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70 Cards in this Set
- Front
- Back
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What does integument mean? |
Covering-- encompasses the skin and its appendages |
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What is the skin continuous with? |
Mucous membranes of oral, nasal cavities and anal canal |
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What is the largest organ in the body? |
Skin-- Weighs about 20 pounds or 16% of total body weight, 2800 square inches |
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Main function of the skin |
Protection from external pathogens and UV radiation |
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Other functions of the skin |
Temperature regulation, excretion (sweat glands), sensory reception, secretion (sebaceous glands, mammary glands), communication/emotional expression |
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The two layers of the skin and what they are made of |
Epidermis: epithelial tissue derived from ectoderm
Dermis: connective tissue derived from mesoderm |
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Classifications of skin |
Thin and thick (based on the thickness of the epidermis) |
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What are the accessory structures associated with the skin? |
Skin appendages: hair, nails and glands |
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What part of the skin is vacular? |
Dermis |
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Main type of epidermal cell and its function |
Keratinocyte; to make intermediate filaments called keratin |
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4 types of epidermal cells |
Keratinocyte Melanocyte Langerhans cell Merkel cell |
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Where are keratinocytes generated? |
Stratum basale |
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What happens as the keratinocytes move superficially? |
They mature and finally die (apoptosis) |
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How many epidermal layers are they and what are they classified by? |
5; they are classified by different stages of keratinocyte maturation |
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What is the full name for the type of epithelium in skin? |
Stratified, keritinized, squamous epithelium
(Derived from ectoderm) |
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5 layers of epithelium from superficial to deep |
Stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, stratum basale |
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What is the thickest layer in the epidermis? |
Stratum spinosum-- has intercellular bridges |
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What are the intercellular bridges between stratum spinosum cells? |
Desmosomes and tight junctions
These are dynamic structures which allow for the cells to migrate to the surface |
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At what stage do the keratinocytes become flattened? |
Stratum granulosum |
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How long does it take to go from stratum basale to stratum corneum? |
about 4 weeks |
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In the process of keratinization, what actually leads to the coalesced keratin in the stratum corneum? |
Cells produce keratin as they migrate superficially but will burst; keratin filaments can coalesce and form a layer
Lipids produced forms a glue between the keratin and really forms a protective layer |
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What is psoriasis? |
Process of division, differentiation and migration is severely accelerated
Less melanin available to be donated to the keratinocytes and skin is less pigmented |
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What is the cause of psoriasis? |
A number of genes involved-- antibiotics in the form of lotion or systemic abx to prevent infection (treating the symptoms) |
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Where does the melanocyte reside? |
The basal layer |
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From where does the melanocyte derive? |
Neural crest cells--> It is highly migratory like most neural crest cells |
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From what amino acid is melanin dervied? |
Tyrosine |
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Melanocyte: what are its roles? |
Protects the dividing cells of the basal layer Converts UV energy to heat energy and then dissipate it |
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What is the function of the long, thin projections from the melanocytes? |
Can extend superficially in between the keratinocytes; invaginate the membrane of the keratinocyte and can donate the melanin to the keratinocyte |
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What is the secondary characteristic of melanin? |
Provides pigment to the skin: on the soles of feet and palms of hands, there are approx 10 keratinocytes per melanocyte |
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Why does the skin of palms of hands tend to be rather light? |
There are approximately 10 keratinocytes per melanocyte |
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What is the ratio of keratinocytes to melanocytes in thin skin? |
4:1 |
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Fair-skinned versus dark-skinned: what is different? |
Fair-skinned: melanin degrades more quickly |
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Why is melanoma so dangerous? |
Dedifferentiated cells can go down into the dermis (because they are migratory cells) and the dermis contains all vasculature and lymphatic vessels |
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What are located in the dermis but derive from the epidermis? |
Follicles of the hair shafts and sebaceous glands |
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Two layers of the dermis |
Papillary layer (interdigitates with the epidermal ridges)
Reticular layer (deeper layer that provides strength and resilience-- dense connective tissue with collagen and elastin) |
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Third fatty later below dermis |
Subcutaneous layer or hypodermis |
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How do you differentiate between papillary and reticular layers of the dermis? |
More cell bodies in the papillary layer; will see more of the fibers in the reticular layer |
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What is the basis of footprints and fingerprints? |
Pronounced primary epidermal ridges |
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What is the kind of cell which resides in the epidermis but interact with tissue in the dermis? |
Langerhans cell; located primarily in stratum spinosum |
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A word meaning that a cell has highly branched processes |
Dendritic cells |
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What system are Langerhans cells a part of? What is their function? |
Immune system: secondary line of defense against pathogens
Begin a series of intercellular signaling |
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What is the goal of the signaling pathway of a Langerhans cell? |
Recruit other cells from the immune system to come and attack the foreign pathogen |
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What are fingernails made of? |
A hard, translucent form of keratin |
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What two things are derivatives of the epidermis but present in the dermis? |
Hair follicles; sebaceous glands |
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What kind of gland empties into the shaft of the hair? |
Apocrine sweat gland
(common in the axilla, genital areas) |
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Muscle which is associated with the hair follicle |
Piloerector muscle
(innervated by part of the autonomic--sympathetic nervous system) |
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Why does the hair of a cat or dog stand on end when the animal is scared? |
Muscle innervated by the sympathetic nervous system (fight or flight)-- will make the animal appear larger |
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This gland's duct enters onto the surface of the skin by passing through the epidermis |
Sweat gland |
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What kinds of cells typically border a sweat duct? |
Simple cuboidal |
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What is the "hole" in the middle of the gland? (These later collect to form the duct) |
Acinus |
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Functions of sweat glands |
Evaporative cooling, temperature control |
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The name for the kind of cell which helps with contraction of the sweat gland |
Myoepithelial sweat cell-- help in pushing sweat into acini |
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With what are sebaceous glands usually associated? |
Hair follicles |
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What do the sebaceous glands produce |
A collection of fatty acids- sebum |
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What is the function of the sebum? |
Provide pliability and protection for the outside of the hair |
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Why is the production of sebum increased during puberty? |
Production of excess androgens which leads to a greater production of sebum |
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What causes acne? |
Hyperproliferation of keratinocytes Sebum too thick or cannot be degraded |
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If there is sebum buildup in the hair follicle, what happens usually? |
Colonization of hair follicle by proponibacterium acnes, inflammation
*Acne vulgaris* |
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What causes a whitehead? |
A follicle with sebum being closed off by excess keratinocytes |
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What causes a blackhead? |
A follicle with excess sebum will be closed by the failure of the sebum to be extruded |
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Temperature-regulating system for the skin |
Arterio-vascular shunt system |
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How does the AV shunt system work? |
Shunt vein dilated: little heat released Shunt vein constricted: Much heat released |
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Is the AV shunt system sympathetic or parasympathetic? |
Sympathetic |
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Only two kinds of nerves enter the epidermis: What are they? |
Free nerve endings and encapsulated nerve endings |
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Free nerve endings: About what do they transmit information about primarily? |
Pain and itch |
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What are the three kinds of encapsulated nerve endings? |
Pacinian corpuscles Meissner's corpuscles Merkel's cells |
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Which cells of the epidermis are closely tied to nerve fibers of the dorsal root ganglion? |
Merkel cells
When they are deformed, release neurotransmitter to the neuron immediately proximal-- generator current produced |
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What does a 1st degree burn mean? |
Only surface layers of epidermis involved |
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What is a second degree burn? |
All epidermal layers and upper layers of dermis involved
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3rd degree burn |
Full thickness burn involving deep dermis (may involve underlying muscle and bone)
High risk of infection |
