Effect Of Environment On Skin

Question 1

What is toxic epidermal necrolysis?

Answer 1

→ Detachment of the epidermis that is fatal

Question 2

What are environmental insults?

Answer 2

→ UV light
→ Physical trauma

→ Microbes
→ Allergens
→ irritants

Question 3

What are fast adaptations of the skin?

Answer 3

→ Sweating and vasodilation in the heat

→ Vasoconstriction in the cold

Question 4

What are two slow adaptations of the skin?

Answer 4

→ Hyperkeratosis : thickening of the stratum corneum with rubbing or pressure
→ Melanocytes : tanning

Question 5

What are AV shunts?

Answer 5

→ Anastomoses between arterioles and venules

Question 6

What do AV shunts respond to?

Answer 6

→ thermoreceptors in the skin

Question 7

What do AV shunts do?

Answer 7

→ Open and close to increase or decrease blood flow to the superficial vascular plexus in the papillary dermis

Question 8

What can AV shunts in the face do?

Answer 8

→ Respond to emotion

→ blushing

Question 9

What happens if AV shunts are shut off for too long?

Answer 9

→ danger of damage (frostbite)

Question 10

What is the color of human skin due to?

Answer 10

→ Melanin and haemoglobin

Question 11

What does melanin do?

Answer 11

→ protect against DNA damage and skin cancer

Question 12

Where do melanosomes get transferred to?

Answer 12

→ basal keratinocytes

Question 13

What happens to melanocytes during tanning?

Answer 13

→Melanocytes increase activity

→ They make and transmit more melanin

Question 14

What 2 things happen to protect against UV?

Answer 14

→ Tanning

→ Skin thickening (Slowly)

Question 15

Describe the process of tanning

Answer 15

→ UV light shines on keratinocytes and damages the DNA if there isn’t enough melanin
→ MSH gets produced by the keratinocytes

→ MSH binds to its receptor MC1R
→ It signals the cAMP pathway
→ More melanin is produced
→ Melanosomes go into the keratinocytes and build up the cap

Question 16

What is tanning set off by?

Answer 16

→ DNA damage

Question 17

Where are Langerhans cells found?

Answer 17

→ In the non basal layers of the skin

Question 18

What is the function of Langerhans cells?

Answer 18

→ Antigen presenting cells

→ form a network in the epidermis

Question 19

What is lichenification and how does this occur?

Answer 19

→ more extreme hyperkeratosis

→ Reaction to excessive rubbing or scratching

Question 20

What are the 3 types of UV rays?

Answer 20

→ UVA and UVB (hit earth)

→ UVC (stopped by ozone)

Question 21

What type of burn is sunburn?

Answer 21

→ A radiation burn

Question 22

What happens during sunburn?

Answer 22

→ Blisters
→ Inflammation

→ Cell death

Question 23

What is sunburn associated with?

Answer 23

→ Risk of cancer

→solar elastosis

Question 24

What is a polymorphic light eruption?

Answer 24

→ Being allergic to sunlight

→ Rash when out in the sun

Question 25

What are naevi?

Answer 25

→ a benign proliferation of melanocytes

Question 26

What do many naevi mean?

Answer 26

→ Risk factor for melanoma, skin cancer

Question 27

What are freckles linked to?

Answer 27

→ Red/fair hair | → MC1R gene variants

Question 28

What are solar lentigos?

Answer 28

→ Liver/Age spots

Question 29

What are solar keratoses?

Answer 29

→ Dysplastic growth of keratinocytes

Question 30

What cells does melanoma affect?

Answer 30

→ melanocytes

Question 31

What cells does non-melanoma affect?

Answer 31

→ keratinocytes

Question 32

What are the two types of non-melanoma cancers?

Answer 32

→ Squamous cell carcinoma | → Basal cell carcinoma

Question 33

What are the characteristics of basal cell carcinoma?

Answer 33

→ It doesn't spread easily | → Often curable by surgery

Question 34

What is UV needed for?

Answer 34

→ Vitamin D3 production in the skin

Question 35

What are the three types of burn?

Answer 35

→ Superficial → Partial thickness- some sacrring → Full thickness- loss of pinprick sensation, scarring

Question 36

When does irritant contact dermatitis occur?

Answer 36

→ Too much exposure to a substance

Question 37

What are the symptoms of irritant contact dermatitis?

Answer 37

→ Redness, itching, swelling, blistering

Question 38

What is allergic contact dermatitis?

Answer 38

→ Allergy to something that contacts the skin | → Small amount is sufficient

Question 39

What are the steps to allergic contact dermatitis?

Answer 39

→ Sensitisation first : Langerhans cells process antigen and present it to the lymphocytes → Delayed hypersensitivity occurs at the next exposure

Question 40

What is paronychia?

Answer 40

→ Nail fold infection | → Can be fungal or bacterial

Question 41

What is tinea capitis?

Answer 41

→ Scalp ringworm

Question 42

What is impetigo?

Answer 42

→ an injury getting infected

Question 43

Where can microbes enter?

Answer 43

→ In a breach in the epidermis

Question 44

What does the AV shunt do in hot temperatures?

Answer 44

→Shunt is closed allowing continuous blood supply through arterioles to subpapillary plexus

Question 45

What does the AV shunt do in cold temperatures?

Answer 45

→Shunts open. Blood is shunted straight to venous so blood id not taking through arterioles to the skin

Question 46

Summarise molecular cascade of suntanning

Answer 46

``` →Tyrosine →L-DOPA →DOPAquinone →TRPs →Eumelanin or pheomelanin ```

Question 47

What bacteria is responsible for cellulitis?

Answer 47

→streptococcus

Question 48

What virus is responsible for warts?

Answer 48

HPV