SKIN

Question 1

Normal proliferation of the skin occurs

Answer 1

just in the basal layer

Question 2

Function of skin

Answer 2

• Barrier to infection
• Thermoregulation
• Protection against trauma
• Protection against UV
• Vitamin D synthesis
• Regulate H2O loss

Question 3

Basic Layers of skin

Answer 3

• Epidermis
• dermis
• Subcutaneous tissue

Question 4

Outermost layer of epidermis

Answer 4

Outermost layer known as the stratum corneum

Question 5

What is epidermis made up of

Answer 5

Made up of corneo-desmosomes and desmosomes

Question 6

Function of corneo desmosomes

Answer 6

Corneo-desmosomes (known as adhesion molecules) keep the corneocytes together

Question 7

Increased numbers of corneodesmosomes are seen in diseases such as

Answer 7

psoriasis in which there is a thickening of the stratum corneum

Question 8

Decreased numbers of corneodesmosomes are seen in diseases such as

Answer 8

atopic eczema in which there is a thinning of the stratum corneum - meaning there is an increased risk of inflammation

Question 9

Function of filaggrin

Answer 9

(derived from profilaggrin (a structural component of the cornfield envelope)) produces natural moisturising factor (NMF)

Question 10

Corneocytes function

Answer 10

Corneocytes are filled with NMF which help maintain the skin’s hydration
- keeps H2O inside the skin

Question 11

NMF function

Answer 11

• help maintain the skin’s hydration

- important in maintaining an acidic environment at the outer surface of the stratum corneum

Question 12

desquamation

Answer 12

In order to balance the introduction of new cells in the basal layer of the epidermis, mature corneocytes are shed from the surface of the stratum corneum in a process called desquamation

Question 13

Process of desquamination

Answer 13

involves the degradationof the extracellularcorneo-desmosomes under the action of protease enzymes

Question 14

Why is The pH of normal skin 5.5

Answer 14

this allows the proteases to remain on the skin thereby enabling the balance of new cells from the basal layers of the epidermis (desquamation

Question 15

Function of Lipid lamellae

Answer 15

• keeps water inside skin cells

- Irritants & allergens tend to “bounce off” the surface of the skin due to thepresence of the lipid lamellae

Question 16

Function of stratum corneum

Answer 16

The normal & intact stratum corneum acts as an efficient barrier to the penetration of irritants and allergens and to the loss of water

Question 17

Stratum corneum

Answer 17

outermost layer of skin

Question 18

What is the brick wall model

Answer 18

The skin barrier can be explained using the brick wall model; whereby the corneocytes are the bricks, the corneodesmosomes are the iron rods & the lipid lamellae is the cement

Question 19

Why is vitamin D important

Answer 19

Vitamin D is essential in producing the anti-microbial peptides necessary to defend the skin from bacteria & viruses

Question 20

What do irritants do to the skin

Answer 20

Irritants break down healthy skin

Question 21

What do allergens do to skin

Answer 21

Allergens trigger skin flare ups by penetrating into the skin and causing the skin to react

Question 22

What are skin flare ups

Answer 22

All caused by allergens which are able to penetrate into the skin, where they are met with lymphocytes which release chemicals that induce INFLAMMATION:

Question 23

3 products of skin flare up inflammation

Answer 23

• Red skin: Dilation of blood vessels - due to lymphocyte activity
• Itchy skin: Stimulation of nerves
• Dry skin: Skin cells leaking - due to lymphocyte activity

Question 24

What is the effect of increased pH on skin

Answer 24

damage to the skin barrier since the corneodesmosomes become damaged by the increased pH resulting in the breakdown of the skin barrier and thus increasing the risk of infection

Question 25

Why can pH of skin be increased

Answer 25

If profilaggrin and thus filaggrin are not present for any reason, there will be a lack of NMF meaning there will be less water retention in the corneocytes

Question 26

How does acne occur (1)

Answer 26

In acne, hypercornificationof the stratum corneum occurs resulting in adherent cells (corneodesmosomes) blocking the entrance to hair follicles

Question 27

What happens when the entrance of the hair follicles are blocked (2)

Answer 27

This results in the increased production of sebum by the sebaceous glands - causing the skin to feel greasy

Question 28

What happens are the increased production of sebaceous glands as a result of the blocked hair follicles (3)

Answer 28

The increased sebum production eventually some of the sebum to become trapped in the narrowed hair follicle

This means that the sebum STAGNATES at the pit of the follicle where there is NO OXYGEN

Question 29

What happens when the sebum stagnates at the pit of the follicle where there is no oxygen (4)

Answer 29

This provides anaerobic conditionswhich allow the propionic bacteriaacnes (p.acnes) to multiply in the stagnant sebum

Question 30

What happens when the p acnes multiply in the stagnant sebum (5)

Answer 30

The p.acnes breakdown the triglycerides in sebum into free fatty acids resulting in irritation, inflammation and the attraction of neutrophils since the p.acnes release chemicals that attract them

Question 31

What happens when the neutrophils go towards the pacnes (6)

Answer 31

This then results in pus formation and further inflammation since the no full hair follicle is rapidly filled with attracted neutrophils

Question 32

How can cosmetics and oily hair gel trigger acne

Answer 32

Cosmetics & oily hair gel can triggeracne since they help “plug” the hair follicle and initiate the acne process - acne caused by these products is known as cosmetically induced acne