Skin

Question 1

Describe the basic function of the skin and the differences between the layers

Answer 1

1. Epidermis - avascular epidermis, It undergoes proliferation and synthesises keritin
2. Dermis - Vascular and tough, contains blood and lymphatic vessels and cutaneous nerves. It also contains collagen and elastin which are not replaced with age
3. Hypodermis - varies with thickness, has blood/lymphatic vessels and nerves. Made of adipose tissue, has skin ligaments.

Question 2

What are the layers of the epidermis?

Answer 2

S.Basale
S.Spinosum
S.Granulosum
S.Lucidum
S.Corneum
Stratified, squamous, keratinised, epithelium.

Question 3

Describe the function of the S.Basale?

Answer 3

It is the site of cell division and interface with the dermis

Question 4

Name and describe a genetic condition that is associated with skin

Answer 4

Dystophic epidermolysis bullosa - mutation in the collagen 7 gene which causes blistering

Question 5

Describe the function of S.Spinosum

Answer 5

The site of intermidate filaments (K1/K10) expression. The cells are joined by desmosomes

Question 6

Describe the function of S.Granulosum

Answer 6

Contains keratohyaline granules and organisted keratin filaments

Question 7

function of S.lucidum?

Answer 7

Involved in specialised cell death

Question 8

Function of S.corneum

Answer 8

Contains waterproof ghost cells.

Question 9

What aids cornification?

Answer 9

Filaggrin in keratohyaline granules

Cornification -process of epithelial cells turning into protective structures

Question 10

What is filaggrin?

Answer 10

filament-associated protein that binds to keratin fibers in epithelial cells

Question 11

Describe some of the features of Filaggrin

Answer 11

Maintains optimal skin barrier along with its precursor profilaggrin, it is the main compounent of keratohyline granules in the S.Granulosum, it aids keratin filament aggregation and inhibits water loss

Question 12

Mutations in filaggrin cause what?

Answer 12

Keratinization disorders (icthyosis vulgaris -eczema)

Question 13

Describe the function of melanocytes and where they are found

Answer 13

Found - basal layer

Function - release melanin

Question 14

What is the function of melanin?

Answer 14

Absorb UV-B and prevents damage to cells in hypodermis. More melanin - less skin cancer

Question 15

Tumour of melanocytes?

Answer 15

Melanoma

Question 16

What are melanosomes?

Answer 16

Organelle responsible for the synthesis and storage of melanin. These are transfered to keratinocytes

Question 17

What are Langerhans cells and describe their function?

Answer 17

Antigen processing and presenting cells.
Derived from monocytes, found mostly in the S.Spinosum.
The cells are activated in skin but migrate to lymph nodes.
They express langerin which help degrade viral particals in endosomes called birbeck granules.

Question 18

Describe the three layers of the dermis

Answer 18

Dermo-epidermal junction - complex to avoid shearing (breaking). Papillae flatten with age making skin more vulnerable
Papillary Dermis - Made of fine collagen, elastic fibres and small blood vessels and nerves
Reticular dermis - coarser collagen and elastic fibres. Larger blood vessels and nerves

Question 19

Describe the structure of the Hypodermis

Answer 19

Loose connective tissue and adipose tissue that varies in thickness. Supports hair follicles and sweat glands.
Superficial blood and lymphatic vessels
Cutaneous nerves
Skin ligaments determine mobility of skin implicated in scarring and incision
Responsible for vitamin D production

Question 20

Describe the eccrine sweat glands

Answer 20

Secrete a water fluid
Lie in dermis and superficial fascia
Duct opens into surface of skin
Controlled in thermorgulation and is controlled by the SNS

Question 21

Describe the Apocrine sweat glands

Answer 21

Found in the axilla and groin.

Open into hair follicles and releases a milky sectretion that contains pheromones.

Question 22

List the components and functions of a pilosebaceous unit

Answer 22

pilosebaceous:
- Sebaceous Gland (Secretes sebum to lubricate hair and skin)
-Hair Shaft (Composed of keratin and grows from the bulb)
Arrector Pili (Contracts smooth muscle attached to papillary dermis)

Question 23

What sensations does skin respond too?

Answer 23

Pain
Temp
Touch
Pressure
Vibration

Question 24

What is the periodontal membrane?

Answer 24

Fibrous joint between teeth and skull