Integumentary System Main functions Organs/parts/cells and their functions Diseases and disorders
Main functions Multiple roles in homeostasis(e.g. temperature change, dehydration) Protects against invasion of infectious organisms, sunburn Protects the body’s internal tissues and organs Maintains the body’s form Generates vitamin D Stores fats, water, glucose and vitamin D
Skin Its your bodys largest organ Average surface area 1.8-2.0m² (19.4-21.5ft² ) Releases around three gallons of sweat in a hot day There are at least five types of receptors in the skin thatrespond to pain and to touch White skin appeared just 20,000 to 50,000 years ago, asdark-skinned humans migrated to colder climes and lostmuch of their melanin pigment.
Three layers or structures of the skin Epidermis Dermis and hypodermis Sweat and oil glands; hair and nails
Cells of epidermis 95% cells are keratinocytes Major function is the defense against environmental damage(pathogens, heat, UV radiation and water loss) Melanocytes ( melanin-producing cells ) Langerhans cells (antigen-presenting immunecells) Merkel cells (oval receptor cells ) Inflammatory cells (a cell participating in theinflammatory response to a foreign substance. )
First and last layers of epidermis basal/germinal layer Cell growth of keratinocytes, attached to basementmembrane. Melanocytes and Merkel cells also can be foundin this layer. cornified layer Keratinocytes are presented at final step of differentiation(corneocytes), surrounded by keratin proteins envelope. Mostof the barrier function are here
DermisTwo layers: Stratum papillare and Stratum reticulare
Stratum papillare This region is composed of loose connective tissue withnetwork of blood capillaries and Meissners corpuscles(type of mechanoreceptors sensitive to light touch) Stratum reticulare Is composed of dense irregular connective tissue withcollagen, elastic and reticular fibers (strength, extensibility,and elasticity)
Hypodermis orsubcutaneous tissue In hypodermis fibroblasts, adipose cellsand macrophages can be found Is used mainly for fat storage In arthropods, the hypodermis is an epidermallayer of cells that secretes the chitinous cuticle
Sebaceous Glands Secrete an oily/waxymatter, called sebum,to lubricate andwaterproof the skinand hair Greatest abundance onthe face and scalp
Sebaceous Glands Diseases Acne Hyperplasia - disorder of the sebaceousglands in which they become enlarged Sebaceous cysts Sebaceous adenoma - a slow-growing tumour Sebaceous gland carcinoma -aggressive malignant cutaneous tumor
Apocrine glands produce a viscous andodorous secretion.They begin secreting atpuberty discharge in the canalsof hair follicles may alsocontain pheromones
Eccrine glands smaller than apocrinesweat glands, andthey do not extend asdeep into the dermis discharge theirsecretions directlyonto the surface ofthe skin• highest density (>250 glands/cm2) being on soles,palms, and scalp
Sweat Glands Diseases Hidradenitis - The inflammation of asweat gland (usually of the apocrine type) Hyperhidrosis - Excessive sweating Hypohidrosis - diminished or absentperspiration Miliaria - A syndrome of cutaneouschanges associated with sweat retentionand extravasation of sweat at differentlevels in the skin.
Ceruminous glands specialized sweat glands located in hypoderm drain into the guard hairs produce cerumen, or earwax, by mixing their secretion with sebum and dead epidermal cells
Ceruminous glands diseases Benign tumors (e.g. ceruminous adenoma - tumour of the external auditory canal in adults, 1% of all external ear tumors) Malignant tumors (e.g. Mucoepidermoid carcinoma - most common type of malignancy in adults. Can also be found in other organs, as bronchi, lacrimal sac and thyroid.
Mammary Glands An organ in women that produces milk Milk is produced by cuboidal cells surrounded by myoepithelial cells – thin layer above the basement membrane
Mammary Glands Diseases Fat necrosis - firm nodule in the breast Fibrocystic change - most common disorder Gynecomastia - bilateral breast enlargement in the male Fibroadenoma: most common benign tumor Breast cancer - most common type of cancer in women
Some other common SkinDiseases Melanoma Eczema Otitis Externa Skin Cancer
Hair facts The fastest growing tissue in the body 90% of scalp hairs are growing and 10% are resting Female hair grows more slowly Lifespan of hair: 2 to 7 years A single hair has a thickness of 0.02 - 0.04mm The average scalp has 100,000 hairs It is normal to lose 100 hairs per day from the scalp A single hair can support up to 100 grams in weight and a whole head of hair could support up to 12 tonnes - the equivalent of two African elephants!
Hair Parts the hair root the hair shaft Hair is composed primarily of proteins (88%). These proteins are of a hard fibrous type known as keratin.
Hair root Is surrounded by a pouch like structure called hairfollicle The terminal part of the hair follicle is called a hairbulb (formed by actively growing cells )• consist of: • Fibrous connective tissue• External/internal root sheath
Hair root At the base of each hair bulb is the dermalpapilla containing a vessel tuft (essential for the nourishment of the growing hairs). Melanocytes – produce pigment melanin. Receptors for the male hormones - androgens, are located on the cells of this structure.
Hair shaft The newly divided hair cells in bulb push the previous cells up. The cells, which move upwards, die slowly forming hard hair shaft. Has three layers: Cuticle Medulla Cortex
Hair diseases and disordersMainly associated with the follicles ofthe hair Hypertrichosis - an abnormalamount of hair growth on the body Alopecia Areata - one of the mostprevalent hair loss diseases
Nails Actually the same as hair Nails grow at the rate of 0.1 mm daily Womens nails grow slowly Toe nails are about twice thicker than finger nails The fastest growing nail is on the middle finger.The slowest – on the thumbnail Nails reflect your health status
(I) Nail structure 6 parts: The root (germinal matrix) - produces most of thevolume of the nail and the nail bed. Nail bed (sterile matrix) - part of the nail matrix.Contains the blood vessels, nerves, and melanocytes.Adds material to the undersurface of the nail making itthicker Nail plate - actualfingernail, made oftranslucent keratin
(II) Nail structure 6 parts : Eponychium (cuticle) – fuseskin and nail plate, providingwaterproof barrier Perionychium (paronychialedge) - the skin that overliesthe nail plate on its sides Hyponychium -the areabetween the nail plate and thefingertip
Nail diseases Fungal infection(Onychomycosis) Beaus Lines Nail Lifting (Onycholysis) Nail Splitting(Onychoschizia) Bacterial infection(Paronychia)
Integumentary System Functions Multiple roles in homeostasis(e.g. temperature change, dehydration) Protects against invasion of infectious organisms, sunburn Protects the body’s internal tissues and organs Maintains the body’s form Generates vitamin D Stores fats, water, glucose and vitamin DSkinHairNail