Structures of skin: hair follicle Invagination of epidermis Hair contains keratin and melanin Dermal papilla Connective tissue invagination into bulb, has capillary network Matrix Germinative layer adjacent to dermal papilla Also contains melanocytes Sebaceous gland Secretion empties into hair follicle(dermal papilla) Arrector pili muscle bulb Smooth muscle, inserts on hair follicle and base of epidermis
The hair is formed of Shaft: medulla, cortex and cuticle The hair follicle is formed of : Inner root sheath formed of: Cuticle ,Huxleys layer,Henles layer Outer root sheath: identical with Malpighian Layer of epidermis Connective tissue sheath
Structures of skin: hairfollicle Arrector pili muscle Sebaceous gland Dermal papilla
Thick skin vs thin skin Thick skin Palms and soles Thicker epidermis Hairless ,more sweat glands Thin skin Everywhere else Thinner epidermis Hair, sebaceous And sweat glands
Exocrine part Stroma : thin C.T capsule &trabeculae. Parencaima : pancreatic acini ,lined with Pyramidal cells with apical acidophilic zymogen granules and basal basophilic striation. Secrete digestive enzymes via duct system starting by intercalated ducts.
PancreasIntercalated ducts&Centroacinar cells
ISLETS OF LANGERHANS Non capsolated anastomosing cords of cells separated by blood sinusoids Alpha-cells 15-20um, prepheral Secrete glucacone 20 % stain pink with Gomori Beta –cells 10-15um, central in position 60-75%, Stain blue with Gomori stain Secrete insulin
Delta cells 2% Secrete somatostatine which supresses A,B cells and growth hormone secretion PP cells 2% secrete pancreatic polypeptide which is involved in protein and carbohydrate metabolism. Ganglion cells Involved in nervous control of islet functions.