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MOHD2: Exam 3 > Skin > Flashcards

Skin Flashcards

1
Q

role of the dermis, epidermis, hypodermis

A

epidermis: first physical barrier
dermis: provides nutrtional and physical support and elasticity to the epidermis; contains immune cells; thermoregulation
hypodermis: stores fat

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2
Q

name the 4 layers of the epidermis

A

stratum basale
stratum spinosum
stratum granulosum
stratum corneum

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3
Q

most common cell type in the epidermis

A

keratinocytes

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4
Q

the epidermis continuously turns over every ___ days

A

28

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5
Q

melanocytes and langerhans cells are found in this layer

A

epidermis

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6
Q

the cytoskeleton is made up of keratin intermediate filaments called _______, which aggregate into _____ and form the cytoskeleton of the cell

A

tonofilaments; tonofibrils

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7
Q

keratins exist as pairs of ____ and ____ keratins, and vary in type with epidermal differentiation

A

acidic; basic

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8
Q

layer of the epidermis that is composed of mitotically active columnar cells, which are attached to a basement membrane via hemidesmosomes

A

stratum basale

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9
Q

keratin types 5 and 14

A

basal keratinocytes

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10
Q

keratin types 1 and 10

A

suprabasal keratinocytes

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11
Q

keratinocytes are connected to one another by what type of junction?

A

desmosomes

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12
Q

this layer has a distinct spiny appearance, due to polygonal keratinocytes with a central nucleus and abundant eosinophilic cytoplasm filled with keratin filament bundles

A

stratum spinosum

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13
Q

desmosomes consist of electron dense attachment plaques between two adjoining keratinocytes, which are composed of ______ and _______.

A

plakoglobin and desmoplakin

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14
Q

layer of the epidermis of varying thickness, that contains flattened keratinocytes filled with keratohyaline granules

A

stratum granulosum

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15
Q

____ _____ are not membrane bound, and contain profilaggrin and filaggrin molecules, that cement keratin filaments together and help form a waterproof barrier to prevent body fluid loss

A

keratohyaline granules

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16
Q

contain many lysosomal enzymes important in the dissolution of the nucleus and organelles in the process of keratinization

A

granular cells

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17
Q

membrane-coating granules that are released into intercellular spaces in the upper granular layer and are crucial for water barrier and stratum corneum cohesion

A

lamellar granules/odland bodies

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18
Q

epidermal layer composed of anucleate cells filled with mature keratin that form a vertical ascending stack, which prevents water diffusion

A

stratum corneum

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19
Q

a structure within the basement membrane zone that has a single attachment plaque composed of bullous pemphigoid antigen 1 (BP1 or BP230)

A

hemidesmosome

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20
Q

layer of the skin that contains mainly fibroblasts, as well as vascular and neural elements and adnexal structures embedded in a connective tissue matrix.

A

dermis

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21
Q

a subdivision of the dermis that is primarily made up of type III collagen and contain’s Meissner’s corpuscles, as well as highly organized vasculature that helps control thermoregulation

A

papillary dermis

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22
Q

a subdivision of dermis that consists of primarily type I collagen, contains hair and gland follicles, and is important in giving the skin its overall strength and elasticity

A

reticular dermis

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23
Q

melanin is produced from the conversion of tyrosine within organelles known as ______

A

melanosomes

24
Q

melanosomes are transferred to keratinocytes by what process?

A

phagocytosis

25
Q

light or dark skin is characterized by smaller, grouped melanosomes that degrade quickly?

A

light

26
Q

bone marrow-derived dendritic cells found in the suprabasilar epidermis and dermis, that play a role in antigen presentation and in contact sensitization and immunosurveillance

A

langerhans cells

27
Q

hair follicles are a type of ____ gland, whose secretions are formed by the decomposition of their cells and are under endocrine control.

A

sebaceous

28
Q

this type of gland is found in the axilla and genital areas and, under adrenergic sympthetic control, employ odorless ____ secretion

A

apocrine gland; decapitation

29
Q

this gland participates in heat regulation and, under cholinergic sympathetic stimulation (hypothalamus), secretes material from its clear and dark cells

A

eccrine gland

30
Q

muscles that are supplied by adrenergic nerves, and contract during cold or emotional stress producing “goose flesh”

A

arrector pili muscles

31
Q

3 cycles of hair growth

A

anagen
catagen
telogen

32
Q

Most hairs (80-90%) of the scalp are in the active phase of hair growth called ____ , which may last for about 3-7 years

A

anagen

33
Q

in the catabolic phase of hair growth called _____, mitotic activity ceases and the bulb shrinks away from the follicular papilla; this phase lasts approximately 3 weeks and less than 1% of hairs are in this phase at any given point in time

A

catagen

34
Q

10-20% of scalp hairs are in this resting phase of hair growth at any given point in time; it lasts about 3 months,

A

telogen

35
Q

the skin underlying the free end of the nail is referred to as the _______ and is contiguous with the skin on the tip of the finger

A

hyponychium

36
Q

these are dendritic cells of neural crest origin and comprise about 1 in 7 cells in the basal layer

A

melanocytes

37
Q

each epidermal melanin unit contains a melanocyte that supplies melanin pigment to about how many keratinocytes?

A

36

38
Q

light or dark skin is characterized by larger, single melanosomes that degrade slowly, and larger more dendritic melanocytes?

A

dark skin

39
Q

True or false: fingernails grow faster than toenails.

A

true

40
Q 
lamellar granule/odland bodies OR keratohyalin granules contain: 
° Electron dense protein
° Profilaggrin
° Keratin intermediate filaments
° Loricrin
A

keratohyalin granules

41
Q 
lamellar granules/odland bodies OR keratohyalin granules contain: 
° Glycoproteins
° Fatty acids
° Phospholipids
° Glucosylceramides
° Cholesterol / Free sterols
A

lemallar granules/odland bodies

42
Q

lamellar granules/odland bodies OR keratohyalin granules are membrane bound?

A

lamellar granules/odland bodies

43
Q

lamellar granules/odland bodies OR keratohyalin granules deliver free amino acids to the outer layers of the stratum corneum?

A

keratohyalin granules

44
Q

lamellar granules/odland bodies OR keratohyalin granules: fuse with the plasma membrane and discharge lipid contents in to the intercellular space (exocytosis)?

A

lamellar granules/odland bodies

45
Q

lamellar granules/odland bodies OR keratohyalin granules: contains filaggrin which promotes aggregation of keratin filaments?

A

keratohyalin granules

46
Q

large nerve end organs in the subcutis that mediate the sense of pressure

A

vater pacini corpuscles

47
Q

heat exchange between the skin and the external environment is largely mediated by what two mechanisms?

A

cutaneous blood vessels and eccrine sweat glands

48
Q

molecules capable of absorbing radiant energy

A

chromophores

49
Q

“tanning rays”

A

UVA

50
Q

“burning rays”

A

UVB

51
Q

carcinogenic rays

A

(particularly) UVC

52
Q

When a chromophore absorbs a photon of UV light, it enters an “excited”, unstable energy state for a brief period of time. To return to its ground state, it must release the absorbed energy in one of what 3 ways?

A
  1. undergo chemical change to form photoproduct
  2. transfer the energy to another molecule
  3. shed the energy as heat
53
Q

Langerhans cells play an important role in antigen presentation and are characterized by a unique cytoplasmic organelle known as what?

A

Birbeck granule

54
Q

t cell skin homing receptor

A

CLA (cutaneous lymphocyte antigen)

55
Q

what is the “triple response of lewis”, and what is responsible for each of these components?

A

erythema (red spots) - capillary dilation
flare (expanding redness) - arteriolar dilation
wheal (edema) - increased vascular permability

MOHD2: Exam 3 (10 decks)

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