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Medicine 1.1 > Skin Structure and Function > Flashcards

Skin Structure and Function Flashcards

1
Q

What are the 3 main layers of the skin?

A

Epidermis, dermis, hypodermis

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2
Q

Generally, what are the 2 types of skin?

A

Thin and hairy- (1-2mm thick)

Thick and hairless- (more than 5mm thick)

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3
Q

What are the 4/5 sub-layers of the epidermis?

A
  • Stratum corneum
  • Stratum Lucidum (in thick skin)
  • Stratum Granulosum
  • Sratum spinosum
  • Stratum basale
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4
Q

How are the epidermis and dermis seperated?

A

Seperated by dermo-epidermal junction, here hemidesmosomes hold the epidermis to the dermis.

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5
Q

What are the sublayers of the dermis?

A
  • Papillary dermis

- Reticullar layer

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6
Q

What is the structure of the hypodermis?

A

Usually consists of adipose tissue (fat stroage) with supporting fibrous strands.

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7
Q

What is the function of the hypodermis and how does this relate to its structure?

A 
Fat storage (adipose tissue) provides energy source as well as insulation.
Pacinian corpuscles often in the hypodermis are responsible for detecting deep pressure and vibration.
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8
Q

What is the dermis composed off and it’s overall role?

A

Formed mostly of fibroblasts, collagen type 1, elastin and ground substance. Overall it provides support to the epidermis.

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9
Q

What are some of the features of the epidermis?

A
  • Cells are in close contact and are polarised as they sit on a basement memebrane.
  • It is stratified squamous epithelium
  • Cells are not vascularised, are nourished by connective tissue
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10
Q

Which cell junctions play a role in the epidermis?

A
  • Adherens- hold epithelial cells together
  • Desmosomes- Provide integrity for the epidermis between keratinocytes
  • Tight junctions in the stratum granulosum provide a seal to prevent fluid passing across an epithelial sheet.
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11
Q

What is the stratum corneum formed of?

A

Formed of numerous flattened dead keratinised cells that will be sloughed off

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12
Q

What is special about the stratum basale?

A

Many stem cells are present here, this layer gives rise to all new epidermis layers.

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13
Q

What is the structure and function of the papillary dermis?

A

It is formed with elastin fibres and type 3 collagen, it is a loose layer where most bloood vessels of the skin will be found.

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14
Q

What is the structure and function of the reticullar dermis layer?

A

Formed of elastin fibre, type 1 and 3 collagen fibres, which all support the epidermis and bind the skin to the hypodermis. Is a deeper denser layer.

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15
Q

What types of cells are found in the epidermis?

A
  • Keratinocytes
  • Melanocytes
  • Langerhans
  • Merkel cells
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16
Q

What is the function of keratinocytes in the epidermis?

A

Largest popoulation of cells in the skin and are important for protection and providing a barrier for the skin against infection and abrasion.

17
Q

What is the function of melanocytes in the epidermis?

A

Found in the basal layer, produce melanin pigment to protect against UV light.

18
Q

What is the function of langerhans cells?

A

In the epidermis, act a santigen presenting cells and induce immune responses to new antigens.

19
Q

What is the function of merkel cells?

A

In basal layer of epidermis and act as touch receptors.

20
Q

What is the function of the dermo-epidermal junction?

A
  • Provides regulated barrier for movement between layers
  • Provides attatchment site from dermis to epidermis using hemidesmosomes
  • Serves as base for wound healing
21
Q

What are the components that make the dermis and their functions?

A
  • Collagen- helps to provide tensile strength
  • Elastin fibres- allows for stretch
  • Lymphocytes- produce immunosurveillance
  • Mast cells- produce inflammatory mediators
  • Blood vessels- found mainly in papillary dermis
  • Free nerve endings
22
Q

What free nerve ending is found in the dermis and its function?

A

Meissner’s corpuscles- rapid acting mechanoreceptors responsible for touch.

23
Q

What glands can be found in the skin and what are their roles?

A
  • Eccrine glands- found in dermis or hypodermis responsible for temp. control
  • Apocrine glands- scent glands
  • Sebaceous glands- in dermis produce sebum (a mix of lipids) that lubricates the skin and protects against friction, they are formed from hair follicles.
  • Sweat glands- for thermoregulation
24
Q

What is the general process of skin regeneration?

A

Stem cells in the stratum basale proliferate and specialise then migrate upward by the leap frog or train methods to produce a new layer of skin.

25
Q

What phases can wound healing be split into?

A
  • Inflammation
  • Proliferative phase
  • Re-modelling
26
Q

Describe the inflammation phase?

A

Platelets initiate blood clots and also a healing cascade. This attracts other cells to the wound to fight infection and transition from inflammation to repair.
Signs of this phase are redneess/swelling

27
Q

Describe the proliferative phase?

A

Re-epithelisation occurs, involves migration of cells upwards by train or leap frog method.
In deeper wound, fibroblasts are recruited under the clot to replace lost molecules such as type III colagen and elastin.

28
Q

Describe the re-modelling phase?

A

Collagen remodelling and vascular maturation occur in this phase.
Type III collagen initially deposited in the 2nd phase is converted to type 1 collagen.
Collagen fibre become more organised into paralell bundles.

29
Q

How do cells know what to do during wound healing?

A

Signal molecules ensure cells know what to do.

30
Q

What are some examples of signals in wound healing and their role?

A

EGF(epidermal growth factor)- signal keratinocytes for re-epithelisation
PDGF(platelet derived growth factor)- increased no. and activity of fibroblasts
Interleukin-inflammation
VEGF(vascular endothelial growth factor)- endothelial cell proliferation and migration

31
Q

What local factors affect wound healing?

A

Infection
Foreign body present
Oxygenation
Vascular supply

32
Q

What systemic factors affect wound healing?

A 
Age 
Diseases 
Alcohol
Smoking
Obesity
Medication
33
Q

What are the roles of protein that keratohylin granules contain?

A

Profilaggrin is converted to filaggrin which forms keratin into tight bundles.

Involucrin and Loricrin is responsible for the formation of the cell envelope around cells in the stratum corneum.

Medicine 1.1 (28 decks)

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