Skin
Characteristics of Meissner's corpuscle receptor
-Tactile receptors -Located directly under epidermis, found under papillae -Contain Schwann cells and unmyelinated endings of nerve fibers
Characteristics of epidermal layer stratum corneum
-Top wispy layer - surface continuously sloughed off -Lack organelles and nuclei -Varies in thickness in different body parts
3 layers of skin
1) Epidermis (outermost layer) 2) Dermis 3) Hypodermis (innermost layer): Subcutaneous fat
3 types of cutaneous burns
1) First degree +Superficial epidermis burned +Stratum basale remains viable 2) Second degree +Epidermis and superficial layer of dermis burned +Fluid links from venules, in thin skin blistering between epidermis and dermis 3) Third degree +Epidermis and dermis destroyed +Graft necessary
3 types of secretion by sweat glands
1) Holocrine - lose whole cell +Occurs in sebaceous gland 2) Merocrine - lose contents of cell 3) Apocrine - lose/pinch off part of cell +Associated with hair follicle
4 types of epidermal cells
1) Keratinocytes 2) Melanocytes 3) Langerhans cells 4) Merkel's cells
2 layers of dermis
1) Papillary layer - loose connective tissue that nourishes epidermis 2) Reticular layer - dense irregular connective tissue
4 major skin functions
1) Protection - against UV; infection and mechanical, chemical or thermal insults 2) Sensory - has nerve receptors for touch, pressure, temperature, pain 3) Barrier - against water loss and for thermoregulation 4) Synthesis - of vitamin D and melanin
4/5 layers of epidermis
1) Stratum basale 2) Stratum spinosum 3) Stratum granulosum 4) Stratum lucidium (thick skin only) 5) Stratum corneum (wispy)
Characteristics of skin circulation
-2 plexuses (shunts) connected by arteriovenous anastomoses +1) Papillary plexus between papillary and reticular dermis layers +2) Cutaneous plexus between dermis and hypodermis
Characteristics of epidermal layer stratum granulosum
-3-5 cell layers -Has numerous dense keratohyalin granules -Have lamellar granules as a barrier and to provide sealant effect -Organelles and nuclei disappear
Characteristics of epidermal layer stratum spinosum
-Active in keratin filament synthesis -Thickest part of epidermis -Cytoplasm filled with keratin bundles - tonofilaments -Have desmosomes & adherens -Give spiny appearance (desmosomes) -Contains Langerhans cells -Much smaller layer in thin skin
ABCD changes in moles for melanoma
-Asymmetry of moles -Border irregular -Color varied -Diameter larger 6mm
Characteristics of secretory eccrine sweat glands
-Contain Clear cells which pump Na to lumen -Dark cells (can't see under LM)
Characteristics of langerhans epidermal cells
-Dendritic cells -Macrophages -Antigen-presenting cells -Derived from bone marrow -Represent 2-8% of cells (don't identify) -Found in (middle) stratum spinosum -Contain Birbeck granules
Characteristics of thick skin
-Epidermal thickness of 400-1500 um -Distinct stratum lucidium -Prominent stratum corneum -Found only on palms and soles of feet -Don't have hair follicles or sebaceous glands -Have sweat glands
Characteristics of thin skin
-Epidermal thickness of about 50-150 um -Lacks stratum lucidium -Small stratum corneum -Found everywhere but palms and soles of feet -Has hair follicles and sebaceous glands
Organization of skin
-Epidermis is keratinized stratified epithelium -Skin has appendages (e.g. nails) - don't visualize -Has hair and arrector pilli muscles for hair to stand on end -Has sweat glands -Have thick and thin skin
Characteristics of dermis layer
-Has elastic fibers -Ducts found throughout dermis to get access to surface
Characteristics of skin nerve supply
-Have encapsulated nerve endings -Has 2 types of receptors (to identify) 1) Pacinian corpuscle 2) Meissner's corpuscle
Characteristics of excretory eccrine sweat glands
-Have narrow lumen -Made of stratified cuboidal epithelium
Characteristics of epidermal layer stratum basale
-Layer next to dermis -Highly mitotic -Contain stem cells, Merkel's cells & melanocytes -Have desmosomes & hemidesmosomes -Has Meissner's corpuscles
Characteristics of apocrine sweat glands
-Located in axilla & genitalia becoming active at puberty -Large lumen surrounded by cuboidal epithelium and myoepithelial cells -Produce milky secretion that gets accessed by bacteria to produce BO -BO produced by bacteria acting on lipids in apocrine gland secretion -Secrete via hair
Characteristics of holocrine glands
-Located only in thin skin & associated with hair follicles -Secrete oily sebum -Discharge entire cell with secretion -Sebaceous gland is a holocrine gland -Cause acne when sebaceous lost and clogs to get pimple +White head - if stays below surface +Black head - if ruptures through surface
Characteristics of melanocyte epidermal cell
-Make melanin which protects against UV -Derived from neural crest -Can become cancerous to produce melanoma -Circular cells with halo around them -Basally located - found in stratum basale
Characteristics of Merkel's epidermal cells
-Neuroendocrine cell -Mechanoreceptor -Associated with sensory nerve endings -Minor (don't need to identify) -Derived from neural crest -Basally located in stratum basale
Functions of skin circulation
-Nutrition of skin and appendages -Increased blood flow for heat loss in heat -Decreased blood flow to minimize heat loss in cold
Characteristics Pacinian corpuscle receptor
-Onion looking -Pressure and vibration receptors -Located between dermis and hypodermis -Struture - Myelinated nerve ending surround by capsule
Characteristics of epidermal layer stratum lucidium
-Only in thick skin -Translucent thin layer -Extremely flattened cells -Lack nuclei and organelles
Function of keratinocyte epidermal cells
-Participate in epidermal water barrier -Outer layer sheds continuously
Suntanning to melanoma
-Phytochemical reaction darkens melanin which rapidly releases to keratinocytes -Rate of melanin synthesis increases in sun
Characteristics of keratinocyte epidermal cells
-Predominant cell type -Make keratin -Keratin is an intermediate filament -All joined by desmosomes -Found throughout all skin layers
Characteristics of eccrine sweat glands
-Secretes watery fluid secretion by exocytosis -Distributed over entire body except lips and genitalia -Most abundant on foot - 620/cm2 -Least abundant on back - 64/cm2 -Important for thermoregulation -2 portions - secretory and excretory
Function of melanocyte epidermal cells
-Synthesize melanin in oval shaped organelles - melanosomes +Tyrosine converted to dopa via tyrosinase enzyme and then to melanin -Racial differences +Melanocyte # same in all races +Melanosome #, size and transfer to keratinocyte varies with race +Difference in how melanin packaged and maintained