The integumentary system

Question 1

What is the integumentary system?

Answer 1

The skin system, sensory nerves & accessory organs:
- hairs
- nails
- cutaneous glands (sweat, sebaceous mammary)

Question 2

What % does the largest organ in the body (skin) make up of the total body weight?

Answer 2

12-15%

Question 3

What is the use of skin?

Answer 3

• barrier to external
• insight to internal health

Question 4

How does the integumentary system provide an insight into internal health?

Answer 4

shows blue veins if the heart isn’t pumping hard enough

Question 5

What are the 2 structures of the skin?

Answer 5

• Epidermis (uppermost) epithelia layer
• dermis

Question 6

What is thicker - dermis or epidermis?

Answer 6

dermis

Question 7

How thick is the dermis?

Answer 7

0.2mm - 2mm

Question 8

What do fibroblasts produce?

Answer 8

ECM (extracellular matrix) - mainly collagen

Question 9

What are the 2 layers of the ECM (extracellular matrix)?

Answer 9

• papillary layer
• reticular layer

Question 10

What is in the papillary layer?

Answer 10

thin loose connective tissue region (areolar) - mobility of leukocytes, mast & macrophage cells.

Question 11

What is the function of the papillary layers?

Answer 11

Mobility of leukocytes, mast & macrophage cells.

Question 12

What is in the reticular layer?

Answer 12

thick dense irregular connective tissue layer - less cells + adipocyte clusters

Question 13

Which has more cells the papillary layer or reticular layer?

Answer 13

papillary layer

Question 14

What type of clusters can be found in the reticular layer?

Answer 14

Adipocyte clusters

Question 15

What are the accessory organs of the integumentary system?

Answer 15

Hair, nails, oil + sweat glands

Question 16

What is the use of having a rich layer of blood & lymphatic vessels, including arteriovenous anastomoses in the accessory organs?

Answer 16

thermoregulation

Question 17

What does the dermal (epidermal boundary look like)?

Answer 17

‘wavy’ boundary of finger-like projections increasing connection (interdigitation)

Question 18

What do dermal papillae create?

Answer 18

raised areas - e.g. fingerprint

Question 19

What facilities nerve fibres reaching close to the surface in highly sensitive areas?

Answer 19

Tall dermal papillae

Question 20

What type of epithelium is found in the epidermis?

Answer 20

Keratinised stratified squamous epithelium

Question 21

Describe the protein content in the upper layers of the epidermis

Answer 21

there is a high protein content in the upper layers of the epidermis

Question 22

Describe the layers of the epidermis (top to bottom)

Answer 22

stratum corneum
stratum lucidum (translucent)
stratum granulosum
stratum spinosum
stratum basale
stratified

Question 23

What are the 2 skin types?

Answer 23

• Thick skin
• Thin skin

Question 24

Describe what thick skin can be found

Answer 24

• Palms (fingertips)
• Feet - no hair (glabrous)

Question 25

How many layers (strata) does thick skin have?

Answer 25

5

Question 26

Where is thin skin found?

Answer 26

the rest of the body (non-glabrous - areas with hair)

Question 27

How many layers does thin skin?

Answer 27

4

Question 28

Describe how many blood vessels are found in thin skin?

Answer 28

Lacks blood vessels - diffusion from underlying connective tissue

Question 29

What is another name given to the stratum basale?

Answer 29

germinativum

Question 30

What are the 3 type of cells found in the stratum basale?

Answer 30

- keratinocytes (most prevalent) - melanocytes - tactile/Merkel cells

Question 31

What is the role of keratinocytes?

Answer 31

they are mitotically active in touch with BM (stem cells)

Question 32

what is the role of melanocytes?

Answer 32

gives skin colour - pheomelanin/eumelanin - brown insoluble pigment - protects skin from UV damage

Question 33

What is the role of tactile/Merkel cells?

Answer 33

connected to sensory nerves (sense of touch)

Question 34

What colour pigment is pheomelanin?

Answer 34

red/yellow pigment

Question 35

What colour pigment is eumelanin?

Answer 35

brown/black pigment

Question 36

What 2 pigments make up skin pigmentation?

Answer 36

melanin + - carotene pigments (orange-yellow) - heels/corns of the feet - blood perfusion + O2 content - haemoglobin (red)

Question 37

What are melanosomes?

Answer 37

organelles responsible for the synthesis, storage & transport of melanin

Question 38

What is usually the thickest layer in the epidermis?

Answer 38

stratum spinosum

Question 39

What does the stratum spinosum produce?

Answer 39

keratin filaments (flatten)

Question 40

What structures strongly link keratinoctyes?

Answer 40

desmosomes?

Question 41

What is the advantage of having tight junctions within the stratum spinosum?

Answer 41

ensures water retention of skin

Question 42

What is the function of the dendritic cells present in the stratum spinosum?

Answer 42

they are immune cells

Question 43

How many layers of keratinocytes do stratum granulosum?

Answer 43

3-5 layers

Question 44

What do the dark-staining granules found in stratum granulosum bind to?

Answer 44

bind to cytoskeleton (keratin precursor)

Question 45

What type of vesicles are produced in the stratum granulosum?

Answer 45

glycolipid-filled vesicles (lamellar bodies/granules) - spread over cell surface - waterproof barrier between Stratum spinosum

Question 46

Describe the cells in Stratum corneum

Answer 46

most part are dead and high in proteins & don't contain nucleus

Question 47

How many layers does the Stratum corneum have?

Answer 47

30

Question 48

What are the 2 parts of the Stratum corneum?

Answer 48

- stratum disjunctum - stratum compactum

Question 49

What is the most superficial layer of the Stratum corneum made of?

Answer 49

15-30 layers of flattened corneocytes/squames

Question 50

What are squames?

Answer 50

enucleated terminally differentiated dead keratinocytes

Question 51

What is the role of Stratum disjunctum in the stratum corneum?

Answer 51

contains corneodesmosomes which regulate desquamation

Question 52

What is the role of the stratum compactum in the stratum corneum?

Answer 52

focuses on cohesion

Question 53

What are the keratins in the stratum corneum enclosed in?

Answer 53

insoluble amalgam of cross-linked proteins

Question 54

What layer of the epidermis are nails derivatives of?

Answer 54

stratum corneum

Question 55

What are nails formed of?

Answer 55

dead scaly cells that are densely packed with "hard" keratin fibres.

Question 56

How are new cells added to nails?

Answer 56

mitosis in the nail matrix

Question 57

What is an underlying health issue that could be indicated as a result of having flat or concave nails?

Answer 57

iron deficiency

Question 58

What is an underlying health issue that could be indicated as a result of having clubbed nails?

Answer 58

long term hypoxemia (low blood oxygen levels)

Question 59

What are the 3 names given to hair (pilus) throughout its lifetime)?

Answer 59

languo --> vellus --> terminal androgenic

Question 60

Describe how hair forms?

Answer 60

hair bulb grow around bud of vascular connective tissue - dermal papilla

Question 61

What part of hair is mitotically active, whilst the remainder is dead?

Answer 61

hair matrix

Question 62

What are the 3 layers in hair?

Answer 62

Medulla - loosely arranged cells Cortex - keratinised cuboidal cells Cuticle - surface layer of scaly cells

Question 63

What are the 5 types of skin gland types?

Answer 63

- eccrine/merocrine (sweat glands) - apocrine sweat glands - holocrine sebaceous glands - ceruminous glands (external ear - wax) - mammary glands (females)

Question 64

What cells are involved in holocrine secretion?

Answer 64

sebocytes

Question 65

What are sebocytes?

Answer 65

differentiated epithelial cells accumulate lipids, eventually rupture to release sebum

Question 66

How many microflora does skin have?

Answer 66

1000 species

Question 67

How does skin act as a physical barrier?

Answer 67

cross-linked keratin layer on keratinocyte scaffold (cuts/burns/vectors/breach)

Question 68

How dies skin act as a biochemical barrier preventing water loss?

Answer 68

- mildly acidic (pH 4-6) - contain sebaceous gland seboctyes (sebum) - C6H can inhibit induction of antibiotic resistance

Question 69

What cells are used in skin to act as an immunological barrier?

Answer 69

Epidermal Langerhans Cells (LC)

Question 70

What layer of the Epidermis are Epidermal Langerhans Cells (LC) located?

Answer 70

stratum spinosum (able to self-renew)

Question 71

How does skin process antigens?

Answer 71

- migrate to lymph nodes for antigen presentation - present antigens to skin lymphocytes

Question 72

What can be found in dermal cells?

Answer 72

- macrophages + monocytes - mast cells - eosinophils - neutrophils - B + T lymphocytes - may have role in tissue remodelling, repair & proliferation

Question 73

Describe the process of Vitamin D synthesis

Answer 73

- increases intestinal absorption of calcium

Question 74

Why is calcium homeostasis?

Answer 74

bone development + maintenance

Question 75

What type of hormone is vitamin D?

Answer 75

fat-soluble hormone

Question 76

What type of receptor allows the synthesis of vitamin D?

Answer 76

Nuclear receptor

Question 77

What photochemical reaction is necessary for the synthesis of vitamin D?

Answer 77

UVB radiation

Question 78

What 4 things are involved in thermoregulation?

Answer 78

- receptors - insulation (piloerection) - sweating - vasodilation/vasoconstriction

Question 79

What volume of skin blood dissipates heat at rest?

Answer 79

250ml/min

Question 80

How many kcal an hour is required for thermoregulation?

Answer 80

80kcal/hr

Question 81

Where are central warm + cold receptors located?

Answer 81

preoptic anterior hypothalamus

Question 82

Between what two blood flows does countercurrent heat exchangers occur?

Answer 82

arterial & venous blood flow

Question 83

What type of skin is arteriole out anastomoses found?

Answer 83

Apical skin

Question 84

How does a reduction in core temperature lead to a reduction in blood flow?

Answer 84

reduction in core temperature = increase in sympathetic tone = reduction in blood flow

Question 85

How does an increase in core temperature lead to a increase in blood flow?

Answer 85

increase in core temperature = decrease in sympathetic tone = increase in blood flow

Question 86

How is non-apical skin thought to act via sympathetic nervous system (SNS) to affect ACh release?

Answer 86

eccrine sweat glands --> vasoactive molecules --> relax VSMC --> increase in perfusion + heat loss