Term
Select the correct answer.
1. odland bodies contain histamine
2. tanning is a response to UV induced skin damage
3. calcium is made by the skin with the help of UV light
4. lamellar granule contain histamine |
|
Definition
|
|
Term
| Select the correct order of UV wavelengths (ascending) |
|
Definition
|
|
Term
| The main contents of the cornified envelope include what? (3) |
|
Definition
| loricrin, involucrin, keratolinin (LIK the envelope) |
|
|
Term
| Which ingredients of sunscreens block UVA? (3) |
|
Definition
| Parsol 1789, titanium dioxide, zinc oxide |
|
|
Term
| How is the skin a protective barrier? (7) |
|
Definition
1. maintains fluid and electrolyte homeostasis
2. protects from toxic environmental substances
3. protects from physical trauma
4. contributes to thermal regulation
5. acts as a barrier to infection
6. protects from UV damage
7. various metabolic functions |
|
|
Term
| Which layer of the skin is most involved in fluid and electrolyte homeostasis? What is it made of? |
|
Definition
stratum corneum
- semipermeable
- hydrophilic corneocytes
-hydrophocbic intercellular lipid matrix |
|
|
Term
| What layer of the skin is the major barrier to environmental toxins? |
|
Definition
|
|
Term
| How does the skin regulate body temperature? |
|
Definition
| blood vessel dilation, constriction and eccrine sweating leading to evaporative cooling |
|
|
Term
| What are some natural defense mechanisms of the skin against micro-organisms? (5) |
|
Definition
1. dryness
2. desquamation of the skin
3. normal flora
4. fatty acids of sebum
5. lactic acid of sweat |
|
|
Term
|
Definition
| complex process of cell maturation manifested by changes in intracellular proteins, cytostructure and deposition of lipid rich material to form a flexible protective barrier; genetically programmed |
|
|
Term
| Describe the process of cellular metabolism from genreal cell metabolism to focused cell metabolism (6) |
|
Definition
1. synthesis and modification of structural proteins and lipids
2. reorganization of proteins and organelles between the spinout and granular layer
3. appearance of new cellular organelles
4. eventual loss of all organelles (apoptosis)
5. flattening
5. increase in cell size with cellular dehydration |
|
|
Term
| What is the end point of keratinization? |
|
Definition
terminally differentiated cells
- dead keratinoxytes (corneocytes) containing keratin and matrix, protein reinforced membrane and surface associated lipids |
|
|
Term
|
Definition
| metabolically inert (dead), enucleated cells formed from keratinocytes in the viable lower layers of epidermis |
|
|
Term
|
Definition
| component of corneocytes contributing tot he barrier, made of cross-linked proteins at the periphery of each cell, resistant to disruption |
|
|
Term
| what enzyme catalyzes the cross links of the cornified envelope? |
|
Definition
|
|
Term
| lipid envelope; what are the major lipid components? |
|
Definition
| surrounds the cornified envelope and replaces the keratinocyte plasma membrane on transition to corneocyte; major components are ceramides |
|
|
Term
|
Definition
| major membrane lipids of the stratum corneum that are tightly packes and impermeable to water |
|
|
Term
| what is the intercellular lipid matrix made from? where is it found? |
|
Definition
lamellar granules (membrane coating granules)
- granules are found between the granular and and corneum layer |
|
|
Term
| Where are the epidermal lipds made? Where are kept? Where are they empited? |
|
Definition
| made in the Golgi of the keratinocytes of the upper layers of the prickle layer (spinulosum), kept in Odland bodies and emptied into intercellular space of upper granular layer |
|
|
Term
| Staphylococcal scalded skin syndrome |
|
Definition
staph toxin splits the skin under the st. corneum and the upper epidermis slough off in sheets breaking the protective barrier
- fluid and electrolyte balance problems, can be life threatening with loss of vapor barrier |
|
|
Term
|
Definition
inherited mutation in transglutaminase 1 leading to an absent cornified envelope
- large, plate-like scaled and everted eyelids |
|
|
Term
|
Definition
auto recessive
lamellar granules absent so no intracellular lipid is excreted and no vapor barrier
severe ichthyosis (massive plates), malformation fo eears, eyes, mouth
death |
|
|
Term
| What do lamellar granules/odland bodies contain? (5) |
|
Definition
1. glycoproteins
2. Fatty acids
3. phospholipids
4. glucosylceramides
5. cholesterol/free sterols |
|
|
Term
| What do keratohyalin granules contain? (4) |
|
Definition
1. electron dense proteins
2. profilaggrin
3. keratin intermediate filaments
4. loricrin |
|
|
Term
| Where are lamellar granules/odland bodies located? are they membrane bound? |
|
Definition
1st seen in the upper spinous layers
primary site = granular cornified layer interface
- membrane bound - yes |
|
|
Term
| where are keratohyalin granules found? are they membrane bound? |
|
Definition
1st seen in the upper spinous layers
primarily in the granular layer and cronified layer
- NO |
|
|
Term
What are the 3 functions of lamellar granules/odland bodies?
- what is the function of lipds in the intercellular space? |
|
Definition
1. deliver precursors of stratum corneum lipids into the intercellular space
2. lipids accumulate in the granules as stacks or discs
3. between the granular and corneum layers, they fuse with the plasma membrane and discharge lipid contents into the intercellular space
- lipid contents function to maintain vapor barrier and are integral to signalling cell turnover |
|
|
Term
What are the 3 functions of the keratohyalin granules?
- what is the function of filaggrin |
|
Definition
1. deliver free amino acids to the outer layers of thes t. corneum as filaggrin monomers
2. convert profillagrin to fillagrin during transition from granular to cornified cell
3. regulate epidermal osmolarity and flexibility
- filaggrin in the cornified cell serves as a matrix protein promoting aggregation of keratin filaments |
|
|
Term
| Why is the stratum corneum so strong? (4) |
|
Definition
1. cornified envelope is resistnat to physical and chemical assault
2. corneocytes are interdigitated
3. desmosomes are in the lower layers of the corneum
4. it is elastic due to its ability to retain water in hydrophilic corneocyte proteins |
|
|
Term
| How does the stratum corneum protect against electrical and thermal damage? |
|
Definition
| due to its low conductivity |
|
|
Term
|
Definition
| neural elements that sense pressure - warning system for trauma and lead to protective responses |
|
|
Term
|
Definition
| neural elements that detects heat, touch, and pain as a warning system |
|
|
Term
| What is normal core body temp? How far ca it vary? |
|
Definition
normal - 37 degrees celsius
varies from 20-40 degrees celsius |
|
|
Term
| What kind of nervous stimulation does the skin get for thermal regulation? |
|
Definition
| sympathetic and adrenergic stimulation |
|
|
Term
| What happens to the skin in a cold environment? hot environment? |
|
Definition
sympathetic stimulation causes contraction of skin BV's decreasing peripheral blood flow conserving central body heat
hot - vessels dilate with decreased sympathetic innervation for rapid heat loss |
|
|
Term
| How is sweat controlled? where does it come from (gland)? how much can be produced per hour? |
|
Definition
- hypothalamus
- eccrine sweat glands
- 1.5 liters/hour
can lead to 10x the basal rate of heat loss
- leads to evaporative cooling |
|
|
Term
| subcutaneous fat function |
|
Definition
an insulator
- decreases heat movement into and out of the body |
|
|
Term
| What vitamin is produced in the skin by the action of UV light on dehydrocholesterol? What is its function? |
|
Definition
Vitamin D3 (cholecalciferol)
- calcium homeostasis, phosphate and mineralization homeostasis |
|
|
Term
| What is the active form of Vitamin D? |
|
Definition
| 1,25-dihydroxycholecalciferol |
|
|
Term
| What does 1,25-dihydroxycholecalciferol do? |
|
Definition
acts on the intestine to increase absorption through stimulation of synthesis of calcium binding proteins in the mucosal cell sof intestine
- also acts on the kidnesy to promote calcium reabsorption |
|
|
Term
| Describe the process of making 7-dehydrocholesterol into the active form of Vitamin D |
|
Definition
1. 7-dehydrocholesterol in the skin from UV light
2. becomes Vitamin D3 (cholecalciferol)
3. in the liver it becomes 25-hydroxycholecalciferol
4. in the kidney it becomes 1, 25-dihydroxycholecalciferol (active form) |
|
|
Term
| What are the structural mechanisms protecting the body from infection? (4) |
|
Definition
1. intact stratum corneum is a structural barrier to microorganisms
2. surface dryaness discourages growth
3. desquamation removes microorganisms
4. fatty acids of sebum and lactic acid of sweat |
|
|
Term
| How do normal flora protect from infection? |
|
Definition
1, competitive inhibitors for space and nutrients
2. antibiotic compounds |
|
|
Term
| What are three cellular immune mechanisms to protect the body from infection through the skin? |
|
Definition
1. langerhans cells (dendritic cells) -
2. inflammatory cells - lymphocytes, histiocytes, neutrophils, eosinophils, mast cells ONLY in the DERMIS (not the epidermis)
3. ability to produce and release cytokines |
|
|
Term
Langerhans cells
Functions (3) |
|
Definition
in the EPIDERMIS to recognize foreign antigens and present it to T cells for an immune response
- play a role in delayed hypersensitivity reactions and immunosurveillance of viral infections
- interact with neighboring keratinocytes to secrete cytokines |
|
|
Term
|
Definition
| chemical messengers released to mediate immune responses |
|
|
Term
| How do sebaceous glands provide chemical protection in the skin? |
|
Definition
| secrete proteina nd lipids with antimicrobial action |
|
|
Term
| What adverse affects can UV light cause to the skin? (3) |
|
Definition
sunburn
chronic photodamage
carcinogenesis |
|
|
Term
WHat is the range of the UV specturm?
- What is the wavelengths for:
a. UVC
b. UVB
c. UVA |
|
Definition
200-400 nm
a. 200-290 (absorbed in ozone)
b. 290-320 nm (burning rays)
c. 320-400 nm (tanning rays) |
|
|
Term
chromophores
- how do they work? |
|
Definition
molecules capable of absorbing radiant energy; mutliple chromophores absorb UV radiation at specific wavelentght (DNA< proteins, urocanic acid)
- low in energy state
- when it absorbs a photon of UV light it becomes excited and unstable and when it returns to ground state the energy is released |
|
|
Term
| How is energy released from chromophores? (3) |
|
Definition
1. undergo a chemical changed to forma photoproduct like a DNA pyrimidine dimer or free radical (photochemical reaction)
2. transfer the energy to another molecule inducing a chemical change (photosensitized reaction) such as a free radical
3. shed the energy as head or fluorescence (safest) |
|
|
Term
| What are some biological responses from UV induced photochemical reactions? |
|
Definition
1. sunburn
2. tanning (not safe)
3. chronic photodamage (dematoheliosis
4. carcinogenesis |
|
|
Term
sunburn
- mediators of erythema? |
|
Definition
UVB >>> UVA
tissue damage in dermis and epidermis
- mediators of erythema - histamine, prostaglandins, cytokines, lysosomal enzymes |
|
|
Term
| How is pigmentation of human skin facilitated? |
|
Definition
1. intrinsic (constitutive and genetic)
2. induced (facultative - tanning) |
|
|
Term
Tanning
- what are two ways in which it affects melanocytes |
|
Definition
UVB and UVA affects melanocytes by:
1. increasing number, size, and dendrite branching of melanocytes
2. increasing melanin and melanosome synthesis
provide some protection from further damage |
|
|
Term
|
Definition
chronic photodamage
- UVB and UVA
- aged appearnace with rough, sallow, pebbly and wrinked skin with telangiectasis (small blood vessels that are dilated) and blotchy pigmentation |
|
|
Term
|
Definition
| normal tumor of melanocytes |
|
|
Term
|
Definition
UV exposure plays a role in skin cancer
ex. basal cell carcinoma (most common), squamous cell carcinoma (dead, dry ulcerated), malignant melanoma ( 3rd most common - cancer of melanocyte) |
|
|
Term
|
Definition
primary cutaneous mechanism for photoprotection and physically blocks, scatter and absorbs UV light ; acts as a free radical trap
- more melanin in darker people |
|
|
Term
| What other things in the epidermis absorb UVB? (5) |
|
Definition
1. keratin
2. keratohyalin
3. nucleic acids
4. nucleoproteins
5. urocanoic acid |
|
|
Term
| What % of UVB and UVA penetrates into the basal layer and beyond? |
|
Definition
|
|
Term
| WHat are some direct responses to tanning? How does it work? |
|
Definition
- immediate oxidation reaction in preexsting melanin by UVA
- delayed tanning reactin of 48-72 hours by UVB and UVA increasing tyrosinase activity and increasing production of melanin in melanosomes |
|
|
Term
| What are some indirect responses to tanning (how does it work)? |
|
Definition
| irradiated keratinocytes release melanogenesis stimulating factors (MSH-apha and ACTH) |
|
|
Term
| What are some cutaneous immunosuppression responses to UV light? (3) |
|
Definition
it is UVA mediated
1. decreased langerhans
2. decreased lymphocytes in skin disorders
3. decreased contact/allergic response |
|
|
Term
| What are the ABCD's of melanoma? |
|
Definition
A - asymmetry
B - border
C - color
D - diameter |
|
|
