Skin Structure and Function 3 Flashcards
what is the dermo-epidermal junction?
interface between epidermis and dermis which holds them together
what is the role of the dermo-epidermal junction?
support/adhesion of basal cells
semi-permeable membrane so allows blood to diffuse across layers
what are the 3 layers of the dermo-epidermal junction?
lamina lucida
lamina densa
sub-lamina densa zone
give an example of what can happen if the dermo-epidermal junction fails?
bullous pemphigoid epidermolysis bullosa (problem with protein)
what problems can arise with the dermo-epidermal junction?
can have antibodies against the junction which can be shown by immunofluorescence
what is ground substance in the dermis?
collections of proteins that give structure to the dermis
what is contained within the dermis?
ground substance
cells - fibroblasts, macrophages, mast cells, lymphocytes, langerhans
fibres - collagen and elastin
muscles, vessels, lymphatics, nerves
what changes happen in the dermis to cause aging?
disordered collagen
disordered, broken up elastin
describe blood flow in the skin
horizontal plexuses
arteriole > precapillary sphincters > arteriole > venous capillaries > post-capillary venules > collecting venules
what are the 2 plexuses in the skin and what do they supply?
deep vascular plexus supplies the hair follicle
superficial vascular plexus just below epidermis
what is angioma?
benign overgrowth of blood vessels
disordered, not well formed blood vessels
describe lymphatic vessels in the skin?
sub-epidermal mesh networks/plexuses which continuously drain plasma proteins, cells and excess interstitial fluid
smaller non-contractile vessels > larger contractile lymphatic trunks
what are the immune functions of lymphatic vessels in the skin?
immune surveillance by circulating lymphocytes and Langerhans cells
channelling of micro-organisms and toxins
what is chronic lymphoedema?
increased pressure on lymphatic system (obesity/infection etc) means muscles cant pump the fluid back up and it gathers in lower limb
what nervous system controls sebaceous glands and arrector pili muscle?
autonomic
what senses deep pressure?
pancinian corpuscles
what is neurofibromatosis?
overgrowth of nerve endings causing multiple tumours
what is the function of sebaceous oil?
lubricates hair and stops bacteria entering the follicle
what causes whiteheads and blackheads?
whitehead = oil covered with skin so doesn’t oxidise
blackhead = oil oxidises and turns black
both result in inflammation and infection of pore
what are the 3 types of gland in the skin?
sebaceous
apocrine
eccrine
what do sebaceous glands do?
hormone sensitive secretion of sebum opening into pilary canal
most in face and chest
what is the function of sebum?
controls moisture loss
protects from infection (mainly fungal)
what do apocrine sweat glands do?
androgen dependant glands that produce oily fluid in axillae and perineum
where are eccrine sweat glands found?
whole skin surface but palms, soles and axillae in particular
what innervates eccrine sweat glands and what is the implication of this?
sympathetic cholinergic innervation
therefore stress, heat and spicy foods can activate them
what is the function of eccrine sweat glands?
cool by evaporation
moisten palms and soles to aid grip
ultrafiltration function as they secrete hypotonic fluid by reabsorbing NaCl and HCO3
