Tissues 10 - Skin

Question 1

Give 8 functions of skin.

Answer 1

1. Protection against injury/pathogenic organisms
2. Waterproofing
3. Thermoregulation
4. Protection against radiation, absorbing UV radiation and Vitamin D production
5. Surface for grip
6. Sensory organ
7. Cosmetics

Question 2

Where do melanocytes sit?

Answer 2

Just above the basement membrane separating the epidermis and the dermis.

Question 3

What cells make up the bulk of the epidermis?

Answer 3

Keratinocytes

Question 4

What are the 4 layers of the epidermis?

Answer 4

Stratum prefix for all of them.

1. Corneum
2. Granulosum
3. Spinosa
4. Parabasale

Question 5

Name some other cell types found in the epidermis.

Answer 5

1. Langerhans cells - Antigen presenting cells
2. Melanocytes - involved in melanin production
3. Merkel cell - involved in sensation

Question 6

Explain how melanocytes work.

Answer 6

1. Produce melanin in organelles called melanosomes.
2. Granules move down the dendritic processes.
3. They are transferred to adjacent keratinocytes by phagocytosis.
4. Melanin granules form protective cap around keratinocyte nuclei, protecting DNA from UV induced damage.
5. More UV radiation stimulates melanocytes to produce more melanin.
6. Variation in skin colour arises from number and size of melanosomes produced.

Question 7

What is keratin?

Answer 7

An intermediate filament protein produced by keratinocytes. Makes up bulk of epidermis.

Question 8

What are 2 dendritic cells in the epidermis?

Answer 8

Langerhans cells and melanocytes

Question 9

How is the epidermis attached to the dermis?

Answer 9

Via hemi-desmosomes, anchoring plaques and a multitude of proteins.

Question 10

What is the dermis? What does it consist of?

Answer 10

Dermis is supportive connective tissue

Consists of collagen, elastin and glycosaminoglycans (GAGs)

Dermis thickness varies

Dermis contains fibroblasts

Question 11

What do fibroblasts do?

Answer 11

Synthesize collagen, elastin and GAGs

Question 12

What is the difference between eccrine sweat glands and apocrine sweat glands?

Answer 12

Apocrine in armpit and groins. Secretes sweat near hair follicles that can be metabolised by bacteria.

Eccrine is located everywhere and releases sweat (not smelly as no bacterial metabolism).

Question 13

What does the subcutaneous layer consist of?

Answer 13

Connective tissue and fat.