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Flashcards in Physiology Deck (40)
1

What is the largest organ in the body?

Skin

2

What is the outermost layer of skin called?

Epidermis

3

Which type of epithelium makes up epidermis?

Stratified squamous epithelium

4

Which layer of skin is deep to epidermis?

Dermis

5

Which tissue type makes up dermis?

Connective tissue

6

Which germ layer forms epidermis?

Ectoderm (forms periderm)

7

Which germ layer forms dermis?

Mesoderm

8

In foetal skin development, which layers are formed after 16 weeks?

Keratin layer + granular layer
Prickle cell layer
Basal layer
Dermis

9

Which cell makes up 95% of epidermis?

Keratinocytes

10

The basal layer of skin is highly metabolically active. True/False?

True
Lots of intermediate filaments

11

Name 3 other epidermal cells (other than keratinocytes)

Melanocytes
Langerhans cells
Merkel cells

12

Where do melanocytes derive from?

Neuronal cell crest

13

What are melanocytes? Which layer of skin are they found?

Pigment-producing dendtritic cells
Basal layer

14

What do melanocytes do?

Convert tyrosine to melanin pigment and load colour onto adjacent keratinocytes

15

Eumelanin is brown/red

Brown

16

Phaeomelanin is brown/red

Red

17

Which disease results due to loss of melanocytes?

Vitiligo

18

Where do Langerhans cells derive from?

Bone marrow

19

What are Langerhans cells? Which layer of skin are they found?

Antigen-presenting cells
Prickle cell layer

20

What are Merkel cells? Where are they found?

Mechanoreceptors that aid sensation
Between keratinocytes + nerve fibres

21

What are the 3 phases of growth of a hair follicle?

Anagen (growing)
Catagen (curve inwards)
Telogen (resting)

22

What is the dermo-epidermal junction (DEJ)?

The interface between the dermis and epidermis

23

List 2 key roles of the DEJ

Support, anchoring, adhesion and growth of epidermal cells
Semi-permeable membrane acts as a filter/barrier

24

Give an example of inherited skin fragility as a result of mutation to one of the proteins in the DEJ

Epidermolysis bullosa complex in young infants

25

Give an example of acquired skin fragility

Dermatitis herpetiformis
Bullous pemphigoid

26

What do fibroblasts in the dermis produce?

Procollagen (becomes collagen)
Elastin

27

The blood vessel supply to skin is greater than its metabolic need. True/False?

True

28

Which nerve receptors sense pressure in skin?

Pacinian corpuscles

29

Which nerve receptors sense vibration in skin?

Meissners corpuscles

30

What do free nerve endings provide sense for in skin?

Temperature
Pain

31

Which inherited condition arises due to overgrowth of nerve endings?

Neurofibromatosis

32

List the 3 main secretory glands in skin

Eccrine
Apocrine
Sebaceous

33

Eccrine glands secrete ?
Apocrine glands secrete ?
Sebaceous glands secrete ?

Eccrine glands secrete sweat
Apocrine glands secrete odourous fluid
Sebaceous glands secrete moisturiser

34

Which areas of the body have a high concn of sebaceous glands?

Head, neck and chest

35

What is the significance of the melanin cap on basal cells?

Absorbs UV rays to protect DNA in the cells' nuclei

36

Which vitamin does skin metabolise?

Vitamin D

37

20% of thyroxine conversion to triiodothyronine (T4 to T3) is done in peripheral tissues such as skin. True/False?

False
80%!

38

Which cells help protect skin from UV rays?

Melanocytes

39

Ratio of melanocytes : basal cells = ?

1:10

40

Where is the papillary dermis found?

Uppermost layer of the dermis