Integumentary system

Question 1

divisions of the integumentary system

Answer 1

cutaneous membrane
- skin

accessory structures
- hair
- nails
- exocrine glands

Question 2

5 general functions of skin

Answer 2

• protect underlying tissues + organs
• excretes salt, water + organic wastes
• maintains body temp
• synthesises vitamin D3
• stores lipids
• detects touch, pressure, pain + temp

Question 3

describe the epidermis

Answer 3

outer, thinner layer
composed of epithelium

Question 4

describe the dermis

Answer 4

inner, thicker layer
composed of connective tissue
contains nerves

Question 5

describe the structureof the hypodermis

Answer 5

fat store
contains blood vessels
has pacinian corpuscles (sensitive to pressure)

Question 6

list the 5 layers of the epidermis in order from outermost

Answer 6

1. stratum corneum
2. stratum lucidum
   3.stratum granulosum
3. strata spinosum
4. stratum basale/germinativum

Question 7

structure of stratum corneum

Answer 7

• multiple layers of dead, flat keratinocytes
• water resistant, X waterproof
• fluid loss via insensible perspiration

Question 8

structure of stratum lucidum

Answer 8

dead keratinocytes
present in thick skin subject to increased friction

Question 9

structure of stratum granulosum

Answer 9

• keratin fibres develop as cells become thinner + flatter
• lamellar granules secrete waterproofing chemical

Question 10

structure of strata spinosum

Answer 10

desmosomes hold cells together

Question 11

structure of stratum basale

Answer 11

attached to basement membrane
made of stem cells, melanocytes, dendritic cells + tactile cells

Question 12

describe the formation of a callus

Answer 12

abnormal thickening of stratum corneum due to constant exposure of skin to friction

Question 13

list the two layers of the dermis

Answer 13

papillary layer
reticular layer

Question 14

structure + function of papillary layer

Answer 14

• areolar tissue
• contains small capillaries, lymphatics + sensory neurons
• contains tactile corpuscles

Question 15

structure + function of reticular layer

Answer 15

• dense, irregular connective tissue
• collagen + elastic fibres provide strength + flexibility
• contains larger blood vessels, lymph vessels + nerve fibres

Question 16

what can be used to assess skin dehydration in the clinic

Answer 16

skin turgor - elasticity of skin + its ability to change shape + return back to normal

Question 17

what is dermatitis + its causes

Answer 17

• inflammation of papillary layer
• caused by infection, radiation, mechanical irritation or chemicals
• itch or pain

Question 18

what causes sagging skin + wrinkles + what is it

Answer 18

• reduced skin elasticity
• dehydration, age, hormonal changes, UV exposure

Question 19

what are stretch marks + what causes them

Answer 19

thickened tissue resulting from excessive stretching of skin due to weight gain or pregnancy

Question 20

medical importance of cleavage lines of dermis

Answer 20

b/c collagen + elastic fibres arranged in parallel bundles, cuts into skin must be made in parallel fashion

Question 21

structure + function of hypodermis

Answer 21

• connects dermis to underlying tissue
• loose connective tissue + fat cells
• contains large blood vessels w/ no vital organs

Question 22

differentiate b/t carotene + melanin

Answer 22

carotene = orange/yellow
- in epidermal cells + fatty tissues or dermis
- can be converted into vitamin A

melanin = yellow/black pigment
- produced in stratum basale of epithelium
- protects DNA in skin cells from sun damage

Question 23

describe hermansky-pudlak syndrome

Answer 23

deficiences in biogenesis of lysosome related organelles including melanosomes (required for transport of melanin)
-> albinism + prolonged bleeding

Question 24

pathway involved in vitamin D production via skin

Answer 24

sunlight
(in skin) steroid compound -> cholecalciferol

intermediary product in liver

calcitriol in kidney
-> stimulate Ca2+ absorption

Question 25

what is hair + its structure

Answer 25

- non living structures produced in hair follicles - dead columns of keratinised cells held together by extracellular proteins (has shaft + root)

Question 26

structures that enable hair movement detection

Answer 26

dendrites of hair root plexuses

Question 27

function of hair

Answer 27

- protects + insulates skull - guards openings against particles + insects - sensitive to very light touch

Question 28

why does hair vary in colour

Answer 28

- amount + type of melanin in keratinised cells - grey hair = progrwssive decline in synthesis of tyrosinase enzyme

Question 29

what causes goosebumps

Answer 29

contraction of arrector pilli muscle - under control of symp. NS

Question 30

structure + function of sebaceous glands

Answer 30

- connected to hair follicles + discharge oily lipid secretion (sebum) onto hair follicle

Question 31

what is the cause of pimples

Answer 31

when the opening of a sebaceous gland is blocked

Question 32

location + function of apocrine sweat glands

Answer 32

- skin of axilla, areolae, pubis + beard (males) - sticky, cloudy secretions which sometimes produce an odour

Question 33

location + function of merocrine (eccrine) sweat glands

Answer 33

- widely distributed on body surface - palms of hands + soles of feet - fluid secreted via pore - fluid made of water + ions, main function is heat loss

Question 34

location + function of ceruminous glands

Answer 34

- external auditory canal - produce ear wax

Question 35

nail structure + function

Answer 35

- plates of tightly packed, hard, keratinised epidermal cells - protect exposed surface of finger + toe tips

Question 36

describe the 3 components of the nail

Answer 36

lunula = area of thickened stratum basale hyponychium (nail bed) = thickened stratum corneum / secures nail to top of digit eponychium (cuticle) = narrow band of epithelium occupying proximal border of nail

Question 37

describe the 4 steps to epidermal wound healing

Answer 37

- basal cells of epidermis break contact w/ basement membrane - enlarge + migrate across wound - stop migration due to contact inhibition - relocated cells divide to build new epidermal layers + thicken epidermis

Question 38

describe the 4 phases of repair of deep wound healing

Answer 38

1. inflammatory blood clot forms, loosely binding wound edges / inflammation 2. migratory phase - clot becomes scab - epithelial cells migrate beneath scan to bridge wound - fibroblasts migrate + form collagen 3. proliferative phase - extensive growth of epithelial cells beneath scab - random deposition of collagen fibres - blood vessel growth 4. maturation phase - collagen fibres become organised - epithelium restored to normal thickness + scab comes off - blood vessels restored

Question 39

differentiate b/t UVA + UVB rays

Answer 39

UVA = skin tanning / long term damage UVB = main cause of sunburn DNA damage in epidermal cells

Question 40

describe the effects of ageing

Answer 40

- increased skin injuries + infections - reduced immune system - muscles weaker - decreased bone strength - increased sensitivity to sun

Question 41

differentiate b/t sensible + insensible perspiration

Answer 41

insensible = interstitial fluid lost via evaporation through stratum corneum sensible perspiration = activation of sweat glands to secrete sweat - cooling effect