Skin

Question 1

Functions of skin

Answer 1

Barrier - water loss and entry. Burned can result in dehydration due to loss of barrier

Microorganisms
- physical barrier
- oil of skin is antibacterial (Sebum)
- sweat (slightly acidic - inhibits bacterial growth)

Ultra-violet radiation - melanin

Excretory organ - sweat

Synthesis of Vit D - by action of UV, Ca2+

Sense organ - touch, pressure etc

Question 2

Layers of skin

Answer 2

Epidermis - keratinocytes
Dermis - layers of connective tissue
Hypodermis - subcutaneous layer

Question 3

List layers of Epidermis

Answer 3

Stratified squamous epithelium

Has 5 zones
Stratum corneum
Stratum Lucidum
Stratum Granulosum
Stratum Spinosum
Stratum basale

Question 4

Stratum corneum

Answer 4

dead cless, lost as skin replaces itself

Question 5

Stratum lucidum

Answer 5

Only in thick skin

Question 6

Stratum granulosum

Answer 6

Oils, proteins - waterproof the skin

Question 7

Stratum spinosum

Answer 7

Structure and strength
Spot desmosomes
Keratin

Question 8

Stratum basale

Answer 8

Basal layer - stem cells
40 days to migrate from base to be lost

Question 9

Thick skin

Answer 9

epidermis: 400-600um
Palms of hands including fingers, soles of feet included toes - protection to areas under stress

Increased Stratum corneum

Question 10

Thin skin

Answer 10

epidermis: 75 to 150 um - rest of body

Question 11

Keratinocyte

Answer 11

Immune role - produce cytokines
Epithelial cells - gives epidermis strength (structure)

Question 12

Melanocyte

Answer 12

Produce melanin
Darker skin - more active melanocytes

Question 13

Langerhans cells

Answer 13

Dendritic cells - detect foreign bodies -> immune response

Question 14

Keratin

Answer 14

Key structural material
Forms intermediate filaments giving strength, protection and waterproofing for skin.

Keratin of hair and nails more tightly packed

Question 15

Melanin

Answer 15

Production occurs afters exposure to UV radiation, causing skin to tna

Released by melanocytes and taken up by keratinocytes

Darker skin is due to more active melanocytes, not a great number

Question 16

Attachment of epidermis to dermis

Answer 16

Epidermis attached by epidermal ridges

Contour of skin follows these ridges - leads to formation of structures like finger prints

Question 17

Layers of dermis

Answer 17

Papillary layer - areolar connective tissue

Reticular layer - dense irregular connective tissue. Bundles of collagen arranged in different orientations. Strength allows movement in different directions

Question 18

Papillary layer

Answer 18

Consists of loose connective tissue, blood vessels, cells and sensory receptors.

Allows movement of immune cells to detect bacteria

Dermal papillae - blood vessels nourish all hair follicles, bring nutrients and oxygen to the lower epidermal cell layers

Question 19

Reticular layer

Answer 19

Dense, irregular collagen I that surrounds hair follicles, blood vessels and glands.

Contains majority of elastin in dermis

Question 20

Fibroblasts

Answer 20

Produce collagen and elastin

Question 21

Mast cells

Answer 21

Produce cytokines

Question 22

Collagen in skin

Answer 22

Responsible for skin strength and elasticity. Its degradation leaks to wrinkles that accompany aging

Question 23

Elastin

Answer 23

Allows skin to return to its original position after stretching or contracting
- aging leads to loss of elastin fibres

Question 24

Hypodermis

Answer 24

Loose connective tissue and adipocytes
Bind skin to underlying tissues, provides padding and thermal insulation

Question 25

Skin derivatives

Answer 25

Nails, hair, sebaceous and sweat glands

Question 26

Nails

Answer 26

Nail body is formed from nail matrix

Question 27

Hair

Answer 27

Hair is produced from hair matrix and hair papilla inside the hair bulb have blood vessels that nourish the hair

Question 28

Sebaceous glands

Answer 28

Oily substance called sebum Holocrine secretion - cells break down

Question 29

Sweat gland

Answer 29

Apocrine swell gland found in axillae, groin and nipples. Produce apocrine sweat -> bacteria and body odor. Loss of part of cell but is replaced Merocrine sweat glands replace via blebs from the membrane and cool the body as sweat evaporates.

Question 30

Skin as a sensory organ

Answer 30

Has thermoreceptors (heat), nociceptors (pain) and mechanoreceptors.

Question 31

Thermoregulation

Answer 31

TRP receptors Primary sensory cortex receives conscious response to temperature Hypothalamus receives autonomic response to temperature

Question 32

Cold thermoreceptors

Answer 32

TRPA1, TRPM8, TRPC5

Question 33

Innocuous thermoreceptors

Answer 33

TRPV4, TRPM2 TRPV3

Question 34

Hot thermoreceptors

Answer 34

TRPV1 (chilli), TRPM3, TRPV2

Question 35

Cold ligands

Answer 35

Eucalyptol, Menthol, Ilicin

Question 36

Warm ligands

Answer 36

Camphor, Carvacrol, Eugenol, thymol