Skin Flashcards
Skin is the ———&———-
Haviest and largest organ
Acounting for———to ——-of body weight
15 to20%
Presents ——-to——- of the surface area to the eternal environment
1.5 to 2
Skin is composed of
An epithelial layer ectodern in origin
And dense irregular connective tissue which is mesoderm in origin
The junction between epiderms and derms is
Coposed of what
Irregular
Dermal papillae and epidermal invaginations
Functions of the skin
1 protection
2 thermoregulation
3 metabolism
4 sensation
5 regulation of immune responnses
Epiderms is
Which type
Types of cellsits thickness
Epithelium
Stratified sqamous keratinized
The cells are called keratinocytes and langerhans cells merkel and melanocytes
Determines the thickness of the skin
In thin skin its about
And thick
75 to 150
400 to 1400
Layers
1 stratum basale or germinativum
2 stratum spinosum
3 stratum granulosum
4 stratum lucidum
5 stratum corneum
Stratum basale
Type
Its responisble for_____ with the initial part of the next layer
Hemi desmosomes and desmosomes
A single colomunar layer or cuboidal and basophilic rest on basal lamina
Epidermal renewing which takes 15 to 30 days
Hemidesmosomes connect the cells to the basal lamina and desmosomes connect the cells in the layer and upper surfaces
Stratum spinosum
Type of cells
Filled with
That assemble into
The initial part can do
Is the thickest layer
Polyhedral or cuboidal with a central nuclei
Bundles of keratin filaments
Microscopically visble bundles that are called Tonofibrils that converge and teraminate at desmosomes connecting the cells together
The initial part of this layer has highly mitotic ability
Stratum granulosum
How may layers
TYPES
Undergo
Contain
In the last activity of keartinocytes they undergo (lamelar granules)
3 TO 5
Fllatened cells
The terminal differentiation process of keratinization
Basophilic keratohyaline granules and membranous glogi derived lamellar granules ovoid shaped that contain various lipids
Lamellar granules undergo exocytosis formin a immpermiable layer preveting water loss
Stratum lucidum
Types
Between them
Organelles and nuclei
Extremely thin layer of flattened eosiniphilic cells
Desmosomes
They are lost cytoplasm consists of densely packed keratin fillaments
Stratum corneum
Type
Contains
They are also called
15 to 20 layers
Non nucleated keratinized squamous cells
Fibrillar and amorphous proteins and thickened plasma membrane
Horny cells
Langerhans cells are most clearly seen in
Their shape and nucleus
How much
Thier cytoplasm processes extend between
Antigen presenting cells stratum spinosum
Star shaped indented nucleas and clear cytoplasm
2 to 8%
The keration cytes of all of the layers
Merkel cells are
Sensitive to
Joined by ___ to____
Abundant in
The contain——- granules
Are in contact
Epithelial tactile cells (mechanoreceptors)
Light touch sensation
Desmosomes to the cells of basal layer
Sensitive skin such as finger prints and hair follicles
Neurosecretory granules
With expanded terminal discs of unmyelinated sensory fibers
Melanocytes are found in
Stain shape
Attached to basal lamina by
Basal layer and hair follicles
Pale staining round cels bodies with log cytoplasmic extentions
Hemidesmosomes
Skin color
By melanin
Yellow to red (pheomelanin)
Brown to black(eumeanin)
Amount of oxygen
Carotene
Dermis is
Functions
Maximum thick ness
Dense irregular C.T
Supports epiderms and binds it to underlying sub cutaeus tissue
4mm
Layers of dermis
Consists of
Anchoring fibrils
Thin papillary layer
Dermal papillae, collagen type 3 and 1 fibroblasts mast cells ,macrophages
Type 7 collagen binding dermis to epiderms
Reticular layer
Inner layer dense iregular C.T mainly collagen type 1 also elastic fibers
And between them is proteoglycans
Blood v and lymphatic v
For touch and pressure
Pacinian and meissner corpuscles
Skin derivatives
Hair
Sabeceous gland
Seat gland
Nail
Hair is
Elongated keratinized structure derived from epidermis
