Chapter 5 Flashcards
1
Q
Skin (2 regions)
A
Epidermis- superficial region
Dermis- underlies epidermis
2
Q
Hypodermis
A
Not part of skin
Mostly adipose tissue
Anchors skin to underlying structures
Muscles
3
Q
Epidermis
A
Keratinized stratified squamous epithelium
4 or 5 layers
4 cell types
4
Q
5 Layers of Epidermis
A
Deep to Superficial Stratum Basale Stratum Spinosum Stratum Granulosum Stratum Lucidum Stratum Corneum
5
Q
4 Cell Types of Epidermis
A
Keratinocytes
Melanocytes
Dendritic (Langerhans) Cells
Tactile (Merkel) cells
6
Q
Keratinocytes
A
Produce fibrous protein keratin
No long living, stratified squamous cells
Location; mostly in epidermis
Connected by desmosomes
7
Q
Melanocytes
A
10-25% of cells in deepest epidermis
Produce pigment melanin
8
Q
Dendritic (Langerhans) Cells
A
Macrophages- involved in the immune system
9
Q
Tactile (Merkel) Cells
A
Sensory touch receptors
10
Q
Layers of Epidermis: Stratum Basale (Basal Layer)
A
Deepest epidermal layer Firmly attached to dermis Single row of stem cells -Actively mitotic -Produces two daughter cells --One cell journeys from basal layer to surface
11
Q
Layers of Epidermis: Stratum Spinosum (Prickly Layer)
A
Several layers thick
Cells contain web-like system of filaments attached to desmosomes
Abundant dendritic cells
12
Q
Layers of Epidermis: Stratum Granulosum (Granular Layer)
A
Thin- 4 to 6 cell layers Cell appearance changes -Cell flatten -Nuclei and organelles disintegrate -Keratinization begins
13
Q
Layers of Epidermis: Stratum Lucidum (Clear Layer)
A
Only in thick skin
Thin, Translucent band superficial to the stratum granulosum
A few rows of flat, dead keratinocytes
14
Q
Layers of Epidermis: Stratum Corneum (Horny Layer)
A
20-30 rows of dead, flat, anucleate keratinized membranous sacs 3/4 of epidermal thickness Cells Functions: -Protection of deep layers -Protection from physical factors -Barrier
15
Q
Cell Differentiation in Epidermis
A
Cells change from stratum basale to stratum corneum
Accomplished by specialized form of apoptosis (flake off)
16
Q
Dermis
A
Strong, flexible connective tissue Many cells Fibers in matrix bind together Contents: -Nerve fibers -Blood and lymphatic vessels -Epidermal hair follicles -Oil and sweat glands Two layers -Papillary -Reticular
17
Q
Papillary Layer
A
Areolar connective tissue with collagen and elastic fibers and blood vessels
Dermal Papillae
18
Q
Dermal Papillae
A
Superficial peglike projections into the epidermis Contents: -Capillary loops -Meissner's corpuscles (Touch receptors) -Free nerve endings (Pain receptors) Function: -Enhance Gripping -Contributes to sense of touch -Contributes to sense of pain -Fingerprints
19
Q
Other Skin Markings
A
Striae
Blister
20
Q
Striae
A
Slivery-White Scars
stretch marks
Extreme stretching causes dermal tears
21
Q
Blister
A
From acute, short term trauma
Fluid-filled pocket that separates epidermal and dermal layers
22
Q
Skin Color
A
Three pigments contribute to skin color
- Melanin- only pigment made in skin
- Carotene
- Hemoglobin
23
Q
Melanin
A
Two forms -Reddish-yellow to Brownish-black Color is due to amount Produced in melanocytes -Same relative number in all people Freckles and pigmented moles -Local accumulations of melanin Sun exposure stimulates melanin production
24
Q
Carotene
A
Yellow to orange pigment
-most obvious in palms and soles
Can be converted to vitamin A for vision and epidermal health
Yellowish-tinge of some Asians- carotene and melanin variations
25
Hemoglobin
Pinkish hue of fair skin
26
Skin Color in Diagnosis Cyanosis
Blueish
| Low oxygen
27
Skin Color in Diagnosis Erythema
Redness
| Fever, Hypertension, Inflammation
28
Skin Color in Diagnosis Pallor
Blanching
| Anemia, Low blood pressure, fear, anger
29
Skin Color in Diagnosis Jaundice
Yellowish
| Liver disorder
30
Skin Color in Diagnosis Bruises
Clotted blood beneath skin
31
Appendages of the Skin
| Derivatives of the Epidermis
Hair and Hair Follicles
Nails
Sweat Glands
Sebaceous (oil) glands
32
Hair
```
Dead keratinized cells of hard keratin
-More durable than soft keratin of skin
Functions include:
-Warn insects on skin
-Physical Trauma
-Heat loss
-Sunlight
Hair pigments
-Melanin gives it color
-Gray/white is decreased melanin production, increased air bubbles in shaft
```
33
Hair Follicles
```
Extend form epidermal surface to dermis
Two layered wall- part dermis, part epidermis
Hair bulb
-Expanded deep end
-Hair follicle
-Sensory nerve endings- touch receptors
-Hair matrix
```
34
Arrector Pili
Smooth muscle attached to hair follicle
| Responsible for "goosebumps"
35
Types and Growth of Hair
Vellus Hair
-Pale, fine body hair of children and adult females
Terminal Hair
-Coarse, long hair of eyebrows, scalp
-At puberty
Nutrition and hormones affect hair growth
Follicles cycle between active and regressive phases
Average 2.25mm growth per week
Lose 90 scalp hairs daily
36
Hair Thinning and Baldness
Alopecia
-Hair thinning in both sexes after age of 40
True Baldness
-Genetically determined and sex-influenced condition
-Male pattern baldness caused by follicular response to DHT (dihydrotestosterone)
37
Nails
Scalelike modifications of epidermis
Protective cover for distal, dorsal surface of fingers and toes
Contain hard keratin
38
Sweat Glands
All skin surfaces except nipples and parts of external genitalia
Two main types
-Eccrine
-Apocrine
Contain myoepithelial cells
-Contract upon nervous system stimulation to force sweat into ducts
39
Eccrine Sweat Glands
```
Most numerous
Abundant on palms, soles, and forehead
Ducts connect to pores
Function in thermoregulation
-Regulated by sympathetic nervous system
Secrete Sweat
```
40
Apocrine Sweat Glands
Confined to axillary and anogenital areas
Secretes sweat + fatty substance + proteins
-Viscous; milky or yellowish
-Odorless until bacterial interactions (body odor)
Duct empty into hair follicles
Begin functioning at puberty
41
Sebaceous (Oil) Glands
```
Widely distributed
-not in thick skin of palms and soles
Secrete into hair follicles
Inactive until puberty
-Stimulated by hormones (especially androgens)
Secrete oily secretion
-Bactericidal
-Softens hair and skin
```
42
Functions of Integumentary System
```
Protection
Body Temperature Regulation
Cutaneous Sensation
Metabolic Functions
Blood Reservoir
Excretion
```
43
Protection 3 Barriers
Chemical
Physical
Biological
44
Protection (Chemical)
Skin secretions
-Low pH retards bacterial multiplication
Melanin
-Defense against UV radiation damage
45
Protection (Physical)
Flat, dead cells of stratum corneum surrounded by lipids
Keratin and glycolipids block most water
Limited penetration of skin
46
Protection (Biological)
Dendritic cells of epidermis
-present foreign antigens to white blood cells
Macrophages of dermis
-present foreign antigens to white blood cells
DNA
-absorption of UV radiation
-Radiation converted to heat
47
Body Temperature Regulation
If body temperature rises
-Dilation of dermal vessels
-Increased sweat gland activity cool the body
Cold external environment
-Dermal blood vessels constrict
-Skin temperature drops to slow passive heat loss
48
Cutaneous Sensations
Sensory receptors (part of nervous system) detect temperature, touch, and pain
49
Metabolic Functions
Synthesis of vitamin D (precursor and collagenase)
| Converts carcinogens and some hormones
50
Blood Reservoir
Up to 5% of body's blood volume
51
Excretion
Nitrogenous wastes and salt in sweat
52
Skin Cancer
Most skin tumors are benign and do not metastasize
Risk Factors:
-Overexposure to UV radiation
-Frequent irritation of skin
53
3 Major Types of Skin Cancer
Basal Cell Carcinoma
Squamous Cell Carcinoma
Melanoma
54
Basal Cell Carcinoma
```
Common
-Most common
Skin Layers
-Stratum Basale Cells proliferate and invade dermis and hypodermis
Malignancy
-Least malignant
Prognosis
-Surgical excision
-99% of cases are cured
```
55
Squamous Cell Carcinoma
```
Common
-Second most common
Skin layers
-Keratinocytes of stratum spinosum
Appearance
-Scaly red on scalp, ears, lower llip, and hands
Malignancy
-Yes, typically metastasize
Prognosis
-Good
-Treated by radiation therapy or removed surgically
```
56
Melanoma
Cancer of melanocytes
Common
-Most dangerous
Malignancy
-Highly metastatic and resistant to chemotherapy
Prognosis
-Treated by wide surgical excision accompanied by immunotherapy
Key to survival is early detection- ABCD rule
57
ABCD Rule
A: Asymmetry; two sides of the pigmented area do not match
B: Boarder Irregularity; exhibits indentations
C: Color; contains several (black, brown, tan, sometimes red or blue
D: Diameter; larger than 6mm (size of pencil eraser)
58
Burns
```
Tissue damage caused by heat, electricity, radiation, certain chemicals
-denatures proteins and kills cells
Immediate Threat
-Dehydration and electrolyte imbalance
To evaluate burns
-Rule of nines
-Used to estimate volume of fluid loss
```
59
Burns Classified by Severity
Partial-Thickness Burns
-First Degree- epidermal damage only; redness, swelling, pain
-Second Degree- epidermal and upper dermal damage; blisters appear, pain
Full-Thickness Burn
-Third Degree- entire thickness of skin involved, cherry red or blackened, not painful (nerve endings destroyed), skin grafting usually necessary
60
Severity and Treatment of Burns
```
Critical if:
- 25% of body has Second Degree Burns
- 10% of body has Third Degree Burns
-Face, hands, or feet bear third degree burns
Treatment includes:
-Debridement (removal) of burned skin
-Antibiotics
-Temporary covering
-Skin Grafts
```
61
Developmental Aspects
Aging Skin
-Epidermal replacement slows, skin becomes thin, dry, and itchy
-Subcutaneous fat and elasticity decrease, leading to cold intolerance and wrinkles
-Increased risk of cancer due to decreased numbers of melanocytes and dendritic cells
-Hair thinning
Ways to prevent/Delay
-UV protection, good nutrition, lots of fluids, good hygiene
