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
Sweat glands - sebaceous
Lubricate skin and hair
Helps prevent water loss
Antibacterial properties
Secretion - sebum (oily)
Exit duct at upper part of hair follicle, sometimes at skin surface
Location - everywhere except palms and soles
Skin functions - protection (physical barrier)
Stratum corneum - multiple layer of dead cells
Acid mantle and chemicals ward off bacterial invasion.
Water resistant glycolipids blocks water-soluble substances
Skin functions - protection (chemical barrier)
Low pH - acid mantle stops bacteria
Dermcidin in sweat and bacterial substances in sebum kill bacteria antibiotics - defensins
Wounded skin releases cathelicidins to prevent infection
Melanin provides shield to prevent UV damage
Skin functions - temperature regulation
Increase - vasodilation, eccrine sweat glands
Decrease - vasoconstriction, erector pilli, muscle contraction
Skin functions - cutaneous sensation
Receptors - respond to stimuli
Meissner’s corpuscles - sensory nerve endings, aware of caresses
Pacinian corpuscles - deep pressure
Hair follicle receptors - vibrations
Free nerve endings - senses painful stimuli
Skin functions - non-verbal communication
Blushing - vasodilation, increase blood flow, cooling, emotions
Pheromones - apocrine sweat glands secrete oily substances during sexual moments
Body odour/stress odour
Thick, non-hairy skin - stratum lucidum
Thin
Translucent
Superficial to the stratum granulosum
2-3 rows of flat dead keratinocytes
Thickens skin
Contains eccrine sweat glands
Skin colour - haemoglobin
Pinkish hue
Crimson pigment in erythrocytes
Dermal capillaries
Skin colour - melanin
Reddish yellow to brownish black
Transported by melanocytes to keratinocytes to protect them
Skin colour - carotene
Yellow to orange pigment found in plant
Converts into vitamin A in the body which id essential to normal vision and epidermal health
Abnormal colouration - cyanosis
Poor circulation
Abnormal colouration - jaundice
Liver disease
Bilirubin
Abnormal colouration - pallor
Blood diverted to internal organs
White sheet
Abnormal colouration - albinism
Lack of melanocytes
Abnormal colouration - Haematoma
Breakdown products of haemoglobin
