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2nd Shifting PHA6131 LEC > Toxic Responses of the Skin > Flashcards

Toxic Responses of the Skin Flashcards

1
Q

Skin as a barrier

  1. protects the body against external insults, thus maintaining _____________.
  2. participates in ________, __________, __________, __________,
    __________, and _________regulation.
  3. may react to noxious physical agents with various defensive mechanisms preventing its widespread ___________and/or ___________injuries
A

homeostasis

thermal; electrolyte; hormonal; metabolic; antimicrobial; immune

cutaneous; internal

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2
Q

This layer of the skin is also known as the stratum basale. This is where cell division happens

A

Stratum germinativum

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3
Q

This layer of the skin has desmosomes. This layer gives strength, and flexibility of the skin

A

Stratum spinosum

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4
Q

This layer of the skin has dead keratinocytes and provides protection

A

Stratum corneum

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5
Q

This layer of the skin, though only present in the palms and face, is between the stratum corneum and stratum granulosum

A

Stratum lucidum

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6
Q

stratified squamous epithelium consisting primarily of keratinocytes

A

interfollicular epidermis

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7
Q

Melanocytes are stimulated by ___________________ in the epidermis to produce melanin granules which are extruded and taken up by the surrounding keratinocytes and become pigmented.

A

ultraviolet light

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8
Q

dendritic, antigen presenting cells involved in the immune response of skin to foreign xenobiotics.

A

langerhans cells

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9
Q

T/F: The langerhans cells contributes in the regulation of the immune system. However, its presence is limited to some parts of the body

A

False. Because it is found all over the body

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10
Q

the stratum corneum is formed during program of _____________________, and is the primary barrier to ______________________

A

terminal differentiation; percutaneous absorption

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11
Q

The stratum corneum…

once compromised, it can permit great ____________ (increase/decrease) of the uptake of poorly permeable substances.

A

increase

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12
Q

The stratum corneum…

having _________ properties, it prevents water loss from underlying tissues by __________.

A

hydrophobic; evaporation

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13
Q

The stratum corneum is ordinarily hydrated (typically ____% water) or the moisture residing in corneocyte protein.

A

20

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14
Q

The degree of uptake through the skin depends on the details of _________ conditions

A

exposure

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15
Q

T/F: the degree of uptake is proportional to solute concentration, time, and the amount of skin surface exposed.

A

True

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16
Q

What are the two intrinsic factors that contribute to the absorption rate of a given compound?

A

Hydrophobicity and Rate of diffusion through the barrier

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17
Q

Identify if the intrinsic factor is hydrophobicity or rate of diffusion

affects ability to partition into epidermal lipid.

A

Hydrophobicity

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18
Q

Identify if the intrinsic factor is hydrophobicity or rate of diffusion

hydrophobic agents of low MW permeate the skin better than those of high MW or those that are hydrophilic

A

Rate of diffusion

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19
Q

Identify if the intrinsic factor is hydrophobicity or rate of diffusion

For small molecules, hydrophobicity is a dominant factor in penetration

A

Rate of dissusion

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20
Q

Identify if the intrinsic factor is hydrophobicity or rate of diffusion

partitioning agent into the skin is greatly affected by its solubility in or adhesion to the medium in which it is applied.

A

Hydrophobicity

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21
Q

Identify if the intrinsic factor is hydrophobicity or rate of diffusion

inverse function of molecular weight (MW) or molecular volume.

A

Rate of diffusion

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22
Q

Identify if the intrinsic factor is hydrophobicity or rate of diffusion

a measure is the commonly used octanol/water partitioning ratio (Kow).

A

Hydrophobicity

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23
Q

Identify if the intrinsic factor is hydrophobicity or rate of diffusion

once in the stratum corneum, may diffuse only very slowly into less hydrophobic.

A

Hydrophobicity

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24
Q

T/F: In percutaneous absorption, diffusion through the epidermis is considerably faster at some anatomical sites than others.

A

True

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25
Q

T/F: foot sole > palm > forehead > abdomen > scrotum.

A

False.

foot sole > palm > scrotum > forehead > abdomen.

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26
Q

Absorption through the _________________ is usually neglected because the combined appendageal surface area is a relatively small fraction of the total available area for uptake.

A

epidermal appendages

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27
Q

Transdermal Drug Delivery

T/F: Its advantages is providing a steady infusion of drug over extended periods, however there is a risk of large variations in plasma concentrations

A

False. …. avoiding large variations in plasma concentrations

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28
Q

Transdermal Drug Delivery

T/F: It prevents exposure to the acidic pH of the stomach, thus preventing biodegradation

A

True

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29
Q

Transdermal Drug Delivery

T/F: It avoids biotransformation in the gastrointestinal tract from first pass removal by the liver.

A

True

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30
Q

Measurements of penetration

For risk assessment and pharmaceutical design, the most useful subject for experimentation is ___________.

A

human skin

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31
Q

Measurements of penetration

For in vitro work, _______________________ can be employed in special diffusion chambers.

A

excised split thickness skin

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32
Q

Measurements of penetration

A simpler setup commonly uses cadaver skin with the ________________ removed.

A

lower dermis

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33
Q

Measurements of penetration

To simplify determination of penetration kinetics, _________ may be employed and the _________ blood flow monitored to measure penetration.

A

skin flaps; capillary

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34
Q

Biotransformation

The ability of the skin to ____________ chemicals that diffuse through it contributes to its barrier function.

A

metabolize

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35
Q

Biotransformation

What are the major sites of biotransformation in the skin?

A

epidermis and pilosebaceous units

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36
Q

Biotransformation

What are the enzymes that are expressed in the skin that participate in biotransformation?

A

cytochrome P450, epoxide hydrolase, UDP glucuronosyltransferase, quinone reductase, and glutathione transferases

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37
Q

Biotransformation

What are the other metabolic enzyme activities detected in human epidermal cells?

A

sulfatases, β glucuronidase, N-acetyltransferases, esterases, and reductases.

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38
Q

Biotransformation

The ______________ region of the stratum corneum has catabolic activities (e.g., proteases, lipases, glycosidases, and phosphatase)

A

intercellular

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39
Q

T/F: Contact dermatitis falls into two major categories, irritant and allergic, which cannot co-exist

A

False. irritant and
allergic may co-exist:

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40
Q

The irritant and allergic categories of contact dermatitis both involve inflammatory responses. What are its clinical characteristics in areas of direct contact with the chemical?

A

erythema (redness), induration (thickening and firmness), scaling (flaking), and vesiculation (blistering)

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41
Q

T/F: Irritant dermatitis arises from the direct action of agents on the skin on a high concentration and on brief exposure.

A

False. Long exposure

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42
Q

Certain chemicals at sufficient concentration produce an acute irritation or ________________ chemical burn.

A

second-degree

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43
Q

T/F: Strong acids and alkalis can produce cytotoxicity directly, but oxidizing or reducing agents produce it indirectly.

A

False. Strong acids, alkalis, and powerful oxidizing or reducing agents can produce cytotoxicity directly.

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44
Q

Contact with a variety of plants can also have irritant effects, resulting in the production of proinflammatory cytokines from keratinocytes. What are these proinflammatory cytokines?

A

IL1α, IL1β, and TNFα

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45
Q

In irritant dermatitis, response to exposure varies depending on the ______________ of the anatomic site.

A

sensitivity

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46
Q

T/F: The eyelids are quite sensitive, and the forearm is more sensitive than the back

A

False. the back is more sensitive than the forearm

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47
Q

T/F: Individuals also vary greatly in sensitivity to irritant dermatitis, where atopic individuals are the most sensitive to irritants

A

True

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48
Q

T/F: In chemical burns (corrosion), extremely corrosive and reactive chemicals may produce immediate liquefactive necrosis that results in substantial tissue damage, with
ulceration and sloughing

A

False. Coagulative necrosis

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49
Q

Chemical burns (corrosion) are sometimes referred to as a ________________ chemical burn

A

third-degree

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50
Q

In chemical burns, a necrotic tissue can act as a _________________ resulting in either continued cutaneous damage or percutaneous absorption and systemic injury after exposure.

A

chemical reservoir

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51
Q

T/F: Allergic contact dermatitis is an immediate hypersensitive reaction because it is T-cell mediated

A

False. It is a delayed hypersensitive reaction

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52
Q

During sensitization in allergic contact dermatitis, the chemical hapten must penetrate the skin and become attached to _____________

A

carrier proteins

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53
Q

In allergic contact dermatitis, complete antigens are processed by _______________ and presented to ____________________ in regional lymph nodes.

A

Langerhans cells; type 1 T-helper cells

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54
Q

T/F: In allergic contact dermatitis, subsequent exposure to the same antigen results in a minimized immune response due to desensitization after adaptation to the allergens

A

False. Amplified immune response characterized by dermal infiltration and spongiosis.

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55
Q

Identify the type of contact allergen:

Bacitracin

A

antibiotics

56
Q

Identify the type of contact allergen:

chlorhexidine

A

antiseptics

57
Q

Identify the type of contact allergen:

formaldehyde

A

personal care products

58
Q

Identify the type of contact allergen:

neomycin

A

antibiotics

59
Q

Identify the type of contact allergen:

chloroxylenol

A

antiseptics

60
Q

Identify the type of contact allergen:

formaldehyde releasers

A

personal care products

61
Q

Identify the type of contact allergen:

polymyxin

A

antibiotics

62
Q

Identify the type of contact allergen:

dichlorophene

A

antiseptics

63
Q

Identify the type of contact allergen:

methylchloroisothiazolone/ methylisothiazolinone (MCI/ MI)

A

personal care products

64
Q

Identify the type of contact allergen:

aminoglycosides

A

antibiotics

65
Q

Identify the type of contact allergen:

glutaraldehyde

A

antiseptics

66
Q

Identify the type of contact allergen:

ethylenediamine

A

personal care products

67
Q

Identify the type of contact allergen:

sulfonamides

A

antibiotics

68
Q

Identify the type of contact allergen:

thimerosal (merthiolate)

A

antiseptics

69
Q

Identify the type of contact allergen:

lanolin

A

personal care products

70
Q

Identify the type of contact allergen:

benzocaine

A

antibiotics

71
Q

Identify the type of contact allergen:

mercurials

A

antiseptics

72
Q

Identify the type of contact allergen:

p-Phenylenediamine

A

personal care products

73
Q

Identify the type of contact allergen:

corticosteroids

A

antibiotics

74
Q

Identify the type of contact allergen:

triphenylmethane dyes

A

antiseptics

75
Q

Identify the type of contact allergen:

propylene glycol

A

personal care products

76
Q

Identify the type of contact allergen:

fragrances

A

personal care products

77
Q

T/F: Erythema is an adverse response to electromagnetic radiation, an evident feature of UV radiation exposure observed in photosensitivity

A

True

78
Q

This is the smallest dose of UV light needed to induce an erythematous response, varies greatly from person to person.

A

minimal erythema dose (MED)

79
Q

What are the environmental conditions that affect UV induced injury:

A

duration of exposure, season, altitude, body site, skin pigmentation, and previous exposure.

80
Q

Adverse responses to electromagnetic radiation

Chronic exposure to radiation induces a variety of characteristic skin changes like
1. ______________ changes such as freckling and hypomelanotic
areas,
2. wrinkling, _______________ (fine superficial blood vessels),
3. _________________ (precancerous lesions),
4. and ____________ skin lesions such as basal and squamous cell
carcinomas and malignant _____________.

A

Pigmentary

telangiectasias

actinic keratoses

malignant; melanoma

81
Q

T/F: Phototoxic reactions may be produced either by systemic or topical exposures.

A

True

82
Q

In acute reactions (phototoxicity), the skin may appear ______, and _________ within minutes to hours after UV light exposure

A

red; blister

83
Q

Chronic phototoxic responses may result in ______________ and ____________ of the affected areas.

A

hyperpigmentation; thickening

84
Q

T/F: UVB (290 to 320 nm) is the most commonly responsible; UVA (320 to 400 nm) may occasionally be involved in phototoxicity

A

False. UVA (320 to 400 nm) is the most commonly responsible; UVB(290 to 320 nm) may occasionally be involved.

85
Q

T/F: photoallergy is a type IV delayed hypersensitivity reaction, leading typically to eczema.

A

True

86
Q

T/F: photoallergy does not require prior sensitization to the chemical

A

False. It requires prior sensitization

87
Q

T/F: Photocontact dermatitis and systemic photoallergy are results of induction and subsequent elicitation of reactions from topical exposure, however, they do not have the same mechanism as that for allergic contact dermatitis

A

False. They have the same mechanism as that of allergic contact dermatitis, though UV light is necessary to convert a potential photosensitizing chemical into a hapten that elicits an allergic response.

88
Q

This may develop for those allergens to which IgE antibodies have been elicited by previous or ongoing exposure, through an immediate type I hypersensitivity reaction.

A

Urticaria

89
Q

In urticaria, ________ are raised wheals that usually itch or sting and may appear reddish.

A

Hives

90
Q

Major causes of acute urticaria

A

food allergies and pharmaceuticals

91
Q

What are the pigmentary disturbances

A

hyperpigmentation, exogenous hyperpigmentation, hypopigmentation, leukoderma (vitiligo) and depigmentation

92
Q

this pigmentary disturbance results from increased melanin production or deposition of endogenous or exogenous pigment in the upper dermis.

A

hyperpigmentation

93
Q

this pigmentary disturbance can arise from deposition of metals and drugs in dermal tissue.

A

exogenous hyperpigmentation

94
Q

this pigmentary disturbance is a loss of pigmentation from melanin loss, melanocyte damage, or vascular abnormalities.

A

hypopigmentation

95
Q

these pigmentary disturbances denote complete loss of melanin from the skin imparting porcelain-white appearance.

A

Leukoderma (vitiligo) and depigmentation

96
Q

T/F: Comedogenic chemicals induce comedone lesions, which may be open or closed (blackhead or whitehead, respectively, in the vernacular).

A

True

97
Q

T/F: papules, pustules, cysts, and scars may complicate the process of healing

A

True

98
Q

This condition happens when hair follicles and associated sebaceous glands become clogged with compacted keratinocytes that are bathed in sebum.

A

acne

99
Q

T/F: the most evident pigmentary change due to melanin is observed in closed comedones

A

False. Open comedones

100
Q

This acne is characterized red, cystic, painful, and inflamed

A

hormonal acne

101
Q

this acne is characterized by tiny white bumps, not painful and red

A

product acne

102
Q

this type of acne is characterized by tiny black spots on the skin

A

blackheads

103
Q

this type of acne is characterized by small bumps sticking out from your skin

A

yuck. char lang shempre whiteheads ang sagot

104
Q

this type of acne is characterized by a pimple with a white colored head that contain pus

A

pustules

105
Q

this type of acne is characterized by large, inflamed bumps that feel firm to the touch

A

nodules

106
Q

this type of acne is large, painful, pus-filled bumps. These are softer than nodules

A

cysts

107
Q

T/F: Inflammatory acnes include blackheads and whiteheads.

A

False. Non-inflammatory acnes don’t cause swelling and includes blackheads and whiteheads. Inflammatory acnes are pimples that are red and swollen

108
Q

It is caused by exposure to polyhalogenated aromatic hydrocarbons, and one of the most disfiguring forms of acne in humans

A

chloracne

109
Q

in chloracne, ___________ and strawcolored _________ are typically present behind the ears, around the eyes, and on the shoulders, back, and genitalia.

A

comedones; cysts

110
Q

what are the other characteristics present in chloracne, in addition to acne?

A

hypertrichosis (increased hair in atypical locations), hyperpigmentation, brown discoloration of the nail, conjunctivitis, and eye discharge

111
Q

Granulomatous disease occurs infrequently toward a variety of agents introduced into the skin through _____________ or after ______________ or abrasion.

A

injection; laceration

112
Q

T/F: In granulomatous disease, persistent lesions with abundant inflammatory cells can be produced, resembling chronic infectious condition and present diagnostic challenges.

A

True

113
Q

Many substances can produce granulomatous reactions, including
_______, talc, paraffin or mineral oil, ____________, and ___________.

A

silica; beryllium; gadolinium

114
Q

Metallic _________ and ___________ compounds, formerly used in deodorants, and _____________ (containing cobalt, chromium, mercury, lead, iron, cadmium, and manganese compounds) can also induce granulomatous reactions that, in rare cases, can be induced by intense ______ treatment.

A

mercury; zirconium; tattoo dyes; light

115
Q

T/F: Toxic epidermal necrolysis (TEN) is a rare life-threatening skin disease.

A

True

116
Q

T/F: Stevens-Johnson syndrome (SJS) is a condition much worse than toxic epidermal necrolysis (TEN)

A

False. SJS severity is below 10% while TEN is above 30%. The overlap of SJS and TEN is between 10-30%

117
Q

T/F: Toxic epidermal necrolysis involves detachment of ≥10% of the epidermal surface from the dermis, commonly accompanied by severe erosions of the mucous membranes.

A

False. ≥30%

118
Q

______________________ involvement in toxic epidermal necrolysis can result in gastrointestinal hemorrhage, respiratory failure, ocular abnormalities, and genitourinary complications.

A

Mucous membrane

119
Q

Nearly 200 drugs have been reported to cause toxic epidermal necrolysis with major contributors being ____________, nonsteroidal anti-inflammatories, antibacterial sulfonamides, ___________, and ______________

A

anticonvulsants; allopurinol; nevirapine

120
Q

Mechanisms leading to this idiosyncratic drug reaction (toxic epidermal necrolysis) are under scrutiny and current hypotheses identify ______________ and ________ background as contributing factors.

A

HLA genotype; ethnic

121
Q

T/F: Radiation from non-ionizing wavelengths to ultraviolet wavelengths has been shown to cause skin cancer.

A

False. Ionizing wavelengths

122
Q

Shortly after the discovery of radioactive elements at the turn of the twentieth century, it was observed that ________ could cause severe burns, squamous cell carcinoma, and basal cell carcinomas.

A

X-rays

123
Q

T/F: Most skin cancers in the United States now are X-ray-induced.

A

False. UV-induced

124
Q

What are the most common UV-induced skin cancers?

A

NMSC and cutaneous malignant melanoma

125
Q

T/F: UV light also has immunosuppressive effects that may help skin tumors survive.

A

True

126
Q

T/F: Skin cancer incidence is highest in the tropics and in pale complexioned whites.

A

True

127
Q

T/F: Even when it does not cause cancer in normal individuals, sun exposure leads to premature aging of the skin.

A

True

128
Q

T/F: Sunblock lotions is encouraged while sunbathing is discouraged

A

True

129
Q

Substances rich in ____________________________ (coal tar, creosote, pitch, and soot) are skin carcinogens in humans and animals.

A

polycyclic aromatic hydrocarbons

130
Q

What causes the production of electrophilic epoxides, which forms DNA adducts, from polycyclic aromatic hydrocarbons?

A

oxidative biotransformation

131
Q

It is produced by rearrangement of the epoxides, and it can be oxidized further to quinones which yields active oxygen species.

A

Phenols

132
Q

T/F: Active oxygen species are not toxic electrophiles

A

False

133
Q

T/F: Occupations at risk of skin cancer from exposure to these compounds (e.g., roofing) often involve considerable sun exposure

A

True

134
Q

The observed incidence of squamous cell carcinomas in ________________ is taken as evidence of a general carcinogenic risk for humans.

A

mouse skin

135
Q

T/F: Squamous cell carcinoma pathogenesis in mouse skin has general applicability to human squamous cell carcinomas.

A

True

136
Q

An advantage of the mouse skin carcinogenesis model is the ability to ___________ the neoplastic process into stages of initiation, promotion, and progression depending on experimental design.

A

separate

137
Q

T/F: Irritants are more difficult to resolve as compared to allergies that manifests immediately.

A

False. Allergies are more difficult to resolve because its manifestations do not show immediately, and gradually worsens (crescendo). While irritants have immediate manifestations

2nd Shifting PHA6131 LEC (6 decks)

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