1
Q
Integumentary system makes up how much of the adult’s body wt? It is continuous with what?
A
- largest organ of the body
- 15% of total adult body wt
- skin is continuous with mucous membranes
- continuous cycle of healing, shedding, and cell regeneration
2
Q
Fxns of the skin?
A
- prevent fluid loss
- protection barrier
- area for heat exchange
- harbors immune cells that protect against invading microorganisms
- neuro receptor relay system: touch, pressure, temp, pain
- vit D synthesis
3
Q
Epidermis - 4 diff cell types?
A
- covers entire body
4 cell types: - keratinocytes: further categorized into stratum layers
- melanocytes
- merkel’s cells (basal layer of epidermis)
- langerhan’s cells
4
Q
Fxn of the keratinocytes?
A
- predominant cell of the epidermis
- change size and shape as they move superficially, replacing cells lost during normal cell shedding
- produces fibrous protein called keratin - which is essential to the protective fxn of the skin and is the structural protein of hair and nails
5
Q
5 separate layers of keratinocytes?
A
- stratum germinativum or stratum basale: single layer of columnar cells, undergo mitosis, no migration
- stratum spinosum: 2-4 layers, cell diff
- stratum granulosum: only few layers, most diff (some losing cytoplasm, other continue to synthesize keratin)
- stratum lucidum: thin, transparent layer mostly confined to palms of the hands and soles of feet, transitional cells
- stratum corneum: many layers (15-100 layers depending on location), dead squamous type keratinized cells - palms and soles have many layers!
6
Q
Location and fxn of melanocytes? MOA of melanin production
A
- located at or in basal layer
- pigment-synthesizing cells (produce melanin): ability to synthesize melanin depends on ability of melanocytes to produce the enzyme tyrosinase (converts AA tyrosine to precursor of melanin) - lacking this enzyme leads to albinism
- each melanocyte supplies several keratinocytes with melanin through cytoplasm-filled extensions
7
Q
What increases the production of melanin? Primary fxn of melanin and melanocytes?
A
- exposure to UV rays
- protect from UV rays (melanin absorbs and scatters radiation)
8
Q
Do darked skinned and light-skinned people have diff amt of melanocytes? Where are there relatively no melanocytes?
A
- they have same amt of melanocytes (just the efficiency of production and shipping differs)
- all people, regardless of skin color, have relatively few or no melanocytes in palms or soles
9
Q
Fxn of merkel’s cells?
A
- fxn as mechanoreceptors (touch receptors) - have a lot on fingertips
- least densely pop. cells of the epidermis
10
Q
Where are langerhan’s cells located? Fxn?
A
- scattered in suprabasal layer of epidermis
- few in number compared to keratinocytes
- fxn: immunologic cells responsible for recognizing foreign antigens harmful to the body
- bind antigen to their surface, process it, and send it on to regional lymph nodes
11
Q
Dermis:
location, composition?
A
- CT layer separating epidermis from the subq fat layer
- Mostly composed of collagen (major stress-resistant material of the skin)
also composed of: - variety of immune cells
- nerves (receptors for touch, pressure, heat, cold, and pain)
- blood vessels: dermis is richly supplied by arteriovenous anastomoses
12
Q
What does the Subq tissue consist of?
A
- primarily of fat and CT that lend support to vascular and neural structures supplying the dermis and epidermis
- eccrine glands and deep hair follicles extend to this layer
13
Q
What are the 4 skin appendages?
A
- sweat glands
- sebaceous glands
- hair
- nails
14
Q
2 types of sweat glands?
A
- eccrine (merocrine) sweat glands: located over entire body surface, originate in dermis and open directly to skin surface, primary fxn is to transport sweat to body surface to reg body temp (cool down body by evaporation)
- apocrine sweat glands: less numerous, larger, located in deep dermal layer, open through a hair follicle, secrete more of an oily substance, sterile until mixed with bacteria. Actual gland itself is breaking off with oily substance to be secreted
15
Q
Sebaceous glands:
location, what do they secrete, fxn?
A
- located over entire skin surface except for palms, soles, and sides of feet
- part of piliosebaceous unit
- secrete a mix called sebum which is composed of lipids, cholesterol, and other substances
- fxn: lubricate hair and skin
- relatively inactive until adolescence (ACNE)
- amt of sebum produced is directly related to gland size
- testosterone - increases gland size
16
Q
Most hair follicles are related to what glands? What does the entire hair structure consist of?
A
- most hair follicles assoc with sebaceous glands (pilosebaceous unit)
- hair structure consists of:
hair follicle and hair shaft
sebaceous gland
hair muscle - arrector pili
sometimes apocrine gland (not as common)
17
Q
Hair shaft is mostly composed of what? What does it undergo? How is hair shed and what determines this?
A
- mostly composed of keratin
- undergoes cyclic shedding
- hair follicles work independently
- human beings shed hair asynchronously
- Once it reaches certain length it will shed, genetics probably determines length of hair
18
Q
What nourishes the hair follicle? What determines hair color?
A
- vascular network at site of follicular bulb nourishes and maintains hair follicle
- melanocytes located in bulb determine color
19
Q
What causes goose bumps?
A
- arrector pili muscle that is located under sebaceous glands
20
Q
Composition of nails?
Fxn of nails?
A
- hardened keratinized plates
- grows from curved transverse groove called nail groove
- floor of groove is nail matrix, which is germinal region of nail plate
- nail plate lies in nail bed
- medical term for cuticle = eponychium
- fxn: protects fingers and toes, enhances dexterity
21
Q
What can skin changes signify?
A
- systemic disease
22
Q
Diff b/t primary and secondary lesions?
A
- primary: arise from previously normal skin
- secondary: created by another process such as scratching or infection
23
Q
What are the primary lesions?
A
- macule, patch
- papule, plaque, nodule, tumor, wheal
- vesicle, bulla, pustule
24
Q
What is a macule?
A
- circumscribed flat lesion that is less than 1 cm
- ex: petechia, freckles
25
What is a patch?
- circumscribed flat lesion that is larger than 1 cm
| - vitiligo
26
What is a papule? What may it become?
- elevated solid lesion with variable color, smaller than 0.5 cm
ex: elevated nevus
- may become confluent and become a plaque
27
What is a plaque?
- raised flat-topped superficial lesion where diameter is greater than the thickness (larger than 0.05 cm) - often formed by coalescence of papules
- psoriasis
28
What is a nodule?
- elevated lesion with a rounded surface (generally deeper and firmer than a papule) - b/t 0.5- 1- 2cm
29
What is a tumor?
- large nodule - greater than 1-2 cm
30
What is a wheal?
- somewhat irregular, transient swelling due to localized skin edema (may be pruritic)
ex: mosquito bite or hive
31
What is a vesicle?
- fluid-filled lesion up to 1 cm
| - herpes
32
What is a bulla?
- serous-filled lesion larger than 1 cm
| - ex: 2nd degree burn
33
What is a pustule?
- circumbscribed lesion filled with pus
| - ex: acne, impetigo
34
What are secondary lesions?
- scales, crust, erosion, ulcer, fissures, atrophy, scar
35
What are scales due to?
- abnormal stratum corneum due to accum of or increased shedding of keratinocytes
36
What are crusts due to?
- dried serum, pus or blood (pt's hx reveals weeping, pus or blood)
37
What is an erosion?
- partial loss of epidermis )doesn't penetrate beneath dermal - epidermal boder and therefore heals w/o scarring)
38
What is an ulcer?
- full thickness loss of epidermis and at least some dermis - maybe all (heals with scarring)
39
What are fissures?
- linear splites in epidermis and may also include the dermis (usually occurs at an orifice, over a jt, or along skin creases)
- soles of feet, corners of mouth
40
What is atrophy?
- depression of the skin surface due to thinning of epidermis or dermis (blood vessels can often be seen)
41
What is a scar?
- abnormal collection of CT implying injury (initially thick and pink but over time becomes white and atrophic)
42
What is an excoriation?
- localized damage to the skin due to scratching and consists of linear or pinpoint erosions or crusts
43
What are comedones? Diff types?
- plug of sebaceous and keratinized material lodged in opening of hair follicle
- blackhead - open
- whitehead -closed
44
What is milia?
- small, superficial keratin cyst with no visible opening
| - fine, granular cysts that are often seen in kids who sweat
45
What is a cyst?
- cavity lined with epithelium containing:
| fluid, pus or keratin
46
What is an abscess?
- infected lesion surrounded by a membrane and filled with exudate
- just an infected cyst
47
What is a burrow?
- narrow elevated tortuous channel produced by a parasite
48
What is a lichenification?
- thickening of epidermis with increased skin markings due to persistent scratching (skin lines are accentuated)
49
WHat does umbilicated mean?
- surface contains a rounded depression in the center
- see in squamous cell carcinoma and basal cell carcinoma
- growth is expanding exteriorly of central lesion
50
What is telangiectasia?
- dilated, superficial blood vessels
51
What is petechia?
- circumscribed deposit of blood less than 0.5 cm large
52
What is ecchymosis?
- circumscribed deposit of blood over 0.5 cm
53
What is a keratin horn?
- accum of abnorm keratin which is usually rough on palpation and difficult to remove
- due to hyperkeratinosis
54
What are warty/papillomatous lesions?
- surface consists of minute finger-like or round projections
- diff wart from callous b/c it is more defined, callous is found on pressure pts
55
What is a furuncle?
- boils: skin disease caused by inflammation of hair follicles, resulting in localized accum of pus and dead tissues
56
What is a carbuncle?
- individual furuncles that can cluster together and form an interconnected network of furuncles
57
What does symmetrical mean? examples?
- involves both sides of body to a similar extent (often endogenous cause like acne, psoriasis)
58
What does asymmetrical mean?
- predom one side involved - often external cause
59
Extensor surfaces are assoc with?
- psoriasis
60
Contact areas are assoc with?
- contact dermatitis
61
Flexural surfaces are assoc with?
- atopic dermatitis
62
Candidal rashes like what kind of areas?
- intertriginous: 2 surfaces rub together (skin folds)
63
Diff in margination?
- sharp, well defined, or circumscribed: able to draw a line around it, transition quickly within 1 mm - vitiligo
- poorly defined: borders that merge into normal skin, transition over 1 mm
64
Diff shape descriptors of lesion?
- annular: ring-shaped with active margin and clear center
- arcuate: arched, bow-shaped
- iris: target lesion
- discoid: disk-shaped
- nummular: coin-shaped
- serpigninous: snakelike
- guttate: drop-sized
- morbilliform: small confluent macules, forming irregular shapes
(measles)
65
Diff in arrangangement of lesions?
- confluent: blending into adjacent lesions
- discrete: separated by normal skin from other similar lesions
- generalized or diffuse: covering most of designated body surface
- disseminated: widespread discrete lesions
- grouped: multiple lesions clustered in one area (but not necessarily blending with each other)
- reticulated: in form of a network
66
Palpation assessment?
- smooth: normal epidermis
- uneven: scaly, warty, etc
- rough: sandpaper like (keratin horn, scarlatiniform rash, crust)
67
What are langer's lines?
- arrangement of collagen bundles - can cut going same direction of lines - and you won't leave scarring
68
Keratin gives structures to?
- stratum corneum, hair and nails
69
Where is a good place to investigate for skin coloring changes in darker pts?
- palrms - lack melanocytes
70
diff b/t lesions in epidermis/dermis and subq tissue?
- collagen (dermis) and keratin (epidermis) - lesion is going to be fixed
- subq lesion - will be mobile b/t of loose nature of subq tissue
71
What glands are the most involved in acne PP?
- sebaceous glands (influenced by testosterone)
Dermatology
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