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Flashcards in Chapter 5 Deck (61)
1

Skin (2 regions)

Epidermis- superficial region
Dermis- underlies epidermis

2

Hypodermis

Not part of skin
Mostly adipose tissue
Anchors skin to underlying structures
Muscles

3

Epidermis

Keratinized stratified squamous epithelium
4 or 5 layers
4 cell types

4

5 Layers of Epidermis

Deep to Superficial
Stratum Basale
Stratum Spinosum
Stratum Granulosum
Stratum Lucidum
Stratum Corneum

5

4 Cell Types of Epidermis

Keratinocytes
Melanocytes
Dendritic (Langerhans) Cells
Tactile (Merkel) cells

6

Keratinocytes

Produce fibrous protein keratin
No long living, stratified squamous cells
Location; mostly in epidermis
Connected by desmosomes

7

Melanocytes

10-25% of cells in deepest epidermis
Produce pigment melanin

8

Dendritic (Langerhans) Cells

Macrophages- involved in the immune system

9

Tactile (Merkel) Cells

Sensory touch receptors

10

Layers of Epidermis: Stratum Basale (Basal Layer)

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

Layers of Epidermis: Stratum Spinosum (Prickly Layer)

Several layers thick
Cells contain web-like system of filaments attached to desmosomes
Abundant dendritic cells

12

Layers of Epidermis: Stratum Granulosum (Granular Layer)

Thin- 4 to 6 cell layers
Cell appearance changes
-Cell flatten
-Nuclei and organelles disintegrate
-Keratinization begins

13

Layers of Epidermis: Stratum Lucidum (Clear Layer)

Only in thick skin
Thin, Translucent band superficial to the stratum granulosum
A few rows of flat, dead keratinocytes

14

Layers of Epidermis: Stratum Corneum (Horny Layer)

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

Cell Differentiation in Epidermis

Cells change from stratum basale to stratum corneum
Accomplished by specialized form of apoptosis (flake off)

16

Dermis

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

Papillary Layer

Areolar connective tissue with collagen and elastic fibers and blood vessels
Dermal Papillae

18

Dermal Papillae

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

Other Skin Markings

Striae
Blister

20

Striae

Slivery-White Scars
stretch marks
Extreme stretching causes dermal tears

21

Blister

From acute, short term trauma
Fluid-filled pocket that separates epidermal and dermal layers

22

Skin Color

Three pigments contribute to skin color
-Melanin- only pigment made in skin
-Carotene
-Hemoglobin

23

Melanin

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

Carotene

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