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Flashcards in Lecture 1 Integument Deck (222)
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1
Q

What does the Integumentary System consist of?

A

Skin and its derivatives

2
Q

What are some skin derivatives?

A

Nails, hair, sweat glands and sebacious glands

3
Q

T/F The integument is a complex organ that contains all four primary tissue classes

A

TRUE

4
Q

What tissue class is found in the epidermis?

A

Epithelium

5
Q

The dermis and hypodermis both contain which three tissue classes?

A

CT, muscle, and nerve

6
Q

The skin functions as a barrier to protect the body from what?

A

Chemical irritants, water loss, microbes, and other orgnisms

7
Q

What are some of the skin’s sensory perceptions?

A

The skin can function to percept heat, cold, touch, itch, pressure and pain

8
Q

The exposure of which cells to UV light allows them to convert a cholesterol derivative into Vitamin D?

A

Epidermal keratinocytes

9
Q

What is the Vitamin D form that is absorbed into blood?

A

Cholecalciferol

10
Q

What hormone is cholecalciferol converted to by enzymes in the liver and kidney?

A

Calcitriol

11
Q

What does calcitriol do?

A

It promotes calcium and phosphorus absorption from the intestines?

12
Q

How does the integument excrete waste?

A

Thru sweat

13
Q

What is sweat?

A

A watery solution of salts and urea (a nitrogenous waste)

14
Q

Thermoregulation of the integument is regulated by which part of the brain?

A

Hypothalamus

15
Q

Nuclei and other organelles break down in which layer of the skin?

A

stratum corneum

16
Q

Name the layers of the skin from basement membrane to surface.

A

basale, spinosum, granulosum, lucidum, corneum

Mnemonic: Buy Some Green Licking Candy

17
Q

What type of granules are found in stratum corneum that condense into dense plates that greatly strengthen cells?

A

keratin

18
Q

Nuclei and other organelles break down in which layer of the skin?

A

stratum corneum

19
Q

In which layer do keratinocytes multiply and start to move up and mature as they start to produce keratin precursor proteins?

A

stratum basale

20
Q

In stratum granulosum, what type of cell produces numerous intermediate filaments that aggregate keratohyalin proteins into granules?

A

keratinocytes

21
Q

What is the name of the intermediate filament that aggregrates keratohyalin proteins into granules?

A

tonofilaments

22
Q

How are the lamellar bodies released in stratum granulosum?

A

By exocytosis

23
Q

What are the 3 contents of the lamellar body?

A

phospholipids, glycosphingolipids, ceramides

24
Q

What is the largest organ of the body? What is its percentage of body weight?

A

Skin. 15% of body weight

25
Q

What are the three main divisions of skin?

A
  1. Epidermis
  2. Dermis
  3. Hypodermis
26
Q

Hair, nails, and skin glands are modified _______ structures.

A

Epidermal

27
Q

What is the nonintermediate filament protein that is the major product of keratinocytes in stratum granulosum which induces the aggregation of keratins?

A

Filaggrin

28
Q

How are the lamellar bodies released in stratum granulosum?

A

By exocytosis

29
Q

What are the 3 contents of the lamellar body?

A

phospholipids, glycosphingolipids, ceramides

30
Q

Which envelope (cell or lipid) helps waterproof the epidermis?

A

lipid envelope

31
Q

Why do our fingers and toes wrinkle after soaking?

A

Prolonged exposure to water triggers the autonomic nervous system to constrict blood vessels in the tissue under the epidermis resulting in a loss of volume in each finger which causes the skin to shrink inward.

32
Q

What is the autoimmune blistering disease that targets desmosomes and hemidesmosomes?

A

Pemphigus

33
Q

What is the thickness of thin skin? How much of the body does it cover?

A

1-2 mm. Thin skin covers all of the body except palms on hands and soles on feet

34
Q

What are the three immigrant cells of epidermis?

A

Melanocytes, Langerhans, Merkel

35
Q

Which two immigrant cells of epidermis originate from neural crest cells?

A

Melanocytes and Merkel

36
Q

Which immigrant cells of epidermis originates from the bone marrow cell?

A

Langerhans

37
Q

How can thick skin be thickened?

A

By repeated pressure or friction

38
Q

Which skin is more likely to have more layers of skin, thick or thin? What skin layer does thick skin have that thin skin does not (usually)?

A

Thick skin has more layers that thin skin. Stratum lucidum is present in thick skin but rare or non-existent in thin skin

39
Q

What is the autoimmune blistering disease that targets hemidesmosomes in the basal layer?

A

advanced pemphigus vegetans

40
Q

Which division of the skin has a papillary region of loose CT and irregular lower region that is dense? What is the dense irregular region called?

A

Dermis. The reticular region of the dermis

41
Q

Which type of skin and hair has stable and abundant amounts of melanin and melanosomes, light-colored or dark-colored skin and hair?

A

dark-colored

42
Q

What do most regions of the hypodermis contain?

A

Adipocytes

43
Q

T/F The dermis contains many collagen fibers, hair follicles, sweat glands, blood vessel, lymphatic vessels, sensory receptors, nerves, and CT cells?

A

True

44
Q

Which melanin pigment is a mixed polymer of tyrosine and cysteine that ranges in color from yellow to brown to reddish?

A

phaeomelanin

45
Q

Which pigment is a yellow pigment found in vegetables and egg yolks that can become concentrated in the stratum corneum and in subcutaneous fat?

A

carotene

46
Q

What is the key enzyme in the production of melanin that is used by neurons in the production of neurotransmitter dopamine?

A

tyrosinase

47
Q

What are the melanin pigment granules produced by melanocytes called?

A

melanosomes

48
Q

What is the process of transferring melanosomes into keratinocytes called? It is also known as melanosome secretion.

A

cytocrine injection

49
Q

What is the abnormal skin color disease associated with yellowing of skin and the sclera due to excess of bilirubin in blood, usually caused by liver disease?

A

Jaundice

50
Q

What is the abnormal skin color disease associated with bronzing which is caused by excessive ACTH from the pituitary gland that stimulates melanocytes?

A

Addison’s disease

51
Q

What appearance do the keratinocytes have in the stratum spinosum?

A

Spiny or “prickled” in appearance

52
Q

Which melanin pigment is a pure polymer of tyrosine?

A

black eumelalnin

53
Q

What do Langerhans cells do?

A

They help protect against pathogens by engulfing them and then presenting characteristic parts of the devoured cells to lymphocytes

54
Q

What are the characteristics of Langerhans cells?

A

Dendritic cell processes, indented nucleus, Birbeck granules

55
Q

Do Langerhan’s Cells have desmosomes?

A

No desmosome junctions since they need to move around the keratinocytes like amoebas

56
Q

What are the layers of the gross structure of the skin and underlying tissues?

A
  1. Epidermis
  2. Dermis
  3. Hypodermis
    4, Fascia
  4. Muscle
    Mnemonic: Every Dog Has [a] Foul Mouth
57
Q

What three other cells does the epidermis have besides keratinocytes?

A

Melanocytes, Langerhans, and Merkel Cells

58
Q

What are layers of the epidermis named for?

A

They are named for the activity and morphology of the keratinocytes in each distinct zone

59
Q

What is the deepest layer of the epidermis?

A

Stratum basale

60
Q

T/F Lines of incision made parallel to Cleavage Lines tend to have slower healing.

A

False, lines of incision made parallel to cleavage lines heal more efficiently.

61
Q

The stratum basale itself is a single layer of ______ cells sitting on the basement membrane

A

columnar

62
Q

Melanocytes and Merkel Cells (tactile cells) are both attached to the basement membrane by what junction?

A

Hemidesmosome

63
Q

Which epidermal layer has keratinocytes that produce intermediate filaments that are precursors to forming keratin?

A

Stratum spinosum

64
Q

Why are spinosum keratinocytes prickled in appearance?

A

Because they undergo shrinkage during histological preparation while at the same time remaining attached to each other by numerous desmosomes

65
Q

Where are lamellar bodies discharged into from the keratinocyte?

A

into the intercellular space to form a lipid envelope around the cell

66
Q

What is the abnormal skin color disease associated with blueness resulting form deficiency of oxygen in the circulating blood?

A

cyanosis

67
Q

What is the abnormal skin color disease associated with redness due to dilated cutaneous vessels which can be cause by anger, sunburn, heat, allergy, and embarrassment?

A

erythema

68
Q

T/F Curly hair is flattened oval in cross section. Straight hair is round cross section.

A

True

69
Q

What is the abnormal skin color disease associated with a patterned albinism thought to be cause by an autoimmune disorder?

A

vitiligo

70
Q

Psoriasis is an example of what kind of abnormal cell growth?

A

Hyperplasia

71
Q

What is the skin marking called when is is discolored by benign tumors of dermal blood capillaries?

A

hemangiomas (birthmarks)

72
Q

T/F Blond hair contains a mixture of small amounts of black or brown eumelanin and red pheomelanin pigments.

A

True

73
Q

T/F Freckles are flat; Moles are elevated

A

True

74
Q

What disease is caused by a virus and can be transmitted by touch and are found in people who have weakened immune system?

A

warts (verruca vulgaris)

75
Q

What is the skin marking that forms a unique pattern during fetal development?

A

friction ridges

76
Q

What is the skin markings that form after birth by repeated closing of the hand or bending of the wrist or elbow?

A

flexion creases

77
Q

What is the flexion crease that is a single palmar crease that is frequently associated with conditions such as Down syndrome and fetal alcohol syndrome?

A

simian crease

78
Q

What are the lines called that indicate the direction of the collagen fibers in the reticular layer of the dermis?

A

cleavage lines (also called langer lines or tension lines)

79
Q

What do you call excessive hair growth usually caused by a hormone imbalance?

A

hirsutism

80
Q

What kind of baldness is under genetic and hormonal control?

A

pattern baldness

81
Q

What disease is the thinning of hair of baldness that can occur in patches or across the entire body due to the body’s immune system attacking hair follicles causing round patches of hair loss?

A

alopecia

82
Q

What are the 3 repeating stages of the growth cycle of hair?

A

growth (anagen), shrinking (catagen), resting (telogen) stages

83
Q

How much does hair grow in young adults?

A

0.3mm/day

84
Q

How long is growth stage in young adults?

A

6-8 years

85
Q

How many inches can hair grow in a year?

A

4.3 inches

86
Q

How long does the shrinking stage (catagen) last?

A

2-3 weeks

87
Q

How long does the resting stage (telogen) last?

A

1-3 months

88
Q

What kind of hair is a mixture of white hairs and some pigmented hairs?

A

gray hair

89
Q

What part of the hair shaft degrades into spongy space making white hair brittle?

A

medulla

90
Q

What type of hair contains a mixture of eumelanin and pheomelanin?

A

red hair

91
Q

What type of hair has proportionally more phaeomelanin?

A

bright red hair

92
Q

What type of melanin is found in black and dark brown hair?

A

eumelanin

93
Q

What are the 3 layers of dead keratinocytes in hair shafts?

A

cuticle, cortex, and medulla

94
Q

T/F Hair color is due to pigment deposited in cells of the cuticle layer.

A

False, the cortex layer

95
Q

What cells in the stratum spinosum layer of the epidermis can be involved in delayed-type hypersensitivity reactions?

A

Langerhan’s Cells

96
Q

Why does the stratum granulosum stain darkly?

A

Because of the increasing protein content of the maturing, squamous kertinocytes

97
Q

Which epidermal layer produces lots of keratin?

A

Stratum granulosum

98
Q

What are keratinocytes filled with abundantly in the stratum granulosum?

A

Granules of keratohyalin

99
Q

What is keratohyalin?

A

A precursor to keratin that combines with other proteins to form a tough protein granule

100
Q

How are vesicles of glycolipid released from keratinocytes?

A

Via exocytosis

101
Q

What do the glycolipids do for the skin?

A

Glycolipids waterproof the skin

102
Q

What role do glycolipids play in the absorption of nutrients from deeper layers of the skin?

A

They block the absorption of nutrients

103
Q

What is the infolding of layers of epidermal keratinocytes on a basement membrane?

A

epithelial root sheath

104
Q

What is the dermal connective tissue that contains the neurovascular supply for the hair?

A

papilla

105
Q

What is the outermost layer of a hair shaft?

A

cuticle

106
Q

What layer is composed of dead, flattened keratinocytes that are compressed against each other to varying degrees?

A

cuticle

107
Q

What is a shaft of keratinized cells?

A

hair

108
Q

What is composed of 3 layers of keratinocytes (cuticle, cortex, and medulla) that emerge out of the skin?

A

hair shaft

109
Q

What is composed of layer of cells below the surface of the skin within the hair follicle?

A

hair root

110
Q

What is the swelling in the base of the root where a hair originates?

A

hair bulb

111
Q

What is the vascular tissue that provides nutrients to the hair bulb?

A

dermal papilla

112
Q

What is the tubular infolding of the skin that a hair grows out of?

A

hair follicle

113
Q

In which layer do keratinocytes begin to die and their nuclei break down?

A

Stratum granulosum

114
Q

Only a few ______ nuclei are observed in cells entering the next layer above stratum granulosum

A

Pyknotic

115
Q

What are the dark staining structures in the cytoplasm of the keratinocytes of the stratum granulosum?

A

Condensing granules of keratin

116
Q

How does the cytoplasm of mature keratinocytes become more smooth and homogenous?

A

By coalescing keratin granules as organelles disintegrate

117
Q

What muscle can lift up hairs and depress the skin around it (causing goosebumps)?

A

piloerector muscle (arrector pili)

118
Q

What muscle is stimulated by sympathetic nerve fibers in response to cold and fear?

A

piloerector muscle (arrector pili)

119
Q

What is associated with apocrine sweat glands and sebaceous oil glands?

A

hair follicles

120
Q

What are peritrichal sensory nerve endings that wrap around each follicle?

A

hair receptors

121
Q

What is the bundle of smooth muscle cells that connects dermal collagen fibers to the epithelial root sheath?

A

piloerector muscle (arrector pili)

122
Q

What is the purpose of body hair?

A

enhances sense of touch

123
Q

What is the purpose of eyebrows?

A

reinforce or exaggerate expression of emotions

124
Q

What is the purpose of scalp hair?

A

heat retention in cold weather and protection from sunburn

125
Q

What is the purpose of facial, pubic, axillary hair?

A

indicates gender and sexual maturity

126
Q

What is the purpose of nose hairs, ear hairs, eyelashes?

A

prevent foreign objects from getting into nostrils, ear canals, or eyes

127
Q

What types of bridges toughen the keratin of hair and nails?

A

disulfide bridges

128
Q

What is given off from disulfide bridges when hair is burned?

A

sulfur

129
Q

What are the 3 types of body hair types?

A

lanugo, vellus, terminal

130
Q

What body hair type is fine fetal hair?

A

lanugo

131
Q

What body hair type is fine, unpigmented hair of children and adults?

A

vellus

132
Q

What body hair type is coarse, long, pigmented?

A

terminal

133
Q

What kind of fat is the thickest in the abdominal wall, hips, and thighs, but is essentially absent from eyelids, dorsal side of hand, scrotum, and penis?

A

subcutaneous fat

134
Q

Which layer of the skin is also called the subcutaneous tissue or the superficial fascia?

A

hypodermis

135
Q

What is another name for the subcutaneous fat found in the hypodermis?

A

adipose

136
Q

What is the function of the hypodermis?

A

energy reservoir; thermal insulation

137
Q

What kind of injections deliver substances into the highly vascular tissue of the hypodermis?

A

hypodermic injections

138
Q

T/F Tattoo ink is applied to the epidermis

A

False; to the dermis

139
Q

The thickness of dermis across the body varies from ___ to ___.

A

0.6mm to 3mm

140
Q

What layer of the skin is composed of collagen, elastic fibers, and reticular fibers produced by fibroblasts?

A

Dermis

141
Q

What are the layers of the dermis?

A

papillary layer and reticular layer

142
Q

Which layer of the dermis is composed of vascular, sensitive, loose connective tissue arranged into dermal papillae?

A

papillary layer

143
Q

What kind of corpuscles are found in the papillary layer of the dermis?

A

Meissner’s corpuscles and Ruffini corpuscles

144
Q

Which region of the dermis is the deeper part and is composed of dense irregular connective tissue?

A

reticular layer

145
Q

Which nerve fibers wrap around hair bulbs and are stimulated by movement of the hair?

A

peritrichal nerve endings

146
Q

Which corpuscles sense pressure, stretch, tickle, and vibration?

A

Pacinian corpuscles

147
Q

Why does the stratum lucidum appear pale in comparison to other adjacent layers?

A

The coalescing keratin protein in this layer does not stain well

148
Q

Up to how many layers of dead, flattened, and keratinized cells is the stratum corneum composed of?

A

Up to 30 layers

149
Q

From what epidermal layer do surface cells continuously flake off or exfoliate?

A

Stratum corneum

150
Q

How long does it take for keratinocytes to mature from the stratum basale to exfoliation?

A

15-30 days

151
Q

Where are Merkel’s cells located?

A

basal layer of epidermis.

152
Q

How abnormally fast do cells move from the stratum basale to the corneum in patients with psoriasis?

A

In seven (7) days

153
Q

What is the outcome of abnormally fast cell maturation in psoriasis?

A

A thicker stratum corneum that forms plaques or flakes

154
Q

Psoriasis is an example of what kind of abnormal cell growth?

A

Hyperplasia

155
Q

What are two treatments for psoriasis?

A

Cortizone cream and coal tar

156
Q

Where are Pacinian corpuscles located?

A

Found in the hypodermis of hands, feet, breasts, and genitals

157
Q

What corpuscles are sensitive to displacement of surrounding collagen fibers due to slow, sustained mechanical stress of skin, ligaments, tendons, and joint capsules?

A

Ruffini’s corpuscles

158
Q

What are the bare dendrites that lack Schwann cell covering and are sensitive to pain and temperature?

A

free nerve endings

159
Q

What cells are sensitive, high resolution tactile receptors in the epidermis used for sensing textures, edges, and shapes?

A

Merkel’s cells

160
Q

Where are Merkel’s cells derived from?

A

neural crest

161
Q

Which corpuscles are composed of a fibrous capsule around a nerve ending?

A

Meissner’s (Tactile) corpuscles

162
Q

Which corpuscles sense light touch, shapes and texture and are located in dermal papillae in fingers, hand, foot, forearm, tongue, and are particularly abundant in the vermillion zone of lips?

A

Meissner’s (Tactile) corpuscles

163
Q

Meissner Corpuscle and the Merkel Cell are both tactile receptors. Are they both found in the same division of skin?

A

No, the Meissner is found in the dermis, while Merkel is found in the epidermis

164
Q

What are the four tactile cells found in the Integument?

A
  1. Merkel cell
  2. Meissner corpuscle
  3. Ruffini corpuscle
  4. Pacinian corpuscle
165
Q

Though the Ruffini and Pacinian corpuscles are structurally similar, they are located in different divisions of the skin. Which one is located in the Dermis? Which one in the hypodermis and deep fascia?

A
  1. Ruffini.
  2. Pacinian.
    Memory tool: RIP (R before P)
166
Q

Which one of the four tactile cells of the integument is a derivative of Neural Crest Cells?

A

Merkel

167
Q

Which of the following six sensory receptors of the skin extend into the epidermis?

  1. Merkel cell
  2. Meissner corpuscle
  3. Ruffini corpuscle
  4. Pacinian corpuscle
  5. Peritrichial nerve endings
  6. Free Nerve endings
A
  1. Merkel cell
  2. Peritrichial nerve endings
  3. Free Nerve endings
168
Q

The nail plate is a derivative of which epidermal layer?

A

Corneum

169
Q

What do nails cover?

A

Fleshy, sensitive fingertips

170
Q

What is the cuticle of the nail called?

A

Eponychium

171
Q

Where is the eponychium located?

A

Where the skin and nail meet on the dorsal surface?

172
Q

What is the epithelium of the nail bed called?

A

Hyponychium

173
Q

Where does the nail root grow out of? What stratum is this location equivalent to in the epidermis?

A

Nail matrix. Basale

174
Q

What does the nail plate rest on?

A

The nail bed

175
Q

T/F New cells are added by mitosis in the nail matrix.

A

True

176
Q

What are the four cutaneous glands?

A

Sweat, sebacious, ceruminous, and mammary

Mnemonic: some say carry money

177
Q

Where is sweat derived from?

A

Blood plasma

178
Q

What are the two types of sweat glands?

A

Eccrine and Apocrine

179
Q

Which sweat gland type exists in millions all over the body and functions to cool skin?

A

Eccrine

180
Q

Which sweat gland type responds to stress and excitement?

A

Apocrine

181
Q

Which sweat glands opens into hair follicles? Which one directly on to skin surface?

A

Apocrine. Eccrine

182
Q

Apocrine glands open their ducts to hair follicles of what areas of the body?

A

Axilla, anus, and genitals

183
Q

Sweat from which glands contains fatty acids?

A

Apocrine

184
Q

What do you call body odor produced by bacterial action on the fatty acids in the apocrine sweat?

A

Bromhidrosis

185
Q

T/F Both eccrine and apocrine glands release their secrection by merocrine process.

A

True

186
Q

What is the benefit of a coiled duct of a sweat gland?

A

Allows duct to stretch with skin

187
Q

Sebaceous glands ducts open into what area of the epidermis? Which type of sweat gland also has ducts to this area?

A

Hair follicle. Apocrine sweat gland.

188
Q

By what process is sebum released from the sebaceous gland?

A

Holocrine

189
Q

What does sebum do to the keratinocytes at the outer layer of the hair shaft?

A

It softens them

190
Q

What is the name of sebum collected from lamb wool and used in some skin creams to soften the corneum?

A

Lanolin

191
Q

Which glands are found only in the external auditory meatus (EAM)?

A

Ceruminous

192
Q

What do ceruminous secretions combine with to produce earwax?

A

sebum

193
Q

What does earwax do?

A

Repels water, keeps eardrum flexible, and repels mites and other pests

194
Q

Lots of accumulated and deeply lodged earwax can cause which hearing impairment that is accompanied by ringing in the ears?

A

Tennitus

195
Q

What kind of sun rays can induce skin cancer?

A

UV rays

196
Q

T/F Skin cancer is most common in fair-skinned and elderly.

A

True

197
Q

What are three major skin cancers? Which one is the most deadly?

A

Basal cell carcinoma, squamous cell carcinoma, and melanoma. Melanoma is the most deadly skin cancer

198
Q

Which stratum of the epidermis does basal cell carcinoma arise from? What layer does it invade?

A

Basale. Invades the underlying dermis.

199
Q

How is basal cell carcinoma treated?

A

By surgical removal and radiation

200
Q

In which stratum of the epidermis does squamous cell carcinoma (SCC) arise?

A

Spinosum

201
Q

SCC is lethal if affected cells metastasize to what part of the body?

A

Lymph nodes

202
Q

From what basal immigrant cell does melanoma arise?

A

Melanocytes

203
Q

What is the ABCDE of identifying melanoma?

A

Assymetry, Border irregular, Color mixed, Diameter over 6 mm, Elevation above skin surface

204
Q

Which melanomas are hard to spot? Why?

A

Amelanotic melanoma. The affected melanocytes do not produce melanin so it is difficult to spot.

205
Q

What are the major causes of burns?

A

Extreme heat, sunlight, radiation, electric shock, and chemicals

206
Q

Causes of death from burns are due to what subsequent effects?

A

Fluid loss and/or infection

207
Q

What do degrees of burns correspond to?

A

The depth of the burn, ie, a first degree burn only goes down to the epidermis. Second degree to dermis, Third to hypodermis

208
Q

Which degree of a burn often requires skin grafts, or may result in disfigurement and fibrosis scarring?

A

3rd degree

209
Q

What are some treatments for a burn?

A

Fluid replacement, infection control, debridement, and intravenous replacement of proteins and nutrients

210
Q

UVA is often called the “tanning rays.” What is UVB called? Which one can cause burns?

A

Burning rays. Both can cause burning depending upon exposure conditions

211
Q

T/F Only UVB is thought to initiate cancer?

A

FALSE. Both UVA and UVB wavelengths of UV rays are thought to initiate cancer.

212
Q

T/F The rate of skin cancer has risen with use of sunscreens.

A

True. There is a statistical correlation

213
Q

Sunscreen chemicals can be altered by UV rays into compounds that damage DNA by generating harmful ______ radicals

A

Free

214
Q

What affect does natural melanin have on free radicals?

A

It can bind to free radicals and neutralize their effects.

215
Q

T/F Melanin is the body’s natural sun screen?

A

FALSE. Melanocytes are basal layer cells that mostly add melanin to cells in the basal layer and therefore would not protect nucleated cells in overlying epidermal layers

216
Q

How do melanocytes protect skin cells from free radicals?

A

By cytocrine injection that neutralizes the inner chemistry of the affected cells

217
Q

T/F Melanin is present in skin, iris, hair follicles, and inner ear.

A

True

218
Q

What does melanin do in the inner ear?

A

Absorbs free radicals from hair cells (mechanoreceptors, not actually made of hair) that are firing action potentials all day. This heavy physiology cranks out a lot of free radicals,

219
Q

What does cutaneous wound healing involve?

A

It involves the release of numerous growth factors from a variety of cells including fibroblasts, macrophages, platelets, and keratinocytes

220
Q

What do the growth factors do during wound healing?

A

Some attract cells into the wound and others stimulate growth of the cells in the epidermis and dermis

221
Q

Where can epidermal keratinocytes come from to heal injuries to the skin?

A

Stratum basale, hair follicles, or sweat glands

222
Q

What kind of wounds require skin grafts?

A

Wounds that leave insufficient sources of keratinocytes to repopulate the area