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PR2202 > Chapter 3 - Skin Anatomy and Physiology > Flashcards

Chapter 3 - Skin Anatomy and Physiology Flashcards

1
Q

What are the three layers of the skin?

A

Epidermis, dermis and hypodermis

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2
Q

What are sebaceous glands?

A

Microscopic exocrine glands in the skin that secrete an oily or waxy matter, sebum, to lubricate and waterproof the skin and hairs of mammals

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3
Q

How does the hair follicles grow?

A

The matrix contains rapidly dividing keratinocytes giving rise to keratinized hair shaft.

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4
Q

How does the hair get its colour?

A

Melanocytes transfer packets of melanin to the hair follicale matrix keratinocytes conferring the color to the hair shaft

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5
Q

Is hair loss reversible?

A

Yes, unless it is due to hormonal drop.

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6
Q

What contributes to beautiful lush hair?

A

More male hormones

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7
Q

What are the four layers of the epidermis?

A

Stratum corneum, stratum granulosum, stratum spinosum, stratum basale

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8
Q

What is the function of keratinocytes?

A

Give strength and resistant to environmental stress

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9
Q

What is the function of melanocytes?

A

Give tone and photoprotection

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10
Q

Describe the stratum corneum.

A

The stratum corneum consists of dead cells, with lipids and keratin molecules and are not water soluble.

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11
Q

Where are the melanocytes present?

A

They are present in the stratum basale, sitting just above the dermal layer

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12
Q

What is the function of the merkel cell?

A

They are very sensitive and able to transfer information to the brain. After a while it gets shut down, acclimatized.

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13
Q

How long does it take for the skin to regenerate?

A

It takes 30 days for the cells to start at basal layer and compress upwards (desquamation) to the stratum corneum.

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14
Q

What is the difference between corneocytes and keratinocytes?

A

Corneocytes are terminally differentiated keratinocytes and composed almost entirely of the stratum corneum. (18-20 layers), does not contain nuclei

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15
Q

What are the 3 layers of the stratum corneum?

A

Profilaggrin -> lower SC (filaggrin) -> middle SC (NMFs) -> Upper SC (modification of NMFs)

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16
Q

Describe the ‘Brick and mortar system’

A

The corneocytes are partially overlapping, making it difficult for molecules to penetrate and the 13 species of lipid provide the permeability and prevent evaporation of water

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17
Q

What is filaggrin?

A

It aligns the keratin and it converts to NMF which are water soluble (glycerol) which keeps the skin hydrated

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18
Q

What are the roles of the stratum corneum?

A

(1) Permeability
(2) Antimicrobial
(3) Antioxidant
(4) Mechanical
(5) UV

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19
Q

Describe the epidermal permeability barrier of the stratum corneum.

A

It prevents loss and ingress of substances to avoid (1) dehydration and (2) maintain body temperature.

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20
Q

What sizes of substances are able to penetrate the stratum corneum?

A

Substances of 500 Da or less

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21
Q

What is the function of the antimicrobial barrier of the stratum corneum?

A

It is acidic of pH of less than 5.5 which increases antimicrobial defenses. Acne is surpressed. Antimicrobial peptides (AMPs) combat broad ranges of microbes (grow in acidic conditions)

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22
Q

What are the water content of stratum corneum and body

A

Stratum corneum - 20-30%

Body - 70%

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23
Q

What is the human skin surface pH?

A

5.4-5.9

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24
Q

Why does a baby when born have a neutral pH?

A

For growth and function of all processes

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25
Q

Where on the human skin are the pH slightly higher?

A

In areas that have higher moisture - ingunal (groin) and back of wrist

26
Q

In which region is the pH more acidic for females than males?

A

Underarm regions

27
Q

What is the difference between deodorant and antiperspirant?

A

Deodorant - blocks bad odour (lower pH or cover the smell)

Antiperspirant - blocks sweating (block loss of water)

28
Q

Why does sweating make you smell?

A

Bacterial released causes the bad smell

29
Q

What is the function of skin microorganisms?

A

They are bacteria, fungi that protect the human from more harmful organisms. They educate the immune T cells in the skin, priming them to respond to similar pathogens

30
Q

What are the factors that cause variation in the microbiota of the skin?

A

(1) Host physiology
(2) Environment
(3) Immune system
(4) Lifestyle (Hot and humid -> more microorganisms)
(5) Host genotype (deficiency of filaggrin)
(6) Pathbiology

31
Q

In what way is UV good?

A

It helps to remove the bacteria which will irritate the skin microbiota

32
Q

Why does diabetes attract microorganism?

A

It makes the skin more basic attracting more pathogens

33
Q

How are the bacterial colonies classified in a human?

A

Sebaceous - face
Moist area - body
Dry sites - feet

34
Q

How does the skin provide antimicrobial defense?

A

Top layer - Dry and densely packed. Salty secretion create an environment that is hyperosmotic and unfavourable to bacteria
Acific bacteria prevent growth of pathogens and allows growth of good bacteria which makes it acidic

35
Q

What happens when sebaceous gland gets clogged?

A

Sebum builds up inside the follicle and Propionibacterium acnes multiplies leading to inflammation (redness, swelling) because microorganism break sebum, causing irritation

36
Q

What is ascorbic acid?

A

Vitamin C

37
Q

What is alpha and gamma-topopherol?

A

Vitamin E

38
Q

What antioxidants regulates the normal skin conditions?

A

Glutathione, vitamin C and E

39
Q

What is the lipid composition of the stratum corneum like?

A

Ceramides (45-50%)
Cholesterol (25%)
Free fatty acids (10-15%)
Other lipids (<5% each)

40
Q

What is the myth of Urocanic acid?

A

It was thought to be a natural sunscreen but later found out to be a mediator of photoimmunosupression with a role in photcarinoogenesis.

41
Q

What is the only natural protection from UV?

A

Melanocytes which produces melanin

42
Q

What are the 3 types of skin disorders?

A

(1) Skin disorder with correlation to microbiota
(2) Skin disorder with currently unidentified microbial component
(3) Skin commensal that can become invasive to cause infection

43
Q

What is Seborrhoerric Dermatitis?

A

Skin disease with correlation to microbiota - chronic, relapsing, mild dermatitis (scaly, flaky, itchy and red skin)

44
Q

How to treat Seborrhoerric Dermatitis?

A

Antifungal drugs and not antibacterial ones. (Treat the yeast Malassezia)

45
Q

How does diabetes (chronic wounds cause skin disorders)

A

The skin microorganism invade and become pathogenic upon the breach of the skin barrier

46
Q

What is staphylococcus epdiermidis?

A

It is the ‘accidental pathogen’, commensal microoganism. When it accumulates, it creates a biofilm which is pathogenic and it is able to transform the antibiotic resistance to others.

47
Q

What are the 3 main strategies of the delivery of cosmetics to the skin?

A

(1) Transcellular
(2) Follicular (Transappendageal route)
(3) Intercellular

48
Q

Which is the most effective way to delivery cosmetics?

A

Intercellular route

49
Q

Describe the transcellular route and the challenges.

A

It passes through the cells (better for water soluble molecules). However, the surface is lipid soluble, making it difficult. (Not many products are water soluble)

50
Q

Describe the transappendageal route and the challenges.

A

Minimal contribution of 0.1% of the whole skin, cannot be exploited. Only good for steroids and hair growth products

51
Q

Describe the intercellular lipid lamella route and the challenges.

A

Corneocytes are partially packed (difficult to pass through). Thus need to be 500 Da or less. They need to be lipid soluble but also a bit water loving.

52
Q

What is special about lipids?

A

They have a water soluble and non water soluble structure.

53
Q

What are chemical enhancers?

A

Ingredients that can help in the penetration of the skin layers.

54
Q

What are the 6 requirements of chemical enhancers?

A

(1) Work rapidly
(2) Non-irritating
(3) No pharmacological activity
(4) Uni-directional (enter skin only)
(5) Restore back to original state of skin (Transitory mechanism)
(6) Appropriate skin feel

55
Q

What are the classes of chemical enhancers?

A

(1) Sulpoxides - (DMSO)
(2) Azone
(3) Pyrrolidones
(4) Fatty acids
(5) Essential oils and terpenes

56
Q

What is the function of keratohyalin granules?

A

They are filled with histidine- and cysteine-rich proteins which help to bind intermediate keratin filaments together.

57
Q

At pH 5.5, what are the 3 micro bacteria that are suppressed?

A

Pseduomonas acne, Staphyrococcus epidermidis and Staphylococcus aureus

58
Q

What are the 3 amino acids that make glutathione (reducing agent)?

A

Glutamate, cysteine and glycine

59
Q

What are the reversible causes of hair loss?

A

Trauma, childbirth, weight loss, severe stress and drugs and malnutrition

60
Q

Name 2 antimicrobial molecules present in sweat.

A

Cathelicidin and dermcidin

61
Q

Which areas are devoid of hair and sebaceous glands?

A

Plantar and palmar

PR2202 (19 decks)

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