Integumentary System Flashcards
Integumentary system basics
Largest organ
4-5kg
1.2-2.2m^2
7% of body mass
Mostly 1-2mm thick
Thick skin - palms and soles (4-6mm)
Thin skin - hair follicles, sweat glands, sebaceous glands
Microbiome
Sloughing
Shedding dead surface cells
Circa 50,000 lost per minute
Outer layer replaces every 21-45 days
Epidermis - keratinocytes
Born deep in epidermis - basal layer
Produce keratin
Epidermis - melanocytes
Deepest layer of epidermis
Secrete melanin which is protective and transported to the keratinocytes to protect them from the sun
Epidermis - merkel cells
Specialised sensory cells
Light touch/textures
Epidermis - dendritic cells
Ingest invaders and foreign material
Antigen presenting cells
Activate immune defences of body
Epidermis layers - stratum basale
Deepest layer
One row off actively mitotic stem cells
Some cells become part of superficial layers
Some melanocytes and Merkel cells
Epidermis layers - stratum spinosum
Several layers of keratinocytes
Unified by desmosomes
Contain thick bundles of intermediate filaments made of pre-keratin
Epidermis layers - stratum granulosum
One to five layers of flattened cells
Organelles deteriorating
Lamellar granules (releasing lipids)
Keratohyaline granules
Epidermis layers - stratum corneal
Most superficial layer
20-30 layers of dead cells
Flat membranous sacs filled with keratin
Glycolipids in extracellular spaces
Dermis layers - papillary layer
Made of areolar connective tissue
Interlaces with collagen and elastic fibres
Phagocytes move freely
Papillary layer - dermal papilae
Peg like projections indent the epidermis
Increase SA for diffusing nutrients
Enhance sense of fine touch
Increase sensitivity of nerve endings
Dermis layers - reticular layer
Made of dense irregular connective tissue
Thick bundles of interlacing collagen fibres to create a thick, tough layer
Sweat glands - eccrine
Temperature control
Antibacterial properties
Secretion - hypotonic filtrate of blood plasma
Exit duct at skin surface
Location - everywhere, especially palms, soles, forehead
Sweat glands - apocrine
Sexual scent glands
Secretion - filtrate of blood plasma with added proteins and fatty substances
Exit duct at the upper part of hair follicle
Location - axillary and anogenital regions