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Intro To Physio With Pharmacology > L11 The Skin > Flashcards

L11 The Skin Flashcards

1
Q

What are the 3 different layers of the skin?

A

Epidermis
Dermis
Hypodermis

Epidermis is the uppermost epithelia layer

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2
Q

What is in the integumentary system?

A

Skin, hair, nails and cutaneous glands (Relates to skin)

Sebaceous and sweat glands relate to the cutaneous glands

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3
Q

What is the largest organ?

A

The skin

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4
Q

What does ECM stand for?

A

Extracellular matrix

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5
Q

Which is bigger in length, the dermis or the epidermis?

A

The dermis is thicker than the epidermis

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6
Q

What are fibroblasts?

A

They are responsible for producing the extracellular matrix (ECM)

Fibroblasts are the most common type of cell in connective tissue.

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7
Q

The dermis is seperated into two zones, what are they?

A

Papillary dermis - The upper layer, which contains loose connective tissue (areolar)
Reticular dermis - The lower layer, thick dense irregular connective tissue

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8
Q

What is the areolar tissue?

A

Characterised by loose arrangment of fibers and cells (fibroblasts, macrophages, and mast cells)

Found in the papillary layer of the dermis.

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9
Q

What is the most abundant protein in the dermis?

A

Collagen

Collagen provides structural support and elasticity

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10
Q

How does the dermis play a crucial role in thermoregulation?

A

It has a dense network of blood vessels which may undergo vasodilation/vasoconstriction and lymphatic vessels

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11
Q

What are arteriovenous anastomoses (AVAs)?

A

They are a direct connection between small arteries and small veins, bypassing the capillary bed

They play a signficant role in regulating blood flow and temperature control

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12
Q

What is one reason why the dermis is essential for sensory perception?

A

The dermis has numerous nerve endings

This allows it to perceive a wide range of sensations, including touch, pressure, temperature and pain

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13
Q

What does DEJ stand for?

A

Dermal - epidermal junction

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14
Q

What is unique about the dermal-epidermal boundary?

A

It has a wavy boundary of finger- like projections (dermal papillae) with epidermal ridges ( rete ridges)

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15
Q

Why is the dermal papillae important in highly sensitive areas?

A

Dermal papillae contain a high concentration of sensory nerve fibres that reach close to the surface

Allows for rapid detection and transmission of sensory signals to the brain, enabling quick responses to stimuli

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16
Q

The epidermis is composed of five distinct layers, what are they? (Don’t necessarily need to know)

A

Stratum basale
Stratum spinosum
Stratum granulosum
Stratum lucidum
Stratum corneum

B,S,G,L,C
Big Sexy Grandma Loves Cookies

All stratified

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17
Q

Epidermis has a thick skin and a thin skin. Where are they generally located?

A

Thick skin - Found on the palms (fingertips) and feet
Thin skin - rest of body

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18
Q

Why does the epidermis rely on diffusion from the underlying connective tissue?

A

It lacks blood vessels

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19
Q

Does the epidermis regenerate?

A

The epidermis (uppermost layer of the skin) undergoes self regeneration, with a complete cycle typically taking 2-4 weeks

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20
Q

What is the stratum Basale?

A

The outermost layer of your skin

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21
Q

What are the key functions of the stratum basale?

A

Contains Keratinocytes which are mitotically active
Melanocytes gives skin colour
Tactile/ Merkel cells - connected to sensory nerves

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22
Q

What are keratinocyte?

A

Keratinocyte stem cells continuously mitotically divide to produce new skin cells

In the stratum basale layer

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23
Q

What do melanocytes do?

A

This produces melanin, the pigment responsible for skin colour. Also protects skin from UV light

In the stratum basale layer

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24
Q

What are Merkel cells?

A

They are reponsible for transmitting information about touch to the brain. They are connected to the sensory nerves

Located in the stratum basale layer

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25
Q

Where is the stratum Spinosum located?

A

Located in the second layer of the epidermis

Between stratum basale and stratum granulosum

26
Q

What is the structure of the stratum Spinosum?

A

Composed of several layers of keratinocytes
Usually the thickest layer of the epidermis

Usually thickest (except in thick skin, where the stratum corneum is thicker)

27
Q

What do keratinocytes produce?

A

It produces keratin filaments which causes cells to flatten (more so in the upper layers)

28
Q

What cell connections are present within the stratum spinosum?

A

Keratinocytes strongly linked by desmosomes
Tight junction ensure water retention of skin
Dendritic cells (Langerhans cells) are present

29
Q

Are keratin filaments present in the Stratum Spinosum?

A

Yes. It contains several layers of keratinocytes which produces keratin filaments

30
Q

Describe the structure of the stratum granulosum

A

Composed of 3-5 layers of flat keratinocytes
Cells are flattened and have a dark appearance due to the present of dark-staining granules

Keratin filaments flatten cells

31
Q

Describe the behaviour of the stratum granulosum

A
  1. Cells are post- mitotic, meaning they are no longer dividing
  2. Tight junctions between cells which contributes to the skin’s barrier function
  3. Cells undergo apoptosis
32
Q

What does the stratum granulosum produce?

A

Produces keratin precursors
Lamellar bodies/ granules which are glycolipid-filled vesicles

33
Q

What is the significance of lamellar bodies in the stratum Granulosum?

A

Lamellar bodies/ granules creates a waterproof barrer between that layer and the Stratum Spinosum

34
Q

Descibe the structure of the Stratum Corneum

A

Composed of 15-30 layers of flattened corneocytes/ squames
Divided into two sublayers: Stratum disjunctum and Stratum comapctum

Stratum disjunction - beneath apical acid mantle and lipid barrier
Stratum compactum - cohesive

35
Q

What are corneocytes (squames)?

A

They are enucleated terminally differentiated, dead keratinocytes

36
Q

What is a cornified envelope?

A

It’s a tough, insoluble structure that surrounds each corneocyte

Cornified envelope - mortar
Corneocyte - bricks

37
Q

What are the main components of the cornified envelope?

A

Keratins
Cross-linked proteins
Lipid envelope

38
Q

What is the main function of the stratum corneum?

A

Prevents water loss
Resistance to abrasion
Resistant to penetration

39
Q

What are nails composed of?

A

Nails are composed of dead scaly cells densely packed with ‘hard’ keratin fibres

40
Q

How do nails regrow?

A

New cells are added by mitosis in the nail matrix

41
Q

What can the appearance of nails indicate?

A

Appearance can indicate underlying health issues, e.g:
Iron deficiency - flat/concave
Long term hypoxemia

42
Q

What are the 5 gland types within the skin?

A

Sebaceous glands
Eccrine sweat glands
Apocrine sweat glands
Ceruminous glands
Mammary glands

S,E,A,C,M

43
Q

How is the skin a multi-layered defense system?

A
  1. Physical barrier
  2. Biochemical barrier
  3. Immunological barrier
44
Q

What is the approximate number of different species that make up the human skin microbiome?

A

Over 1000 species

45
Q

How does the skin act as a physical barrier?

A

Cross- linked keratin layer - provodies impenetrable barrier
Keratinocyte scaffold

46
Q

How does the skin act as a biochemical barrier?

A
  1. Midly acidic pH (4-6)
  2. Sebacaeous gland sebocytes (sebum) contains:
    saturated+ unsaturated FA = inhibit bacterial growth
    Lysozymes
    C6H - inhibit development of antiobiotic resistance

FA = fatty acids

47
Q

What does LC stand for?

A

LC - Langerhans Cells

48
Q

Where within the cell are Langerhan cells present?

A

Stratum spinosum

Dendritic cell

49
Q

What are dermal cells?

A

They are cells that make up the dermis, the middle layer of the skin

50
Q

Does the dermis have more different types of cells compared to the epidermis?

A

Yes. Dermis layer has a larger variety

51
Q

What is vitamin D

A

It is a fat-soluble hormone that maintains calcium homeostasis

52
Q

What is UVB?

A

Ultraviolet B radiation

53
Q

What causes photochemical reactions?

A

UVB radiation does

Photochemical reaction is essential for vitamin D synthesis. Without UVB radiation, our bodies would not be able to produce this vital vitamin

54
Q

What are the key mechanisms in skin’s thermoregulation?

A
  1. Vasodilation/ vasoconstriction
  2. Sweating
  3. Insulation - pilerection
55
Q

Where are central thermoreceptors located?

A

Located in the preoptic anterior hypothalamus

56
Q

How does countercurrent heat exchange work?

A

Minimises heat loss in extremities (dermis) by transferring heat from arterial blood to venous blood

57
Q

What does overperfused mean?

A

Means that a particular tissue or organ is receiving more blood flow than it typically needs

58
Q

What is AVA?

A

Arteriovenous anastomoses

They regulate body temperature

59
Q

Why does the apical skin have a rich sympathetic innervation?

A

It’s due to the high density of arteriovenous anastomoses (AVA) in apical skin

60
Q

What is the dermis predominantly made up of?

A

Connective tissue
Richly innervated and vascular accessory organs

61
Q

What is the skin made up of?

A

A superficial epidermal layer with an underlying dermal layer

62
Q

What are the keratinocyte changes as they push upwards from the basement membrane?

A
  1. Cell shape - keratinocytes flatten as they move towards the skin’s surface
  2. Cytoplasm - more filled with keratin filaments (provides protection)
  3. Cell connections - Number od desmosomes, and cell to cell junctions
  4. Lipid production - produces lamellar granules which forms a water-resistance barrier

Intro To Physio With Pharmacology (20 decks)

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