The Mouth

Question 1

What are the 3 overall processes occurring due to the mouth?

Answer 1

1. Salivation
2. Mastication (formation of a bolus)
3. Swallowing

Question 2

What epithelia line the tongue? What other mechanisms does the tongue have to perform its sensory and motor role?

Answer 2

Stratified squamous non keratinized

• Has dorsal papillae - some with taste buds
• Movement/Skeletal muscle: fibres oriented in multiple planes with the intrinsic muscles ingurgitating directly with the CT of the tongue

Question 3

How much saliva do we produce a day? Name 3 of its general functions

Answer 3

1. 5L
2. Lubrication
3. Starts digestion of carbs (amylase)
4. Protects the oral environment (Contains many potent anti-bacterial substances)

Question 4

Name 5 mechanisms saliva uses to protect the oral environment

Answer 4

1. Keeps mucosa moist
2. High calcium concentration washes and protects the teeth
3. Maintaining a highly alkaline environment neutralizes the acid produced by bacteria
4. Proteolytic enzymes (lysozyme, lactoperoxidase) attack/destroy the bacteria
5. Secretory antibodies like IgA destroy some microbes in the mouth

Question 5

What enzymes does each of the major salivary glands produce if any? What is the structure of each of the glands?

Answer 5

Parotid: a-amylase, acinar glands
Submandibular: a-amylase and lysozyme, tubuloacinar
Sublingual: purely mucous (no enzymes), tubuloacinar

Question 6

What does the acinar secretion and ductal modification determine about the saliva?

Answer 6

Acinar secretion: determines the volume

Ductal modification: determines the composition

Question 7

What is the primary role of ductal modification?

Answer 7

To make hypotonic saliva by reducing the [Na+]

Question 8

What determines the [HCO3-] in the saliva?

Answer 8

Whether it is saliva at rest or saliva being produced when stimulated, when saliva is stimulated the [HCO3-] rises dramatically

Question 9

What is the primary difference between resting and stimulated saliva? Name 3 characteristics of each

Answer 9

In stimulated, the saliva has to do more work and requires more enzymes. It is also needed much quicker so there is less time for modification:

Resting: low volume, very hypotonic (a lot of Na+ removed), neutral or slightly acid

Stimulated: high volume, less hypotonic (less time to remove Na+), more alkaline

Question 10

What are the two main parasympathetic nerves that control salivary secretion? Which structures do they act upon?

Answer 10

CN IX Glossopharyngeal: Parotid via the otic ganglion

CN VII Facial: submandibular and sublingual

Question 11

Where does the afferent information that inevitably triggers salivation come from?

Answer 11

Taste receptors in the mouth and tongue (especially stimulated by acid), the nose and conditioned reflexes all travel to the centres in the medulla via CN IX and VII

Question 12

How does the efferent information affect salivation? What is the sympathetic and parasympathetic output?

Answer 12

Stimulates the acinar cells, the ductal cells to promote HCO3- secretion (so the [HCO3-] rises)
Sympathetic: reduces blood flow so the mouth is drier and saliva is thicker
Parasympathetic: the release of fluid secretions and increased bloodflow

Question 13

What cell type surrounds the acini and helps saliva move towards the oral cavity

Answer 13

Myoepithelial cells

Question 14

Name 4 muscles that aid in mastication and how they act on the mandible

Answer 14

1. Masseter: elevates
2. Temporalis: elevates and retracts
3. Medial pterygoid: elevation and side-side movements
4. Lateral pterygoid: protrusion and side-side movements

Question 15

What innervates the mandible muscles?

Answer 15

The V3 mandibular nerve (branch of trigeminal (V) nerve) and the facial nerve VII

Question 16

What are the three phases of swallowing? Which parts are voluntary and involuntary

Answer 16

1. Oral phase: voluntary
2. Pharyngeal phase: involuntary
3. Esophageal phase Involuntary

Question 17

What triggers the swallowing reflex. Name 6 things that occur to allow food to safely passage down the esophagus.

Answer 17

Once the bolus is moved to the pharynx the tactile receptors in the oropharynx (stimulated by the pressure/food) begin the swallowing reflex

1. Soft palate lifts to cut off the nasal ways
2. Tongue blocks oral cavity to prevent food from going back into it
3. Epiglottis pushed over the larynx
4. Larynx and vocal cords contract to cover entry to the trachea
5. Respiration temporarily blocked
6. Upper esophageal sphincter opens to allow passage down

Question 18

What is dysphagia and achalasia?

Answer 18

Dysphagia: problems swallowing
Achalasia: is a motility problem in that the muscles of the lower part of the esophagus cannot relax so food can’t pass into the stomach

Question 19

Which nerves might be affected to acquire dysphagia?

Answer 19

The Lower cranial nerves: V trigeminal, VII facial, IX glossopharyngeal, X vagus, XI accessory, XII hypoglossal

Question 20

Name 4 ways one can acquire dysphagia

Answer 20

1. Cervical spinal cord injury
2. Post-surgery
3. Guillian Barre
4. Poliomyelitis

Question 21

Name 6 neuro-degenerative diseases

Answer 21

1. Parkinsons
2. Alzheimer’s
3. Dementia
4. Multiple sclerosis
5. Myasthenia gravis
6. Muscular dystrophy

Question 22

What is amyotrophic lateral sclerosis (ALS)

*Hint: another neurodegenerative disease!

Answer 22

Progressive degeneration of nerve cells controlling muscle movement

Question 23

What condition describes a reduced salivary flow

Answer 23

Xerostomia