Skin structure and function 4 Flashcards
name 6 functions of the skin
barrier metabolism/detoxification thermoregulation immune defence communication sensory function
what is acute skin failure?
loss of cohesion between epidermis and dermis (usually due to a drug)
what are the negative consequences of acute skin failure?
loss of moisture/fluid through the skin
loss of heat causing hypothermia
loss of proteins and electrolytes (e.g - low albumin causing swelling, jaundice, illness etc)
what is erythroderma?
not a diagnosis, just a term for red skin
what are the consequences of erythroderma?
loss of heat and proteins
loss of infection barrier leading to higher infection risk
consequence of loss of barrier function?
fluid loss = dehydration
protein loss = hypoalbuminaeia
infection
consequence of loss of thermoregulation function?
heat loss = hypothermia
consequence of loss of immune defence function?
spread of infection
consequence of loss of metabolic function?
disordered thyroxine metabolism
consequence of loss of communication function?
inability to display healthy skin > stigma
consequence of loss of sensation function?
pain sensation
the epidermis acts as a two way barrier against what 3 categories?
physical (trauma)
chemical (irritants, allergens etc)
pathogens (bacteria etc)
what is steroid - sulphatase deficiency X-linked ichthyosis?
don’t have normal lipids in keratin resulting in dry scaley skin
how does cumulative irritant hand dermatitis occur?
exposure to irritant over time (can vary to days to weeks) results in dermatitis (skin inflammation etc)
E.g - washing dishes every day
which wavelength of light has deeper penetration in the skin?
longer wavelengths
which wavelengths of light cause quicker damage (e.g sunburn)?
shorter wavelengths (UV rays) longer wavelengths require repeated exposure for longer time to cause damage
ratio of melanocytes to basal cells?
1:10
how does melanin protect against skin cancer?
creates a cap on top of basal cells and absorbs UV rays to protect DNA in the cell nuclei
what type of metabolism occurs in the skin?
Vit D metabolism
thyroid hormone metabolism
defence against chemicals, drugs etc
how is Vitamin D synthesised in the skin?
UV rays convert cholecalciferol (vit D precursor) to Vitamin D3
occurs in epidermis
what happens to vitamin D once synthesised?
stored as hydroxycholecalcefirol in liver
converted to 1,25 hydroxycholecalcefirol in kidney which increases calcium absorption and promotes bone mineralization
how is thyroid hormone metabolised in the skin?
thyroxine (T4) converted to triiodothyronine
only 20% occurs in liver
80% in other tissues like skin
how does skin control temperature?
vasoconstriction/dilation
sweating
hair
what are the parts of the skins immune defence function?
Langerhans cells
T cells
epidermis and dermis interact
what is the skins immune function used for?
protect against infection, sunlight and allergens
what are the 2 types of immune response in the skin?
non-specific
specific (to antigens which have been encountered before and established immunity)
give examples of diseases which can occur if the non-specific response in the skin fails?
crusted scabies
tuberculoid leprosy (hansens disease
eczema herpeticum?
lupus?
what are the social and communication effects of skin conditions?
visual changes
odour
influence on sociosexual behaviour
do skin conditions actually affect life opportunities?
yes - acne is associated with unemployment
due to employer prejudice and effects of acne on feelings of self worth
give 4 sensory functions of the skin
touch, pressure, vibration
pain and itch
temperature
nerve endings/receptors on skin
