Structure and Function of the Skin Flashcards

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1
Q

Describe skin

A

Largest organ in the body
Contains adnexal structures - hair, nails, glands and sensory structures
Important role in protection, homeostasis and transmission of sensations

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2
Q

What are the layers of the skin?

A

Skin - epidermis and dermis
Subcutaneous tissue below

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3
Q

Describe the process of cell development in the skin

A
  1. Stratum basale - cells divide by mitosis and some newly formed cells become superficial strata
  2. Stratum spinosum - keratin fibres and laminar bodies accumulate
  3. Stratum granulosum - keratohyalin and hard envelope form
  4. Stratum lucidum - dead cells lie within keratohyalin
  5. Stratum corneum - dead cells with hard protein envelope
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4
Q

Describe the nail anatomy

A

Hyponychium
Nail plate
Lateral nailfold
Nail bed
Lunula
Cuticle
Proximal nailfold
Nail matrix

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5
Q

What are the 3 stages of the hair cycle?

A

Anagen
Catagen
Telogen

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6
Q

What is the anagen phase?

A

Active growing phase
80-90% of hair
Where chemo effects

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7
Q

What is the catagen phase?

A

2-3 weeks phase growth stops/ follicles shrink
1-3% of hairs

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8
Q

What is the telogen phase?

A

Resting phase for 1-4 months
Up to 10% of hairs in a normal scalp

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9
Q

What are the functions of the skin?

A

Thermoregulation
Skin immune system
Barrier
Sensation
Vitamin D synthesis - UV light converts 7-dehydrocholesterol to cholecalciferol
Interpersonal communication

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10
Q

Describe the epidemiology of skin disease

A

22-30% of population affected
50% skin cancer/ lesions
25% require surgical procedure

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11
Q

Why is skin disease important?

A

Disfigurement, discomfort, disability, depression and death

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12
Q

What are some external causes of skin disease?

A

Temp., UV, chemical, infection and trauma

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13
Q

What are some internal causes of skin disease?

A

Systemic disease, genetics, drugs and infection

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14
Q

What are some cold injuries to skin?

A

Frostbite, chilblains, skin necrosis and cold urticaria

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15
Q

What is an example to trauma causing skin disease?

A

Dermatitis Artefacta - self induced trauma

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16
Q

What is an example of an autoimmune disease causing skin disease?

A

Bullous pemphigoid

17
Q

What is a macule and a patch?

A

Macule -Small flat circumscribed area
Patch - larger flat circumscribed area

18
Q

What is a papule and a plaque?

A

Papule - small raised area
Plaque - larger raised area

19
Q

What is a vesicle and a bulla?

A

Vesicle - small fluid filled
Bulla - large fluid filled

20
Q

What is a pustule and an abscess?

A

Pustule - small pus filled
Abscess - large pus filled

21
Q

What is a erosion and an ulcer?

A

Erosion - loss of epidermis
Ulcer - loss of epidermis and dermis

22
Q

Describe a macule

A

Non-palpable change in skin colour with distinct borders

23
Q

Describe a papule

A

Solid lesion less than 1cm in diameter

24
Q

Describe a nodule

A

Palpable lesion more than 1cm in diameter which is taller then it is wide
Ex. neurofibromatosis and rheumatoid nodules

25
Q

What is an example of an erosion?

A

Toxic epidermal necrolysis - severe drug reaction

26
Q

What is an example of an ulcer?

A

Pyoderma gangerosum

27
Q

What is distribution?

A

How skin lesions are scattered or spread out
May be isolated or multiple
Localised, generalised, symmetrical…

28
Q

What are the most common skin conditions?

A

Acne, psoriasis, rosacea, skin lesions, urticaria, warts, leg ulcers, scalp/ nail disorders, eczema and infections

29
Q

What are some conditions which can have cutaneous signs?

A

Erythema nodosum, sarcoidosis, vasculitis, malignancy and auto-immune conditions

30
Q

What is a skin change which shows hyperlipidaemia?

A

Eruptive xanthoma

31
Q

Describe acanthosis nigricans

A

Associated with insulin resistance, obesity and malignancy
Flexural distribution
Hyperkeratosis and hyperpigmentation papules
Velvety appearance

32
Q

Describe thyroid skin disease

A

Pretibial myxoedema
5% of Graves disease
Same process behind eyes - mucinosis

33
Q

What are some investigations in dermatology?

A

Bacterial infection - charcoal swab and ask for MC&S (microscopy, culture and sensitivities)
Viral - Swab for PCR, swab vesicle, and throat swab
Fungal - skin scrapping, nail clipping and hair sample

34
Q

What is a simple way to take a skin biopsy?

A

Punch biopsy
Takes all 3 layers of the skin
Numb with local anaesthesia