Intro to derm

Question 1

What are the layers of the skin?

Answer 1

Epidermis

Basement membrane (dermal-epidermal junction)

Dermis

Subcutaneous fat

Question 2

What is the epidermis composed of ?

Answer 2

Keratinocytes

Question 3

What are the layers of keratinocytes?

Answer 3

Progressive differentiation / flattening towards surface:
Stratum basale
Stratum spinosum
Stratum granulosum
Stratum lucidum (palms and soles only, no nuclei or organelles)- skin thicker on palms and soles.
Stratum corneum (no nuclei or organelles)

Question 4

How long does cellular progression in epidermis from basal layer towards surface take?

Answer 4

30 days, but accelerated in certain skin diseases

Question 5

What type of cell are melanocytes?

Answer 5

Dendritic

Question 6

What do melanocytes do?

Answer 6

Distribute melanin pigments (in melanosomes) to keratinocytes

Question 7

What type of cells are Langerhans cells?

Answer 7

Dendritic APCs

Question 8

What type of receptors do Merkel cells have?

Answer 8

Mechanosensory receptors

Question 9

What are the 2 layers of the dermis? (top to bottom)

Answer 9

Papillary dermis

Reticular dermis

Question 10

What makes up 80-85% of the dermis?

Answer 10

Collagen, mainly types 1 and 3

Question 11

What makes up 2-4% of the dermis?

Answer 11

Elastic fibres- fibrillin and elastin

Question 12

What glycoproteins are in the dermis?

Answer 12

fibronectin, fibulin, intregrins

Question 13

What do glycoproteins in the dermis do?

Answer 13

facilitate cell adhesion and cell motility

Question 14

Where is ground substance located?

Answer 14

between dermal collagen and elastic tissue

Question 15

What is ground substance made of?

Answer 15

glycosaminoglycan

Question 16

What are the primary cells within the dermis?

Answer 16

Fibroblasts

Question 17

Does blood supply cross into the epidermis?

Answer 17

No

Question 18

What are the 3 types of corpuscles?

Answer 18

Meissner’s, Ruffini, and Pacinian

Question 19

Where are Meissner’s corpuscles most concentrated?

Answer 19

thick hairless skin, (finger pads and lips)

Question 20

What sort of touch are Meissner’s corpuscles most sensitive to?

Answer 20

Light Touch (+slow vibration)

Question 21

Where are Ruffini corpuscles most concentrated?

Answer 21

around fingernails

Question 22

What are Ruffini corpuscles sensitive to?

Answer 22

skin stretch

Question 23

What do Ruffini corpuscles monitior?

Answer 23

Slippage of objects

Question 24

Where are Pacinian corpuscles most concentrated?

Answer 24

Dermal papillae of hands and feet

Question 25

What are Pacinian corpuscles sensitive to?

Answer 25

Deep pressure and vibration (deep touch)

Question 26

What do Pacinian corpuscles detect?

Answer 26

Surface texture

Question 27

What do Merkel cells detect?

Answer 27

Light touch

Question 28

Are dermal and epidermal receptors encapsulated or unencapsulated?

Answer 28

Dermal nerve receptors (Meissner’s / Ruffini / Pancinian corpuscles) are encapsulated while epidermal (Merkel cell) receptors are not

Question 29

What are the 6 functions of skin?

Answer 29

Physical barrier Immunological barrier Thermoregulation Sensation Metabolism Aesthetic appearance

Question 30

What cells carry out immune surveillance in the dermis?

Answer 30

Tissue‐resident T-cells Macrophages Dendritic cells

Question 31

How are cornified cell envelope and stratum corneum important in the role of skin as a physical barrier?

Answer 31

restrict water and protein loss from skin

Question 32

How is subcutaneous fat important in the role of skin as a physical barrier?

Answer 32

important role in cushioning trauma

Question 33

How are melanocytes important in the role of skin as a physical barrier?

Answer 33

protection against UV-induced DNA damage

Question 34

How does the skin regulate body temperature (thermoregulation)?

Answer 34

Vasodilatation or vasoconstriction in deep or superficial vascular plexuses → regulate heat loss Eccrine sweat glands → cooling effect

Question 35

What are the 6 functions of hair?

Answer 35

Protection against external factors Sebum Apocrine sweat Thermoregulation Social and sexual interaction Epithelial and melanocyte stem cells

Question 36

What are the 2 types of hairs?

Answer 36

Terminal and vellus

Question 37

Where are terminal hairs located?

Answer 37

scalp, eyebrows and eyelashes

Question 38

Where are vellus hairs located?

Answer 38

Rest of body (except palms, soles, mucosal regions of lips, and external genitalia)

Question 39

What ae the 3 stages of the hair cycle?

Answer 39

Anagen (where new hair forms and grows), catagen (regressing phase), telogen (resting phase)

Question 40

What % of hair is in anagen?

Answer 40

85%

Question 41

What % of hair is in catagen?

Answer 41

1%

Question 42

What % of hair is in telogen?

Answer 42

15%

Question 43

How long does anagen last?

Answer 43

2-6 years

Question 44

How long does catagen last?

Answer 44

3 weeks

Question 45

How long does telogen last?

Answer 45

3 months

Question 46

What happens after the 3 phases of the hair cycle?

Answer 46

Old hair falls out

Question 47

What 3 things are contained in a pilosebaceous unit?

Answer 47

hair shaft, hair follicle, sebaceous gland

Question 48

What is the Infundibulum?

Answer 48

Uppermost portion of the hair follicle extending from opening of sebaceous gland to surface of the skin

Question 49

What is the Isthmus?

Answer 49

Lower portion of upper part of hair follicle between opening of sebaceous gland and insertion of arrector pili muscle

Question 50

Where are eccrine sweat glands located?

Answer 50

Almost everywhere

Question 51

Where do eccrine sweat glands open to?

Answer 51

directly onto the skin’s surface

Question 52

Where are apocrine sweat glands located?

Answer 52

in areas with many hair follicles such as the scalp, armpits, groin

Question 53

Where do apocrine sweat glands open into?

Answer 53

open into the hair follicle

Question 54

Where does the nail plate emerge from?

Answer 54

proximal nail fold

Question 55

How much do nails grow a month?

Answer 55

1-3mm

Question 56

Where does the nail plate detach?

Answer 56

hyponychium

Question 57

What does the nail matrix produce?

Answer 57

the nail plate

Question 58

Where does the nail matrix lie?

Answer 58

Lies under proximal nail fold, above bone of distal phalanx (to which it is connected by a tendon

Question 59

What is the visible part of the nail matrix called?

Answer 59

Lunula

Question 60

What are the 5 functions of the nails?

Answer 60

Protection of distal phalanx Counterpressure effect to pulp - important for walking and tactile sensation Increase dexterity / manipulation of small objects Enhance sensory discrimination Scratching or grooming