Week 8 - skin physiology

Question 1

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What are the different functions of the skin

Answer 1

1. Protective barrier – physical ( tightly packed cells preventing anything from entering ) and chemical ( antimicrobial peptides and oils preventing bacteria and pathogeneic bacteria from entering)

2* Involved in mechanical support

3. Prevents loss of moisture
   * Reduces harmful effects of uv radiation (melanin production)
4. Sensory organ – touch, temperature, pressure etc
5. Helps regulate body temperature ( capillaries under the skin )
6. Immune organ to detect infections
   * Involved in production of vitamin D
   * Excretion of waste products

Question 2

What are the three layers of the skin?

Answer 2

1. Epidermis - epithelial cells layer ( no blood supply nutrient acquired from dermis layer)
2. Dermis - vascular and connective tissue rich
3. Hyperdermis - fat area w adipose tissue

Question 3

Describe the layers of the Epidermis

Answer 3

1. Strateum corneum
2. Stratum lucidem
3. Stratum granulosum
4. Stratum spinosum
5. Stratum basale

Question 4

Describe the cell types present in the Epidermis layer?

Answer 4

1. Keratinocytes
   - Main cell type - derived from basal area in epidermis
   – Numerous layers
   – Stem cells
2. Merkel cells
   - sensory cells
   – Pressure, attached to nerves
   – Different locations in skin
3. Melanocytes

– Melanin secretion , protect from uv
– Basal region

4. Langerhan cells

– Immune - Dendritic cells
– All layers of epidermis

5. T Cells

– CD8 positive

Question 5

Describe how keratinocytes develop through the epidermis layer

Answer 5

• Stem cells specialise into keratinocytes at the basal layer

Question 6

What is the function of the dermis layer of the skin?

Answer 6

• Support layer for the skin madde up of fibrous and elastin tissue
• contains immune cells

Question 7

What is the hypodermis layer ?

Answer 7

• Acts as a mechanical protecror for inner organs against damage
• Therrmal insulator
• Energy store

Question 11

Skin immune system

Answer 11

• dendritic cermal cells - antigen presenting cell
• CD8 postibeb cells
• macrophages engulf any dangers and debris
• NKC innate immune cells
• \mast cells
• Fkibreblasts - collagen helps remodel skin if theres damage

Question 12

Discuss the different cells in the skin that defend against harmful environmental agents or injury ( 50%)

Answer 12

Mention both Epidermis and Dermis unless told otherwise

• • melanocytes
• LAngerhan cells- sample areas for potential antigens
• Keraticnocytes packed tightly tohether provide physocial barriar agaisnt pathogens
• ## stem cells - continual renewal of these cells also proivde continual protection

Question 13

Skin micorbiome

Answer 13

microbiome including surface level microorganisma including bacteris fungi viruses and mitees

beneficial as they protect against diseas e

[prevent pathogenic speces colonolising

interact with host immune system

Question 14

Describe how the skin microbiome interscts with and is beneficial to the host the factors that can influrnce this interaction (30%)

Answer 14

1. Protects it from diseasee bio- directional interaction we provide nutrients and ( how it interacts w us)

2- influences and teaches immune system both adaptibve and innate to recognise self and non-self oragnicsms ( key benefit)

3 - factors: Key factors

• Lifestyle factors such as smoking a

Question 15

Skin problems

Question 16

Inflammation in the skin

Answer 16

signal mediated response caused by

Infectious agents - Bacteria Fungi Viruses Parasites

Toxins - Chemical Radiation UV biological

Physical Stresses

Question 17

Discuss processes and proteins involved in the different phases of acute
wound healing. (70%)