Lecture: Anatomy 4: The integumentary system

Question 1

What is the epidermis?

Answer 1

Superficial layer of keratinocytes.

Question 2

What is the dermis?

Answer 2

Deeper layer of connective tissue and skin appendages.

Question 3

Where does the epidermis originate from?

Answer 3

The ectoderm

Question 4

Where does the dermis originate from?

Answer 4

The mesoderm

Question 5

What are keratinocytes?

Answer 5

Keratinized squamous cells

Question 6

What are melanocytes?

Answer 6

Melanin producing cell; delivers melanin to keratinocytes via dendrites, and lie near the BM. Melanin protects against UV radiation.

Question 7

Where do melanocytes originate from?

Answer 7

Originate from the neural crest cells

Question 8

How many melanocytes for each keratinocyte?

Answer 8

1 melanocyte to roughly 36 keratinocytes.

Question 9

What are Langerhans cells?

Answer 9

Cells that house antigen presenting cells (APCs) and immune sentinels which survey the microbiome of the skin

Question 10

Where do Langerhans cells originate from?

Answer 10

Originate from the bone marrow

Question 11

What are Merkel cells?

Answer 11

Cells that mediate tactile sensation to light and touch

Question 12

Where do Merkel cells originate from?

Answer 12

Originate from neural crest cells

Question 13

What are the functions of the skin?

Answer 13

• Mechanical barrier
• Waterproofing
• Protection from injury
• Protection from infection
• Cushioning and insulation
• UV protection
• Thermoregulation

Question 14

Describe the composition of the epidermis

Answer 14

Composed of stratified squamous epithelium with keratinocytes undergoing terminal differentiation. Has a basement membrane (collagen layer) at the junction with the dermis.

Question 15

What are the 4 layers of the epidermis?

Answer 15

• Horn cell layer (stratum corneum)
• Granular cell layer (stratum granulosum)
• Prickle cell layer (stratum spinosum)
• Basal cell layer (stratum basale)

Question 16

Describe the composition of the basement membrane

Answer 16

Layer below epidermis that is resistant to shearing forces and composed of collage type IV.

Question 17

What is the purpose of the basement layer?

Answer 17

Protect against shearing forces and control mesenchymal/stromal interactions (e.g. invasion) of epithelium.

Question 18

What are the consequence of damage to the basement membrane?

Answer 18

Damage to basement membrane can mean that cancerous cells in the epithelium have the potential to migrate and metastasize.

Question 19

Describe the composition of the dermis

Answer 19

Dense connective tissue containing supportive structures

Question 20

What are the 4 layers of the dermis?

Answer 20

1. Collagen, elastin, and extracellular matrix
2. Nerves, blood vessels and lymphatics
3. Mechanoreceptors, etc.
4. Subcutaneous fat

Question 21

What is the purpose of the reticular dermis?

Answer 21

Makes the skin sensitive to touch and pressure

Question 22

What is the purpose of the papillary dermis?

Answer 22

Forms fingerprints

Question 23

What are basal cell carcinomas?

Answer 23

Tumours that originate in the hair follicle and are caused by exposure to UV. Invasive and locally destructive but very unlikely to metastasize.