The Skin

Functions:

Barrier & defence (keratinised surface limit H2O loss/pathogens, immune cells (Langerhans) detect threats)

Temp. Regulation (sweat glands & changes in blood flow to skin to regulate heat loss)

Sensation (Merkel cells, Hair follicle afferents, Free nerve endings, Ruffini endings, Meissner & Pacinian corpuscles)

Vit D production (UVB trigger synthesis from cholestrol precursor, NB 4 absorb Ca2+ & Phosphorus 4 healthy bones)

Selective Absorption (intact skin limit entry but Transdermal Drug Delivery Systems- inject into Hypodermis (Adipose tissue). Transdermal patches- fat soluble drugs diffuse thru fatter layer into dermis & enter b.vessels there)