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