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Dermatology > Physiology of Skin > Flashcards

Physiology of Skin Flashcards

1
Q

In foetal skin development what are the first three layers formed?

A

Periderm
Basal layer
Dermis

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2
Q

What are the final five layers of skin?

A 
Keratin Layer 
Granular Layer 
Prickle Cell Layer 
Basal Cell Layer 
Dermis
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3
Q

What are blaschko’s lines?

A

Developmental growth patterns of skin not following vessels, nerves or lymphatics

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4
Q

What type of cell makes up the epidermis?

A

Stratified squamous epithelium

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5
Q

Describe the basal layer

A

Usually one cell thick contains lots of stem cells & free nerve endings

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6
Q

Describe the prickle cell layer

A

Cells move upwards to fit into each other - contains lots of desmosomes to connect intermediate filaments. Keratin is produced.

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7
Q

What substance does the granular layer contain that contributes to skin hydration?

A

Filaggrin - repeat amino acid gets broken down by enzymes. The free amino acid binds to water resulting in a natural moisturiser

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8
Q

What happens to the cell structure in the granular layer?

A

Cell nuclei are lost and lamellar bodies present

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9
Q

Name the lamellar bodies

A

Odland bodies (secretory organelle)

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10
Q

What is the other name for the keratin layer?

A

Stratum corneum

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11
Q

Describe the keratin layer

A

Insoluble cornfield envelope, 80% keratin and filaggrin. Granules release lipids to produce a waterproof barrier

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12
Q

What are corneocytes?

A

Overlapping non-nucleated cell remnants

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13
Q

Define a scar

A

Loss of skin appendages

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14
Q

Where can mucosal membranes be found?

A

Eyes, genitourinary tract, GI tract & mouth

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15
Q

Name three specialised epidermal cells

A
  • melanocytes
  • langerhans cells
  • merkel cells
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16
Q

Where are melanocytes found?

A

Basal layers & above

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17
Q

What is the function of melanocytes?

A

Contains melanosomes where tyrosine is converted to melanin in response to UV. Once full of melanin granules the melanosomes are transferred to adjacent keratinocytes by dendrites and the melanin cap protects the nuclei in basal cells from further UV exposure.

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18
Q

Where are langerhans cells found?

A

Originate in the bone marrow - found in the prickle cel layer, dermis & within lymph nodes

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19
Q

What is the function of langerhans cells?

A

Part of the immune system - present antigens & circulate to lymph nodes

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20
Q

Describe Merkel cells

A

In basal layer between keratinocytes & nerve fibres act as mechanoreceptors

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21
Q

What is the name of the unit which contains a hair?

A

Pilosebaceous unit

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22
Q

What does the pilosebaceous unit consist of?

A

Epidermal component plus dermal papilla - adjacent sebaceous gland with arrestor pili muscle

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23
Q

What are the three phases of hair growth?

A

anagen - growing
catagen - shrinking
telogen - resting

24
Q

Describe the impact of hormonal secretion on the pilosebaceous unit

A

Cells at the centre of the gland fall apart to produce sebum - holocrine secretion

25
Q

Give an example of a hormone that acts on the pilosebaceous unit

A

Androgens

26
Q

What does the nail matrix consist of?

A

Rapidly dividing epidermal cells situated at the proximal end of each nail - protected by the cuticle & nail fold

27
Q

What is the nail bed made of?

A

Tough collagen

28
Q

State the name of the white bit at the bottom of a nail

A

Lunula

29
Q

What is the epithelium underlying the free edge known as?

A

Hyponychium

30
Q

State the role of the dermo-epidermal junction

A

support, anchor & adhese basal cells

31
Q

How is the dermo-epidermal junction maintained?

A

Hemi-desmosomes (whereas the prickle cell contains desmosomes)

32
Q

How is the DE junction strengthened & increased in surface area?

A

Papilla from both layers - rete pegs from the epidermis

33
Q

Name the general components of the dermis

A
  • ground substance
  • cells
  • fibres
  • muscles/blood vessels/lymphatics/nerves
34
Q

What cells can be found in the dermis?

A

fibroblasts, macrophages, mast cells, lymphocytes, langerhans

35
Q

What fibres can be found in the dermis?

A

Collagen & elastin

36
Q

Describe the ground substance

A

Semisolid matrix of glycosaminoglycans which allow some dermal structures to move

37
Q

What is the role of fibroblasts?

A

Synthesise - collagen, elastin & glycosaminoglycans

38
Q

Describe the relationship between supply and metabolic need in the dermis

A

Supply > need (vessel walls are well supported for blood flow)

39
Q

Describe the role of lymphatic vessels in the dermis

A

Provide continual drainage of plasma proteins, extravasated cells & excess interstitial fluid

40
Q

What is the somatic sensory supply to the dermis?

A

Free nerve endings - dermatones
Pacinian - pressure
Meissners - vibration

41
Q

What is the autonomic supply to the dermis?

A

Through blood vessels, nerves and glands

42
Q

Name the three types of skin gland

A

Sebaceous
Apocrine
Eccrine

43
Q

Describe the sebaceous gland

A

Hormone sensitive they grow & activate in puberty. Produce sebum by holocrine secretion which cells disintegrate & then release their lipid cytoplasm

44
Q

What is the function of the sebaceous gland?

A
  • controls moisture loss

- protects from fungal infections

45
Q

Describe the apocrine gland?

A

Part of the pilosebaceous unit in the axilla and perineum - androgen dependent it produces an odour after bacterial decomposition

46
Q

Describe the eccrine gland

A

Found everywhere on skin surface, cholinergic nerve supply (mental, thermal, gustatory). Role is to cool & moisten.

47
Q

State six functions of skin

A
  • barrier
  • metabolism & detoxification
  • thermoregulation
  • immune defence
  • communication
  • sensory function
48
Q

In what ways does the epidermis act as a barrier

A
  • physical barrier trauma/UV
  • immune system stops pathogens entering body
  • chemical barrier
49
Q

What happens if the skin loses its barrier function?

A

Fluid & protein loss, potential infection

50
Q

How does the skin help with metabolism?

A

Vitamin D metabolism - UVB converts 7- dehydrocholesterol to vitamin D
Thyroid metabolism - thyroxine (T4) is converted to triiodothyronine (T3)

51
Q

What happens if the skin can no longer help with metabolism?

A
  • Rickets

- Disordered thyroxine metabolism (hypothyroidism)

52
Q

How does the skill control temperature and what will failure result in?

A

Regulates heat to prevent extremes by thermoreceptors failure will result in heat loss

53
Q

Describe the skins role in immune defence

A

Prevents infection by acting as a barrier, produces a response to sunlight & allergic reactions - both specific and non-specific

54
Q

What will happen if the skin does not adequately defend against infection?

A

Spread of infection into the body

55
Q

Name three ways the skin contributes to communication

A
  • visual
  • odour
  • sociosexual
    Massively contributes to skin stigma and social exclusion
56
Q

What will failure in sensory function of skin result in?

A

Pain/Injury

Dermatology (13 decks)

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