Structure and function of Skin

Question 1

What does integument or integumentary system refer to?

Answer 1

Refers to the skin and it’s appendages including hair, nails and glands

Skin is the LARGEST and HEAVIEST organ in the body

Question 2

What are the main function of skin?

Answer 2

1) Barrier against:
- Dehydration
- Infection
- Injury
- Solar radiation
2) Thermoregulation
3) Sensation
4) Repair
5) Vitamin D production

Question 3

What are the 3 layers of skin?

Answer 3

• Epidermis
• Dermis
• Hypodermis

Question 4

Where does the thickness of the epidermis vary?

Answer 4

Thickness varies around the body e.g thin skin on the abdomen and thick skin on the heel of the foot

Question 5

What are the 4 main layers of the epidermis?

Answer 5

• Stratum basale (basal layer)
• Stratum spinosum (spiny layer)
• Stratum granulosum (granular layer)
• Stratum corneum (cornified layer)

Question 6

What does the basal layer contain?

Answer 6

Contain the stem cells of skin that constantly proliferate

This layer is attached to the dermis

Question 7

What does the stratum spinosum have many of?

Answer 7

The cells have many desmosomes visible as spines between cells

Question 8

What is the stratum granulosum?

Answer 8

1-4 layers of cells containing prominent granules of keratinohyalin (precursor of keratin)

Also contain lamellar bodies which are high in lipids

Question 9

What do the cell of the stratum granulosum do?

Answer 9

The cells are differentiating to form the outer most protective layer called the stratum corneum

Question 10

What is the stratum corneum?

Answer 10

It is the outer protective layer of the epidermis

Question 11

What is the stratum corneum made up of?

Answer 11

Are squamous cells which have lost their nucleus

Question 12

What does it mean by the stratum corneum being cornified?

Answer 12

Are ‘cornified‘ full of horny keratin (from keratinohyalin granules) that are tough and resistant to injury

Question 13

What are between the cells in the stratum corneum layer?

Answer 13

Non-polar lipids are between the cells

Question 14

What are the other epidermal cell types?

Answer 14

• Melanocytes
• Langerhans cells
• Merkel cells

Question 15

What do melanocytes synthesise?

Answer 15

Synthesise melanosomes and transfer them to basal keratinocytes through long dendrites

Question 16

How do keratinocytes arrange melanin pigments?

Answer 16

Keratinocytes arrange melanin pigments in a cap distal to the nucleus

Question 17

What are langerhans cells involved in?

Answer 17

Involved in the immune system as antigen presenting cells

Question 18

What type of cells are langerhans cells?

Answer 18

Are dendritic cells

Question 19

Where does vitamin D production occur?

Answer 19

Made in the epidermis, mostly in the basal cells and also stratum spinosum

Question 20

What does vitamin D production require?

Answer 20

Requires UV light

Question 21

Where is vitamin D converted into the active form?

Answer 21

Converted to active form in liver and kidney:

-1,25 dihydroxyvitamin D3

Question 22

What is the dermis?

Answer 22

Is dense, irregular connective tissue

Question 23

What does collagen in the dermis provide?

Answer 23

Collagen in the dermis provides tensile strength hence protection against abrasion and impact

Question 24

What does the dermis contain giving its elasticity?

Answer 24

Contains elastin

Question 25

What does the dermis carry?

Answer 25

Carries blood and nerve supply for the epidermis

Question 26

Properties of the dermal epidermal border?

Answer 26

Dermal epidermal border is often wavy to resist shear forces

• Can have finger like dermal papillae
• The epidermis can have rete ridges

Question 27

What is one effect of UV light on skin?

Answer 27

One effect of UV light on skin is damaged/loss of elastic fibres, resulting in loss of elasticity
-Wrinkles
SOLAR ELASY

Question 28

What syringe do you use for the hypodermis?

Answer 28

Where you put a hypodermic syringe for a subcutaneous injection

Question 29

What is the hypodermis composed of?

Answer 29

Composed of fat, containing glands, hair follicles, nerves and blood vessels

Question 30

What is the thickest layer of skin?

Answer 30

The hypodermis

Question 31

What is the function of the hypodermis?

Answer 31

Function is to provide insulation, cushioning and energy storage

Question 32

What does the sebaceous gland secrete?

Answer 32

Secretes oily sebum into hair follicles

Question 33

What is the eccrine sweat gland and what does it secrete?

Answer 33

• Normal sweat glands

- Watery secretions onto skin surface and cools body by evaporation

Question 34

What does the apocrine secrete?

Answer 34

Secretes oily fluids into hair follicles.
Contains pheromones, source of body odour after bacterial action
Only after puberty

Question 35

Where are apocrine glands found?

Answer 35

Found in armpits and any genital region

Question 36

What sense organs are present in the skin?

Answer 36

Thermoreceptors
-Senses heat or cold
Meissner's corpuscle
-Senses touch
Nociceptor
-Senses pain
Pacinian corpuscle
-Senses pressure

Question 37

Keratinocytes

Answer 37

Epithelial cells, main cells composing the epidermis

Question 38

Identify three sweat glands.

Answer 38

Eccrine Sweat Gland = normal sweat gland, watery secretion on to skin surface, cools body via evaporation

Sebaceous Glands = Secrete oily sebum ’lanolin‘ into hair follicle

Apocrine sweat Glands = secrete into hair follicles, oily fluid located in the armpit and anogenital region, source of body odour after bacterial action