Skin

Question 1

Skin Functions

Answer 1

• protection against injury and pathogenic organisms
• waterproofing and fluid conservation
• Thermoregulation
• Surface for grip
• sensory organ

Question 2

Basic Skin Layers

Answer 2

• Epidermis
• Dermis
• Subcutis
• Apendigeal structures include: pilo-sebaceous unit (follicle, hair shaft, sebaceous gland, pilo erecti muscle), sweat glands (apocrine,eccrine)

Question 3

Epidermis Levels Ascending

Answer 3

• Stratum Basale
• Stratum Spinosum
• Stratum granulosum
• stratum corneum

Question 4

Stratum Basale Features

Answer 4

• single layer of cells closest to the dermis

- cells divide and move up to the next layer

Question 5

Stratum Spinosum Features

Answer 5

• lots of desmosomes. These anchor the cells together.

- defect causes pemphigus (autoimmune disease with blisters)

Question 6

Stratum Granulosum Features

Answer 6

• cells lose nuclei and organelles

- Granules in cells contain lipid rich secretion (act as a water sealant)

Question 7

Stratum Corneum Features

Answer 7

• corneocytes (flat cells with no nuclei and contain densely packed Keratin). They are dead
• Functional barrier
• defects lead to eczema with the Filagrin gene mutation common in patients

Question 8

Other Epidermis Cell Types

Answer 8

• Melanocytes
• Langerhans Cells (APCs)
• Merkel Cells (sensation)

Question 9

Describe the Basement Membrane Zone

Answer 9

A specialised region where the epidermis is attached to the dermis by hemi-desmosomes, anchoring plaques and a multitude of proteins. Mutations lead to conditions such as epidermolysis bullosa

Question 10

Dermis Constituents

Answer 10

• Collagen (70%)
• Elastin
• Glycosaminoglycans
• Fibroblasts
• Immune Cells

Question 11

Subcutaneous Layer Structure

Answer 11

Connective tissue and fat

Question 12

Describe Melanocyte Structure and Function

Answer 12

• dendritic cells located within the basal layer of the epidermis
• Produce melanin pigment in organelles known as melanosomes.
• These arepacked into granules which move down the dendritic processes and transferred by phagocytosis to adjacent keratinocytes
• The melanin granules then form a protective cap around the keratinocyte nuclei to protect the DNA from UV induced damage.