Skin Flashcards
(178 cards)
1
Q
What is the heaviest single organ of the body and what percentage of total body weight does it constitute?
A
The skin; 15% of total body weight
2
Q
The skin presents between ___ and ___ square meters of surface area (average __ m²).
A
1.2 - 2.3 m2; 2 m2
3
Q
What are the two main layers composing the skin?
A
Epidermis and dermis
4
Q
The epidermis is an epithelial layer of ___ origin.
A
Ectodermal
5
Q
The dermis is a connective tissue layer of ___ origin.
A
Mesodermal
6
Q
What type of epithelium makes up the epidermis?
A
Stratified squamous keratinized epithelium
7
Q
What is the predominant cell type in the epidermis?
A
Keratinocytes
8
Q
Name the three less abundant cell types in the epidermis.
A
Melanocytes, Langerhans cells, Merkel’s cells
9
Q
Melanocytes and Merkel’s cells in the epidermis are derived from
A
Neural crest
10
Q
Langerhans cells in the epidermis are derived from
A
Bone marrow precursor
11
Q
___ are neural crest-derived cells found in the epidermis.
A
Melanocytes and Merkel’s cells
12
Q
___ are derived from bone marrow precursors and found in the epidermis.
A
Langerhans cells
13
Q
A
14
Q
Which cells of the epidermis are derived from neural crest and involved in pigment production?
A
Melanocytes
15
Q
Which cells of the epidermis are neural crest-derived and associated with sensory function?
A
Merkel’s cells
16
Q
Which cells of the epidermis are antigen-presenting and derived from bone marrow?
A
Langerhans cells
17
Q
A
18
Q
List the layers of keratin-producing cells in the epidermis from innermost to outermost.
A
Stratum basale (germinativum), Stratum spinosum, Stratum granulosum, Stratum lucidum, Stratum corneum
19
Q
Which layer of the epidermis contains a single layer of basophilic columnar or cuboidal cells resting on the basement membrane at the dermal-epidermal junction?
A
Stratum basale
20
Q
Which layer of the epidermis is a translucent thin layer of flattened eosinophilic cells?
A
Stratum lucidum
21
Q
Which layer consists of 3–5 layers of flattened polygonal cells with cytoplasm filled with keratohyalin granules?
A
Stratum granulosum
22
Q
Which epidermal layer has cells without organelles and nuclei?
A
Stratum lucidum
23
Q
Which layer of the epidermis consists of cuboidal or slightly flattened cells with central nuclei and cytoplasmic processes?
A
Stratum spinosum
24
Q
Which epidermal layer consists of 15-20 layers of flattened non-nucleated keratinized cells?
A
Stratum corneum
25
Which layer of the epidermis has cytoplasm densely packed with keratin filaments and desmosomes between adjacent cells?
Stratum lucidum
26
Which junctional complexes are present in stratum basale?
Desmosomes and hemidesmosomes
27
Stem cells in which epidermal layer show intense mitotic activity?
Stratum basale
28
Which two layers are responsible for the constant renewal of epidermal cells?
Stratum basale and initial portion of stratum spinosum
29
Stratum basale and stratum spinosum form ____ which shows _____
Stratum Malpighi; mitotic activity
30
How often is the human epidermis renewed?
Every 15–30 days
31
The spine-studded appearance of cells in the stratum spinosum is due to?
Bundles of keratin filaments (tonofilaments)
32
What is the function of tonofilaments in the stratum spinosum? 2
Maintain cohesion among cells and resist the effect of abrasion
33
Cytoplasm in flattened polygonal cells of stratum granulosum is filled with ___
Keratohyalin granules
34
What granules are membrane-coated and contain lamellar disks in the stratum granulosum?
Lamellar granules
35
Lamellar disks in the lamellar granules are formed by ____
Lipid bilayers
36
Lamellar granules discharge contents into ______ to form sheets containing lipid
Intercellular spaces of stratum granulosum
37
Which is the outermost layer of the epidermis?
Stratum corneum
38
How many layers of cells make up the stratum corneum?
15–20
39
What type of cells are found in the stratum corneum?
Flattened non-nucleated keratinized cells
40
The cytoplasm of stratum corneum cells contains what protein?
Birefringent filamentous scleroprotein (keratin)
41
Cells of stratum corneum contain only fibrillar and amorphous proteins with thickened plasma membrane after ____
Keratinization
42
After keratinization, cells of stratum corneum become ____
Horney cells or corneocytes
43
Which cells in the epidermis are found beneath or between the cells of stratum basale and in hair follicles
Melanocytes
44
Where are melanocytes located in the skin?
Beneath or between the cells of the stratum basale & in the hair follicles
45
Melanocytes are derived from _____.
Neural crest cells
46
Are hemidesmosomes present or absent in melanocytes?
Present
47
Are desmosomes present or absent in melanocytes?
Absent
48
Hemidesmosomes are absent and desmosomes are present in melanocytes. T or F
False
49
Where is tyrosinase synthesized?
Rough Endoplasmic Reticulum (RER)
50
Where does tyrosinase accumulate?
Golgi complex
51
Where is tyrosinase stored?
In vesicles called Melanosomes
52
In what stages of melanosome development does melanin synthesis occur, forming melanin granules?
Melanosome II and III stages
53
Where do melanin granules migrate after synthesis?
To keratinocytes of the Malpighian layer
54
Where do melanin granules accumulate in keratinocytes?
Supranuclear region of the cytoplasm
55
What is the function of accumulation of melanin granules in the supranuclear region of cytoplasm o keratinocytes?
To protect from the deleterious effects of solar radiation
56
Langerhans cells are located in the ____.
Stratum spinosum
57
What is the shape of Langerhans cells?
Star-shaped
58
Langerhans cells are derived from _____.
Bone marrow
59
What is the function of Langerhans cells?
Important in immunologic skin reactions
60
Where are Merkel’s cells generally found?
Thick skin of palms and soles
61
Merkel’s cells resemble _____.
Epidermal epithelial cells
62
Merkel’s cells contain ____ granules in cytoplasm
Small dense granules
63
What type of nerve ending is present at the base of Merkel's cells?
Free nerve ending
64
Epidermal cells found between the cells of the stratum basale & in the hair follicles
Melanocytes
65
Epidermal cells found between the cells of the stratum basale & in the hair follicles
Melanocytes
66
Epidermal cells found in the stratum spinosum
Langerhans cell
67
Epidermal cells found in the thick skin of palms and soles
Merkel's cells
68
List four reasons for immunologic activity in the skin.
Large size, presence of lymphocytes and APCs, close contact with antigenic molecules, epidermal immune response roles
69
The dermis is what type of tissue?
Connective tissue
70
2 functions of the dermis
Supports the epidermis and bind the epidermis to the hypodermis
71
The dermis has an irregular surface due to _____.
Dermal papillae interlocking with epidermal ridges
72
Thickness of dermis is constant T or F
False
73
Name the two layers of the dermis.
Papillary layer and Reticular layer
74
The papillary layer is composed of ____ connective tissue.
Loose
75
The reticular layer is composed of ____ connective tissue.
Irregular dense
76
What cells are found in the papillary layer? 4
Fibroblasts, mast cells, macrophages, and extravasated leukocytes
77
The type of collagen found in the reticular layer is ____.
Type I collagen
78
Anchoring fibrils in _____ layer of dermis are ____
Papillary layer; Special collagen fibrils that help hold the layers together
79
The reticular layer contains more ____ and fewer ____ compared to the papillary layer.
Fibers, cells
80
What is responsible for the elasticity of the skin?
Network of fibers of the elastic system in the reticular layer
81
The _____ contains a rich network of blood and lymphatic vessels.
Dermis
82
What structure in the dermis helps with temperature regulation?
Arteriovenous shunts
83
Name three epidermal derivatives found in the dermis.
Hair follicles, Sweat and sebaceous glands, Nerves
84
Subcutaneous tissue is composed of ____ connective tissue.
Loose
85
Fat cells in the subcutaneous tissue vary in ____ and ____.
Number, size
86
Another name for subcutaneous tissue is ____ or ____.
Superficial fascia, panniculus adiposus
87
The arterial vessels form how many plexuses in the skin?
Two
88
The venous vessels form how many plexuses?
Three
89
How many plexuses do lymphatic vessels form?
Two
90
Where are the arterial plexuses located?
Between the papillary and reticular layers, and between the dermis and subcutaneous tissue
91
List the three locations of venous plexuses.
Between the papillary and reticular layers, between the dermis and subcutaneous tissue, and middle of the dermis
92
How do lymphatic vessels begin?
As closed sacs in the dermal papillae
93
Composed of loose connective tissue, contains fibroblasts, mast cells, macrophages, and extravasated leukocytes, and has anchoring fibrils.
Functions of?
94
Composed of irregular dense connective tissue, contains type I collagen, more fibers and fewer cells.
Functions of?
95
Supporting the epidermis, housing blood vessels, sweat glands, hair follicles, and playing a role in thermoregulation.
Functions of?
96
3 types of skin sensorial receptors
Free nerve endings, expanded receptors, encapsulated receptors
97
Example of expanded receptors
Ruffini endings
98
Examples of encapsulated receptors
Vater-Pacini corpuscles, Meissner corpuscles, Krause corpuscles
99
What detect stretch & pressure, deep pressure & vibration, light touch, cold respectively?
Ruffini endings, Vater-Pacini corpuscles, Meissner corpuscles, Krause corpuscles
100
Free nerve endings are responsible for sensing what?
Pain and temperature
101
Name the three types of skin glands.
Sweat glands, sebaceous glands, mammary glands
102
Eccrine sweat glands are also called?
Merocrine sweat glands
103
Eccrine sweat glands are classified as?
Simple coiled tubular glands
104
Function of eccrine sweat glands?
Regulating body temperature
105
What two types of cells are found in the secretory units of eccrine sweat glands?
Dark cells and clear cells
106
4 areas where apocrine sweat glands found?
Axilla, areola, nipple, and anal region
107
What are 2 examples of modified apocrine sweat glands?
Ceruminous glands in the ear and glands of Moll in the eyelids
108
Which is larger and has larger lumen of secretory tubules: eccrine or apocrine sweat glands?
Apocrine glands
109
Where do sebaceous glands empty their secretory product?
Into the upper parts of hair follicles
110
List areas where sebaceous glands are NOT found.
Palms of hands, soles of feet, sides of the feet, inferior of hairline
111
Why are sebaceous glands clinically important?
They are liable to infections (e.g. with the development of acne)
112
___ are made of highly keratinized epithelial cells arranged in plates of hard keratin
Nails
113
Nails grow or develop from ____
Nail matrix (nail root)
114
The stratum corneum forms what part of the nail plate?
Eponychium (cuticle) of the nail plate
115
What epidermal layer forms the eponychium (cuticle) of the nail plate
Stratum corneum
116
The nail plate lies on ___
Nail bed
117
Nails correspond to what in animals?
Hooves and claws
118
Hairs are elongated, ____ structures that develop from _____ (skin layer) and invade ____ and _____.
Keratinized; Epidermis; Dermis and hypodermis
119
Where are hairs NOT found? 5
Palms, soles, glans penis, clitoris, labia minora
120
Hair grows discontinuously in which two phases?
Anagen and Telogen
121
Which phase of hair growth is the growth phase?
Anagen
122
Which phase of hair growth is the rest phase?
Telogen
123
How long does the growth (anagen) phase last in the scalp?
Several years
124
How long does the rest (telogen) phase last in the scalp?
About 3 months
125
Which 3 hormones influence hair in the scalp, face, and pubis?
Androgens, adrenal hormones, thyroid hormones
126
What type of keratin is found in nails and hair?
Hard keratin
127
What type of muscle is the arrector pili?
Smooth muscle
128
Hair papilla is made of which tissue type?
Connective tissue
129
The hair bulb contains what type of cells surrounding the papilla?
Epithelial cells
130
List three functions of hair.
Warmth, sense light touch, protection (especially scalp)
131
____ part of the hair is embedded in the skin and _____ part of the hair projects above the skin surface
Root; Shaft
132
What are the three concentric layers of hair?
Medulla, cortex, cuticle
133
Which layer of the hair is the core?
Medulla
134
Which layer of hair surrounds the medulla?
Cortex
135
Which hair layer is made of a single layer of overlapping cells?
Cuticle
136
The 3 types of hairs are
Vellus (fine, short), Intermediate, Terminal (longer, coarser)
137
Fine, short hairs are called ____ and Longer, coarser hairs are called ____
Vellus hairs; Terminal hairs
138
Hair growth rate averages what per week?
2 mm per week
139
Describe the basic cycle of hair growth.
Active phase → Resting phase → Hair shed
140
Hair loss or thinning (male pattern baldness or age-related thinning) is termed
Alopecia
141
Hair color is determined by ____ for black and brown hair
Amount and type of melanin
142
Hair color is determined by ____ for red hair
Distinct form of melanin
143
What causes white hair?
Decreased melanin and air bubbles in the medulla
144
Hair color is genetically determined but influenced by?
Hormones and environment
145
Which cells are active during the inflammation stage of wound healing?
Neutrophils, macrophages, lymphocytes
146
What major structural protein is deposited during fibroplasia?
Collagen
147
What molecule is associated with fibroplasia alongside fibroblasts?
Proteoglycans
148
What key process occurs during epithelialization?
Angiogenesis
149
What occurs during remodeling of a wound?
Collagen fibril crosslinking
150
Final stage of wound healing?
Scar maturation
151
What is the primary threat to life in burns?
Catastrophic loss of body fluids
152
Burns can lead to dehydration and fatal ______.
Circulatory shock
153
Name three complications of burns.
Dehydration, fatal circulatory shock, infection
154
Which degree of burn affects the epidermis only and causes ____ e.g ____
First-degree; redness (e.g sunburn)
155
Second degree burn involves _____ and cause ____
Epidermis and upper dermis; Blister
156
Third-degree burns destroy which layers?
Epidermis, dermis, and often part of hypodermis
157
Burn that destroys full thickness of skin is called?
Third-degree burn
158
Name the three types of skin damage mentioned apart from burns.
Infections, inflammation, skin cancer
159
List the three types of skin cancer.
Basal cell carcinoma, squamous cell carcinoma, melanoma
160
Diameter greater than how many millimeters is suspicious for melanoma?
6 mm
161
Which skin cancer is most dangerous?
Melanoma
162
Critical burn criteria includes what percentage of third-degree burns?
Over 10% of the body
163
Critical burn criteria includes what percentage of second-degree burns?
25% of the body
164
Third-degree burns on which body parts are considered critical regardless of extent?
Face, hands, or feet
165
Anterior and posterior head and neck account for what percentage in Rule of 9’s?
0.09
166
Rule of 9’s Anterior and posterior upper limbs together account for what percentage?
0.18
167
Rule of 9’s Anterior and posterior trunk account for what percentage?
0.36
168
Rule of 9’s Anterior and posterior lower limbs account for what percentage?
0.36
169
Rule of 9’s Perineum accounts for what percentage?
0.01
170
Benign tumors of the skin include what example?
Warts
171
Skin cancers are associated with what environmental factor?
UV exposure
172
UV exposure also contributes to what besides skin cancer?
Skin aging
173
Which skin lesion is premalignant?
Aktinic keratosis
174
Basal cell carcinoma arises from which skin layer?
Stratum basale
175
Squamous cell carcinoma arises from what type of cell?
Keratinocytes
176
Melanoma arises from which cells?
Melanocytes
177
Melanoma is recognized using which rule?
ABCD Rule
178
A, B, C, D in ABCD Rule stands for?
Asymmetry, Border irregularity, Colors, Diameter larger than 6mm
