Skin Structure and Function 2 Flashcards Preview

2nd Year - Dermatology > Skin Structure and Function 2 > Flashcards

Flashcards in Skin Structure and Function 2 Deck (51):
1

In what layers of the skin are melanocytes found?

Basal and suprabasal

2

In what parts of the skin are Langerhans cells found?

Prickle cell layer, dermis and lymph nodes

3

In what part of the skin are merkel cells found?

Basal layer

4

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

During the first 3 months of foetal development

5

What organelles do melanocytes contain?

Melanosomes

6

What do melanosomes do?

Convert tyrosine (amino acid) to melanin pigment

7

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

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

8

What happens to melanin produced in melanosomes?

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

9

What is another name for full melanosomes?

Melanin granules

10

What causes a tan when we go into the sun?

An increase in the melanin produced

11

What is the origin of langerhans cells?

Mesenchymal origin - bone marrow

12

What is the function of langerhans cells?

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

13

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

Birbeck granules
Also called racket organelle

14

Where in basal layer are merkel cells found?

Between keratinocytes and nerve fibres

15

What is the purpose of merkel cells?

Act as mechanoreceptors

16

What makes up the pilosebaceous unit?

Hair shaft
Hair follicle
sebaceous gland
erector pili muscle

17

What type of muscle is the erector pili muscle?

Smooth

18

Parts of the hair shaft from outside in?

Cuticle
Cortex
Medulla

19

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

Hair follicle

20

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

papilla of hair follicle

21

What are the 2 parts of the hair root sheath?

Internal root sheath
External root sheath

22

What pigments hair?

Melanocytes above dermal papilla (pigmented melanisation of the matrix)

23

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

Matrix

24

What are the 3 phases of hair growth?

Anagen
Catagen
Telogen

25

What is the hair doing during anagen?

Growing

26

How long is anagen typically?

3 - 7 years

27

What happens to hair during catagen?

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

28

How long is catagen usually?

Few weeks

29

What happens to hair during telogen?

Resting - falls out/ gets pushed out

30

How long is telogen generally?

3-4 months

31

Is phases of hair growth normally synchronised in humans?

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

32

What endogenous group of chemicals impacts phases of hair growth?

Hormones e.g. thryoxine, androgen

33

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

Virilisation
Excess androgen from a tumour

34

Type of hair in utero?

Lanugo

35

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

Vellus - "peach fuzz"

36

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

Terminal hair

37

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

hard keratin

38

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

Soft keratin

39

What part of the hair follicle contains multiple vascular channels?

Papilla

40

What part of the hair follicle contains keratin producing cells?

Matrix

41

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

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

42

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

Cuticle

43

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

Lunula

44

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

Nail plate

45

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

Hyponychium

46

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

Nail bed

47

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

Nail matrix
Cells divide and then produce hard keratin

48

What type of connective tissue are nails made of?

Specialised keratin

49

On average, how much do nails grow per day?

0.1mm

50

Do finger nails or toe nails grow faster?

Finger nails

51

Do nails grow faster in the summer or winter?

Summer