Structure and Function of Skin Flashcards
Skin - Fxns
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Barrier Thermoregulation Convey somatosensory information from environment to nervous system Immunologic - antigen presentation Endocrine Excretion
Epidermis - Characteristics and components
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Keratinized stratified squamous epithelium
from Ectoderm
Avascular
Composed of kerationocytes, melanocytes and Langerhen’s cells
Dermis - Characteristics and components, origin
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Dense irregular connective tissue
from Mesoderm
imparts mechanical support
Hypodermis - Characteristics and components, origin
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Variable amounts of lobules of adipose tissue seperated by connective tissue
Insulates and provides energy
Thin skin v Thick skin
hair follicles NOT in thick skin
Thick - adapted for great amount of abrasion e.g. palmar
Stratum Basale - a.k.a, desc, fxn, components
SB - Germinativum
Stem cells on basal lamina
Give rise to to keratinocytes
includes Keratinocytes & Melanocytes
Keratinocytes - fxn
Form physical and chemical barrier of skin
through production of cytokeratin proteins which organize as intermediate filaments
Melanoctyes - location, fxn, origin
in SB
Synthesize melanin pigment from the amino acid tyrosine
Neural crest derivatives
Stratum Spinosum
cell layers w/ desmosome at ends forming attachment between adjacent cells.
Stratum Granulosum
thin layer, w/ intense basophilic (dark staining) as result of keratohyalin, a precursor to filaggrin - which bundles keratin filaments in SC.
Stratum Corneum
lucidum
most superficial layer
No Nucleus or cell organelles in cells. only keratin.
Water proofing in skin
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At base of SC.
by complex arrangement of submembrane proteins and lipids secreted from lamellar bodies from stratum granulosum keratinoctyes
Life progression of Keratinocyte
- Basal Cell
- Spinous Cel
- Granule Cell
4 Stratum corneum
5.
Stage 1- keratinocyte progression
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Basal cell synthesize intermediate filaments( keratin), which bundles together as Tonofilaments. => Spinous layer
Stage 2 - keratinocyte progression
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Spinous layer make keratohylain granules and lamellar bodies
Stage 3 - keratinocyte progression
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Granule Cell layer makes Keratohyalin granules and lamellar bodies.
Secreted by exocytosis into extracellular space btwn SG and SC
Stage 4 - keratinocyte progression
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Stratum Corneum cells are Keratinized
Stage 5 - keratinocyte progression
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pH decrease controls desquamation of cells Protease molecules lead to digestion and detachment of most superficial layer of SC
Filagrin - fxn, origin
Bundles Keratin filaments in SC.
precursors are keratohylanin granules
Melanocyte - fxn, action, origin
formation of melanin pigment and secretion into keratinocytes
neural crest
Langerhans Cells - def, origin
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Antigen presenting cell in epidermis
derived from Bone Marrow - part of mononuclear phagocytic system
Dermal Papillae
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Fingler-like extension in dermis projecting into epidermis
accomadate mechanical stress/increased abrasion forming pattern on hands and feet
Dermis Layers
Papillary Layer
Reticular Layer
Dermis - cellular components
Fibroblasts
Lymphocytes, mast cells, macrophages and graanulocytes
Langerhan cells
Dermis - EC components + other components
Collage fibers (type 1) Elastic Fibers
Blood vessels
Muscle - Arrector pili mm
Nerves and Sensory receptors
Meissner Corpuscles (MC) - def, location **
touch receptor
low frequency stimuli
in dermal papillae
Pacinian Corpuscles - location, def
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Dermis
Sensitive to vibration an deep pressure
Autonomic motor nerves in skin innervate …
Blood vessels, arrector pili muscle, and glands
Eccrine Glands - def, nervous regulation, components
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Simple coiled tubular glands
Autonomic Cholinergic innervation for temperature regulated sweat
Andergenic innervation for emotional related secretion
Contains Myoepithelial cells which cause rapid excretion from sweat gland when contracted
Apocrine Sweat Gland - def, locations, characteristics**
Simple coiled tubular and branched tubular gland w/ dust reaching skin through hair follicle
specific to axilla, inguinial and perianal areas
active at puberty, affected by pheromones
Majorhistocompatabilty complex (MHC) within define scent and composition of secretions
Sebaceous Gland - def, characteristics
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Outgrowth from epithelium that gives rise to hair
Contains oily sebum
Cause acne when fat (skin irritant) in sebum broken down by bacteria
Temperature regulation
Eccrine sweat glands and blood vessels
if hot, more seat and vasodilation
Epidermal cancers
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Basal Cell Carcinoma - does not metastasize
Squamous Cell Carcinoma - can metaztasize if basement membrane disrupted
Malignant Melanoma - SERIOUS
Skin Repair
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Primary Union (least severe) Secondary Union --Dermal Repair --Epidermal Repair Skin graftin (for major damage)
