Week 1 Skin Structure and Function

Question 1

What are the functions of skin

Answer 1

Protection (against pressure, temperature, micro-organisms, radiation, chemicals, mechanical impact), Regulation (fluid, temperature, blood flow, vitamin content), Sensory (via network of nerve cells) .

Question 2

What are the different types of skin cells of the epidermis? What are their functions?

Answer 2

Stem cells: undergo mitosis to aid skin regeneration.
Keratinocytes: keratin (structural protein, IF) for protection and vitamin D production
Melanocytes: melanin
Langerhan Dendritic cells: originate in bone marrow, aids phagocytosis
Merkel cells: Sensory

Question 3

What is the role of profilaggrin?

Answer 3

Converts to filaggrin and aids keratin formation into tight bundles.

Question 4

What aids the formation of the cell envelope around cells in the stratum corneum?

Answer 4

Involucrin.

Question 5

Which two proteins form cross links in the stratum corneum?

Answer 5

Loricrin and Involucrin

Question 6

What are the three components of lamellar granules?

Answer 6

Polysaccharides, glycoproteins, lipids (cement that hold stratum corneum together)

Question 7

Identify the layers of the dermis.

Answer 7

Papillary and reticular. They increase tensile strength allowing skin to stretch.

Question 8

What are the components of the dermis?

Answer 8

Elastin, ground substance, collagen type 1, lymphocytes, fibroblasts (cell that makes collagen and ECM), mast cells (produces histamines, WBC), dermal dendritic cells (for antigen presentation)

Question 9

What is the name of mechanoreceptor responsible for light touch?

Answer 9

Meissner’s corpuscles

Question 10

What is the role of pacinian corpuscles?

Answer 10

Allows you to feel stronger pressures (usually located in the subcutis)

Question 11

Identify the external factors that may influence skin.

Answer 11

Local: Infection, foreign body, oxygenation, vascular supply
Systemic: Age, disease, alcohol, smoking, immunocompromised conditions, medication, obesity

Question 12

What cells protect DNA from UV light (mutagen)?

Answer 12

Melanosomes (produced from melanocytes)

Question 13

Describe the normal stages of wound healing.

Answer 13

1. Inflammatory: platelets undergo clotting, attracts neutrophils to remove bacteria, macrophages phagocytose dead tissue
2. Proliferatory: cell-to-cell adhesions loosen, migrate to wound site (via leapfrog method), cover granulation and meet in the middle. Once it meets, it starts to proliferate –> granulation tissue. Angiogenesis occurs.
3. Remodelling: granulation tissue –> mature scar tissue. Collagen goes from type 3 to type 1 (thick bundles, cross-linked)

Question 14

Describe the signals involved in wound healing.

Answer 14

EGF: signal to re-epithelialise
Platelet-derived Growth factor: matrix formation, remodelling
Vascular Endothelial Growth Factor: angiogenesis
IL1,6, Tumour Necrosis Factor a: inflammation

Question 15

Define a wound.

Answer 15

Loss of continuous epithelium.