Layers of the Skin

Question 1

What is skin?

Answer 1

The largest and most visible organ of the body
- 16% of body weight
- 1.5-2m^2 of surface area
Bare sweaty skin makes us unique, evolved from needing more efficient cooling mechanism due to hunting, running etc.

Question 2

What are some of the general functions of the skin?

Answer 2

Protection, producing keratin, producing melanin, lipid storage, detecting touch (sensory receptors)

Question 3

What tissue is the skin made out of?

Answer 3

All 4 tissue types (epithelial, connective, muscle and nervous)

Question 4

What are the 3 primary layers of the skin?

Answer 4

Epidermis
Dermis
Hypodermis

Question 5

What is the epidermis?

Answer 5

Outermost layer of the skin
Stratified squamous (multiple layer, flat) barrier
Mostly keratinocytes (cells that contain lots of keratin)
No blood circulation (avascular)

Question 6

What is the dermis?

Answer 6

Middle layer
Protein fibres for strength - holds everything together
Proteins include collagen and elastin
Vascular (nourishes itself and epidermis)

Question 7

What layers make up the cutaneous?

Answer 7

Epidermis and Dermis

Question 8

What is the hypodermis?

Answer 8

Layer below dermis/innermost layer of skin
Consists mostly of adipose tissue (subcutaneous fat producing cells)
Subcutaneous fat stores energy and provides insulation
Common site of injections using hypodermic needles

Question 9

What layer makes up the subcutaneous?

Answer 9

Hypodermis

Question 10

What tissue type dominates the epidermis?

Answer 10

Epithelial tissue as it is the tissue that covers exposed surfaces and forms secretory glands

Question 11

What are the two types of epithelia and what are the three ways they can be arranged?

Answer 11

Simple epithelia meaning ‘single’ layer
Stratified epithelia meaning ‘stacked’ layer
Squamous (flat), cubodial (cube) and columnar (tall columns)

Question 12

What are the four layers in regards to THIN skin?

Answer 12

Stratum Corneum (spiky layer)
Stratum Granulosum (granular layer)
Stratum Spinosum (spinous layer)
Stratum Basale (basal layer)
Come Get Some Bagels (corneum, granulosum, spinosum, basale)

Question 13

What are the five layers in regards to THICK skin?

Answer 13

Stratum Corneum (spiky layer)
Stratum lucidum (transparent layer)
Stratum Granulosum (granular layer)
Stratum Spinosum (spinous layer)
Stratum Basale (basal layer)

Come Let’s Get Some Bagels (corneum, lucidum, granulosum, spinosum, basale)

Question 14

What is the stratum corneum?

Answer 14

Spiky layer of dead dried out hard cells without nuclei, easily flakes off and can be completely removed

Question 15

What is the stratum lucidum?

Answer 15

Dead, transparent, extra layer for thick skin

Question 16

What is the stratum granulosum?

Answer 16

Granular layer that contains granules that promote dehydration of the cell, crosslinking of keratin fibres
Waxy material is secreted into the intracellular spaces (fills gaps in between granules)

Question 17

What is the stratum spinosum?

Answer 17

Spinous layer made up of desmosomes that link the cells together which are increasingly flattened as they move upward

Question 18

What is the stratum basale?

Answer 18

Basal layer made up of columnar regenerative cells (stem cells)
As the basal cell divides, a daughter cell migrates upwards to replenish the layer above, pushed up the layers until they flake off

Question 19

What is the basal membrane?

Answer 19

Membrane that is found at the bottom of the epidermis and is shared with the dermis

Question 20

What are desmosomes?

Answer 20

Cells that anchor adjacent/neighbouring cells in the epidermis

Question 21

What are hemidesmosomes?

Answer 21

Cells that anchor stratum basale to the dermis

Question 22

What are some properties of thick skin?

Answer 22

Has 5 layer, found in palms of hands and soles of feet, no hair, extra epidermal layer for durability

Question 23

What is the dermal papilla?

Answer 23

Provides epidermis with nutrients and blood received from papillary layer

Question 24

Where is the dermis situated?

Answer 24

It is situated below the epidermis and anchors via hemidesmosomes
Not shed
Divided into two layers : papillary and reticular

Question 25

What is the papillary layer?

Answer 25

Layer consisting of highly vascularised tissues for nourishment
Supplies blood to epidermis and dermis

Question 26

What is the reticular layer?

Answer 26

‘Mesh like’ structure of collagen and elastin fibres (for strength), contains blood vessels

Question 27

What is the cutaneous plexus?

Answer 27

Network of blood vessels present in between the dermis/hypodermis
Supplies nutrients to hypodermis, deeper dermis, capillaries for hair follicles and sweat glands

Question 28

What is the subpapillary plexus?

Answer 28

Branches from the cutraneous plexus
Lies deep to papillary layer of dermis
Network of blood vessels providing oxygen and nutrients to the upper dermis and epidermis

Question 29

What is a first degree burn?

Answer 29

Superficial (only involves the outer layers of the epidermis)
Red/pink, dry, painful (erythema)
Usually no blisters e.g. mild sunburn
Skin remains a water and bacterial barrier (can still perform functions)
Usually heals 3-10 days

Question 30

What is a second degree burn?

Answer 30

Normally: epidermis and varying amounts of dermis affected, painful, moist, red and blistered, heals in approx 1-2 weeks
Deeper: whiteish wax looking areas, hair follicles & sweat glands may stay intact, heals in 1 month, may have loss of sensation and scarring

Question 31

What is a third degree burn?

Answer 31

Extends into the subcutaneous tissue (full thickness burn), may involve muscle and bone
Varied colour from waxy white through to deep red or black
Hard, dry and leathery skin
No pain in these areas as sensory nerve endings are destroyed
May require skin graft, weeks to regenerate and scarring