OB P1 - Oral mucosa

Question 1

What are the 2 basic tissues of oral mucosa?

Answer 1

– epithelium (superficially) (tightly packed)

– connective tissue (underlying)

Question 2

What is the role of oral mucosa?

Answer 2

> Protection
– mechanical
– bacterial
– chemical
– prevent dehydration (barrier)

> Secretion
thermal regulation

Question 3

Describe the sensation of oral mucosa?

Answer 3

richly innervated

Question 4

Describe the oral mucosa layers from the teeth up.

Answer 4

• Free gingiva
• attached gingiva
• alveolar mucosa

Question 5

what junction is between alveolar mucosa and attached gingiva?

Answer 5

Mucogingival junction

Question 6

What are the 3 main types of mucosa in the mouth?

Answer 6

• Masticatory (tough , around the teeth and hard palate)
• Lining mucosa
• Specialised (dorsum of the tongue - receptors for taste)

Question 7

What are the layers of non-keratinised lining mucosa?

Answer 7

• Epithelium
• Lamina propria
• submucosa
• bone or muscle

Question 8

Where is non-keratinsed lining mucosa found?

Answer 8

Inside the lips, alveolar mucosa, floor of the mouth, soft palate , buccal mucosa

Question 9

Describe the features of non-keratinised lining mucosa.

Answer 9

• Undulating interface with lamina propria
• few rate pegs
• Lamina propria and submucosa
• no muscularis mucosae
• flexible
• not subjected to high stress

Question 10

Name the layers of the epithelium of non-keratinised lining mucosa.

Answer 10

• Superficial layer
• intermediate layer
• Prickle cell layer
• basal cell layer

Question 11

Name the layers of the epithelium of non-keratinised lining mucosa using terms used in Berkovitz et al.

Answer 11

• Stratum superficiale
• Stratum intermedium
• Stratum spinosum
• Stratum germinativum

Question 12

How did the prickle cell layer get its name?

Answer 12

When you fix a tissue -shrinkage occur

-Cells shrink but they are still attached by desmosomes so have prickly appearance

Question 13

What do all epithelial cells have?

Answer 13

• filaments

- desmosomes

Question 14

Describe basal cells (lining mucosa).

Answer 14

• Least differentiated

- mitosis often visible

Question 15

Describe prickle cells (lining mucosa).

Answer 15

Membrane coating granules (MCGs)

Question 16

Describe the intermediate layer (lining mucosa).

Answer 16

MCGs discharge contents between cells:

• permeability barrier
• not wholly effective

Question 17

What is the clinical importance of MCGs discharging its contents between cells?

Answer 17

-Drugs absorbed such a sublingual GTN sprays for angina (rich blood supply to oral mucosa so it is rapidly absorbed and pain goes away)

Question 18

Describe the superficial layer (lining mucosa).

Answer 18

• flattened cells
• nuclei persist
• not dehydrated so flexible

Question 19

Why are superficial cells in lining mucosa alive?

Answer 19

Nutrients from the basal layer come through the spaces to the superficial layer

Question 20

What are the layers of keratinised masticatory mucosa?

Answer 20

• Epithelium
• lamina propria
• periosteum
• bone

Question 21

What are the 2 layers of lamina propria?

Answer 21

• papillary layer

- reticular layer

Question 22

Describe the features of keratinised masticatory mucosa.

Answer 22

• many rete pegs /ct papillae
• no submucosa
• thick lamina propria
• lamina propria firmly anchored to bone
• resistant to compression
• relatively immobile
• mechanically tough

Question 23

Describe the difference in the sensation of local anaesthesia between lining mucosa and masticatory mucosa.

Answer 23

• Lining mucosa - flexible - can be pain free if done properly
• Masticatory mucosa -tightly bound down - can hurt

Question 24

Name the layers of the epithelium of keratinised masticatory mucosa.

Answer 24

• Keratinised layer
• granular layer
• prickle cell layer
• basal cell layer

Question 25

Name the layers of the epithelium of keratinised masticatory mucosa using terms used in Berkovitz et al.

Answer 25

- Stratum corneum - Stratum granulosm - Stratum spinosum - tratum germinativum

Question 26

Describe the basal cells (masticatory mucosa).

Answer 26

like non-keratinised epithelium

Question 27

Describe the prickle cells (masticatory mucosa).

Answer 27

filaments organised into bundles -tonofibrils

Question 28

Describe the keratohyaline granular in the granular layer cells (masticatory mucosa).

Answer 28

Keratohyaline granules: - 0.5 to 1 microns - associated with tonofibrils - filaggrin (forms matrix for filaments in keratinised layer)

Question 29

Describe the MCGs in the granular layer cells (masticatory mucosa).

Answer 29

MCGs discharge contents sealing cells together : - effective permeability barrier - cells beyond this barrier zone are de-hydrated (-stuff from outside will not get beyond this layer i.e drugs -also nutrients dont get to keratiniased cells (so they are dead)

Question 30

Describe the keratinised layer (masticatory mucosa)

Answer 30

- Flattened cells - "squames" - no organelles - contain filled with keratin - dehydrated -not flexible

Question 31

What is para-keratinised?

Answer 31

Incomplete removal of organelles from the superficial layers : -nuclei shrunken -pyknotic

Question 32

What is epithelial turnover?

Answer 32

From cell dividing to cell being lost (i.e basal to shed)

Question 33

What is the epithelial turnover for junctional epithelium?

Answer 33

5 days

Question 34

What is the epithelial turnover for the cheek?

Answer 34

10-14 days

Question 35

what epithelial turnover is slower?

Answer 35

masticatory mucosa

Question 36

what is the speed of healing process?

Answer 36

rapid ( no scarring in the mouth)

Question 37

Describe the epithelial abnormalitie acanthosis.

Answer 37

– Hyperplasia of the prickle cell layer | – e.g. psoriasis

Question 38

Describe the epithelial abnormalitie acantholysis.

Answer 38

– Disruption of intercellular connections | – e.g. pemphigus

Question 39

what are keratinocytes characterised by?

Answer 39

– Tonofillaments | – Desmosomes

Question 40

How many cells within the epithelium are keratinocytes ?

Answer 40

90%

Question 41

what make up the other 10% of cell in epithelium?

Answer 41

Non-kerartinocytes - "clear cells"

Question 42

What do non-keratinocytes lack?

Answer 42

tonofilaments and desmosomes

Question 43

what do non-keratinocytes include?

Answer 43

– Merkel cells – Melanocytes – Langerhan’s cells – Inflammatory cells

Question 44

Why do non-keratinocytes appear clear under light microscopic appearance?

Answer 44

After fixing, the cells shrink and with no desmosome attachments they do not stay attached to neighbouring cells and look like a clear space

Question 45

What are the 2 types of clear cells in a basal layer?

Answer 45

-Merkel cells : touch receptors -Melanocytes : dense melanosomes melanin

Question 46

what is the degree of pigmentation due to?

Answer 46

Due to the activity of melanocytes , not the number (everyone has a similar number of melanocytes )

Question 47

What are the 2 types of suprabasal layer clear cells?

Answer 47

- Langerhans cells | - Inflammatory cells

Question 48

Describe langerhans cells.

Answer 48

- In more superficial layers - Dendritic - Process antigenic material

Question 49

Describe inflammatory cells.

Answer 49

- transiently migrate into epithelium | - lymphocytes common

Question 50

what structures are found between the epithelium and the connective tissue papilla?

Answer 50

Rete peg

Question 51

Describe the epithelium-lamina propria interface.

Answer 51

Large surface interface area: – disperses applied forces | – metabolic interchange

Question 52

what is controversial about rate pegs?

Answer 52

Is it pegs of epithelium in connective tissue? OR Is it pegs of connective tissue in epithelium? OR Is it folding?

Question 53

What is in the basal lamina?

Answer 53

- Basal cell - hemi-desmosomes - lamina lucida - lamina densa - anchoring filaments - collagen fibrils - anchoring fibrils

Question 54

what are the 2 layers of the basal lamina?

Answer 54

-Lamina lucida : >45nm thick >glycoprotein -laminin -Lamina densa: >50nm thick >type IV collagen and laminin

Question 55

What is found in the lamina propria?

Answer 55

``` - Collagen: > 90% type I >8% type III - Loose in papillary layer - More organised in the reticular layer - Fibroblasts - Defence cells ```

Question 56

What is the sensory innervation of connective tissue?

Answer 56

– free nerve endings – krause end bulbs – ruffini corpuscles

Question 57

What is the sensory innervation in epithelium?

Answer 57

– free nerve endings | – Merkel cell ‐ neurite complexes