Integumentary System Flashcards Preview

Human Physiology 101 > Integumentary System > Flashcards

Flashcards in Integumentary System Deck (88):
1

How much body weight does the integumentary system account for?

16%

2

What is the size of the surface of the integumentary system?

1.5-2m^2 in area

3

What is continually happening to the integumentary system?

It is continually abraded, attacked by microorganisms, irradiated by sunlight and exposed to environmental chemicals

4

What are two major components of the integumentary system?

Cutaneous Membrane
> Epidermis
> Dermis

Accessory Structures
> Nails
> Hair
> Exocrine Glands
> Sebaceous Glands
> Sebaceous Glands

5

Does the integument function in isolation?

No. An extensive network of blood vessels branch through the dermis, and sensory receptors provide information to the CNS

6

What are fingerprints?

Epidermal ridges of thick skin

7

What are the general functions of the skin?

- Protects underlying tissues and organs
- Excretes salts, water and organic wastes (glands)
- Maintains body temperature (insulation and evaporation)
- Synthesises Vitamin D3
- Stores Lipids
- Detects touch, pressure, pain and temperature

8

Skin Structure Summary

- Epidermis
- Dermis
- Hypodermis Layer

9

Skin Structure: Epidermis

- Outer, thinner layer
- Composed of epithelium

4-5 layers depending on where the skin is on our body

10

Skin Structure: Dermis

- Inner, thicker layer
- Composed of connective tissue
- Further broken down into papillary layer and reticular layer

11

Skin Structure: Hypodermis Layer (AKA: Subcutaneous Layer)

- Fat store
- Blood vessels
- Pacinian corpuscles (sensitive to pressure)
- This area has a blood supply

12

What epithelium does the epidermis consist of and what is its function?

A stratified squamous epithelium. It provides mechanical protection and also helps keep microorganisms outside the body

13

What is the epidermis dominated by?

Keratinocytes

14

Thin Skin

Covers most of the body's surfaces, contains four layers. About 0.08mm

15

Thick Skin

Contains a fifth layer, about 0.5mm

16

Epidermis Characteristics Summary

- Stratum Corneum
- Stratum Lucidium
- Stratum Granulosum
- Stratum Spinosum
- Stratum Basale

17

Epidermis Characteristics: Stratum Corneum

- Multiple layers of flattened, dead, interlocking keratinocytes
- Water resistant but not waterproof
- Permits slow water loss by insensible perspiration
- Continuously shed and replaced by cells from deeper strata

18

Epidermis Characteristics: Stratum Lucidium

- Appears as a glassy layer in thick skin only
- Dead keratinocytes
- Present in thick skin subjected to much friction

19

Epidermis Characteristics: Stratum Granulosum

- Keratinocytes produce keratohyalin and keratin
- Keratin fibres develop as cells become thinner and flatter
- Gradually the plasma membranes thicken, the organelles disintegrate, and the cells die
- Keratinocytes undergo apoptosis
- Lamellar granules release waterproof secretion

20

Epidermis Characteristics: Stratum Spinosum

- Keratinocytes are bound together by desmosomes

21

Epidermis Characteristics: Stratum Basale

- Deepest, basal layer
- Attachment to basement membrane
- Contains basal cells (stem cells), melanocytes, and tactile cells (Merkel Cells)
- Undergoes continuous cell division

22

How long does the migration of cells take?

Approx. 4 weeks

23

Cells of the Epidermis Summary

- Keratinocytes
- Melanocytes
- Langerhans Cells
- Merkel Cells

24

Cells of the Epidermis: Keratinocytes

- Produce Keratin
- Waterproofing sealant

25

Cells of the Epidermis: Melanocytes

- Produce melanin

26

Cells of the Epidermis: Langerhans Cells

- Macrophages
- Involved in the immune response

27

Cells of the Epidermis: Merkel Cells

- Touch sense

28

Clinical Note: Callus (CORN)

Abnormal thickening of the stratum corneum due to the constant exposure of skin to friction

29

What are the factors influencing skin colour?

Epidermal pigmentation and dermal circulation

30

What does the epidermis contain?

Carotene and Melanin

31

Carotene

- Accumulates within epidermal cells and fatty tissues of the dermis
- Can be converted to Vitamin A (retinol)

32

Melanin

- Produced by melanocytes in stratum basale
- Stored and transported within melanosomes
- Transferred to keratinocytes
- Protect use from ultraviolet (UV) radiation

33

Clinical Note: Hermansky-Puolak Syndrome

- Deficiencies in the biogenesis of lysosomes related organelles including melanosomes
- Characterised by albinism and prolonged bleeding

34

Clinical Note: Dermal Circulation/Blood Flow

- Haemoglobin bound to oxygen is bright red
- Dilated vessels cause skin to look red
- Constricted vessels cause skin to become pale
- Reduced supply of oxygen causes skin to become bluish which can lead to cyanosis

35

Clinical Note: Skin Colour

- Vitiligo: melanocytes destroyed
- Jaundice: high bilirubin

36

Vitamin D Synthesis

- Sunlight causes epidermal cells to convert a steroid into vitamin D3
- Epidermal cells synthesise vitamin D3 or cholecalciferol, when exposed to the UV radiation in sunlight
- Low vitamin D > rickets

37

Epidermal Growth Factor

- Has several effects on the epidermis and epithelia
- Promotes growth, division and repair of the epidermis, and epithelial gland synthetic activity and secretion

38

Dermis (Tissue) Summary

- Papillary Layer
- Reticular Layer

39

Papillary Layer

- Areolar tissue
- Small capillaries, lymphatics and sensory nerves that supply the epidermis
- Sensory receptors; tactile corpuscles (light touch)

40

Reticular Layer

- Dense irregular connective tissue
- Larger blood vessels, lymph vessels, sensory neurons
- Collagen, elastic fibres, connective tissue proper
- Sensory receptors: Lamellated corpuscles (pressure and vibration)
- Skin turgor

41

Clinical Note: Dermatitis

- Inflammation of the papillary layer
- Caused by infection, radiation, mechanical irritator or chemicals
- Characterised by itch or pain

42

Clinical Note: Sagging skin and wrinkles

- dehydration
- age
- hormonal changes
- UV exposure

43

Clinical Note: Stretch Marks

- extensive distension of the dermis
- thickened tissue resulting from excessive stretching of skin due to: pregnancy or weight gain

44

Cleavage Lines

- Formed by the pattern of collagen and elastic fibres arranged in parallel
- Resist force in specific direction
- Parallel cut remains shit and will heal well
- A random cut will pull dermis open and scars

45

Hypodermis/Subcutaneous Layer

- Connects dermis to underlying tissue
- Loose connective tissue with fat cells
- Large blood vessels
- Absence of vital organs

46

Innervation of the skin

Nerve fibres in skin control blood flow, regulate gland secretions and sensory receptors

47

What are the accessory structures derived from?

Embryonic epidermis

48

Where are the accessory structures located?

In the dermis

49

Where do the accessory structures project through?

The skin surface

50

What is hair composed of?

Kerotinised dead cells that have been pushed to the surface

51

Hair Follicles

Non-living structures produced in organs

52

What is hair?

- Hairs (pili) composed of columns of dead, keratinised cells held together by extracellular proteins
> shaft: superficial portion
> root: penetrates skin
> surrounded by follicle

53

What surrounds each hair follicle?

Dendrites of hair root plexuses. They generate nerve impulses if shaft or hair is moving

54

What is a club hair?

A hair that has stopped growing

55

Sebaceous (oil) Glands

- Majority connected to hair follicles
- Secretory portion in the dermis
- Absent in thick skin
- Discharges waxy sebum into lumen and ultimately, into hair follicle

56

What are sebaceous follicles?

Large sebaceous glands that discharge sebum directly onto the epidermis

57

What is the role of sebum?

Moistens hairs, waterproofs, softens skin and inhibits bacterial growth

58

Clinical note: Zits

- Mostly at puberty
- Opening of sebaceous gland blocked
- 'whitehead'
> Pustule - superficial layers
> Papule - deeper layers
> Cyst - deepest layer

59

Sweat (Sudoriferous) Glands

- Limited in distribution to the skin of the axilla (armpit), areolae (around nipples), pubis (groin) and beard in males
- Ducts into hair follicles
- Sticky, cloudy secretions which sometimes produce an odor
- Do not begin to function until puberty

60

Merocrine (Eccrine) Sweat Glands

- Widely distributed on body surface, especially palms and soles
- Discharge directly onto skin surface
- Excretes water and electrolytes
- Main function is heat loss

61

Temperature Homeostasis: Regulating cutaneous blood flow

- Increased dilation of skin blood vessels as core temperature increases
- during intense exercise skin blood vessels constrict>rapid increase in core temperature results

62

Temperature Homeostasis: Perspiration/Sweating

Sympathetic

63

Cutaneous Blood Flow

- Blood flow from inside of the body affects the skin's temperature (lost by radiation and conduction and convection)
- Dilation of skin blood vessels
- Constriction of skin blood vessels

64

Sweating/Perspiration

Insensible Perspiration:
Interstitial fluid lost by evaporation through the stratum corneum

Sensible Perspiration:
Water excreted by sweat glands

65

Other Integumentary Glands Summary

- Ceruminous Glands
- Mammary Glands

66

Other Integumentary Glands: Ceruminous Glands

- Modified sudoriferous glands
- Located in external auditory canal
- Produce waxy substance called cerumen (ear wax) which impedes entrance of foreign bodies

67

Other Integumentary Glands: Mammary Glands

Specialised sweat glands

68

Nails

- Plates of tightly packed, hard, keratinised epidermal cells
- Consist of: nail body, free edge and nail root

69

Nail Structures

- Lanula
- Hyponychium
- Epinychium

70

Lanula

Area of thickened stratum basale

71

Hyponychium (nail bed)

- Area of thickened stratum corneum
- Secures nail to tip of digit

72

Eponychium (cuticle)

Narrow band of epithelium occupying proximal border of nail

73

Nail growth: Nail matrix

- Epithelium deep to nail root
- Cells divide by mitosis
- Superficial cells of matrix converted to nail cells
- Average growth 1mm per week

74

Epidermal wound healing

- Basal cells of epidermis break contact with basement membrane
- Enlarge and migrate across wound (stimulated by EGF)
- Stop migration due to contact inhibition
- Relocated cells divide to build new epidermal layers and thicken epidermis

75

Deep Wound Healing

Injury extends to dermis and/or subcutaneous layer (4 phases)

1) Inflammatory Phase
2) Migratory Phase
3) Proliferative Phase
4) Maturation Phase

76

Deep Wound Healing: 1) Inflammatory Phase

- Blood clot forms loosely binding wound edges
- Inflammation

77

Deep Wound Healing: 2) Migratory Phase

- Clot becomes a scab
- Epithelial cells migrate beneath scab to bridge wound
- Fibroblasts migrate and form collagen

78

Deep Wound Healing: 3) Proliferative Phase

- Extensive growth of epithelial cells beneath scab
- Random deposition of collagen fibres
- Blood vessel growth

79

Deep Wound Healing: 4) Maturation Phase

- Collagen fibres become organised
- Epithelium restored to normal thickness and scab sloughs off
- Blood vessels restored

80

Clinical Note - Lines of Clevage

Collagen and elastic fibres in the dermis are arranged in parallel bundles and resist force in a specific direction

81

Why do clevage lines establish important pattens?

- A parallel cut remains shut, heals well
- A cut across (right angle) pulls open and scars

82

Photodamage

UVA, UVB, UVC

UVA: long term damage
UVB: main cause of skin tanning and sunburn, DNA damage in epidermal cells

83

Types of skin cancer

UVB rays can damage DNA in epidermal cells
> disable tumour suppressor gene
> cells multiply uncontrollably = tumour

84

Burns: First Degree

- Superficial, discomfort, days to heal

85

Burns: Second Degree

- Partial thickness, painful, weeks to heal

86

Burns: Third Degree

- Full-thickness, complications, months/years to heal

87

Burns

- Burns >20% life threatening
- Any partial or full thickness burn that involves the genitals, eyes, ears, hands, feet, or burns over major joints regardless of size requires urgent medical care

88

Effects of ageing

- increased skin injuries and infections
- immune system is reduced
- muscles become weaker
- decrease in bone strength
- increased sensitivity to the sun
- skin dries and becomes scaly
- hair changes
- reduced ability to lose heat
- skin repair slows