Introduction to Dermatology: Structure and function of the skin Flashcards
what is skin?
Largest organ in the body
Contains adnexal structures
Hair, nails, glands, sensory structures
Important role in protection, homeostasis and transmission of sensations
describe the anatomy of skin?
describe the anatomy of nail?
what is anagen hair phase?
active growing phase
80-90% of hair
what is catagen hair phase?
2–3 week phase growth stops/follicle shrinks
1–3% of hairs
what is telogen hair phase?
resting phase for 1–4 months
up to 10% of hairs in a normal scalp
what is the function of the skin?
Thermoregulation
Insulation, Heat transfer
Skin immune system
Innate and Adaptive functions
Barrier
Protects against Mechanical, Chemical, microorganisms, Ultraviolet light
Keeps in water and Electrolytes, Macromolecules
Sensation
Temperature, touch and pain
Vitamin D synthesis
UV light converts 7-dehydrocholesterol to cholecalciferol
Interpersonal Communication
Physical appearance, smell, self -identity
why is skin disease important?
Disfigurement
Discomfort
Disability
Depression
Death
what are external causes of skin disease?
Temperature, UV, chemical (allergen or irritant), infection, trauma
what are internal causes of skin disease?
Systemic disease, genetics, drugs, infection
what is photosensitivity?
Commonly caused by medications
Exposed sites affected
Can be sensitive to UVA, UVB, visible light or a combination of these.
what are examples of cold injury?
Frostbite, Chilblains
Skin Necrosis
Cold Urticaria
what is an example of trauma to the skin that is self inflicted?
Dermatitis Artefacta
how are skin lesions described?
Macule Small flat circumscribed area Patch Larger flat circumscribed area
Papule Small raised area
Plaque Larger Raised area
Vesicle Small Fluid filled
Bulla Large Fluid filled
Pustule Small Pus filled
Abscess Large Pus filled
Erosion Loss of Epidermis
Ulcer Loss of Epidermis and dermis
what is macule?
Non-palpable change in skin color with distinct borders
what is papule?
Palpable, solid lesion less than 1 cm in diameter
what is plaque?
Palpable, solid lesion greater than 1 cm in diameter
what is a nodule?
give examples
Palpable, lesion more than 1 cm in diameter which is taller than it is wide
Neurofibromatosis
Rheumatoid Nodules
what is a vesicle?
Fluid-containing, superficial, thin-walled cavity less than 1 cm
what is a bulla?
Fluid-containing ,superficial, thin-walled cavity greater than 1 cm
what is an erosion?
A skin defect where there has been loss of the epidermis only
what is an ulcer?
A skin defect where there has been loss of the epidermis and dermis
what is a pustule?
Pus containing, superficial, thin-walled cavity
what is an abscess?
Thick-walled cavity containing pus
The distribution of a dermatosis refers to how the skin lesions are scattered or spread out.
Skin lesions may be isolated (solitary or single) or multiple.
The localisation of multiple lesions in certain regions helps diagnosis, as skin diseases tend to have characteristic distributions.
Acanthosis Nigricans
Associated with insulin resistance, obesity, malignancy
Flexural distribution
Hyperkeratosis and Hyperpigmentation, papules
‘velvety’ appearance
thyroid skin disease?
Pretibial myxoedema
5% of Graves Disease
Same process behind eyes – mucinosis
Other skin changes seen in both hyper and hypothyroidism
what investigations are offered in dermatology?
Charcoal swab
Ask for MC&S
Microscopy
Culture
Sensitivities
if viral infection is suspected what tests should be done?
Viral swab for PCR
Can swab vesicle/bulla if vesicular eruption
If systemic illness, can take throat swab
if fungal infection is suspected what tests should be done?
Skin scraping
Nail clipping
Hair sample
Fungal cultures
what is a simple way to take a skin biopsy?
punch biopsy
