Skin Flashcards
(78 cards)
1
Q
Skin
A
Largest organ of body, ~ 15-20% of body mass
2
Q
4 main functions of the skin
A
- protection
- sensation
- thermoregulation
- metabolic functions
3
Q
3 main layers of skin
A
- epidermis
- dermis
- hypodermins = subcutis
4
Q
epidermis
A
Consists of keratinized, stratified squamous epithelium
5
Q
ketatinocytes
A
Cells of epidermis
6
Q
thick skin
A
thick, highly keratinized layer
•Restricted to volar (soles) & palmar (palms) surfaces
•lacks hair (glabrous)
•Most of body covered in “thin skin”, with thin keratinized epidermis
7
Q
what does the epidermis lack?
A
blood vessels. Do not penetrate BM
8
Q
Epidermis role
A
supplied & nourished by blood vessels in underlying (subjacent) dermis
9
Q
Dermis composition
A
Composed of dense, irregular, collagenous connective tissue (Type I collagen), interspersed with elastic fibers
10
Q
what is the progressive damage to elastic fibers?
A
- dermis
- “aging”, loss of skin tone
11
Q
Layers of the dermis
A
- superficial papillary later
2. reticular layer
12
Q
Papillary layer
A
-relatively thin
-interdigitates with epidermis
•Corrugations ↑surface area for attachment, prevent shear & mechanical abrasion
13
Q
Epidermal ridges (rete ridges)
A
epidermal projections into dermis
14
Q
Dermal ridges (dermal paillae)
A
- dermal projections into epidermis
- finerprints
15
Q
dermatoglyphs
A
fingerprints, unique to individual
16
Q
dermatoglyphics
A
form basis of study
17
Q
reticular layer of dermis
A
- thicker and less cell than papillary layer
- Contains hair follicles, sweat & sebaceous glands
18
Q
subcutis
A
Interdigitates with underlying hypodermis
19
Q
Langer’s lines
A
- Thick collagen bundles & elastin fibers in reticular layer form lines of tension
- skin incisions parallel to this for less scarring
20
Q
hypodermis
A
- Located below dermis
- layer of loose, irregular connective tissue & adipose tissue
21
Q
panniculus adiposus
A
= superifical fascia= subcutis
22
Q
what are the 3 vascular plexi
A
- subcutaneous
- subpapillary plexus
- cutaneous plexus
23
Q
Subpapillary plexu
A
located at junction of papillary & reticular layers
24
Q
Cutaneous plexus
A
located at junction of reticular layer & hypodermis
25
Subcutaneous plexus
-located deep within hypodermis; largest of three
26
what plexus is used in thermoregulation?
subcutaneous plexus; in fingertips & ears, associated with AV shunts containing glomus bodies
27
Subcutaneous plexus, contains glomus bodies for thermoregulation. What are glomus bodies?
- Thickened regions of smooth Mm in arterioles, surrounded by connective tissue capsule
Bypass capillary bed, re-route blood from arterial to venous circulation-
28
Growth of epidermis
* Skin continuously grown & replaced
| * Takes ~25-50 days for cells to travel from deep to superficial
29
psoriasis
keratinocyte maturation only takes ~1 wk => Absence of a granular layer and abnormal keratohyaline & tonofibrils
30
Stratum basale
=stratum germinativum
| - basal layer
31
hemidesmosomes
How mitotic layer of cuboidal germinal cells bound to basement membrane
32
what do hemidesmosomes attach to?
Attach to underlying dermis via anchoring filaments& microfibrils
33
Stratum spinosum
“prickle cell layer”—cells look spiny; thickest layer of epidermis in thin skin
34
what cells does the stratum spinosum have a lot of?
Polyhedral cells with prominent intercellular bridges (desmosomes), numerous cytoplasmic processes & lateral folding of cell membrane
35
what is the predominant cell product in desmosomes
Predominant cell product, cytokeratin, forms tonofilaments, aggregate into larger tonofibrils, anchor onto desmosomes
36
Stratum granulosum
- granular cell layer
| - characterized by kertohylaine graules
37
keratohyaline granules
non-membrane bound, electron dense granules
38
keratinization of cells
interaction between keratohyaline granules & tonofibrils
39
how is kertainization initiated?
by release of lysosomal enzymes => rupture of keratohyaline granules & polymerization of their contents
40
kertain
Forms a matrix for tonofibrils of cytokeratin => amorphous mass of mature kertin
41
release of lysosomes is known as what?
death of the cell
41
release of lysosomes is known as what?
death of the cell
42
what happens when keratinocytes mature?
die and lose nuclei
43
keratinsomes
Cells of granular layer contain membrane-bound, lamellar structures
44
what does kertinosomes contain?
contain glycolipids, provide waterproofing coat for skin cells
45
stratum lucidum
- present on in thick skin
| - Homogenous, compact layer of enucleate cells between stratum granulosum & stratum corneum
46
Stratum corneum
- cornified layer
- most superficial layer
- thickest layer of epidermis in thick skin
47
squames
- in stratum corenum
| - Contains flattened, enucleate, dead cell remnants
48
what do squames composed?
Composed 1’ of soft keratin—acts as hydrophobic barrier, prevents desiccation
49
desquamation
Continuously exfoliated
50
In females, what is routinely examined?
Pap smear, to detect cervical cancer
51
What are the common skin tumors?
* Squamous cell carcinoma
* Basal cell carcinoma
* Melanoma
52
what two skin tumors are derived from epithelia cells?
1. squamous cell carcinoma
| 2. basal cell carcinoma
53
what is melanoma dervied from?
melanocytes
54
what do all aggressive cancers have a tendency to undergo?
metatstasize
55
first intention healing
from a clean (surgical), approximated incision
56
incision
immediately fills with blood & clots
57
in first intention healing, what happens within 3-24 hrs?
neutrophils infiltrate clot (acute phase)
58
what occurs within 24-48 hrs in first intention healing?
Epithelial cells of stratum basale begin mitosis => epithelial closure (reapproximation)
59
what occurs in day 3-7 in would repair?
neutrophils begin to be replaced by M(transition from acute to subacute phase)
60
In production of granulation tissue, what are the 3 processes
1. neovascularization,
| 2. fibroplasia 3.re-epithelialization
60
In production of granulation tissue, what are the 3 processes
1. neovascularization,
| 2. fibroplasia 3.re-epithelialization
61
fibroplasia
(fibroblasts elaborate collagen
62
re-epithelialization
epithelial proliferation) => production of granulation tissue
63
what occurs in week 2 of wound repair
continued fibroplasia & collagen accumulation => mature granulation tissue
•Progressive ↓in inflammation
•Presence of inflammatory cells & inflammatory cell products => itching while healing
64
what occurs in month 2 of wound repair?
connective tissue scar, without inflammation, covered by intact epithelium
•With Vit C deficiency, collagen breaks down; old scars can re-open & bleed
65
Keloid
excess fibroplasia => raised, thickened
66
Second intention healing
- occurs with more extensive loss of tissue
| - where wound edges do not approximate
67
what happens following an intial flot formation in second intention healing?
epithelial cells of stratum basale migrate from edges of wound at ~ 0.5 mm/day
68
In hair skin, what happens to the migration of cells in second intention healing?
migration of cells from external root sheath of hair follicles augments re-epithelialization
69
overall significance of second intention healing?
Simultaneous proliferation/ maturation of keratinocytes behind migrating front slowly restores multilayered, stratified epidermis
70
hwo long does keratinization occur in second intention healing?
Takes ~ 25 days for cells to mature from stratum basale to stratum corneum
71
Keratinazation of new cells will undergo what?
desquamation & lifting of scab from periphery after ~ 3 wks
| •Followed by wound contraction due to myofibroblasts
72
when is grafting generally necessary?
In full thickness abrasion, or third degree burns, re-epithelialization limited by size of wound
73
what are the burn classifications according to severity?
1st degree
2nd degree
3rd degree
74
1st degree burn
involves only epidermis
75
2nd degree burn
involves both epidermis & dermis
76
3rd degree burns
ivolves all three layers, epidermis, dermis & hypodermis
