normal skin cell histopathology

Question 1

3 layers that make up skin

Answer 1

epidermis
dermis
subcutis / hypodermis

Question 2

epidermis - main cells found in this layer

Answer 2

keratinocyte
melanocyte
langerhans cell
merkel cell

Question 3

epidermis - what type of epithelium is it

Answer 3

stratified squamous epithelium
ie columns of flattened cells stack on one another

Question 4

broadly, the 2 types of epithelium and what’s the difference

Answer 4

epidermis, mucous membrane
- epidermis has a keratin layer that makes it hard and dry
- mucous membranes by comparison don’t have keratin layer and are moist

Question 5

what are the rete ridges

Answer 5

parts of epidermis that protrudes or invaginates into the dermis
- they look like unitary protrusions, but they’re actually a continuous network hence rete
- they’re what make the small lines on the surface of your skin

Question 6

what are the dermal papillae

Answer 6

little nipple-like projections from the dermis that fit between the rete ridges. these are solitary hence nipple-y, unlike rete ridges

Question 7

what is the suprapapillary plate

Answer 7

the section of epithelium that’s between each ridge, it sits on top of a dermal papule

Question 8

natural progression of keratinocytes

Answer 8

start off deep, moving outwards to the surface
keep accumulating keratin
by the time they’re on the surface they get hard, the nucleus is gone
then eventually its shed off

Question 9

4((+1) cell layers in epithelium - from deep to superficial

Answer 9

Lucidum is +1

Question 10

stratum basale
- what layer is it, adjacent layers

Answer 10

• deepest layer of epidermis
• sits superficial to basal lamina, and deep to spinosum

Question 11

stratum granulosum - characteristics (3)

Answer 11

• sits superficial to stratum spinosum, deep to lucidum/corneum
• cells have basophilic granules
• waxy substance secreted between cells

Question 12

stratum spinosum - characteristic that gives its name

Answer 12

• desmosomes connect the cells like little prickles

Question 13

stratum corneum - characteristics

Answer 13

dead, dried out cells without nuclei at the surface of skin

Question 14

what macroscopic skin structure do the rete ridges correspond with

Answer 14

small lines on the surface of skin correspond with rete ridges

Question 15

another name for stratum basale

Answer 15

stratum germinativum

Question 16

another name for stratum germinativum

Answer 16

stratum basale

Question 17

histology - what does squamous mean

Answer 17

flat, like a roof tile or a lizard scale

Question 18

name of blood vessels inside the epidermis

Answer 18

none, its avascular

Question 19

histology - difference between thin skin and thick skin

Answer 19

thick skin has a stratum lucidum

Question 20

what parts of the body have ‘thick skin’

Answer 20

palms, soles of feet

Question 21

cell type that makes up 95% of epidermis

Answer 21

keratinocyte

Question 22

role of keratinocyte in skin

Answer 22

produces and stores keratin

Question 23

(skin) basal cells
- what does it look like

Answer 23

cuboidal shape

Question 24

(skin) basal cells
- what cells do these produce

Answer 24

stem cells that produce keratinocytes

Question 25

what stem cell is the precursor to keratinocytes

Answer 25

basal cell

Question 26

stratum basale - how does it connect to the dermis layer

Answer 26

intertwining collagen fibres, known as the basement membrane

Question 27

stratum basale - main role - other cells found in this layer

Answer 27

- its where the basal cells sit and produce keratinocytes - melanocytes, merkel cells and langerhan cells

Question 28

merkel cell - main function

Answer 28

touch sense receptor, sends message to nerves

Question 29

stratum spinosum - what gives this layer a spiny appearance

Answer 29

- structures called desmosomes connect the cells in this layer - its only visible on stained skin cells

Question 30

stratum granulosum - what gives the keratinocytes in this layer a granular appearance

Answer 30

keratohyalin accumulation inside the cell

Question 31

stratum granulosum - what are the keratinocytes in this layer getting up to

Answer 31

- producing heaps of keratin and keratohyalin - nucleus and other organelles in the cells die, eventually turning it into a mass of keratin

Question 32

stratum lucidum - characteristics (2)

Answer 32

- translucent layer, above granulosum - dead, flattened keratinocytes

Question 33

stratum lucidum - which body parts is it found

Answer 33

thick skin of palms and soles

Question 34

stratum lucidum - what gives it a translucent appearance

Answer 34

eleiden, a protein rich in lipids

Question 35

eleiden - what is it - what is it derived from - role in skin

Answer 35

a protein rich in lipids derived from keratohyalin acts as a thick waterproof barrier in stratum lucidum

Question 36

what layer of epidermis is eleiden found in

Answer 36

stratum lucidum, epidermis

Question 37

layer of epidermis exposed to environment

Answer 37

stratum corneum

Question 38

stratum corneum - characteristics (2)

Answer 38

stack of 15-30 layers of cells, mostly keratin, sitting on the surface of skin

Question 39

stratum corneum - how long does this layer take to be replaced

Answer 39

4 weeks

Question 40

when a bad sunburn happens, why does the skin peel in sheets

Answer 40

stratum corneum cells still have desmosomes connecting to one another, so it comes off as a sheet

Question 41

ground substance - brief description - what's it made of

Answer 41

- translucent gel component of connective tissue - made up of large carbohydrates, mucopolysaccharides / glycosaminoglycans

Question 42

dermis - name of the 2 layers

Answer 42

papillary layer reticular layer

Question 43

dermis papillary layer - description

Answer 43

its the layer that forms the dermal papillae, and anchors the epidermis

Question 44

what skin structures give rise to fingerprints

Answer 44

dermal papillae and rete networks

Question 45

what skin structures are in dermis (4)

Answer 45

- blood - lymphatic vessels - hair follices - sweat glands

Question 46

what cell produces connective tissue substances

Answer 46

fibroblast

Question 47

role of fibroblasts

Answer 47

produce elastin, collagenous fibres, ground substance

Question 48

characteristics of glycosaminoglycans (3) and their effect

Answer 48

- highly negative charge, which attracts Na+ and therefore water by osmotic pressure - inflexible, so they resist compressive forces - hydrophilic ++, keeps them hydrated

Question 49

4 types of glycosaminoglycans

Answer 49

hyaluronic acid chondroitin sulphate and dermatan sulphate heparan sulphate keratan sulphate

Question 50

hypodermis - main role

Answer 50

connect skin to underlying fascia (fibrous tissue)

Question 51

the types of proper 'non-specialised' connective tissue and the difference between them

Answer 51

- loose and dense irregular connective tissue - loose tissue has more actual cells, dense is mostly extracellular matrix

Question 52

difference in connective tissues of the dermal layers

Answer 52

papillary layer - loose CT rete layer - dense irregular CT

Question 53

other names for hypodermis (2)

Answer 53

subcutis, superficial fascia

Question 54

what makes up the subcutis layer

Answer 54

loose CT and adipose tissue

Question 55

what layer of epidermis are the melanocytes located

Answer 55

stratum basale

Question 56

how do keratinocytes get their pigment

Answer 56

melanocytes produce melanin, which gets deposited in keratinocytes as melanosomes

Question 57

mechanism for skin tanning

Answer 57

excess UV exposure drives up melanin production, which gets deposited in keratinocytes when UV drops, production drops and skin eventually reverts back to previous color

Question 58

what role does melanin play in UV exposure

Answer 58

melanin protects DNA from excess UV exposure

Question 59

what is keratohyalin

Answer 59

protein structure found in granular vesicles inside stratum granulosum, containing keratin, filaggrin

Question 60

epidermal appendages and their functions

Answer 60

eccrine glands - produce sweat apocrine glands - scent glands in armpits, groin pilosebaceous unit - hair and sebaceous gland nails - to scratch people

Question 61

what are the eccrine glands

Answer 61

regular sweat producing gland

Question 62

what are the apocrine glands, where are they located

Answer 62

scent glands in armpits and groin

Question 63

what are the arrector pili muscles where are they located in skin layer

Answer 63

muscle attached to hair follicles, controls where the hair points in the dermis

Question 64

langerhans cells are part of what body system

Answer 64

immune system

Question 65

what cells are langerhans cells derived from

Answer 65

there's debate, some claim monocyte-macrophage, others claim dendritic cells

Question 66

what immune role do langerhans cells have

Answer 66

antigen presenting cells

Question 67

characteristic finding of langerhans cells on histopathology

Answer 67

cytoplasmic birbeck granules

Question 68

what are birbeck granules

Answer 68

cytoplasmic organelles shaped like tennis rackets

Question 69

what cells are birbeck granules found in

Answer 69

langerhans cells

Question 70

where do langerhans cells normally reside when inactive

Answer 70

prickle cell layer of epidermis (stratum spinosum)

Question 71

once activated, where do langerhans cells move to

Answer 71

lymph nodes