dermis contain?

A

Fibrous connective tissue containing elastin, blood vessels, nerves and the down growth adnexal organs of epidermis.

50
Q

Meissner’s corpuscle

  • where are they found?
  • purpose
A

Mechanoreceptor in the dermis esp in hairless skin. Encapsulated unmyelinated nerve endings.
Fine touch detector.

51
Q

Pacinian corpuscle

A

Onion like. Found in the subcutaneous tissues and deeply in the interosseous membranes and the mesenteries of the gut.
Vibration and tickle.

52
Q

Purpose of subcutis

A
  • Insulation
  • Shock absorber
  • Food store
53
Q

Breast tissue

A

Myoepithelial system of ducts and lobules set in fibroadipose connective tissue. Tissue present from birth but develops at puberty. Ducts all empty at the nipple.

54
Q

How many cells line the ducts and lobules of breast tissue?

A

2

  • outer myoepithelial
  • inner columnar epithelial

Phase 1 revision (5 decks)

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