3: Skin structure & function 2

Question 1

Where do melanocytes originate from?

Answer 1

Neural crest

Question 2

Which organelle, found in melanocytes, is responsible for producing converting an amino acid to melanin?

What is this amino acid called?

Answer 2

Melanosomes

Tyrosine

Question 3

Melanin absorbs ___ ___.

Answer 3

UV radiation

Question 4

Melanocytes have long projections which allow them to transfer melanosomes between themselves - what are these projections called?

Answer 4

Dendrites

Question 5

___ caps protect the nuclei of ___ layer cells.

Answer 5

Melanin , basal

Question 6

Name an autoimmune disease which targets melanocytes.

Answer 6

Vitiligo

Question 7

Where are melanocytes found?

Answer 7

Basal layer AND above the basal layer

Question 8

Where are Langerhans cells found?

Answer 8

Suprabasal (i.e in the prickle cell layer)

Question 9

Where are Merkel cells found?

Answer 9

Basal layer

Question 10

What is vitiligo?

Answer 10

Autoimmune disease causing destruction of melanocytes

Patient presents with loads of hypopigmented patches

Question 11

What is albinism?

Answer 11

Complete / partial lack of pigment in skin, hair and eyes

Classic white appearance

Question 12

What is Nelson’s syndrome?

What causes it?

Answer 12

Excess melanin production leading to hyperpigmented skin

Overproduction of MSH by anterior pituitary

Question 13

What is a tumour of melanocytes called?

Answer 13

Malignant melanoma

Question 14

Where do Langerhans cells originate from?

Answer 14

Bone marrow (immune function)

Question 15

Langerhans cells pick up ___ and transfer them to lymph nodes via lymph vessels.

Answer 15

antigens

Question 16

What are the tennis-racquet-shaped organelles found exclusively in Langerhans cells?

Answer 16

Birbeck granules

Question 17

What is the function of Merkel cells?

Answer 17

Mechanoreceptors

Question 18

Cancer of which epidermal cell is caused by viral infection and has a high mortality rate?

Answer 18

Merkel cell cancer

Question 19

Which layer(s) of skin are hair follicles found in?

Answer 19

Epidermis

and

Dermis

Question 20

What substance is a hair follicle made of?

Answer 20

Keratin

Question 21

Which type of gland is found adjacent to hair follicles?

Answer 21

Sebaceous gland

Question 22

What is the deepest component of a hair follicle called?

Answer 22

Dermal papilla

Question 23

Hair follicles are pigmented by melanocytes - where are these found?

Answer 23

Nail matrix (above the dermal papilla)

Question 24

What is another name for a hair follicle?

Answer 24

Pilosebaceous unit

Question 25

What are the muscles responsible for moving hair follicles?

Answer 25

**Arrector pili** muscles

Question 26

What are the **three phases** of hair growth?

Answer 26

**Anagen** **Catagen** **Telogen**

Question 27

What happens in the **anagen** phase of hair growth?

Answer 27

**Hair growth**

Question 28

What happens in the **catagen** phase?

Answer 28

**Involution** - hair follicles get ready to shed

Question 29

What happens in the **telogen** phase?

Answer 29

**Hair sheds**

Question 30

Name a hormone which influences hair growth.

Answer 30

**Thyroxine** **Androgens** - e.g testosterone

Question 31

For roughly how long is hair in the anagen phase of growth?

Answer 31

**3 - 7 years**

Question 32

Roughly how many hairs are shed every day by the average person?

Answer 32

**30 - 150 hairs**

Question 33

Not all human hair enters the telogen phase at the same time - this prevents total loss of hair. What is this characteristic called?

Answer 33

**Asynchronicity**

Question 34

What is **telogen effluvium**?

Answer 34

**Marked increase in hair loss triggered by a stressful event** (e.g childbirth, bereavement)

Question 35

What is **alopecia areata**?

Answer 35

**Hair loss caused by an autoimmune disorder** (attacking the hair follicles)

Question 36

What is **androgenic alopecia**?

Answer 36

**Pattern hair loss** i.e male pattern baldness **caused by decrease in androgens**

Question 37

What is the bed of keratinocytes below the proximal nail plate called?

Answer 37

**Nail matrix**

Question 38

What is the name of the layer of epithelium found deep to the distal nail plate?

Answer 38

**Hyponychium**

Question 39

What is the white half moon part of a nail called?

Answer 39

**Lunula**

Question 40

What is the part of the nail proximal to the lunula?

Answer 40

**Cuticle**