1
Q
what is the largest organ in the body?
A
the skin, ~15-20% of body mass
2
Q
2 components of the integumentary system?
A
1) skin 2) epidermal derivatives (nails, hair, sweat and sebaceous glands and mammary glands)
3
Q
3 layers of integumentary system?
A
epidermis (ectoderm)
dermis (mesoderm)
hypodermis
4
Q
4 main functions of skin
A
- protection: UV light, mechanical, chemical and thermal insult
- water barrier
- sensation: largest sense organ in the body, contains receptors for touch, pressure, pain and temperature
- thermoregulation: insulation via hair and SQ fat; heat loss facilitated by sweating and dermal capillary network
- metabolic functions: synthesis of the precursors of vitamin D, energy stored as fat
5
Q
protection
A
from UV, mechanical, chemical, & thermal insult
Prevents dehydration; provides physical barrier to microorganisms
6
Q
sensation
A
largest sense organ of body; contains receptors for touch, pressure, pain, & temperature
7
Q
thermoregulation
A
nsulation via hair & SQ fat; heat loss facilitated by sweat glands & dermal capillary network
8
Q
metabolic functions
A
energy stored in SQ fat(1’ as triglycerides); Vit D synthesized in skin via hv
Maintains homeostasis; excretory function (sweating); immune defense
9
Q
3 layers of the skin
A
epidermis
dermis
hypodermis (=subcutis)
10
Q
what does epidermis consist of
A
keratinized, stratified squamous epithelium
11
Q
cells of the epidermis are called
A
keratinocytes
12
Q
thickness of the epidermis
A
from <1 mm to >5 mm; dubbed “thin skin” or “thick skin,” respectively
13
Q
“Thick skin” has thick, highly — layer
A
keratinized
14
Q
thick skin is restricted to (2)
A
volar (soles) & palmar (palms) surfaces
15
Q
thick skin lacks
A
hair (glabrous)
16
Q
Most of body covered in —, with thin keratinized epidermis
A
“thin skin”
17
Q
Epidermis lacks blood vessels—do not penetrate
A
basement membrane
18
Q
Epidermis supplied & nourished by blood vessels in
A
underlying (subjacent) dermis
19
Q
dermis is composed of
A
dense, irregular, collagenous connective tissue (Type I collagen), interspersed with elastic fibers
20
Q
Progressive damage to elastic fibers results in
A
“aging”, loss of skin tone
21
Q
dermis is highly vascular, contains many
A
sensory receptors
22
Q
what are the two layers of the dermis?
A
papillary layer
deep reticular layer
23
Q
Papillary layer relatively thin and interdigitates with
A
epidermis
24
Q
Corrugations increases surface area for —, prevent (2)
A
attachment, prevent shear & mechanical abrasion
25
Epidermal ridges (rete ridges)
epidermal projections into dermis
26
Dermal ridges(dermal papillae)
dermal projections into epidermis
27
Large dermal ridges in thick skin called
fingerprints (= dermatoglyphs); unique to individual
28
dermal ridges form basis of study of
dermatoglyphics
29
reticular layer compared to papillary layer
Deep reticular layerof dermis thicker & less cell than papillary layer
30
dermis contains (3)
hair follicles, sweat & sebaceous glands
31
dermis interdigitates with underlying
hypodermis(= subcutis)
32
Thick collagen bundles & elastin fibers in reticular layer form lines of tension,
Langer’s lines
33
Skin incisions --- to Langer’s lines heal with less scarring
parallel
34
hypodermis is located
below dermis
35
hypodermis
layer of loose, irregular connective tissue & adipose tissue (= subcutis= superficial fascia= panniculus adiposus)
36
vascular plexus consist of (3)
Superficial subpapillary plexus, deep cutaneous plexus, & deeper subcutaneous plexus
37
Subpapillary plexus located at junction of
papillary & reticular layers
38
Cutaneous plexus located at junction of
reticular layer & hypodermis
39
Subcutaneous plexus located deep within
hypodermis
40
largest of the three layers of the vascular plexi
subcutaneous plexus
41
vascular plexi is used in --- in (2)
Used in thermoregulation—in fingertips & ears
42
vascular plexus is associated with
AV shunts containing glomus bodies
43
glomus bodies
Thickened regions of smooth Mm in wall of arterioles, surrounded by connective tissue capsule
44
vascular plexi bypasses capillary bed, to re-route blood from
arterial to venous circulation
45
Skin is continuously (2)
grown & replaced
46
skin takes ~25-50 days for cells to travel from deep germinal layer, mature, & be sloughed from
superficial epidermis
47
psoriasis
absence of a granular layer and abnormal keratohyaline & tonofibrils
48
In psoriasis, keratinocyte maturation only takes ~
1 wk
49
Stratum basale=
stratum germinativum
50
stratum basale is the --- layer
basal
51
Mitotic layer of cuboidal germinal cells bound to basement membrane by
hemidesmosomes
52
Attach to underlying dermis via (2)
anchoring filaments & microfibrils
53
Stratum spinosum
“prickle cell layer”
| cells look spiny
54
thickest layer of epidermis in thin skin
Stratum spinosum
55
Polyhedral cells with
prominent intercellular bridges (desmosomes), numerous cytoplasmic processes & lateral folding of cell membrane
56
Predominant cell product, cytokeratin, forms tonofilaments, aggregate into
larger tonofibrils, anchor onto desmosomes
57
Stratum granulosum—--- cell layer
granular
58
Characterized by cells containing basophilic
keratohyaline granules
59
keratohyaline granules
non-membrane bound, electron dense granules
60
Keratinization of cells represents interaction between
keratohyaline granules & tonofibrils
61
Keratinization initiated by release of lysosomal enzymes results in
rupture of keratohyaline granules & polymerization of their contents
62
Forms a matrix for tonofibrils of cytokeratin results in
amorphous mass of mature keratin
63
Release of lysosomes also results in
death of the cell
64
As keratinocytes mature, they
die & lose nuclei
65
Cells of granular layer contain membrane-bound, lamellar structures called
keratinosomes
66
keratinosomes contain ---, provide waterproofing coat for skin cells
glycolipids
67
Cells of granular layer mature to form waterproof layer of keratinized cells, with --- coating on surface of epidermis
glycolipid
68
Stratum lucidum is present only in
thick skin
69
Stratum lucidum
Homogenous, compact layer of enucleate cells between stratum granulosum & stratum corneum
70
Stratum corneum—(cornified layer)
most superficial layer; thickest layer of epidermis in thick skin
71
stratum corner contains
flattened, enucleate, dead cell remnants, called squames
72
Composed 1’ of soft keratin—acts as hydrophobic barrier, prevents
desiccation
73
desquamation
Continuously exfoliated
74
In females, exfoliated cervical epithelial cells routinely examined in --- ---, to detect cervical cancer
Pap smear
75
common skin tumors (3)
* Squamous cell carcinoma
* Basal cell carcinoma
* Melanoma
76
squamous cell carcinoma and basal cell carcinoma are derived from
epithelial cells
77
melanoma is derived from
maloncytes
78
squamous cell carcinoma, basal cell carcinoma, and melanoma are all aggressive cancers with tendency to
metastasize
79
First intention healing—from a
clean (surgical), approximated incision
80
Incision immediately fills with
blood & clots
81
Within 3—24 hrs,
neutrophils infiltrate clot (acute phase)
82
Epithelial cells of stratum basale begin mitosis results in
epithelial closure (reapproximation) within 24—48 hrs
83
Day 3-7—neutrophils begin to be replaced by
macrophages (transition from acute to subacute phase)
84
3 processes: neovascularization, fibroplasia (fibroblasts elaborate collagen), & re-epithelialization (epithelial proliferation) results in
production of granulation tissue
85
~ Day 5—incision filled with
granulation tissue
86
Week 2—continued fibroplasia & collagen accumulation results in
mature granulation tissue
87
progressive decrease in
inflammation
88
Presence of inflammatory cells & inflammatory cell products results in
itching while healing
89
Month 2—connective tissue scar, without inflammation, covered by
intact epithelium
90
With Vit C deficiency, collagen breaks down; old scars can
re-open & bleed
91
Keloid
excess fibroplasia
92
Keloid results in
raised, thickened connective tissue scar
93
Second intention healing—occurs with more extensive loss of tissue, where wound edges do not
approximate (e.g., infarct, ulcer, abscess)
94
Following initial clot formation, epithelial cells of --- --- migrate from edges of wound at ~ 0.5 mm/day
stratum basale
95
Takes ~3 weeks to fill a 1 cm wide
cut
96
In haired skin, migration of cells from external root sheath of hair follicles augments
re-epithelialization
97
Simultaneous proliferation/ maturation of keratinocytes behind migrating front slowly restores multilayered,
stratified epidermis
98
Takes ~ 25 days for cells to mature from stratum basale to stratum corneum, results in
keratinization
99
Keratinazation of new cells results in
desquamation & lifting of scab from periphery after ~ 3 wks
100
wound repair is followed by wound contraction due to
myofibroblasts
101
In full thickness abrasion, or third degree burns, re-epithelialization limited by
size of wound; grafting generally necessary
102
1st degree—involves
only epidermis
103
2nd degree—involves
both epidermis & dermis
104
3rd degree— involves
all three layers, epidermis, dermis & hypodermis
D1 Fall Histology
flashcards
Decks in class (33)
# Cards
-
Introduction71
-
Cell Ultrastructure and Cytoskeleton100
-
Cytoskeleton and Cell Division133
-
Erythrocytes104
-
Leukocytes116
-
Connective Tissue101
-
Epithelial Tissue121
-
Nervous Tissue89
-
CNS120
-
Muscle180
-
Circulatory System94
-
Circulatory System Part 283
-
Skin104
-
Skin Part 276
-
Skin Part 378
-
Skeletal System Part 1111
-
Skeletal System Part 2124
-
Lymphoid Tissue Part 187
-
Lymphoid Tissue Part 288
-
Respiratory System Part 1104
-
Respiratory System Part 276
-
Oral Cavity and Tooth Development107
-
Oral Cavity and Tooth Development Part 2116
-
GI Tract Part 195
-
GI Tract Part 258
-
GI Tract Part 353
-
Accessory Digestive Organs106
-
Urinary System Part 181
-
Urinary System Part 275
-
Endocrine Glands Part 193
-
Endocrine Glands Part 2133
-
Exam 3 Test File30
-
Exam 1 Slide ID Practice190
