Skin

Question 1

role of the dermis, epidermis, hypodermis

Answer 1

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

Question 2

name the 4 layers of the epidermis

Answer 2

stratum basale
stratum spinosum
stratum granulosum
stratum corneum

Question 3

most common cell type in the epidermis

Answer 3

keratinocytes

Question 4

the epidermis continuously turns over every ___ days

Answer 4

28

Question 5

melanocytes and langerhans cells are found in this layer

Answer 5

epidermis

Question 6

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

Answer 6

tonofilaments; tonofibrils

Question 7

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

Answer 7

acidic; basic

Question 8

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

Answer 8

stratum basale

Question 9

keratin types 5 and 14

Answer 9

basal keratinocytes

Question 10

keratin types 1 and 10

Answer 10

suprabasal keratinocytes

Question 11

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

Answer 11

desmosomes

Question 12

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

Answer 12

stratum spinosum

Question 13

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

Answer 13

plakoglobin and desmoplakin

Question 14

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

Answer 14

stratum granulosum

Question 15

____ _____ 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

Answer 15

keratohyaline granules

Question 16

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

Answer 16

granular cells

Question 17

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

Answer 17

lamellar granules/odland bodies

Question 18

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

Answer 18

stratum corneum

Question 19

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

Answer 19

hemidesmosome

Question 20

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

Answer 20

dermis

Question 21

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

Answer 21

papillary dermis

Question 22

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

Answer 22

reticular dermis

Question 23

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

Answer 23

melanosomes

Question 24

melanosomes are transferred to keratinocytes by what process?

Answer 24

phagocytosis

Question 25

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

Answer 25

light

Question 26

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

Answer 26

langerhans cells

Question 27

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

Answer 27

sebaceous

Question 28

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

Answer 28

apocrine gland; decapitation

Question 29

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

Answer 29

eccrine gland

Question 30

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

Answer 30

arrector pili muscles

Question 31

3 cycles of hair growth

Answer 31

anagen catagen telogen

Question 32

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

Answer 32

anagen

Question 33

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

Answer 33

catagen

Question 34

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

Answer 34

telogen

Question 35

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

Answer 35

hyponychium

Question 36

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

Answer 36

melanocytes

Question 37

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

Answer 37

36

Question 38

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

Answer 38

dark skin

Question 39

True or false: fingernails grow faster than toenails.

Answer 39

true

Question 40

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

Answer 40

keratohyalin granules

Question 41

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

Answer 41

lemallar granules/odland bodies

Question 42

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

Answer 42

lamellar granules/odland bodies

Question 43

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

Answer 43

keratohyalin granules

Question 44

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

Answer 44

lamellar granules/odland bodies

Question 45

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

Answer 45

keratohyalin granules

Question 46

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

Answer 46

vater pacini corpuscles

Question 47

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

Answer 47

cutaneous blood vessels and eccrine sweat glands

Question 48

molecules capable of absorbing radiant energy

Answer 48

chromophores

Question 49

"tanning rays"

Answer 49

UVA

Question 50

"burning rays"

Answer 50

UVB

Question 51

carcinogenic rays

Answer 51

(particularly) UVC

Question 52

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?

Answer 52

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

Question 53

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

Answer 53

Birbeck granule

Question 54

t cell skin homing receptor

Answer 54

CLA (cutaneous lymphocyte antigen)

Question 55

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

Answer 55

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