The Integumentary System. Integumentary System Includes the Skin, Hair & Nails.
Integumentary System
description
Transcript of Integumentary System
Integumentary System
Integument(Skin) Integument is nothing
but the skin. Integument(=to cover in
latin Skin and its appendages
are the largest organ of the body
Functions:1. Protection2. Heat regulation3. Sensation4. Synthesis and storage
of Vit D
Integumentary systemSkin along with the exocrine
gland(sebaceous gland
HairNailsAssociated blood
vessels and Associated nerves Comprise
integumentary system
SkinSuperficial epidermismiddle dermisDeep
hypodermis(superficial fascia)
EpidermisSuperficial layer
composed of keratinized stratified squamous epithelium
Avascular with no blood vessels or lymphatics
Has basal cells which has regenerative capacity
Thick skin has 5 layers of cells
Thin skin has 4 layers of skin
DermisMiddle layer
composed of Dense irregular connective tissue
Contains nerve endings,hair follicles, and glands
They nourish the avascular epidermis
Contains dermal papillae(projections of dermis into epidermis)
Langer(incision or tension) lines in skin
They are the direction in which the most collagen fibres run in any particular location in the skin.
Incision should be made parallel to the direction to avoid minimal scarring.
HypodermisDeepest layerStores fat and anchors
upper layers to other tissues
Composed of areolar and adipose connectieve tissue
Epidermal layersFrom base to topStratum basaleStratum spinosumStratum granulosumStratum lucidumStratum corneum
Stratum basaleSingle layer of columnar or cuboidal cells
resting on basement membraneThe epidermis is renewed every 15-30
days; proliferative activity takes place in this layer; cells are very mitotic
Stratum spinosumseveral layers of polygonal shaped cells
with spines.Spines are nothing but keratin filaments.It resists the effects of abrasion and the
layer is thicker in thick skin which is subjected to continuous friction and pressure(eg: soles and palms)
Stratum granulosum3-5 layers of flattened polygonal cells with
visible granulesCells undergo keratinization which is a
process in which nucleus shivels up, cells dies, and cell fills up with protein keratin
This layer acts as a barrier to penetration by foreign materials and provides sealing effect
Stratum lucidum2-3 layers of dead, anucleated, clear cells.
Only found in thick skin
Stratum Corneum20-30 layers of dead, anucleated cells.They are cornified( brittle, hardened).
These outer cells are constantly shed
Epidermal cellsKeratinocytes: most numerous(90%);found
in all layers; produces keratin which provides the protective barrier mechanically as well as immunologically
Melanocytes: 2nd most numerous(8%);found in stratum basale;produces melanin which is a photoprotector
Epidermal cellsMerkel cells: 3rd numerous(1%) found in
stratum basale;provides tactile(light touch) sensation
Langerhans cells: <1% found in stratum spinosum; phagocytic action
Dermal layersPappillary Layer: uppermost; composed of dermal papillae; contatains blood vessels, sensory receptors, ducts of glands; and hair shafts
Reticular Layer: deepest;contains blood vessels; sensory recptors(neurons); secretory poertions of glands and hair follicles
Epidermal derivatives(skin appendages)
Hair : contains bulb, root and shaft ; associated with arrector pili muscle; functions to protect UV light, trauma, and heat loss
Nails : formed from stratum corneum ; functions in protection and grasping
Exocrine Glands: 1. Sebaceous glands2. Sweat (sudoriferous) glands3. Ceruminous
Exocrine glands in skin
Sebaceous glands(sebum=oil):associated with hair follicles and functions in lubrication and bactericidal
Sweat(sudoriferous) glands: appocrine: in axiallary and pubic regions,
secreates onto hair shafts and release an odiferous secretion
Eccrine : found everywhere, funtioning to release perspiration
Ceruminous: modified sweat glands ; found in external auditory canal; cerumen is an insect repellent and a water proofing agent