Week 1

Question 1

Which germ layers do epidermis and the dermis come from?

Answer 1

ectoderm cells - epidermis

mesoderm - dermis

Question 2

What type of epithelium is the epidermis?

Answer 2

stratified epithelium

Question 3

What are the layers of the skin?

Answer 3

epidermis
keratin layer
granular layer
prickle cell layer 
basal layer
dermis

Question 4

Where are melanocytes found in the skin and where did they migrate there from?

Answer 4

basal epidermis or in the matrix of hair during embryological development - migrated from neural crest

Question 5

How is the neural crest formed?

Answer 5

during the formation of the neural tube (precursor to spinal cord) embryological cells are pinched off = neural crest

Question 6

What happens during epidermis differentiation? How long does it take?

Answer 6

Keratinocytes migrate from the basement membrane to the surface of the epidermis = continuous regeneration of the epidermis.
Takes 28 days.

Question 7

How many weeks into foetal development does the epidermis comprise 4 layers?

Answer 7

16 weeks

Question 8

Name the layer of epidermis:
one cell thick
small cuboidal 
lots of intermediate filaments (keratin)
highly metabolically active

Answer 8

basal layer

Question 9

What are corneocytes and which epidermis layer has them?

Answer 9

overlapping non-nucleated remnants of terminally differentiated keratinocytes

therefore found in keratin layer

Question 10

What are the features of the keratin layer?

Answer 10

corneocytes 
insoluble cornified envelope
80% keratin & filaggrin
lamellar granules release lipid
tight waterproof barrier

Question 11

Which layer:
2-3 layers of flatter cells
large keratohyalin granules
Odland (lamellar) bodies 
high lipid content
cell nuclei lost

Answer 11

granular layer

Question 12

Which layer is the origin of the ‘cornified envelope’?

Answer 12

granular layer - granules burst and release contents in layer, left over lipids and proteins come together to form an evelope

Question 13

Which layer:
larger polyhedral cells
lots of desmosomes
intermediate filaments (connect desmosomes)

Answer 13

prickle cell layer

Question 14

Describe melanocytes.

Answer 14

melanin (pigment) producing dendritic cells
contain organelles called melanosomes
form protective cap over nucleus

Question 15

Which chemical conversion occurs in melanocytes?

Answer 15

tyrosine to melanin pigment;

eumelanin and phaeomelanin

Question 16

Which type of melanin pigment is brown/black?

Answer 16

eumelanin

Question 17

which type of melanin pigment is red/yellow?

Answer 17

phaeomelanin

Question 18

What is the function of melanin and melanin granules?

Answer 18

melanin absorbs light and therefore a natural density filter (sun cream)

full melanosomes (‘melanin granules’) are transferred to adjacent keratinocytes via dendrites (bud off)

Question 19

What is the correct name for the smooth muscle fibres attached to hair follicles?

Answer 19

arrector pili muscles

Question 20

What type of unit is a hair follicle?

Answer 20

pilosebaceous unit

Question 21

What is the name for the ‘natural moisturiser’ that is continuously secreted? Which gland secretes it?

Answer 21

sebum from sebaceous gland

Question 22

What are the 3 phases of growth?

Answer 22

angen
catagen
telogen

Question 23

Angen phase takes place during which years of life and producing what percentage of hairs?

Answer 23

3-7 years, 90%

angen = growing

Question 24

Catagen phase occurs for how long?

Answer 24

3-4 weeks, 10% hairs

catagen = involuting

Question 25

Telogen phase also known as what phase? Occurs when?

Answer 25

shedding phase, each day <1% hairs | telogen = resting

Question 26

What is the growth rate of nails?

Answer 26

0.1mm per day

Question 27

Toe nails grow faster than finger nails?

Answer 27

False, fingers > toes | summer > winter

Question 28

Nail plate sits on top of ?

Answer 28

nail bed

Question 29

White area at base of nail plate?

Answer 29

lunula

Question 30

What secures the free nail?

Answer 30

hyponychium

Question 31

What cellular processes occur in the nail matrix?

Answer 31

cells divide and then produce hard keratin

Question 32

What is a cuticle?

Answer 32

an extension of free skin fold covering the nail root

Question 33

What is the interface between the epidermis and the dermis?

Answer 33

the dermo-epidermal junction

Question 34

What are the key roles of the DEJ?

Answer 34

support, anchorage, adhesion, growth and differentiation of basal layer semi-permeable membrane acting as barrier and filter

Question 35

Name the condition where antibodies are formed against the DEJ.

Answer 35

bullous pemphigoid

Question 36

Babies with a 'mitten deformity'

Answer 36

epidermolysis bullosa

Question 37

Rash and large itchy blisters found on the arms, legs and middle of body...

Answer 37

bullous pemphigoid

Question 38

A group of genetic skin disorders that make skin very fragile - any trauma or friction to the skin can cause painful blisters...

Answer 38

epidermolysis bullosa

Question 39

What do fibroblasts do?

Answer 39

collagen and extracellular matrix synthesis

Question 40

Where are retentions ridges found and what is their role?

Answer 40

papillary dermis (top layer) - epithelial extensions that project into the underlying areolar connective tissue

Question 41

What is the layer of dermis below papillary dermis?

Answer 41

reticular dermis - dense irregular connective tissue featuring densely packed collagen fibres. Primary location of dermal elastic fibres

Question 42

What is elastin?

Answer 42

the protein which allows skin to be pinched and return back to its normal position

Question 43

Name the sweat glands active only upon puberty. Where are they found and what do they secrete? Which hormone are they dependent on?

Answer 43

Apocrine sweat glands develop as part of pilosebaceous unit - produce oily fluid -> odour after bacterial decomposition axillae, nipples, perineum androgen dependent

Question 44

What are holocene secretions?

Answer 44

produced in cytoplasm and released by the rupture of the plasma membrane which destroys the cell and results in the secretion of the product into the lumen.

Question 45

Which sweat gland utilises holocrine secretions? Where are they found & what is their function?

Answer 45

sebaceous glands - holocrine secretions opening into pillary canal widely distributed - largest glands in face and chest lobulated masses in dermis which secrete sebum into hair follicle to coat hair and skin control moisture loss, protection from fungal infection

Question 46

Where are sebaceous glands not found?

Answer 46

palms and sole skin

Question 47

When are sebaceous glands dormant?

Answer 47

pre-puberty (hormone sensitive)

Question 48

Which sweat glands are found on the whole skin surface, except lips & genitalia?

Answer 48

eccrine sweat glands | found on palms, soles and axillae in particular

Question 49

What is the stimulation of eccrine sweat glands? What are their functions?

Answer 49

sympathetic cholinergic nerve supply - mental, thermal & gustatory stimulation Coiled tubular structure which regulate heat & salt loss; cooling by evaporation; moisten palms/soles to aid grip

Question 50

Which sweat gland has the best filtration rate?

Answer 50

eccrine ultrafiltration: can be >10L per day NaCl + HCO3 reabsorbed - hypotonic fluid

Question 51

Name conditions that occur if the skin barrier function is lost.

Answer 51

``` dehydration hypoalbuminaemia steroid-sulphatase deficiency x-linked ichthyosis cumulative irritant hand dermatitis ulcer following compound fracture ```

Question 52

Erosions on fingertips; redness and scaling in-between fingers - type IV hypersensitivity

Answer 52

cumulative irritant hand dermatitis

Question 53

condition characterised by loss of barrier function due to no normal lipids present in keratin layer...

Answer 53

steroid-sulphatase deficiency x-linked ichthyosis

Question 54

Which sweat gland type is triggered in thermoregulation?

Answer 54

eccrine

Question 55

What cell types are found in the dermis and involved in sensation?

Answer 55

pacinian corpuscles | meissner's corpuscles

Question 56

Which structure is involved in deep pressure sensation?

Answer 56

pacinian corpuscles

Question 57

Which structure is used for tactile sensation?

Answer 57

messier's corpuscles

Question 58

Pain is detected by free nerve endings found in which layer of skin?

Answer 58

basal layer of epidermis

Question 59

Define stigma.

Answer 59

the term describes the situation of an individual who is disqualified from full social acceptance

Question 60

Skin is metabolically active in which metabolisms?

Answer 60

vitamin D and thyroid hormone

Question 61

Skin absorbs which frequency of UV light to cause which conversion in vitamin D synthesis?

Answer 61

290-320nm | cholecalciferol (7-dehydrocholesterol) converted to vitamin D3

Question 62

Vitamin D3 is stored by the liver as which compound?

Answer 62

hydroxycholecalciferol

Question 63

What conversion does the kidneys do in vitamin D synthesis?

Answer 63

hydroxycholecalciferol -> 1,25-dihydroxycholecalciferol

Question 64

What is the effect of 1,25-hydroxycholecalciferol on the bowel?

Answer 64

increased calcium absorption

Question 65

What is the role of skin in thyroid hormone metabolism?

Answer 65

80% of the conversion of T4 -> T3 occurs in peripheral (to thyroid) tissues including the skin; remaining 20% occurs in thyroid gland

Question 66

What is PVL?

Answer 66

Panton Valentine Leukocidin is a cytotoxin associated with highly virulent strains of Staph aureus causing necrolytic skin infections by directly killing leucocytes.

Question 67

Which virulence factor causes damage to the host directly?

Answer 67

Aggressin

Question 68

Which virulence factor enables the organism to invade a host tissue?

Answer 68

Invasin

Question 69

Which virulence factors enables binding of the organism to host tissue?

Answer 69

Adhesin

Question 70

Which virulence factor enables the organism to avoid host defence mechanisms?

Answer 70

Impedin

Question 71

Which virulence factor causes damage to the host indirectly?

Answer 71

Modulin

Question 72

3 y/o boy presents on sunny day, mother reports crying & rubbing skin when outside. Skin sometimes red but no rash, clear now. Skin type 1 with few freckles.

Answer 72

erythropoietic protoporphyria

Question 73

deficiency of which enzyme causes erythropoietic protoporphyria (EPP)?

Answer 73

ferrochelatase

Question 74

What accumulates due to the enzyme deficiency in erythropoietic protoporphyria?

Answer 74

protoporphyrin IX in RBCs (erythrocytes), plasma, skin, and liver.

Question 75

What is impaired in acute intermittent porphyria?

Answer 75

porphobilinogen - results in acute neurotoxic reaction in many tissues