Pigmentary System

Question 1

Where is melanin formed? What happens to it as cells mature?

Answer 1

• melanocytes produce melanosomes in basal layer of epidermis
• transferred to keratinocytes
• during anagen transerred to hair matrix cells
• as keratinocytes -> stratum coreum granules degraded by lysosomes.

Question 2

2 types of melanin

Answer 2

> eumelanins 
- black
- insoluble
- oval melonsomes
- much researched
> phaemelanins
- red bornw/yellow
- soluble in alkali
- round melanosomes
- little researched

Question 3

Where must diseases affect in order to cuase pigmentary changes?

Answer 3

• hair matrix

- basal layer of epidermis

Question 4

causes of hyperpigmentation?

Answer 4

• recent inflammation
• endocrine
• lentigo (macular melanosis in mature dogs, +- epidermal thickening)
• lentigo simplex (orange cats <1yr black spots on lips, gums, eyelids, nose)

Question 5

Causes of hypopigmentation?

Answer 5

• damage to epidermis/hair follicle
• interface autoimmune disease
• viteligo (autoimmune attack against melanocytes)

Question 6

2 causes of sunlight based skin damage?

Answer 6

1. excessive exposure on lightyl pigmented skin

2. photosensitivity or photoallergy (reaction of chemical promoted bu UV light)

Question 7

causes of photosensitisation>

Answer 7

• administered drugs
• absorbed from food (plants)
• abnormal metabolism due to hepativ disease/genetic abnormalities