T21 Integument Flashcards
1
Q
What is Skin =
A
Skin = Epidermis + Dermis
2
Q
What is the largest organ?
A
Skin
3
Q
What percent of body weight does skin account for ?
A
7%
4
Q
What is the thickness of skin?
A
1.5-4.4mm
5
Q
What is the hypodermis?
A
Hypodermis lies deep to the dermis, and is NOT part of the skin
6
Q
What is the order of the layers of skin?
A
Epidermis, dermis, hypodermis, deep fascia, muscle
7
Q
What are the functions of the skin?
A
- Protection—cushions organs and protects from bumps, chemicals, water loss, UV radiation
- Regulation of body temperature
- Excretion—urea, salts, and water lost through sweat
- Production of vitamin D in deep epidermis
- Sensory reception—keeps us aware of conditions at the body’s surface
8
Q
What is the embryonic origin of the epidermis?
A
Embryoic ectoderm
9
Q
What is the embryonic origin of melanocytes?
A
Neural crest cells (which are of ectoderm origin)
10
Q
What is the embryonic origin of the dermis and hypodermis?
A
Mesoderm
11
Q
What are the layers of the epidermis (think the nemonic XD)
A
- Stratum corneum
- Stratum lucidum (only in thick skin)
- Stratum granulosum
- Stratum spinosum
- Stratum basale (stratum germinativum)
12
Q
What are the 4 distinct cell types of the epidermis?
A
Keratinocytes, dendritic cells, melanocytes, tactile epithelial cells
13
Q
What type of epithelium is the epidermis?
A
Stratified Squamous Epithelium
14
Q
What are keratinocytes?
A
Most common cell type in epidermis
15
Q
What are dendritic cells and where are they located?
A
Located in stratum spinosum and stratum basale; part of the immune system; macrophage-like
16
Q
What are melanocytes and where are they located?
A
Located in basal layer; manufacture and secrete pigment
17
Q
What are tactile epithelial cells and where are they located?
A
Located in the basal layer, attached to sensory nerve endings
18
Q
What is the difference between keratinocytes and keratocytes?
A
- Keratinocytes: predominant cell-type in skin epidermis
* Keratocytes: specialized fibroblasts in the cornea
19
Q
What are keratinocytes?
A
- Most abundant cell type in epidermis
- Present in all epidermis layers
- Cells are tightly connected by a large number of desmosomes
20
Q
What do keratinocytes produce?
A
- Antibodies and enzymes that detox chemicals exposed to our skin
- Keratin
21
Q
What is keratin?
A
A touch fibrous protein that gives skin epidermis its protective properties
22
Q
What are the desmosomes?
A
Anchoring junctions bind adjacent cells together and help form an internal tension-reducing network of fibers.
23
Q
Where to keratinocytes arise from?
A
Deepest layer or epidermis (stratum basale) and from stem cells that undergo continuous mitosis. By the time they reach the surface of the skin, they are dead flat cells full of keratin. Millions of these dead cells rub off from our skin every day.
24
Q
How long does it take from keratinocyte birth –> sloughing off of exterior skin
A
35-45 days
25
How many pounds of skin does an average person shed in a lifetime?
40 pounds
26
How do calluses form?
Persistent friction can cause signifiant thickening, bc cell production and keratin production are accelerated in places of friction.
27
What layer is the stratum basale?
Deepest layer of the epidermis
28
What is stratum basale attached to?
Underlying dermis
29
How does the stratum basale get its nutrients?
Relies on capillaries in underlying dermis for nutrients
30
What are the tactile epithelial cells (merkel cells) in the stratum basale?
Associated with sensory nerve endings are sparsely distributed among the keratinocytes in the stratum basale
31
What percentage of stratum basale is made up of melanocytes?
10-25%
32
What do melanocytes do?
Make melanin and transport it through its spider shaped cells process to nearby keratinocytes
33
What does melanin do?
Shield cell nuclei from incoming UV radiation
34
How does melanocytes respond to UV radiation?
By increasing production of melanin and increasing its transfer to keratinocytes, the protective response which results in a suntan.
35
How is Vitamin D3 cholcalciferol formed?
Formed from 7-dehydrocholesterol in deep epidermis (basale and spinosum) after exposure to UVB light
36
What is vitamin D important for?
Uptake of calcium from the diet and formation of healthy bones as well as providing other health benefits
37
What is the relationship between level of melanin in keratinocytes and ability to produce vitamin D given same UV exposure?
Inverse relationship (e.g. more melanin = less of an ability to produce vit D)
38
Relationship between melanin and region of world.
Humans w high level of melanin = originate from regions of world with large amt of UV light exposure, humans w low levels of melanin = from areas of low UV light exposure
39
What is a nickname for the stratum spinosum?
Spiny layer
40
What does stratum spinosum contain?
Thick bundles of intermediate filaments (tonofilaments), and dendritic cells
41
What is intermediate filaments made of?
Protein pre-keratin (tension resisting)
42
What are dendritic cells?
Immune cells that engulf foreign antigens which have invaded epidermis and generate an immune response
43
What does the stratum granulosum consist of?
1-5 layers of flattened keratinocytes
44
What does the stratum granulosum reply on for nutrients?
Capillaries in the underlying dermis
45
What does stratum granulosum contain?
Intermediate filaments and keratohyaline granules, lamellated granules
46
What do keratohyaline granules do?
Help form keratin
47
What do lamellated granules do?
Contain a waterproofing glycolipid that is secreted into extracellular space
48
Where is stratum lucidum found?
Only in thick skin (e.g. palms)
49
How is stratum lucidum composed?
Few rows of flat, dead, keratinocytes which are like cells in the stratum corneum
50
What is the nickname for the stratum corneum?
Horny layer hehe
51
What is the stratum corneum made up of?
Thick layer of dead keratinocytes
52
What are dead keratinocytes?
Flat sacs filled with keratin
53
What does stratum corneum protect from?
Skin abrasions and penetration
54
What is intercellular glycolipid?
Keeps layer waterproof
55
What are the three types of skin pigments which contribute to skin color?
Melanin, carotene, and hemoglobin
56
What is melanin?
Most important pigment for skin color, made from tyrosine
| Differences both in the amount and type of melanin in humans.
57
What is carotene?
Yellowish pigment from carrots and tomatoescan accumulate in stratum corneum and in the hypodermis
58
What is hemoglobin?
Skin with low amounts of melanin allows crimson color of blood to show through skin
59
What is albinism
People who lack or have a defect in the tyrosinase enzyme necessary to make melanin
60
What do freckles and moles share in common?
Both freckles and moles are localized accumulations of melanin in the skin
61
What are frecklesa result of?
repeated exposure to sunlight
62
Where does the increase of melanin happen with freckles?
Basal layer of epidermis
63
What types of people tend to get freckles?
People with light complexions (white people @ hehdr)
64
Why do moles form?
When clusters of melanocytes are transformed into melanin-containing cells (nevus cells)
65
What are moles?
Clusters of cells in both the lower layer of epidermis and top layer of dermis
66
What are the 3 types of possible skin cancer?
Basal cell carcinoma, squamous cell carcinoma, and melanoma
67
What is basal cell carcinoma?
least malignant and most common, emerges ins stratum basale
68
What is squamous cell carcinoma and where does it arise?
Arises from keratinocytes of stratum spinosum
69
What is a melanoma?
A cancer of the melanocytes that is the most dangerous type of skin cancer
70
What is the dermis?
Second major layer of the skin
71
What is the dermis made of?
Strong, flexible connective tissue
72
What does the dermis do?
Binds the entire body together like a body stocking
73
What does the dermis correspond to on an animal?
Animal hides used to make leather
74
What does the connective tissue proper contain?
arteries, capillaries, veins, fibroblasts, macrophages, mast cells, and white blood cells as well as collagen, elastic, and reticular fibers
75
What is dermis supplied with?
Nerves and blood vessels configured in two vascular plexuses
76
What two vascular plexuses is the dermis configured in?
More superficial subpapillary vascular plexus, and deep dermal vascular plexus
77
What is the superficial subpapillary vascular plexus?
located just below the dermal papillae and supplies superficial dermal tissue, the dermal papillae, and the epidermis
78
What is the deep dermal vascular plexus?
configured between the hypodermis and the dermis and it nourishes the hypodermis and deep dermis
79
What ensures temperature regulation in the hands?
Blood running through the hands
80
What are the 3 components of the dermis?
Papillary layer, reticular layer, and flexure lines
81
What is the papillary layer made up of?
Made up of areolar connective tissue proper
82
What are dermal papillae?
Finger-like projections that interface with overlying epidermis and increase SA for exchange of gases, nutrients, and waste products
83
Where is and what is the papillary layer of the dermis?
- One the palms of hands and soles of feet
- Dermal papillae lie atop larger mounds called dermal ridges which elevate overlying epidermis into epidermal ridges (creating finger prints)
84
What % does reticular layer make up of dermis?
Makes up 80% of thickness of dermis
85
What is reticular layer made up of?
Dense irregular connective tissue, thick bundles of interlacing collagen and elastic fibers give skin its stretch and recoil properties
86
What are the reticular layer cleavage lines of the dermis?
Separations or less dense regions between the collagen bundles form the cleavage lines or tension lines in the reticular dermis of the skin over the entire body
87
What are cleavage lines and how do they run?
Cleavage lines run longitudinally in the skin of the limbs and head and in circular patterns around the neck and trunk
88
Why is knowledge of cleavage lines important?
So surgeons know when possible it is best to cut parallel to cleavage lines
89
What causes stretch marks?
Extreme sustained stretching of the skin which can occur with obesity and pregnancy can tear collagen in reticular dermis --> Causing linear patches on skin called striae (stretch marks)
90
Where do flexure lines arise from and how are they formed?
Arise from the deep part of the
dermis and result from the repeated folding of the skin such as in the palms of your hands and around joints e.g., at the wrist, fingers, and toes
91
What is the hypodermis?
Deep to the skin
92
What does the hypodermis contain?
Areolar and adipose connective tissue
93
What does the hypodermis do?
Anchors skin to underlying structures e.g. deep fascia and muscle
Helps insulate the body
94
Why does hypodermis thicken?
It thickens dramatically with development of increased adipose tissue in people with obesity (e.g. FReShMaN 15)
95
What are the 3 types of skin burns?
First degree burn, second degree burn, third degree burn
96
What is a first degree burn?
Only epidermis id damaged
97
What is a second degree burn?
Epidermis and upper part of dermis damaged (blisters form from separation of epidermis from dermis, typically heals with no scar formation tho)
98
What is a third degree burn?
Damages entire thickness of epidermis and extends into dermis and produces permanent scar
99
Using the rule of nines, estimate body surface... (wtf is this)
* Perineum (genital area) = 1%
* Total Head = 9%
* Right upper extremity = 9%
* Left upper extremity = 9%
* Anterior trunk = 18%
* Posterior trunk = 18%
* Right lower extremity = 18%
* Left lower extremity = 18 %
100
What are the 2 types of responses that tissue have to injury?
Inflammatory response and immune response
101
What is inflammatory response of skin?
Nonspecific, local response. Limits damage to injury site.
102
What is immune response of skin?
Takes longer to develop and is very specific, destroys particular microorganisms at infection site
103
What are some acute inflammation responses?
Heat, redness, swelling, pain, chemical signal nearby blood vessels to dilate and histamine increases permeability of capillaries producing edema in region
104
What does edema do?
* Accumulation of fluid in tissue as local blood vessels become more permeable
* Helps dilute toxins secreted by pathogen
* Brings white blood cells and antibodies from blood to fight infection
* Brings nutrients from blood
* Brings clotting factors from blood
105
What are the steps to repairing skin?
1) Inflammation
2) Organization
3) Fibrosis
4) Regeneration
106
What is happens at step 1: Inflammation?
Bleeding happens, inflammatory chemicals are released, blood vessels are more permeable, and blood clot in wound
107
What happens at step 2: Organization?
Clot replaced by granulation tissue that restores blood supply
108
What happens at step 3: Fibrosis?
proliferation of underlying scar tissue
109
What happens at step 4: Regeneration?
Fibrosed area matures and contracts and scar tissue is covered by fully regenerated epithelium
110
What are the 3 types of skin glands that we talk about?
Sebaceous glands, sweat glands, and apocrine sweat glands
111
Where are your sebaceous glands?
Everywhere except palms and soles
112
What does sebaceous glands secrete?
Sebum (oily substance)
113
What is the function of sebum?
Softens, lubricates, and waterproofs hair and skin
114
What types of secretory structure does sebaceous glands take on?
Simple branched alveolar glands
115
What type of secretion does sebaceous glands do?
Holocrine secretion: entire cell breaks up to form secretion
116
What is acne?
Wow we love acne. It is associated with an increased production of sebum due to androgen hormonal factors, especially in TEENS except WE ARENT TEENS ANYMORE
Increase in production of sebum can lead to blockage of sebaceous gland duct, which then result to infection with bacteria P. acnes
117
Where are sweat glands found?
Widely distributed in body
118
What is sweat made up of?
Sweat is a blood filtrate, it is 99% water with some salts, a sprinkle of metabolic waste (e.g. urea and ammonia)
119
How much sweat do humans typically produce in 1 day?
500ml although this can increase with exercise and heat etc.
120
What does an eccrine sweat glands do?
Produce true sweat, it is the most numerous type of sweat gland distributed over body for cooling purposes
121
Where is eccrine sweat glands highest in concentration?
Palms, soles, and forehead
122
Where are apocrine sweat glands found?
Apocrine sweat glands are large sweat glands confined to axillary, anal, genital, and breast areas
123
What do apocrine sweat glands produce?
Special kind of odorless sweat that contain fast and proteins mixed with the sweat
124
If apocrine produces special sweat that is odorless and mixed with fats and proteins, then whyy tf is our armpit sweat smelly?
Organic compounds in sweat are broken down by bacteria on skin resulting in musky odor
125
When does the activity of apocrine glands increase?
During sexual foreplay and around time of ovulation (Certain apocrine secretions may function as a pheromone and can contribute to mate attraction)
126
What is so special about MHC?
Women tend to be more attracted to body odor scents of males with MHC immune systems different than their own
127
What are the three modified sweat glands?
Ceruminous glands, mammary glands, and ciliary glands
128
Where is and what does ceruminous glands?
Modified apocrine glands in external ear canal that produce cerumen
129
Where is and what does mammary glands do?
Specialize glands modified to secrete milk
130
Where is and what does ciliary glands do?
On margins of eyelids producing secretions and lubricate the eyball
131
What are nails made of?
Modified epidermis made of hard dead keratinized cells that do not flake off
132
What does the nail correspond do on other mammals?
Hoof or claw
133
What does the nail rest on?
Nail bed of deep epithelium
134
What is the nail matrix?
Thickened, actively growing area at the nail root
135
What is the lunule?
Visible white crescent of proximal nail which represents the thickened nail matrix
136
What is the eponychium?
cuticle
137
What are the 2 structures associated with hair?
Sebaceous oil glands and arrector pili muscles
138
What are sebaceous oil glands on hair?
Produce sebum that protects hair shaft
139
What are arrector pili muscles on hair?
Stands hair up in response to cold or fear
140
What are the 6 different parts of hair?
Hair shafts, hair root, hair follicles, hair bulb, and root plexus
141
Where is the hair shaft?
Extends above skin surface, and are flexible strands of dead keratinized cells that are tough and durable
142
Where is the hair root?
Embedded into the dermis
143
Where is the hair follicles?
Extend from epidermis to dermis
144
Where is the hair bulb?
Deep expanded end of the hair follicle
145
Where is the root plexus?
Know of sensory nerves around hair bulb
146
What is hair matrix?
Epithelial cells in hair bulb, just above the papilla which proliferate to form the hair shaft
147
What is hair papilla?
CT papilla which is a nipple like bit or the dermis that protrudes into each hair bulb
148
What are the 4 hair follicle layesr?
CT root sheath, glassy membrane (basement membrane), external epithelial tissue root sheath, and internal epithelial tissue root sheath
149
What are the 3 concentric layers of keratinized cells
Cuticle, cortex, and medullar
150
What is the cuticle of hair?
outermost layer with single layer of cells that overlap like shingles on roof
151
What is the cortex of hair?
Surrounds medulla and contains several layers of flattened cells
152
What is the medulla of hair?
Central core which consists of large cells and air spaces
153
What is does the cross sections of straight hair look like?
Round
154
What is does the cross sections of wavy hair look like?
Oval
155
What is does the cross sections of kinky hair look like?
Flattened
156
Does hair lice attach to one type of hair easier?
Hair lice attaches easier to round cross-section hair than flattened cross-section hair
157
How is hair color made?
Hair pigment is made by melanocytes at base of hair follicles and is transferred into cells of hair root
158
How are different hair colors made?
Different proportions of 2 types of melanin (black-brown and yellow-rust color) combine to make hair colors
159
What month is skin formed on the fetus?
4th month
160
What is lanugo?
Downy hairs on fetus
161
What month is fetus covered with lanugo?
5-6 months
162
What does the fetal sebaceous glands produce?
Vernix caseosa
163
What happens to our skin as we age?
Skin thins, becomes less elastic, shows harmful effects of environmental damage, and skin inflammations become more common
