Skin Structure and Function 2

Question 1

In what layers of the skin are melanocytes found?

Answer 1

Basal and suprabasal

Question 2

In what parts of the skin are Langerhans cells found?

Answer 2

Prickle cell layer, dermis and lymph nodes

Question 3

In what part of the skin are merkel cells found?

Answer 3

Basal layer

Question 4

When do melanocytes migrate from the neural crest to the epidermis?

Answer 4

During the first 3 months of foetal development

Question 5

What organelles do melanocytes contain?

Answer 5

Melanosomes

Question 6

What do melanosomes do?

Answer 6

Convert tyrosine (amino acid) to melanin pigment

Question 7

What are 2 types of melanin and what colour are they?

Answer 7

Eumelanin (brown or black)
Phaeomelanin (red or yellow)
Different combinations of these give different hair colours)

Question 8

What happens to melanin produced in melanosomes?

Answer 8

Melanin is sent in packages (melanin granules) to surrounding keratinocytes through the melanocyte limbs (dendritic processes) where it absorbs light (neutral density filter)
Form protective melanin caps over the nucleus protecting the DNA in basal cells

Question 9

What is another name for full melanosomes?

Answer 9

Melanin granules

Question 10

What causes a tan when we go into the sun?

Answer 10

An increase in the melanin produced

Question 11

What is the origin of langerhans cells?

Answer 11

Mesenchymal origin - bone marrow

Question 12

What is the function of langerhans cells?

Answer 12

Antigen presenting cell - pick up antigen in skin and circulate to lymph nodes via lymphatic system

Question 13

What is the name(s) of the characteristic organelle found in Langerhans cells?

Answer 13

Birbeck granules

Also called racket organelle

Question 14

Where in basal layer are merkel cells found?

Answer 14

Between keratinocytes and nerve fibres

Question 15

What is the purpose of merkel cells?

Answer 15

Act as mechanoreceptors

Question 16

What makes up the pilosebaceous unit?

Answer 16

Hair shaft
Hair follicle
sebaceous gland
erector pili muscle

Question 17

What type of muscle is the erector pili muscle?

Answer 17

Smooth

Question 18

Parts of the hair shaft from outside in?

Answer 18

Cuticle
Cortex
Medulla

Question 19

What is the name of the part of the pilosebaceous unit that produces hair?

Answer 19

Hair follicle

Question 20

What is the name of the structure at the base of the hair follicle?

Answer 20

papilla of hair follicle

Question 21

What are the 2 parts of the hair root sheath?

Answer 21

Internal root sheath

External root sheath

Question 22

What pigments hair?

Answer 22

Melanocytes above dermal papilla (pigmented melanisation of the matrix)

Question 23

What structure is located around the papilla of the hair follicle?

Answer 23

Matrix

Question 24

What are the 3 phases of hair growth?

Answer 24

Anagen
Catagen
Telogen

Question 25

What is the hair doing during anagen?

Answer 25

Growing

Question 26

How long is anagen typically?

Answer 26

3 - 7 years

Question 27

What happens to hair during catagen?

Answer 27

Involuting - transition phase where hair cell division declines and the root shrinks to 1/3 of original size

Question 28

How long is catagen usually?

Answer 28

Few weeks

Question 29

What happens to hair during telogen?

Answer 29

Resting - falls out/ gets pushed out

Question 30

How long is telogen generally?

Answer 30

3-4 months

Question 31

Is phases of hair growth normally synchronised in humans?

Answer 31

No, however you can synchronise you hair cycle e.g. chemo

Question 32

What endogenous group of chemicals impacts phases of hair growth?

Answer 32

Hormones e.g. thryoxine, androgen

Question 33

What is the name for the development of male sexual characteristics in females? what is an example of a cause of this?

Answer 33

Virilisation | Excess androgen from a tumour

Question 34

Type of hair in utero?

Answer 34

Lanugo

Question 35

Type of hair found on a woman's cheek or a prepubescent child (soft and lacks pigment)?

Answer 35

Vellus - "peach fuzz"

Question 36

Name of thick, strong, pigmented hair that has fully matured e.g. head hair?

Answer 36

Terminal hair

Question 37

What is the cortex of the hair sheath made up of?

Answer 37

hard keratin

Question 38

what is the medulla of the hair sheath made up of?

Answer 38

Soft keratin

Question 39

What part of the hair follicle contains multiple vascular channels?

Answer 39

Papilla

Question 40

What part of the hair follicle contains keratin producing cells?

Answer 40

Matrix

Question 41

On a typical head of hair, what % of hair will be in each phase of growth?

Answer 41

``` 90% = anagen 10% = catagen <1% = telogen ```

Question 42

What is the name for the extension of skin fold covering the nail root?

Answer 42

Cuticle

Question 43

What is the name for the white crescent at the bottom of the nail?

Answer 43

Lunula

Question 44

What is the proper name for the actual hard part of the nail?

Answer 44

Nail plate

Question 45

What is the name of the part under the nail plate that secures the free nail edge?

Answer 45

Hyponychium

Question 46

What is the name of the part under the nail plate that you can see (up until the lunula)?

Answer 46

Nail bed

Question 47

What is the name of the part under the nail plate that you can't see? What happens here?

Answer 47

Nail matrix | Cells divide and then produce hard keratin

Question 48

What type of connective tissue are nails made of?

Answer 48

Specialised keratin

Question 49

On average, how much do nails grow per day?

Answer 49

0.1mm

Question 50

Do finger nails or toe nails grow faster?

Answer 50

Finger nails

Question 51

Do nails grow faster in the summer or winter?

Answer 51

Summer