Skin (lectures 1 to 3)

Question 1

Name for skin accessories and function

Answer 1

Integumentary system

Question 2

Roles of integumentary sytstem

Answer 2

-Protects underlying tissues and organs from abrasions, fluid loss, chemicals etc.
-Excretes salts, water, and organic wastes using glands
-Temperature regulation by insulation or evaporative cooling
-Produces melanin: protects underlying tissues against UV
-Produces keratin: Protection against abrasions & water repellent
-Synthesize Vitamin D3 (steroid) converted to calcitriol (hormone important for normal calcium metabolism)
-Lipid storage in adipocytes, some in dermis and mostly in adipose tissue in hypodermis
-Detect touch, temperature, pain, and pressure stimuli and relay information to nervous system

Question 3

The primary layers of skin

Answer 3

Epidermis, dermis, hypodermis

Question 4

Epidermis

Answer 4

-Stratified barrier, mostly keratinocytes, no blood circulation (avascular)
-Cutaneous layer

Question 5

Dermis

Answer 5

-Protein fibres for strength, vascular (nourishes epidermis), not shed
-Cutaneous layer.
-Papillary layer and reticular layer
-Situated below the epidermis &
anchors via hemidesmosomes

Question 6

Hypodermis

Answer 6

-Adipose tissue
-Subcutaneous layer (not considered part of the
skin)
-Dominated by adipocytes that produce subcutaneous fat
-Subcutaneous fat stores energy & provides insulation
-Common site of injections using hypodermic needles

Question 7

What tissue type is predominant in epidermis?

Answer 7

Epithelial tissue (covers exposed surfaces, lines internal passageways and chambers, forms secretory glands)

Question 8

Types of epithelia

Answer 8

-Simple (single) epithelia (squamous, cuboidal, columnar)
-Stratified (layered) epithelia (squamous, cuboidal, columnar)

Question 9

What type of epithelia makes up the majority of the epidermis?

Answer 9

Stratified squamous epithelia

Question 10

Layers of the epidermis

Answer 10

-Stratum corneum (spiky layer)
-Stratum granulosum (granular layer)
-Stratum spinosum (spinous or prickly cell layer)
-Stratum basale (basal layer)

Question 11

Stratum corneum

Answer 11

(spiky layer), dead, dried-out hard cells
without nuclei, easily flakes off & can be
completely removed

Question 12

Stratum granulosum

Answer 12

(granular layer), contain granules that promote
dehydration of the cell, crosslinking of keratin fibre, waxy material is secreted into the
intercellular spaces

Question 13

Stratum spinosum

Answer 13

(spinous or prickly cell layer), intercellular bridges (desmosomes) link cells together, cells become increasingly flattened as they move upward, contains dendritic (immune) cells

Question 14

Stratum basale

Answer 14

(basal layer), columnar regenerative cells, as basal cell divides, daughter cell migrates upwards to replenish layer above

Question 15

Desmosomes function in skin

Answer 15

Anchors adjacent/neighboring cells in epidermis

Question 16

Hemidesmosomes function in skin

Answer 16

Anchors stratum basale to the dermis

Question 17

Stratum lucidum

Answer 17

extra layer, only in thick skin

Question 18

Thick skin

Answer 18

Palms of hands and soles of feet, no hair, extra epidermal layer (Stratum lucidum)

Question 19

Dermal papillae

Answer 19

Projections from dermis adjacent to epidermal
ridges, both increase surface area and bind
epidermis and dermis closely

Question 20

Reticular Layer of dermis

Answer 20

-Mesh like structure of collagen and elastin fibres (for strength)
-Both papillary and reticular layers contain blood vessels, lymphatics, sensory nerve fibres and accessory structures

Question 21

Papillary Layer of dermis

Answer 21

-Consists of highly vascularised tissues (for nourishment).
-Both papillary and reticular layers contain blood vessels, lymphatics, sensory nerve fibres and accessory structures

Question 22

Plexuses of the Dermis

Answer 22

Cutaneous Plexus and Subpapillary Plexus

Question 23

Cutaneous Plexus

Answer 23

• Network of blood vessels present at junction of dermis/hypodermis.
• Supplies hypodermis, deeper dermis, including capillaries for hair follicles and sweat glands
  -Plexus=network of blood vessels or nerves

Question 24

Subpapillary Plexus

Answer 24

• Branches from cutaneous plexus
• Lies deep to papillary layer of dermis
• Network of blood vessels providing O2
  and nutrients to upper dermis and epidermis
  -Plexus=network of blood vessels or nerves

Question 25

First degree burns

Answer 25

-Superficial (outer layers of epidermis) -Red/pink, dry, painful (Erythema) -Usually no blisters (mild sunburn) -Skin remains a water and bacterial barrier -Usually heals 3-10 days

Question 26

Second degree burns

Answer 26

Normal 2nd degree burns: -Epidermis and varying amounts of dermis -Painful, moist, red and blistered -Usually heal in approx. 1-2 weeks (needs good dressings) Deeper 2nd degree burns: -May include whiteish, waxy looking areas -Hair follicles, sweat glands may remain intact -Usually heal in 1 month -May have some loss of sensation and scarring

Question 27

Third degree burns

Answer 27

Full thickness burns (extend into subcutaneous tissue and may involve muscle and bone -Varied color from waxy white through to deep red or black -Hard, dry and leathery skin -No pain in these areas as sensory nerve endings destroyed -May require skin grafting -Weeks to regenerate and scarring

Question 28

What cell dominates the hypodermis?

Answer 28

Adipocytes

Question 29

Accessory structures

Answer 29

Hair, nails, sweat glands, receptors

Question 30

Hair

Answer 30

All over body except palms, soles and lips -Made of dead, keratinized cells produced inside hair follicle -Hair shaft projects from follicle Consists of: Arrector pili muscle, root hair plexus, sebaceous glands

Question 31

Arrector pili muscle

Answer 31

Contraction produces goosebumps, improves insulation

Question 32

Root hair plexus

Answer 32

Collection of sensory nerves at base of each hair follicle, heightened sensation