Structure and function of skin

Question 1

From what embryological layer is the skin epidermis from?

Answer 1

Ectoderm

Question 2

From what embryological layer is the dermis formed from?

Answer 2

Mesoderm

Question 3

From what embryological layer are melanocyte cells from?

Answer 3

The neural crest

Question 4

What describes the growth pattern of skin?

Answer 4

Blashkos lines

Question 5

What kind of epithelium is the epidermis?

Answer 5

Stratified squamous

Question 6

What is the most numerous cell in the epidermis?

Answer 6

Keratinocytes

Question 7

How long on average does it take cells to migrate through the epidermis from the basement layer?

Answer 7

28 days

Question 8

What happens when the time for cells to migrate up through the epidermis greatly increases?

Answer 8

Psoriasis

Question 9

What are the four layers of the epidermis (from bottom to top_

Answer 9

1. Basal layer
2. Prickle cells
3. Granular layer
4. Keratin layer

Question 10

What layer connects the epidermis to the dermis?

Answer 10

The basal layer

Question 11

What type of cells dominate the prickle cell layer?

Answer 11

Desmosomes

Question 12

How does disruption of the prickle cell manifest?

Answer 12

Moist skin

Question 13

Describe the cells of the granular layer?

Answer 13

No nuclei

Large numbers of lipid granules

Question 14

What two proteins make up the keratin layer?

Answer 14

Keratin and filaggrin

Question 15

Where are basal cell carcinomas derived from?

Answer 15

Hair follicle cells

Question 16

What do melanocytes do?

Answer 16

They convert tyrosine to the melanin pigment (melanin) which is brown

Question 17

How do melanocytes achieve this pigmentation?

Answer 17

Inside the melanocytes their are organelles called melanosomes. These absorb light and convert it into melanin granules which are then transferred to keratinocytes through dendrites. When we are in the sun this pre formed melanin spreads out into the surrounding cells to give a tan.

Question 18

What is the purpose of a tan?

Answer 18

The melanin cap works to protect DNA is the basal cells

Question 19

What is vitiligo?

Answer 19

An autoimmune disease in which there is a loss of melanocytes

Question 20

What is albinism?

Answer 20

A genetic condition where there is loss of pigment production due to an enzyme deficiency.

Question 21

What is nelsons syndrome?

Answer 21

An excess of melanins stimulating hormone being produced from the pituitary gland.

Question 22

What do langerhans cells do?

Answer 22

The constantly scan the epidermis for microbes and present these

Question 23

Where do langerhans cells originate from?

Answer 23

Bone marrow

Question 24

What are merkel cells?

Answer 24

Mechanoreceptors

Question 25

What is the pilosebaceous unit?

Answer 25

The epidermal component of the hair follicle and the dermal papilla.

Question 26

How does the hair become coloured?

Answer 26

Melanocytes lying above the dermal papilla

Question 27

What do arrestor pilli muscles do?

Answer 27

Contract to cause the hair to become erect

Question 28

What are the three phases of hair growth?

Answer 28

``` Anagen = growing Catagen = Involuting Telogen = resting ```

Question 29

Where are new hair cells formed?

Answer 29

The hair matrix

Question 30

Why, when hair grows back is it initially white?

Answer 30

Melanin cells take longer to return than hair cells.

Question 31

What are nails made of?

Answer 31

Keratin

Question 32

In the derma - epidermal junction, what cells act as ties?

Answer 32

Hemidesmosomes

Question 33

What is epidermolysis bullosa simplex?

Answer 33

A congenital problem with the dermal epidermal junction which causes newborn babies to blister on touch.

Question 34

What do fibroblasts do?

Answer 34

Secrete collagen

Question 35

What do macrophages do?

Answer 35

Scavenge and present antigens

Question 36

What do mast cells do?

Answer 36

Chemical messengers

Question 37

What three cell types do you find in the epidermis?

Answer 37

Melanocytes Langerhans cells Merkel cells

Question 38

What fibres does the dermis contain?

Answer 38

Collagen and elastin

Question 39

In there a blood supply to the epidermis?

Answer 39

No. Blood must diffuse across

Question 40

In the skin, what does the upper horizontal arterial plexus supply?

Answer 40

The epidermis

Question 41

What does the lower horizontal arterial plexus supply?

Answer 41

The dermis (hair root etc)

Question 42

What is a port win stain?

Answer 42

Permanent dilatation of blood vessels in the skin

Question 43

What do pacinian cells sense?

Answer 43

Pressure

Question 44

What is neurofibromatosis? How does it manifest?

Answer 44

An overgrowth of nerve endings. Brown swelling on the skin.

Question 45

What are cafe au lait spots a sign of?

Answer 45

Neurofibromatosis

Question 46

Describe sebaceous glands

Answer 46

Hormone sensitive glands the produce sebum. The open out onto the hair follicle and protect from infection

Question 47

What glands are mostly found on the face, back and chest?

Answer 47

Sebaceous

Question 48

Describe apocrine glands

Answer 48

Androgen dependant scent glands that form part of the pilosebaceous unit and so release onto the hair follicle, lubricating the hair.

Question 49

What glands are found mostly on the axillae and perineum

Answer 49

Apocrine

Question 50

What are eccrine glands

Answer 50

Glands found across the whole skin surface that allow the body to cool by expiration. They have a sympathetic cholingeric nerve supply.

Question 51

What glands are found on the whole skin surface?

Answer 51

Eccrine

Question 52

What is erythroderma

Answer 52

Redness over most of the skin

Question 53

Where are melanocytes found?

Answer 53

Dermo epidermal junction

Question 54

How do melanocytes transfer pigment to keratinocytes?

Answer 54

Dendritic processes

Question 55

What two types of collagen make up the dermis

Answer 55

type 1 and type 111 collagen

Question 56

Describe briefly the pathogenesis of acne

Answer 56

Sebum produced by the sebaceous glands pigs the pilo sebaceous unit. Keratin and sebum build up to produce blackheads/whiteheads. Rupture causes acute inflammation and foreign body granulomas