Structure of the Skin

Question 1

Where does the epidermis of the skin originate from?

Answer 1

Ectoderm

Question 2

Where does the dermis of the skin originate from?

Answer 2

Mesoderm that comes in contact with the inner surface of epidermis

Question 3

What happens week 5 in skin development?

Answer 3

1. Epidermis forms as a single layer of cuboidal cells
2. Secondary layer of squamous, non keratinising cuboidal cells (periderm) form
3. Periderm generates white, waxy protective substance - vernix caseosa

Question 4

What is the periderm?

Answer 4

Cells with projecting globules covered with small protusions

Question 5

What happens around week 11 of skin development?

Answer 5

Basal layer of cuobidal cells (stratum germinativum) proliferates to form multilayered intermediate zone

Question 6

What happens around week 20 of skin development?

Answer 6

Further differentiation of the cuboidal cells into spinosum, granulosum, lucidum and corneum

Question 7

Superficial strata: Spinosum

Answer 7

Spinous

Question 8

Superficial strata: Granulosum

Answer 8

Granular

Question 9

Superficial strata: Lucidum

Answer 9

Clear, found on palms of hands and sole of feet

Question 10

Superficial strata: Corneum

Answer 10

horny

Question 11

What happens between weeks 9-13? (hair follicles)

Answer 11

Development of hair follicles in stratum germinativum and appearance of lanugo hair

Question 12

What happens weeks 12-14? (dermis)

Answer 12

Epidermal ridges protrude as troughs into developing dermis beneath (rete ridge)

Question 13

Structure of the skin superficial to deep

Answer 13

Epidermis , Basement membrane, Dermis, Subcutaneous fat

Question 14

What is called the building blocks of eppidermis in the skin?

Answer 14

Keratinocytes

Question 15

Division of cells in basal layers (progressive differentiation/flattening towards surface away from basal membrane)

Answer 15

Basement membrane, basal layer, spinous layer, granular layer, stratum corneum

Question 16

Stratum lucidum found only?

Answer 16

Palms and soles (no nuclei or organelles)

Question 17

Which cells in basal layer do not have nuclei or organelles?

Answer 17

Stratum lucidum and corneum

Question 18

Cellular progression from basal layer in how long?

Answer 18

30 days

Question 19

Filamentous cytoskeleton of keratinocytes comprises of:

Answer 19

Actin- containing microfilaments (7nm)
Tubulin containing microtubules (20-25nm)

Question 20

Role of Keratins (5)

Answer 20

Structural properties, cell signalling, stress repsonse, apoptosis, wound healing

Question 21

Role of desmosomes (3)

Answer 21

Major adhesion complex in epidermis
Anchor keratin intermediate filaments to cell membrane and bridge adjacent keratinocytes
Allows cells to withstand trauma

Question 22

Role of gap junctions (2)

Answer 22

directly form connections between cytoplasm of adjacent keratinocytes

cell synchronization and coordination

Question 23

Role of adherens junctions (1)

Answer 23

engage with actin skeleton

Question 24

Role of tight junctions (1)

Answer 24

Role in barrier integrity and cell polarity

Question 25

Melanocyes function (1)

Answer 25

Distribute melanin pigment to keratinocytes (dendritic)

Question 26

Langerhnas cells (1)

Answer 26

Antigen presenting cells (dendritic)

Question 27

Merkel cells function (1)

Answer 27

mechanosensory receptor

Question 28

Structure of the basement membrane (1)

Answer 28

(Aka dermal-epidermal junction) Proteins and glycoprotiens

Question 29

Proteins and glycoproteins found in basement membrane

Answer 29

Collagen (IV, VII) Laminin Integrins

Question 30

Role of basement membrane (4)

Answer 30

Cell adhesion Cell migration Diffusion of bioactive molecules Rete ridges

Question 31

Dermins function (1)

Answer 31

extracellular matrix- provides resilience

Question 32

Two layers of dermis are ...

Answer 32

Papillary dermis Reticular dermis

Question 33

Papillary dermis (3)

Answer 33

Superficial Loose connective tissue Vascular

Question 34

Reticular Dermis (3)

Answer 34

Deep Dense connective tissue Forms bulk of dermis

Question 35

Glycoproteins found in dermis (3)

Answer 35

Fibronectin, fibulin, integrins

Question 36

Role of glycoproteins in dermis (1)

Answer 36

Facilitate cell adhesion and cell motility

Question 37

Proteins in skin with proportions (2)

Answer 37

Collagen (80-85%)- mianly type I and III Elatin fibres (2-4%)- fibrillin, elastin

Question 38

Where is ground substance found in terms of the dermis?

Answer 38

Between dermal collagen and elastic tissue

Question 39

Primary cells present in dermis:

Answer 39

Fibroblasts

Question 40

Blood supply of skin

Answer 40

Deep and superficial vascular plexus

Question 41

Autonomic innervation of skin (2)

Answer 41

Cholinergic- eccrine Adrenergic- eccrine and apocrine

Question 42

What's in a pilosebaceous unit?

Answer 42

The hair follicle itself with an attached sebaceous gland and arrector pili muscle

Question 43

What three body sites has the highest sensory innervation?

Answer 43

Face Extremeties Genitalia

Question 44

Innervation of dermis

Answer 44

Afferent nerves- Corpuscular -- Encapsulated receptor e.g corpuscle (Meissner)

Question 45

Innervation of epidermis

Answer 45

Afferent nerves --- Free --- Non encapsulated receptors e.g Merkel cell

Question 46

Meissner's corpuscle aka

Answer 46

Tactile corpuscle

Question 47

Where Meissner's corpuscle located?

Answer 47

Superficial dermis

Question 48

Where are Meissner's corpuscle most concentrated?

Answer 48

Thick hairless skin e.g finger pads and lips

Question 49

Ruffini Corpuscle aka

Answer 49

Bulbous corpuscle

Question 50

What is Ruffini Corpuslce?

Answer 50

Slow acting mechanoreceptor

Question 51

Where is Ruffini Corpuslce located?

Answer 51

Deeper in dermis

Question 52

HIghest density of Ruffini Corpuscle?

Answer 52

Around fingernails

Question 53

What is Ruffini Corpuscle sensitive to?

Answer 53

Skin stretch

Question 54

Role of Ruffini Corpuscle (1)

Answer 54

Monitors slippage of objects

Question 55

Pacinian corpuscle aka

Answer 55

Lamellar corpuscle

Question 56

What is Pacinian corpuscle ?

Answer 56

Rapidly adapting (phasic) mechanoreceptor

Question 57

What are Pacinian corpuscle sensitive to?

Answer 57

Deep pressure and vibration

Question 58

Where Pacinian corpuscle ?

Answer 58

Dermal papillae of hands and feet

Question 59

What are Merkel Cells?

Answer 59

Non-encapsulated mechanoreceptors

Question 60

What are Merkel cells sensitive to?

Answer 60

Light/sustained touch, pressure

Question 61

Location of Merkel cells

Answer 61

Stratum basale, directly above basement membrane

Question 62

Area with highest density of Merkel cells

Answer 62

Fingertips

Question 63

Merkel cells also found in ...

Answer 63

Palms, soles, oral and genital mucosa

Question 64

Fibre of Merkel and Meissner cells

Answer 64

AB

Question 65

Insert fibres and modality

Answer 65

at some point

Question 66

Role of microbiota skin (2)

Answer 66

Chronic disease, Immune- modulation and epithelial cell

Question 67

Function of the skin (6)

Answer 67

Immunological barrier Physical barrier Thermoregulation Sensation Metabolism Aesthetic appearance

Question 68

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