Structure and Function of the Skin Flashcards
What are the 5 layers of the skin from basement mambrane to surface?
- Stratum Basale
- Stratum spinosum
- Stratum granulosum
- Stratum lucidum
- Stratum corneum
What is the function of the stratum basale?
Cells divide by mitosis and some of the newly formed cells become the cells of the more superficial strata
What is the function of the stratum spinosum?
Keratin fibers and lamellar bodies accumulate
What is the function of the stratum granulosum?
Keratohyalin and a hard protein envelope form; lamellar bodies release lipids; cells die
What is the function of the stratum lucidum?
Dead cells lie within dispersed keratohyalin
What is the function of the stratum corneum?
Dead cells with a hard protein envelope; the cells contain keratin and are surrounded by lipids
What are the functions of the skin?
Thermoregulation
Skin immune system
Barrier
Sensation
Vitamin D synthesis
Interpersonal Communication
How does the skin provide thermoregulation?
Insulation through fat layer below dermis and hair follicles on surface
Heat transfer through sweating
How does the skin act as a barrier?
Protects against: Mechanical, Chemical, Microorganisms, Ultraviolet light
Keeps in water and Electrolytes, Macromolecules
How is the skin involved in Vitamin D synthesis?
UV light converts 7-dehydrocholesterol to cholecalciferol
How is the skin ivolved in interpersonal communication?
Physical appearance
Smell
Self-identity
How common is skin diseas?
22-30% of Population affected
15% of GP consultations
6% of hospital referrals
What is the majority of dermatology work made up of?
50% skin cancer/ lesions
25% require surgical procedure
10% require patch testing
What percentage of dermatology patients dont see a doctor about their problem?
80%
No need and can usually be dealt with at home.
What factors make skin disease important?
Disfigurement Discomfort Disability Depression Death
What are the external causes of skin disease?
- Temperature
- UV
- Chemical (allergen or irritant)
- Infection
- Trauma
What are the internal causes of skin disease?
- Systemic disease
- Genetics
- Drugs
- Infection
What is photosensitivity?
Abnormal reaction of the skin to sunlight
Burn when they have had an abnormally low level of UV exposure
What sites are effected in Photosensitivity?
Exposed sites around neckline and arms
Under chin usually spared
What causes photosensitivity?
Commoly caused by medications
What should you test in photosensitivity?
Patient can be sensitive to UVA, UVB, visible light or a combination of these.
Need to test different wavelengths of light
What are chilblains?
A painful, itching swelling on a hand or foot, caused by poor circulation in the skin when exposed to cold.
What is frostbite?
Injury to body tissues caused by exposure to extreme cold, typically affecting the nose, fingers, or toes and often resulting in gangrene
What is Cold Urticaria?
Cold urticaria (essentially meaning “cold hives”) is an allergy where hives (urticaria) or large red welts form on the skin after exposure to a cold stimulus.
The welts are usually itchy and often the hands and feet will become itchy and swollen as well.
Are cold injuries such as Frostbite and chilblains always physiological?
No
May be due to poor circulation maybe due to hyperviscosity
What is dermatitis artefacta?
Dermatitis artefacta is a condition in which skin lesions are solely produced or inflicted by the patient’s own actions.
This usually occurs as a result or manifestation of a psychological problem.
It could be a form of emotional release in situations of distress or part of an attention seeking behaviour.
In very rare cases there may be an underlying attempt to secure an insurance claim.
What is bullous pemphigoid?
Bullous pemphigoid is an autoimmune, supepidermal blistering disease
Result of an attack on the basement membrane of the epidermis by IgG +/- IgE immunoglobulins (antibodies) and activated T lymphocytes.
Hemidesmosomes, (structures that ensure the epidermal keratinocyte cells stick to the dermis to make a waterproof seal) are damaged.
Give some internal causes of skin disease
Genetic
Drug reaction
Autoimmune
What is a macule?
Small circumscribed area
flat change in colour
What is a patch?
Larger sicumscribed area
(flat change in colour)
> 1cm
What is a papule?
Small raised area
What is a plaque?
Larger raised area
> 1cm
What is a vesicle?
Small fluid filled lesion
usually clear fluid
What is a bulla?
Larger fluid filled lesion
(usually clear fluid)
> 1cm
What is a pustule?
Small puss filled lesion
What is an abscess?
Large puss filled lesion
> 1cm
What is erosion?
Loss of epidermis?
What is an ulcer?
Loss of epidermis and dermis
What is leukocytoclastic vasculitis?
Cutaneous vasculitis is a group of disorders in which there are inflamed blood vessels in the skin. These may include capillaries, venules, arterioles and lymphatics.
Cutaneous vasculitis has several different causes
There are a wide variety of clinical presentations.
It is associated with systemic vasculitis in a minority of patients
In most cases an underlying cause is not found and the disease is self-limiting.
What are petechiae?
Is a small (1–2 mm) red or purple spot on the skin, caused by a minor bleed (from broken capillary blood vessels).
Petechia refers to one of the three descriptive types of bleeding into the skin differentiated by size, the other two being purpura and ecchymosis. Petechiae are by definition less than 3 mm.
What is the difference between erythema and bleeding into the skin such as petechiae, pupura or ecchymosis?
Erythema will blanch as blood vessels flow is cut of by pressure applied to skin.
Petechiae, pupura and ecchymosis do not blanch as blood is in the skin not in vessels.
What do we mean by the distribution of skin disease?
The distribution of a dermis refers to how the skin lesions are scattered or spread out.
Skin lesions may be isolated (solitary or single) or multiple
What may a generalised distribution indicate?
Symmetrical and generalised distribution tends to be an internal problem
What cutaneous signs are useful in diagnosing meny conditions?
Erythema nodosum
Sarcoidosis
Vasculitis
Malignancy
Auto-immune conditions
What is eruptive xanthoma?
Crops of small, red-yellow papules
Most commonly arise over the buttocks, shoulders, arms and legs but may occur all over the body
Rarely the face and inside of the mouth may be affected
Lesions may be tender and usually itchy
Lesions may resolve spontaneously over a few weeks
Associated with hypertriglyceridaemia (increased triglyceride levels in blood) often in patients with diabetes mellitus
What is Acanthosis Nigricans
Skin disorder characterised by darkening (hyperpigmentation) and thickening (hyperkeratosis) of the skin, occurring mainly in the folds of the skin in the armpit (axilla), groin and back of the neck.
Acanthosis nigricans is not a skin disease per se but a cutaneous sign of an underlying condition or disease.
What are xanthomas?
Xanthomas are skin lesions caused by the accumulation of fat in macrophage immune cells in the skin and more rarely in the layer of fat under the skin.
Some types of xanthoma are indicative of lipid metabolism disorders (e.g. hyperlipidaemia or high blood fats), where they may be associated with increased risk of coronary artery heart disease and occasionally with pancreatitis.
What is acanthosis nigricans associated with?
Associated with insulin resistance, obesity and malignancy
What is Pretibial Myxoedema
Pretibial myxoedema is a form of diffuse mucinosis in which there is an accumulation of excess glycosaminoglycans in the dermis and subcutis of the skin.
Pretibial myxoedema is aka, thyroid dermopathy
It is most commonly seen on the shins (pretibial areas) and is characterised by swelling and lumpiness of the lower legs.
Same process behind thyroid eye disease (mucinosis)
What is topical therapy?
Medication applied to the skin.
vehicle + active component
Give an examples of different topical therapy vehicles
Solution Gel Cream Lotion gel Ointment Foam Paste Spray powder Shampoo
What vehicle may you select for hair treatment?
Foam, gel or shampoo
What vehicle may you select to cover a wide area?
Cream or lotion
What vehicle may you select to cover a more localised area?
Something thicker so doesnt spread
e.g. paste
Give some examples of active component in topical treatment
Corticosteroid Antibiotic Antiviral Dithranol Vitamin analogues Chemotherapy Parasiticidals Coal Tar Anti-inflammatory Salicylic acid
What factors effect the absorption of topical treatment?
Concentration
Base/ vehicle
Partition co-efficient
Thickness and hydration of stratum corneum
Temperature
Skin site (flexor rather than extensor, thin rather than thick)
Occlusion
What are some of the side effects of topical steroids?
- Thinning/ atrophy
- Striae
- Bruising
- Hirsutism
- Telangiectasia
- Acne/ rosacea/ perioral dermatitis
- Glaucoma
- Systemic absorption
- Cataracts
