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The Patient (Y3-1) > Skin > Flashcards

Skin Flashcards

1
Q

What are the four layers of the epidermis?

A

Stratum:

  • Corneum
  • Granulosum
  • Spinosum
  • Basale
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2
Q

What is the main function of the epidermis?

A

Replace damaged cells - to maintain skin’s protective properties

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3
Q

Which two cells are contained in the stratum basale layer?

A

Keratinocytes

Melanocytes

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4
Q

How does the skin replace damaged cells?

A

Continual production of keratinocytes - these are pushed up through the four layers of the epidermis until they are shed

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5
Q

What is the role of melanocytes?

A

Production of melanin which acts to protect the skin from UV by absorbing it. Melanin is produced on exposure to sunlight

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6
Q

What is the role of the stratum spinosum?

A

Anchors cells together by interlocking cytoplasmic processes

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7
Q

What takes place in the stratum granulosum?

A

Cells undergo enzyme-induced destruction - losing their nuclei and cytoplasmic organelles.
Lipid-rich secretions acting as the skins water sealant
Keratin is laid down, further meshing structures together

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8
Q

What does the stratum corneum consist of?

A

Dead cells which are flattened and contain densely packed keratin
Corneocytes are shed from the skin

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9
Q

What is the function of the dermis?

A

Provides strength (contains fibroblasts and collagen) but also provides elasticity (contains elastin)

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10
Q

Name some specialised structure that are present within the dermis

A

Nerves
Sweat glands
Hairs
Smooth muscle

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11
Q

What is the function of the hypodermis?

A

Cushions and insulates tissue below the hypodermis

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12
Q

Which layer of the skin contains fat?

A

Hypodermis

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13
Q

What are the three layers of the skin from top to bottom?

A

Epidermis
Dermis
Hypodermis

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14
Q

What are the four main functions of the skin?

A

Production of Vitamin D
Sensory organ for touch, pain and temperature
Controls body temperature
Barrier to protect tissues and organs

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15
Q

Describe the function of the skin in producing vitamin D

A

7-dehydrocholestrol in the skin produces vitamin D3 (cholecalciferol) in the presence of sunlight/UV
Vit D3 is then converted into calcidiol in the liver
calcidiol -> calcitriol in the kidney
calcitriol is the active form of vitamin D

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16
Q

How does vitamin D increase calcium levels?

A

It stimulates intestinal epithelium to produce more carrier protein molecules for calcium transport

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17
Q

Name three sensory receptors in the skin and outline their role

A

Mechanoreceptors - light touch and deep pressure detection
Thermoreceptors - warmth and cold detection
Nociceptors - respond to pain

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18
Q

Describe the role of the skin in controlling body temperature

A

Contains capillaries
In hot weather - capillaries open, increasing blood flow = vasodilaton -> heat loss at surface of skin
In cold weather - vasoconstriction -> minimising heat loss
Sweat glands actively secrete water and salts when body temperature is above 37 to cool body down

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19
Q

The skin acts as a protective barrier for tissues and organs. Name four things it protects against

A

Mechanical damage and trauma
UV radiation
Bacteria
Dehydration

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20
Q

Which cells in the skin are involved in the immune response against foreign matter and where are they found?

A

Langerhans cells found in the epidermis. They are antigen-presenting and so ingest the foreign particles and present them to T and B cells to induce immune response

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21
Q

What are the four phases in the healing process of the skin?

A

Haemostasis
Inflammatory phase
Proliferative phase
Maturation phase

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22
Q

What events take place if the epidermis of the skin is broken as a result of a burn/graze?

A

Keratinocytes in the stratum basale break from the basement membrane.
They enlarge and move across the wound until they meet another cell = contact inhibition, where growth and stops

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23
Q

What happens in the haemostasis stage of skin healing, following injury to the epidermis and dermis?

A

Main priority is to stop bleeding
Platelets recognise exposed collagen in the exposed dermis. They become sticky and release thromboxane A2. Platelets are now activated and begin to aggregate, forming a temp. plug.
Seratonin is released from activated platelets and works to reduce blood supply around the wound.
Both the plug and vasoconstriction reduce blood loss from the injury.
Thromboplastin, released from damaged tissues combines with calcium to form insoluble fibrin at the end of the clotting cascade
The fibrin combines with platelet aggregates to form a clot, and if this is left uncovered -> dries -> scab

24
Q

What takes place in the inflammatory phase of skin healing?

A

The main aim is to clean the wound
Langerhans cells are activated and release inflammatory mediators
Bradykinin increases pain at the site
Leukotrienes increase blood flow causing the skin to warm
There is an increase in vascular permeability, allowing WBCs to move to the wound from the blood
WBCs produce neutrophils which digest bacteria
Monocytes then move to the wound, maturing into macrophages which continue the wound cleaning process throughout healing

25
Q

What takes place in the proliferative stage of skin healing?

A

Main aim is dermis repair and epidermis regeneration
Macrophages commence this stage
If the wound has low oxygen levels, macrophages release angiogenic growth factors to develop new blood vessels
Macrophages release chemicals to attract granulation tissue to the wound -> new connective tissue
Platelet derived growth factors and macrophages activate fibroblasts which grow and divide to produce a collagen network to strengthen the wound
Epithelial cells move over the top of the moist granulation tissue. Once the cells meet at the top of the wound, they stop due to contact inhibition

26
Q

What takes place in the maturation stage?

A

The phase forms a scar. This can take up to 2 years
Collagen is re-aligned to improve strength. Collagen strands pull the wound inwards
Extra blood vessels close

27
Q

Which intrinsic patient factors affect the wound healing process?

A 
Nutrition - vitamins and proteins needed
Skin perfusion - disease such as peripheral vascular disease can affect this and so reduce O2 levels
Age - younger patients better perfusion
Weight 
Co-morbidities/meds 
Smoking
28
Q

Which extrinsic factors affect the wound healing process?

A 
Moist wound - better
Wound temp - 37 degrees optimal
Tissue oxygenation
pH
Infection
Clean wound surface
29
Q

Where are sebaceous glands found?

A

Dermis

30
Q

What is isotretinoin used for and what is its mechanism of action?

A

Treatment of severe acne, unresponsive to topical treatments and oral antibiotics
Reduces sebum excretion by ~90% after 6 weeks
Decreases hyperkeratinisation
Anti-inflammatory effects

31
Q

What are the risks associated with use of isotretinoin?

A

Teratogenic
Alters mental state - depression, anxiety
Dry and fragile skin
Impaired night vision

32
Q

What extra precautions are needed for someone who takes isotretinoin and is sexually active?

A

Pregnancy prevention programme
Effective contraception needs to be used 1 month before and 1 month after treatment
Pregnancy checks need to be taken throughout and 1 month after
Even women that are not sexually active are enrolled onto pregnancy prevention programme

33
Q

What is first-line treatment for psoriasis?

A 
Emollients 
Topical corticosteroids 
Coal tar
Dithranol 
Topical D3 analogue
34
Q

What is the most common form of psoriasis?

A

Chronic plaque psoriasis

35
Q

What is psoriasis?

A

Chronic inflammatory skin disease

36
Q

What are the major biological abnormalities in psoriasis?

A

Hyperproliferation of the epidermis leading to thickening of the epidermis
Abnormal differentiation of keratinocytes
Infiltration of dermis and epidermis with activated T-lymphocytes and neutrophils
Stimulation of cutaneous vasculature leading to new blood vessel formation in the psoriatic plaques

37
Q

What is PUVA and what is its indication?

A

Psoralen + UVA

Used in treatment of psoriasis (not 1st line)

38
Q

How does PUVA work?

A

Psoralen oral tab given 2 hours before UVA exposure
It disrupts DNA synthesis, inhibiting basal cell proliferation. Slowing basal cell growth to normal
Given 2-3 times weekly

39
Q

What is the name of the drug that is similar in structure to isotretinoin but used for treatment of psoriasis?

A

Acitretin

40
Q

What precautions are associated with treatment of psoriasis with acitretin?

A
  • Teratogenic - contraception needed for 3 years after use
  • Hyperlipidaemia - CV risk assessment needed and lipid profile monitoring
  • Hepatoxic - monitor liver function every 3 months, avoid alcohol or keep to minimum
41
Q

How does methotrexate work in the treatment of psoriasis?

A

Blocks DNA synthesis so slows basal cell proliferation

42
Q

How does methotrexate work in eczema?

A

Anti-inflammatory action

- enzyme inhibition leads to increased adenosine which inhibits neutrophil chemotaxis and cytokine secretion

43
Q

What are the risks associated with methotrexate treatment?

A

liver cirrhosis
blood disorders
GI symptoms

44
Q

Which drug that is used for treatment of both psoriasis and eczema blocks calcineuirin dependent factor?

A

Ciclosporin

45
Q

What are the risks associated with ciclosporin treatment?

A

Nephrotoxic
Hypertension
Teratogenic
Immunosuppressant

46
Q

How do biological agents work in the treatment of psoriasis and what are the risks?

A

Block TNF. Risks are:

  • Increased risk of infection
  • CV risk
  • Worsening neurological disease
47
Q

How do emollients work?

A

Form an oily layer above the skin to prevent water evaporation.
The water, trapped in the stratum corneum passes into the corneocytes, which swell, closing intercellular gaps

48
Q

How do humectants work?

A

Attract water from the dermis to the epidermis. They can improve epidermal barrier function and increase hydration of the stratum corneum

49
Q

What is the benefit of adding antiseptics to emollients?

A

To control flares

50
Q

Which types of dressings are best for necrotic wounds?

A

Hydrocolloid, hydrogel

51
Q

Which type of dressing is not suitable for dry wounds and why?

A

Hydrocolloid because due to their occlusive nature they may prevent overgrowth of anaerobic bacteria so are therefore C/I in infected wounds

52
Q

Which type of dressing contains gelatine from pigs?

A

Hydrocolloid

53
Q

Why aren’t alginate dressings suitable for dry wounds?

A

Because they stick to the wound and cause trauma when removed

54
Q

Explain the pathiophysiology of psoriasis

A

Hyperproliferation of dermis
Abnormal differentiation of keratinocytes
Activated T-cells and lymphocytes infiltrate dermis and epidermis
Blood vessels form in plaques

55
Q

What are the two types of psoriasis?

A

Chronic plaque

Guttate

56
Q

What factors can exacerbate psoriasis?

A 
Smoking
Alcohol
Drugs e.g. B-blockers, ACEI
Profound psychological stress
Hormones - e.g. menstruation 
Infection - esp. guttate triggered by throat strep
Trauma - injury site
57
Q

What are the trigger factors for atopic eczema?

A

Irritants such as soap detergents and clothes
Allergens
Stress
Food hypersensitivity

The Patient (Y3-1) (8 decks)

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