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Pharmacy; The Healthy Body 2 > The Skin > Flashcards

The Skin Flashcards

1
Q

WHAT DOES THE INTEGUMENTARY SYSTEM CONSIST OF?

A

The skin and its accessory structures (hair, nails. glands and sensory receptors)

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2
Q

THE INTEGUMENTARY SYSTEM

•Comprises the skin and its accessory structures

–hair, nails, glands and sensory receptors

•Covers the _ surface of the body

–Adult human skin has:

  • a surface area of between 1.8 and 2.0 m2
  • a _ of between 0.5 and 4.5 mm
  • a mass of between 4.5 and 5 kg
  • an extensive vasculature
  • an abundance of secretory glands (sweat, sebaceous)
  • an abundance of _ receptors (touch, pain, thermal)
A

External

Thickness

Sensory

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3
Q

INTEGUMENTARY SYSTEM; STRUCTURE

A
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4
Q

TWO MAJOR SKIN TYPES

A
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5
Q

THE EPIDERMIS- A KERATINISED, STRATIFIED SQUAMOUS EPITHELIUM

Composed of layers or strata of _ that differ in form and function

  • Stratum basale - single layer of columnar keratinocytes resting on a basement membrane: site of production of new keratinocytes.
  • Stratum spinosum – multiple rows of closely packed, many sided keratinocytes tightly linked by desmosomes
  • Stratum granulosum – multiple rows of flattened keratinocytes containing darkly staining keratohyalin granules and lipid-rich lamellar bodies – on release these form an hydrophobic, impermeable barrier
  • Stratum lucidium – multiple rows of clear, flat, dead, keratin-rich keratinocytes; present only in _ skin.
  • Stratum corneum - multiple rows of dead, flat, enucleate keratinocytes that comprise mostly cross-linked keratin fibres (squame cells)
A

Keratinocytes

Thick

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6
Q

WHAT IS THE STRATUM SPINOSUM?

A

Multiple rows of closely packed, many sided keratinocytes tightly linked by desmosomes

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7
Q

WHAT IS THE STRATUM GRANULOSUM?

A

Multiple rows of flattened keratinocytes containing darkly staining keratohyalin granules and lipid-rich lamellar bodies – on release these form a hydrophobic, impermeable barrier

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8
Q

WHAT IS THE STRATUM CORNEUM?

A

Multiple rows of dead, flat, enucleate keratinocytes that comprise mostly cross-linked keratin fibres (squame cells); the stratum corneum allows you to get wet without absorbing lots of water

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9
Q

WHAT IS THE STRATUM BASALE?

A

Single layer of columnar keratinocytes resting on a basement membrane: site of production of new keratinocytes

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10
Q

WHAT IS THE STRATUM LUCIDIUM?

A

Multiple rows of clear, flat, dead, keratin-rich keratinocytes; present only in thick skin

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11
Q

WHAT IS THE EPIDERMIS COMPOSED OF?

A

Layers of strata of keratinocytes that differ in form and function

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12
Q

STRUCTURE OF THE EPIDERMIS

A
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13
Q

KERATINS

•Family of _ filament-forming proteins

–54 proteins in two families: type I (acidic) & type II (neutral or basic)

•Comprise 25-30 % of total protein in the epidermis

–80 - 85 % of total protein in the stratum corneum

•Form branching, rope-like bundles in the cell _.

–associate with junctional (anchoring) complexes at the cell periphery

  • Desmosomes (cell-cell) and hemidesmosomes (cell-matrix)
  • Maintain the structural integrity of the epidermis
  • Allow the epidermis to resist and dissipate mechanical forces
A

Cytoskeleton

Cytoplasm

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14
Q

WHAT ARE KERATINS AND WHAT DO THEY DO?

A

Family of cytoskeleton filament-forming proteins that maintain the structural integrity of the epidermis

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15
Q

JUNCTIONAL COMPLEXES ANCHOR KERATINOCYTES TO EACH OTHER AND TO THE BASEMENT MEMBRANE

A
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16
Q

PRESENCE AND DISTRIBUTION OF OTHER CELL TYPES IN THE EPIDERMIS

Langerhans cells- they move within the epidermis, they are also _-presenting cells. They will present antigens to T-cells.

Merkel cell- Sensory- synaptic connections to _ endings.

Melanocyte cell- makes _.

A

Antigen

Nerve

Melanin

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17
Q

WHAT DO LANGERHANS CELLS DO?

A

They move within epidermis and are antigen-presenting cells (they will present antigens to T-cells)

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18
Q

TRANSFER OF MELANOSOMES FROM MELANOCYTES TO KERATINOCYTES IN THE EPIDERMIS

A
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19
Q

MELANOSOMES TRANSFERRED TO KERATINOCYTES MIGRATE TO THE PERI-NUCLEAR REGION AND FORM A PROTECTIVE ‘CAP’

A
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20
Q

WHAT DETERMINES SOMEONE’S SKIN COLOUR?

A

Determined by the absolute and relative amounts of eumelanin and pheomelanin synthesised (the number of melanocytes in the skin is similar in all individuals).

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21
Q

STRUCTURE OF THE DERMIS

A
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22
Q

WHAT ARE THE TWO REGIONS OF THE DERMIS?

A
  • Papillary (20% of total dermis thickness)
  • Reticular (80% of total dermis thickness)
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23
Q

ACCESSORY SKIN STRUCTURES: HAIR

•Grow from hair _ located in the dermis

–follicles develop from downward projections of the _.

•Composed of columns of dead, keratinized epithelial cells

–originate from a germinal matrix or stratum _ located in the hair bulb.

A

Follicles

Epidermis

Basale

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24
Q

WHERE DOES HAIR GROW FROM?

A

Hair follicles located in the dermis (hair follicles develop from the downwards projections of the epidermis).

25
Q

WHAT IS HORRIPILATION?

A

Goosebumps

26
Q

THE GROWTH OF HAIR IS CONTINUOUS.

TRUE OR FALSE?

A

FALSE

It isn’t continuous

27
Q

WHAT ARE THE FOUR STAGES OF THE HAIR GROWTH CYCLE?

A
  1. Anagen/Growth phase
  2. Catagen/Transition phase
  3. Telogen/Resting phase
  4. Exogen/Shedding phase
28
Q

THE HAIR GROWTH CYCLE

THE GROWTH OF HAIR IS NOT CONTINUOUS

  1. Anagen or growth phase:

–85-90% of all body hair

–Duration determines _ of hair

  • scalp: 2-8 years; eyebrows: 4-7 months
  • Catagen or transition phase

–Hair follicle shrinks and detaches from _.

  • scalp: 2-3 weeks; eyebrows: 3-4 weeks
  • Telogen or resting phase

–10-15% of all body hair

  • scalp: ~ 3 months; eyebrows: ~ 9 months
  • Exogen or shedding phase

–extension of the resting phase

•normal scalp 50-100 hairs shed per day

A

Length

Papilla

29
Q

WHAT DETERMINES THE LENGTH OF YOUR HAIR?

A

The duration of the Anagen/growth phase in your hair

30
Q

ACCESSORY SKIN STRUCTURES: GLANDS

•Specialised, secretory structures formed by _ cells

–two categories: endocrine (ductless) and exocrine (with ducts)

All the glandular structures in the skin are _.

•exocrine glands can be categorised further according to:

–their structure (simple or compound)

–their mode of _ (merocrine, apocrine or holocrine)

A

Epithelial

Exocrine

Secretion

31
Q

WHAT ARE THE TWO CATEGORIES OF GLANDS?

A

Endocrine (ductless)

Exocrine (with ducts)

32
Q

ALL THE GLANDULAR STRUCTURES IN THE SKIN ARE ENDOCRINE.

TRUE OR FALSE?

A

FALSE

They are exocrine

33
Q

WHAT TWO THINGS CAN YOU USE TO CATEGORISE EXOCRINE GLANDS?

A

Their structure (simple or compound)

Their mode of secretion (merocrine, apocrine or holocrine)

34
Q

WHAT ARE THE TWO MAIN TYPES OF GLAND IN THE SKIN?

A

Sebaceous

Sudoriferous (eccrine and apocrine)

35
Q

SEBACEOUS GLANDS

•Produce lipid-rich sebum:

  • triglycerides ~ 40%
  • wax esters ~ 26%
  • squalene ~ 12%
  • free fatty acids ~ 16%
  • cholesterol ~ 4%

•Holocrine secretion

  • directly into hair _ or onto _ surface

•Active at birth

  • activity increases at _

•Absent from plantar and palmar surfaces

A

Follicles

Skin

Puberty

36
Q

SUDORIFEROUS (APOCRINE AND ECCRINE) SWEAT GLANDS

Apocrine (25% of total):

  • Limited distribution (axilla, groin, bearded regions of face)
  • Duct opens into the hair follicle
  • Secretory mechanism is merocrine
  • Similar to eccrine but more viscous due to presence of _ and proteins
  • Activity linked to emotional state (secretion may contain pheromones)
  • Active from _

Eccrine (75% of total):

  • Widely distributed esp. forehead, plantar and palmar surfaces
  • Duct opens at the _ surface
  • Secretory mechanism is merocrine
  • Hypotonic and slightly _

contains H2O, Na+, Cl-, K+, urea, lactate

  • ~ 600 ml/day at rest
  • Active from shortly after _
A

Lipids

Puberty

Epidermal

Acidic

Birth

37
Q

WHEN DO ECCRINE SWEAT GLANDS BECOME ACTIVE?

A

Shortly after birth

38
Q

WHERE DO APOCRINE GLANDS OPEN UP INTO?

A

Into the hair follicle

39
Q

WHAT ARE THE THREE TYPES OF SKIN (CUTANEOUS) SENSORY RECEPTORS?

A

Mechanoreceptors

Thermoreceptors

Nociceptors

40
Q

MECHANORECEPTORS IN THE HUMAN HAND

A
41
Q

FUNCTION: THERMOREGULATION

A
42
Q

BARRIER FUNCTION OF THE SKIN

A
43
Q

PRODUCTION OF VITAMIN D3

A
44
Q

STRATUM CORNEUM: A PERMEABILITY BARRIER THAT MINIMISES TRANS-EPIDERMAL WATER LOSS (TEWL)

A
45
Q

FACTS ABOUT THE SKIN

  • Thickness = ~1 mm, on average
  • Epidermis is only 1/10th of the total membrane (~0.1 mm)
  • Stratum corneum represents 1/10th of the _. (~0.01 mm)
  • 60% of an adult’s weight is _.
  • Total surface area of skin in a typical adult = ~2 m2 = 20,000 cm2
  • Concentration of water inside the body = ~50 Molar!!!!
  • Concentration of water outside the body is usually very small
  • However, we only lose 200-300 mL across the skin per day due to the stratum _.
A

Epidermis

Water

Corneum

46
Q

WHAT IS A COMMENSAL RELATIONSHIP?

A

One of the partners benefits but the other suffers no harm

47
Q

WHAT IS A MUTUALISTIC RELATIONSHIP?

A

Where both partners benefit

48
Q

WHAT IS A PATHOGENIC RELATIONSHIP?

A

Causing or capable of causing disease

49
Q

THE HUMAN EPIDERMIS IS COLONISED BY A WIDE VARIETY OF MICRO-ORGANISMS (MICROBIOTA OR MICROBIOME)

A
50
Q

PATHOGENIC STRAINS CAN EMERGE FROM COMMENSAL POPULATIONS OF BACTERIA.

TRUE OR FALSE?

A

TRUE

51
Q

THE ANTIMICROBIAL BARRIER FUNCTION OF THE SKIN IS MULTIFACTORIAL AND NOT LIMITED TO THE STRATUM CORNEUM

  • Intact skin presents a physical barrier to invasion
  • Acidity of the skin surface and stratum corneum (pH 4.5 - 5.5)

–secretion of sebum and _ sweat

–enzymatic breakdown of _ to produce free fatty acids

–extrusion of H+ in exchange for Na+ by cells in the stratum granulosum

–release of acidic _ by-products by microorganisms

•Production of a wide range antimicrobial peptides (AMPS)

–potent, broad spectrum

–rapidly produced in response to invading _ (0 - 4 hrs)

Form a major part of the innate immune response!!!

A

Eccrine

Phospholipids

Metabolic

Pathogens

52
Q

WHAT IS THE pH OF THE SKIN SURFACE AND STRATUM CORNEUM?

A

4.5-5.5

53
Q

WHY IS THE SKIN SURFACE AND STRATUM CORNEUM ACIDIC?

A

–Secretion of sebum and eccrine sweat

–Enzymatic breakdown of phospholipids to produce free fatty acids

–Extrusion of H+ in exchange for Na+ by cells in the stratum granulosum

–Release of acidic metabolic by-products by microorganisms

54
Q

ANTIMICROBIAL BARRIER FUNCTION OF THE SKIN: PRODUCTION OF AMPs IN RESPONSE TO INVADING PATHOGENS

A
55
Q

EPIDERMAL KERATINOCYTES AND LANGERHAN’S CELLS CO-OPERATE IN THE MOBILISATION AND TARGETING OF CELLS OF THE ADAPTIVE IMMUNE SYSTEM

•Release of intercellular chemical messengers

–cytokines

•e.g., Interkeukins: IL-1, IL-6, Tumour Necrosis Factor (TNF)-a

–chemokines (CC- and CXC-chemokine ligands)

  • e.g., CCL20, CXCLs 8 (also known as IL-8), 9 and 10
  • Dynamic adjustment of tight junctions

–allows Langerhan’s cells to sample antigens in the stratum corneum

A
56
Q

BARRIER FUNCTION OF THE SKIN: RAPID ACTIVATION OF INNATE IMMUNITYLEADS TO DELAYED ACTIVATION OF ADAPTIVE IMMUNITY

Innate section shows within hours

Adaptive shows within days

A
57
Q

IN HEALTH, EPIDERMAL HOMEOSTASIS MAINTAINS THE BARRIER FUNCTION OF THE SKIN

Loss of cells from the stratum corneum is precisely matched by the proliferation, upward migration and differentiation of cells from the stratum _.

In the human epidermis stem cells are located in specialised ‘niches’ within the inter-follicular epidermis and bulge region of the hair _.

A

Basale

Follicle

58
Q

WHERE IN THE HUMAN EPIDERMIS ARE STEM CELLS LOCATED?

A

They are located in specialised ‘niches’ within the inter-follicular epidermis and bulge region of the hair follicle

59
Q

KINECTICS OF TURNOVER IN THE HUMAN EPIDERMIS

  • In healthy skin, homeostasis maintains a functional barrier.
  • However, in atopic dermatitis, or eczema, the balance is disrupted.
  • Desquamation accelerates and barrier is weakened.
  • More facile penetration of irritating chemicals now possible.
  • Exacerbates the disruption.
A

Pharmacy; The Healthy Body 2 (10 decks)

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