M1 L1

Question 1

Largest and most visible organ in the body

Answer 1

Skin

Question 2

what % of body weight is skin?

Answer 2

16%

Question 3

what surface area does skin occupy?

Answer 3

1.5-2 m^2

Question 4

What evolutionary features make us unique and why?

Answer 4

• “Bare and sweaty” skin
• Less body hair therefore more sweat glands for more effective cooling. Since we evolved for hunting and moving.

Question 5

skin performs (complex/simple) roles in the body?

Answer 5

complex

Question 6

Pranksters Easily Make Ketchup Stains Last Decades

functions of skin and accessory structures

Answer 6

• protection
• Excretion
  -Maintanence
  -melanin
  -keratin
  -synthesis vitD
  -lipids
  -detect

Question 7

What basic tissue types are skin made of?

Answer 7

Composite organ therefore all 4 basic tissue types.
- epithelial
- connective
- muscle
- nervous

Question 8

3 Layers of the skin

Answer 8

• Epidermis (cutaneous)
• Dermis (cutaneous)
• Hypodermis (subcutaneous)

Question 9

Epidermis

Answer 9

• stratified barrier
• mostly keratinocytes
• Avascular (no blood circulation)

Question 10

How does the epidermis get nutrients?

Answer 10

From blood vessels from the dermis layer

Question 11

what basic tissue is the epidermis mainly made up of?

Answer 11

epithelial tissue
(stratified squamous epithelium) - acting as a barrier

Question 12

3 different types of epithelia

Answer 12

Simple (single layer of) or Stratified (stacks of)
- squamous (flattened)
- cuboidal
- columnar

Question 13

Come Get Some Burgers

Epidermis layer for thin skin (from external down)

Answer 13

• stratum corneum (squamous)
• stratum granulosum (squamous)
• stratum spinosum (cuboidal)
• stratum basale (columnar)

Question 14

Come Lets Get Some Burgers

Epidermis layer for thick skin (from external down)

Answer 14

• stratum corneum (squamous)
• stratum lucidum
• stratum granulosum (squamous)
• stratum spinosum (cuboidal)
• stratum basale (columnar)

only difference is stratum lucidum is present in thick skin

Question 15

examples and features of thick skin

Answer 15

• e.g. palms of hands, soles of feet
• no hair is present
• has an additional epithelial layer (stratum lucidum)

Question 16

spiky layer

Stratum Corneum

Answer 16

• dead, dried out, hard cells
• no nuclei
• easily flakes off

Question 17

granular layer

Stratum Granulosum

Answer 17

Has granules to promote
- dehydration of cell
- cross-linking of keratin fibres

Waxy material secreted into intercellular space

Question 18

spinous or prickly cell layer

Stratum Spinosum

Answer 18

• Desmosomes anchor neighbouring cells WITHIN the epidermis.
• cuboidal

Question 19

basal layer

Stratum Basale

Answer 19

• regenerative stem cells
• As it divides, the daughter cell replenishes the layer above.

Question 20

Basement Membrane

Answer 20

• made of hemidesmosome
• anchors stratum basale (of epidermis) to dermis

Question 21

Stratum Lucidum

Answer 21

• only in thick skin
• dead cells

Question 22

layer(s) of epidermis that are dead in thin skin

Answer 22

Only Stratum corneum

Question 23

layer(s) of epidermis that are dead in thick skin

Answer 23

stratum corneum
stratum lucidum

Question 24

Dermis

Answer 24

• protein fibres for strength and toughness (collagen and elastin)
• vascular for nourishment
• not shed

Question 25

what anchors the dermis to epidermis

Answer 25

hemidesmosomes

Question 26

layers of dermis (from external to in)

Answer 26

- papillary - reticular

Question 27

Papillary layer of dermis

Answer 27

- outer layer - highly vascularised tissues

Question 28

Reticular layer of dermis

Answer 28

- collagen and elastin "mesh-like" structure for strength

Question 29

Similarities of both layers of the dermis

Answer 29

blood vessels lymphatics sensory nerve fibres accessory structures

Question 30

what is a plexus

Answer 30

network of blood vessels OR nerves

Question 31

2 types of plexuses of the dermis

Answer 31

- cutaneous plexus - sub-papillary plexus

Question 32

Cutaneous Plexus

Answer 32

- network of blood vessels present at the very bottom of reticular dermis layer (at junction b/w dermis and hypodermis) - supplies nutrients to hypodermis and the deeper dermis

Question 33

Sub-Papillary Plexus

Answer 33

- branches from cutaneous layer (epidermis + dermis) - lies deep to papillary layer (of dermis) - provides nutrients and O2 to upper dermis and epidermis

Question 34

Hypodermis

Answer 34

-Adipose tissue - subcutaneous layer

Question 35

functions of hypodermis

Answer 35

The subcutaneous fat... - stores energy - gives insulation Site of injections (hypodermic needles)

Question 36

1st degree burns

Answer 36

- superficial (only outer layer of epidermis) - red/pink (erythema), dry and painful - no blisters - skin retains function of repelling water and pathogens - 3-10 days healing - e.g. mild sunburn

Question 37

Two types of 2nd degree burns

Answer 37

normal and deeper

Question 38

normal 2nd degrees

Answer 38

- affects epidermis + parts of dermis - painful, moist, red and blistered - heals in 1-2 weeks (with good dressing)

Question 39

deeper 2nd degrees

Answer 39

- can include whiteish, waxy looking areas - hair follicles and sweat glands may stay in tact - heals in ~ 1 month - loss of sensation and scarring

Question 40

3rd degree burns

Answer 40

full thickness burns - even extends into subcutaneous tissue (and maybe involving muscle and bone) - varied colour (waxy white to deep red to black) - Hard, dry & leathery skin - No pain (bc nerve endings are destroyed) - may require skin grafting (one piece of skin transplanted from one area to another) - weeks to regenerate + scarring