Structure and Function 3 & 4 Flashcards
What is the DEJ?
A semi-permeable membrane acting as a barrier and filter and has a key role in epithelial-mesenchymal interactions
What are the epithelial-mesenchymal interactions the DEJ is involved in?
support, anchorage, adhesion, growth and differentiation of epidermal cells
In the DEJ where are hemidesmosomes found? What is their role?
Found in the basal cells and their role is to keep the DEJ together
What are the other layers of the DEJ? From directly beneath the basal cells downwards
lamina lucida
lamina densa
sub-lamina densa zone
What are inherited diseases of the DEJ? Give some examples
Skin fragility conditions due to a mutation in one of the proteins in the DEJ
Epidermolysis bullosa simplex (EBS) or dystrophic (EBD)
What are acquires diseases of the DEJ? Give some examples
Auto-antibodies to proteins in the DEJ
Dermatitis herpetiformis, pemphigoid
What are the components of the dermis?
Fibroblasts Macrophages Langerhans cells Mast cells Ground substance Blood vessels, lymphatics, nerves
Does the epidermis have a blood supply per se?
No. Blood flows through the dermis into the epidermis
In skin, where are lymphatic vessels found?
Sub-epidermal meshed networks
What is the important immune function of lymph vessels?
Immune surveillance by circulating lymphocytes and Langerhans cells and the channelling of micro-organisms
What kinds of nerves are there in skin? And what do they sense?
Somatic sensory (dermatomes):
Free nerve endings
Special receptors : Pacinian (pressure) and Meissners (vibration) corpuscles
Autonomic nerve supply:
blood vessels, nerves and glands
Where are the largest pilosebaceous units found?
face and chest
found as “lobules” of sebaceous glands
To what substance are pilosebaceous units sensitive to?
Hormones - quiescent pre-puberty
What is contained in the sebum that is secreted by the pilosebaceous units?
squalene
wax esters
triglycerides
free fatty acids
Where do pilosebaceous units open on to?
Hair follicles
Give the functions of pilosebaceous units.
Control moisture loss
protection from bacterial and fungal infection
Where are apocrine glands found?
axillae and perineum
What are apocrine glands dependent on?
androgen
What do apocrine glands do?
produce oily fluid which gives the odour after bacterial decomposition “scent glands”
Where are eccrine glands found?
Whole skin surface esp. palms, soles and axillae
What are the functions of eccrine sweat glands?
Control moisture loss
Moisten alms/soles to aid grip
What stimulates the eccrine sweat glands?
sympathetic cholinergic nerve supply –> mental, thermal and gustatory stimulation
What are the 6 main functions of the skin?
Barrier Thermoregulation Communication Sensation Immune defence Metabolic
What are the consequence of failure of the barrier function of skin?
fluid loss –> dehydration
Infection
Protein loss –> hypoalbuminaemia
What is the consequence of failure of the thermoregulation function of skin?
Heat loss –> hypothermia
What is the consequence of failure of the immune function of skin?
Spread of bacteria, infection
If the metabolic function of skin stopped working, what would happen?
disordered thyroxine metabolism
If you are unable to display healthy skin, what may this lead to?
Stigma
What are the 3 categories of external things that the skins barrier function can stop?
Physical
Chemical
Pathogens
What metabolic processes is the skin involved in?
Vitamin D metabolism (7-dehydrocholesterol –> Vitamin D3 when UV light is present)
Thyroid hormone metabolism (thyroxine T4 –> triiodothyronine T3)
