L28. oral cavity

Question 1

What does the digestive system consists of

Answer 1

1. oral cavity
2. alimentary canal
3. accessory glands

Question 2

What are the functions of the bolus

Answer 2

1. mastication (chewing)
2. swallowing /deglutttion
3. bolus formation
4. ingestion /taste

Question 3

What are the 3 compoents of the lips?

Answer 3

1. external
2. intermediate/vermillion
3. internal

Question 4

Describe the external aspect of the lips

Answer 4

• continuous with the skin

- keratinizes stratified squamous epithelium

Question 5

Describe the intermediate vermillion section of the lips?

Answer 5

1. highly vascularized lamina propria

2. no hair, sweat , sebacous glands

Question 6

Describe the internal aspect of the lip

Answer 6

• continuous with the cheek (same histology)
  1. epithelium: non-keratinized stratified squamous epithelium
  2. lamina propria: dense irregular CT.
  3. submucosa: contains mucous gland which keeps lips moistened
  4. adventitia: skeletal muscles (orbicularis oris muscles) continuous with gums ( gingiva)

Question 7

Describe the gingiva

Answer 7

• gums
• forms a bacterial barrier around the roots of the teeth
• junctional epithelim protects the periodental ligament by acting as a bacterial barrier
• lamina propria mingles with the periodental ligament and fuses tooth with bony sockets

Question 8

Describe the epithelium of the gingiva

Answer 8

slightly keratinized stratified squamous epithelium

Question 9

Describe the mucosal layer of the gingiva

Answer 9

dense irregular connective tissue contains a lot of collagen 1 fibers

Question 10

Describe the adventitia layer of the gingiva

Answer 10

bone ( maxilla: upper ;mandible: lower)

Question 11

Describe bacterial gingivitis ( redness of the gum)

Answer 11

due to inflammation of the lamina propria layer

if untreated: periodental ligament: collagen 1 fibers anchor the teeth to the underlying gum line

Question 12

When does tooth formation begin

Answer 12

6 week of gestation

Question 13

What are the components of the tooth

Answer 13

1. enamel
2. dentin
3. pulp cavity

Question 14

Describe the enamel

Answer 14

• 95% hydroxapetite crystals /mineralized
• non-regenerative (non-vital) once degraded by bacteria ( cavity) cannot be re-formed
• formed by ameloblast (on outer surface of tooth: dies after teeth erupts)

Question 15

Describe dentin

Answer 15

• minearlized 70% hydoxyapetite
• regenerative
• pain if injured
• produced by odontoblast on the inner surface of the tooth lining in pulp chamber

Question 16

Describe the pulp chamber

Answer 16

• nerves and vessles enter and exit the narrow space
• loose CT and high GAG content
• highly vascularized and innervated

Question 17

Where are ameloblast derived from

Answer 17

oral ectoderm/ dental placode

Question 18

Where are odontoblasts derived

Answer 18

mesoderm

Question 19

Describe odontogenesis

Answer 19

1. INDUCTION: dental placode forms above the mesnchyme and there are paracrine signaling factors (SHH and BMP) exchanged between the dental placode and the mesenchyme layer. induces differentiation and the dental placode sinks into the mesenchyme
2. MORPHOGENESIS: placode sinks to form a folded cap (enamel organ gives rise to the ameloblast that forms enamel). mesenchyme forms odontoblast . pulp forms from mesenchyme. mesenchyme differentiates to form the periodontal ligaments besides the oral ectoderm and cementoblasts
3. DEVELOPMENT: ameleoblasts die after the tooth erupts, enamel is revealed

Question 20

Describe the crown of the teeth

Answer 20

2 types anatomical and clinical

• anatomical: portion of tooth covered by the enamel
• clinical: enamel above the gingiva (visible portion of teeth)
• anatomical crown:anatomical crown is surrounded by junctional epithelium from the gingiva -> protects against pathogenic invasion

Question 21

Describe the periodental ligament

Answer 21

1. highly vascularized
2. highly innervated
3. mesodermally derived
4. collagen 1 fibers embed the spongy bone and the cementum (collagen 1 fibers radiate into the lamina propria of the gingiva)

Question 22

Describe the alveolus

Answer 22

socket of spongy bone in the mandible and maxilla

Question 23

Describe the cementum

Answer 23

1. directly attached to the outer aspect of dentin
2. bone-like and produced by cementoblast (like osteoblast)
3. resorbed by cementoclast ( like osteoclast)

Question 24

Describe the palate

Answer 24

• roof of the oral cavity
• separates the nasal and oral cavities
• hard palate is located anteriorly and the soft palate is located posteriorly

Question 25

Describe the hard palate

Answer 25

• keratinized stratified squamous layer

- adventitia contains bone

Question 26

Describe the soft palate

Answer 26

• non-keratinized stratified squamous layer
• contains skeletal muscles -elevates the soft palate during swallowing to prevent food from going upwards to the nasal cavity
• elevates uvula during swallowing to close nasal cavity

Question 27

Describe the tongue

Answer 27

• floor of the oral cavity
• contains papillae
• consists of keratinized stratified squamous keratinized epithelium and a core lamina propria. contains dense irregular connective tissue
• lamina propria (posterior aspect) contains MALT: lingual tonsiles
• serous glands are prominent in the submucosa; secretions from these glands trap tastant molecuels that can stimulate dendritic microvili of sensory receptors

Question 28

What is papillae

Answer 28

mucosal specializations

Question 29

are lymphoid nodules basophilic or acidophilic

Answer 29

basophilic

Question 30

Where are lingual tonsiles (lymphoid nodules) found

Answer 30

lamina propria of tongue papilia

Question 31

Describe the taste buds

Answer 31

• found in the epithelium
• spindle shaped sensory cells with dendritic microvili protruding apically from taste pore
• tastants dissolved in the serous fluid bind to G-protein coupled receptors and ion channels on the microvili
• downstream signals stimulate synapse like release and activation of afferent sensory neurons