Salivation And Swallowing

Question 1

Describe the composition of saliva

Answer 1

Mostly water
Hypotonic 
Rich in K+ and bicarbonate 
Mucins
Amylase, lingual lipase
Immune proteins (IgA, lysozyme, lactoferrin)

Question 2

What is lactoferrin?

Answer 2

A molecule which binds iron

Bacteria need iron to reproduce therefore bacteria cannot multiply

Question 3

Name some of the functions of salvia

Answer 3

Phonation 
Lubrication of food
Oral hygiene 
Anti-bacterial effects 
Solvent for tasting 
Initiation of digestion

Question 4

What is xerostomia?

Answer 4

Dry mouth

Question 5

What are some of the consequences of xerostomia?

Answer 5

Inflamed and dry tongue 
Sore lips 
Dysphagia 
False teeth fall out 
Poor dentition

Question 6

What are the 3 pairs of salivary gland?

Answer 6

Parotid
Sublingual
Submandibular

Question 7

Describe the parotid gland

Answer 7

Large
Sits over the angle of the mandible
Penetrates the buccinator muscle opposite the 2nd upper molar

Question 8

Describe the sublingual gland

Answer 8

Just above the floor of the mouth

Lots of little ducts under the tongue

Question 9

Describe the submandibular gland

Answer 9

Just under the floor of the mouth
Sits above and below a particular muscle (around it)
Big gland

Question 10

Describe the neural control of glands

Answer 10

Autonomic
PNS - increased production
SNS also stimulates secretion but smaller amounts
Parotid = IX cranial nerve
Sublingual and submandibular = VII cranial nerve (facial nerve)

Question 11

Which branch of cranial nerve VII innervates the sublingual and submandibular gland?

Answer 11

Chorda tympani of VII

Question 12

Why can saliva production be reduced during ear infections?

Answer 12

Chords tympani of VII cranial nerve runs through the ear

Innervates the sub salvia glands

Question 13

Describe mumps

Answer 13

Inflammation of the parotids
Can also have testes and brain involvement
Extremely painful because fascial sheath of the parotid gland is not very distensible and infection causes swelling

Question 14

Describe a parotid sialography

Answer 14

Radiological investigation of salivary glands
Catheter into the mouth, insert contrast into ducts
Useful for finding stones or visualising a tumour

Question 15

How many stages are there in swallowing?

Answer 15

3

Question 16

Describe the first phase of swallowing

Answer 16

Oral preparatory phase
Voluntary
Push bolus towards the pharynx via a convulsive wave over the tongue

Question 17

Describe the second phase of swallowing

Answer 17

Pharyngeal phase
Involuntary phase
Soft palate seals off the nasopharynx
Pharyngeal constrictors push the bolus down
Larynx elevates, closing the epiglottis
Vocal cords adduct - breathing temporarily ceases
Opening of upper oesophageal sphincter

Question 18

Describe the third phase of swallowing

Answer 18

Oesophageal phase
Involuntary
Closure of upper oesophageal sphincter
Peristaltic wave carries bolus downwards into oesophagus

Question 19

How is the epiglottis different in a baby?

Answer 19

Epiglottis extends into the nasopharynx in a baby

They can breathe and drink at the same time

Question 20

Describe the neural pathway controlling swallowing

Answer 20

1. Mechanoreceptors in pharynx detect bolus
2. Sensory glossopharyngeal nerve
3. Medulla
4. Vagus nerve
5. Contraction of pharyngeal constrictors

Question 21

How does the gag reflex differ in babies?

Answer 21

Hyperactive - because the gag relax sits more anteriorly

Why they often dribble food

Question 22

Where are the narrowings of the oesophagus?

Answer 22

Junction with pharynx (upper sphincter)
Where arch of aorta crosses
Compressed by left main bronchus
Oesophageal hiatus through diaphragm