Lecture 7-Salivation and Swallowing

Question 1

What are the functions of saliva?

Answer 1

• lubrication of food and structures in mouth
• keep teeth healthy
• transmit disease eg rabies
• contains lysozyme to destroy bacteria in food
• taste molecules
• first aid in digestion

Question 2

What are the components of saliva?

Answer 2

• mostly water
• K+ and HCO3-
• mucins for lubrication
• amylase
• lingual lipase
• immune proteins

Question 3

Which gland produced 3-5% of saliva?

Answer 3

Sublingual gland

Question 4

What type of secretions does the sublingual gland produce?

Answer 4

Mucous-like secretions

Question 5

What type of secretions does the submandibular gland produce?

Answer 5

Mixed serous and mucous secretions

Question 6

What type of secretions does the parotid gland produce?

Answer 6

Serous saliva, watery solution with enzymes

Question 7

Which salivary gland is the largest and most lateral?

Answer 7

Parotid

Question 8

Which muscle does the parotid duct pass through?

Answer 8

Buccinator

Question 9

Which nerve innervates the parotid gland?

Answer 9

CN IX

Question 10

True or false: the submandibular gland sits above the mylohoid muscle in the floor of the mouth

Answer 10

FALSE - sits below. Sublingual gland sits above

Question 11

Is the submandibular gland located medially or laterally in the floor of the mouth?

Answer 11

Medially (Medial, subMandibular. subLingual is Lateral)

Question 12

Which nerve innervates the submandibular and sublingual glands?

Answer 12

Chorda tympani (branch of CN VII)

Question 13

Which drugs cause xerostomia?

Answer 13

Anti-muscarinics

Question 14

What is xerostomia?

Answer 14

Dry mouth

Question 15

What are the 3 stages of swallowing?

Answer 15

Oral phase
Pharyngeal phase
Oesophageal phase

Question 16

Describe the oral phase of swallowing

Answer 16

• voluntary

- tongue pushes bolus towards pharynx

Question 17

Describe the pharyngeal phase of swallowing

Answer 17

• involuntary
• soft palate seals nasopharynx
• pharyngeal constrictors push bolus down
• larynx elevates to close epiglottis
• vocal cords adduct and breathing temporarily ceases
• UOS opens

Question 18

Describe the oesophageal phase of swallowing

Answer 18

• involuntary
• UOS closes
• peristaltic wave carries bolus down

Question 19

If swallowing closes the airway and inhibits breathing, how is breastfeeding possible?

Answer 19

The epiglottis projects up into the nasopharynx so the baby can breathe and drink but it means the baby cannot speak. Milk hits the epiglottis and is diverted laterally into the oesophagus

Question 20

Describe the neural control of the gag reflex

Answer 20

Mechanoreceptors in the wall of the pharynx detect the bolus -> CN IX is the afferent limb -> medulla -> CN X is the efferent limb -> pharyngeal constrictors

Question 21

True or false: baby’s gag reflex is more anterior than adults

Answer 21

TRUE

Question 22

What are the four points along the oesophagus where it can be narrowed due to anatomical relations?

Answer 22

• junction with pharynx
• arch of aorta crosses
• left main bronchus crosses
• where oesophagus passes through diaphragm (oesophageal hiatus)

Question 23

Describe the muscle in the:

1) superior 1/3 of the oesophagus
2) middle 1/3
3) inferior 1/3

Answer 23

1) voluntary striated
2) voluntary striated and smooth muscle
3) smooth muscle

Question 24

How is the LOS formed?

Answer 24

Thickening of smooth muscle

Question 25

What prevents gastro-oesophageal reflux?

Answer 25

- diaphragm surrounds oesophagus and pinches it to prevent backflow of stomach contents - intra-abdominal oesophagus gets compressed when intra-abdominal pressure rises - mucosal rosette/folds - acute angle of entry of oesophagus into stomach

Question 26

What is dysphagia?

Answer 26

Difficulty swallowing

Question 27

How can a stroke cause dysphagia?

Answer 27

Part of the brain supplying the face is infarcted and sits close to the part of the brain supplying the pharynx and muscles for swallowing