Integumentary system Skin

Integumentary system
Skin
2009
Skin
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Epidermis
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Dermis
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Tela subcutanea
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Hair
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Nails
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Glands
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Mammary gland
Skin
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1,2 – 2,3 m2
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Epidermal ridges and grooves
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Dermal papillae
Melanin
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Synthesis of vitamine D3 - activation
Cell renewal – 15 – 30 days
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Epidermis
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Stratified squamous epithelium keratinized +
melanocytes, Langerhans cells, Merkel cells
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Thick type: palms of hands and soles of feet
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Thin type: other places
Epidermis
Cells of stratum spinosum – synthesis of
acylglucosylceramide – RER + GA = membrane-coating
granules (ot lamellar bodies)
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Bb. stratum granulosum –proteosynthesis = keratohyalin
granules, lamellar bodies release ceramide into the
intercellular spaces
Bb. stratum lucidum – intermediate layer - eosinophilic
Bb. stratum corneum – cells without nuclei, keratin
croslinked by filaggrin, together with ceramide form cell
envelope, cells are joined by desmosomes
Renewal – 15 – 30 days
Cytokeratines in epidermal cells

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Stratum basale – low
molekular weight
cytokeratines CK 18,14, 17
Stratum spinosum –
high molecular weigh
cytokeratines CK 10,
18
Melanocytes

Development from – neural crest

Tyrosine – dopa – dopaquinone – melanin
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Tyrosinase
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Melanosome visible by LM, size 1x0,4 µm
Melanocytes
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Cytocrine secretion – melanosomes are injected
into keratinocytes
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Melanin in keratinocytes – protection from UV
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Melanin unit – approximately 1000/mm2

Higher (two times) in pigmented type of skin
(scrotum, circum-anal region, areola mammae)
Merkel cells

Found in stratum basale, common in thin type of
skin
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Content of dense granules (neurotransmitters)
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Free nerve ending
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Senzoric mechanoreceptors
Langerhans cells
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Present in stratum spinosum of epidermis
From bone marrow - antigen presenting cells –
They differentiate in dendritic cells within
lymphatic nodes (contai of Birbeck granules rodlike)
Melanocytes and Merkel cells
Dermis

Dense collagen connective tissue with elastic
fibres. Main glycosaminoglycan is dermatan
sulphate

Stratum papillare
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Stratum reticulare
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Appendages – glands, nails and hairs
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Senzoric organs (Vater-Paccini and Meissner
bodies, etc.)
Glands
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Sebaceous – holocrine,
compound alveolar
They are not present in
thic type of skin
Excretory duct opens into
the hair follicle
Without hair follicle:
glans penis, clitoris, labia
minora, lip, areola
mammae
Glands

Sweat eccrine glands – Simple coiled tubular glands
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Dark cells– mucoid glycoproteins
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Clear cells – glycogen, basolateral labyrinth – transport of water
and ions
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Duct directly on the surface
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Duct with two layers of cuboid cells
Glands

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Apocrine sweat glands –
axilla, anal region, areola
mammae, modified in ear
(ceruminal) and in eyelid
(Moll)
Secretory part is wider,
ducts open in hair follicle
Hair
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Hair follicle
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Hair bulb (bulbus pili)
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Dermal papilla
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Hair (cuticle of hair, cortex, and medulla)
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Internal (epithelial) root sheat
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External (epithelial) root sheat
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Connective tissue sheat
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Arrector pili muscle
Thick type



Thick stratum
corneum of epidermis
+ Stratum lucidum
Only eccrine sweat
glands
Senzoric ending –
Meissner and VaterPaccini bodies
Axilla

Thin type

Hair follicle

All three types of skin glands
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Sebaceous glands
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Eccrine sweat glands
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Apocrine glands
Skin from abdomen

Thin type
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Hair follicles

Sebaceous and sweat glands

Thick hypoderm – adipose tissue
Scrotum

Thin type
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Pigmentation in stratum basale - melanocytes
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Smooth muscle cells in dermis
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Thin type

Many hair follicles

Sebaceous and eccrine
sweat glands
Mamma


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15-20 compound tubo-alveolar glands
Ducts = lactiferous ducts → lactiferous sinuses
→ nipple (mammary papilla) and areola
Lobes → lobules →glandular alveoles
surrounded by dense connective tissue and
adipose tissue
Lactation

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Estrogenes, progesterone, prolactin and placental
lactogen – growth and differentiation of secretory ducts
Nerve stimulus – oxytocin – contraction of
myoepithelial cells – rejection of milk
Colostrum nad Milk –

Proteins – merocrine secretion
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Lipids -apocrine secretion
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Sugar (lactosa) production in GA
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Immunoglobulins (IgA) -plasma cells
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Decrease of prolactin level – apoptosis - regression