Salivation and Swallowing

Question 1

Describe the composition and functions of saliva

Answer 1

mucins = lubrication of food and mouth to eat and speak

amylase = digestive enzyme

Lingual lipase = digestive enzyme

IgA, lysozyme, lactoferrin = immune production, oral hygiene

Medium through which taste molecules get to the taste buds

Question 2

What is xerostomia?

Answer 2

Dry mouth

Problems = dysphagia, cavities, ulcers, problems with speech, bad breath, infections

Question 3

Name the salivary gland?

Answer 3

Parotid = duct medially over masseter, penetrate buccinator into oral cavity

Sublingual = multiple ducts open to oral floor laterally, gland sits above mylohyoid

Submandibular = duct opens to oral floor medially, gland sits below mylohyoid, superficial/deep lobe

Question 4

What is the mylohyoid muscle?

Answer 4

Forms the floor of the oral cavity

Question 5

What controls the secretion from the salivary glands?

Answer 5

Submandibular/sublingual = parasympathetic from the facial N = increase secretion

Parotid = parasympathetic glossopharyngeal N

Sympathetic = vasoconstriction = cant make saliva

Question 6

How can drugs effect salivation?

Answer 6

Any drug that can inhibit muscarinic acetylcholine receptors = decrease salivary prod

Question 7

Outline how mumps effects the parotid gland

Answer 7

Inflam of parotid gland

Pain = parotid contained within fibrous capsule that doesn’t expand

Question 8

How can the duct system of the salivary system be investigated?

Answer 8

Contrast media = Sialography

Stones can be visualised

Question 9

Describe the structure of the oesophagus and outline its functions

Answer 9

Pierce diaphragm at T10

Posterior to trachea, larynx

Right of the thoracic aorta

1st narrowing = junction with pharynx
2nd narrowing = when arch of aorta crosses it
3rd narrowing = left main bronchus crosses in front
4th narrowing = passing through diaphragm

Muscle varies down its length: top = skeletal, middle = mix, bottom = smooth

Question 10

What are the phases of swallowing?

Answer 10

Oral preparatory

Pharyngeal

Oesophageal

Question 11

Outline the oral preparatory phase

Answer 11

Voluntary

Pushes bolus toward pharynx by tongue

Question 12

Outline the pharyngeal phase

Answer 12

Involuntary

Soft palate flaps backward to seal nasopharynx = stops bolus going into the nasal cavity

Pharyngeal constrictors push bolus downwards

Larynx elevates (suprahyoid muscles pull it up), closing epiglottis

Vocal cords adduct (protecting airway) and breathing temporarily ceases

Opening of the upper oesophageal sphincter

Question 13

Outline the oesophageal phase

Answer 13

Involuntary

Closure of the upper oesophageal sphincter

Peristaltic wave carries bolus downwards into oesophagus

Question 14

How are babies able to drink milk and breath at the same time

Answer 14

Epiglottis projects up into nasopharynx = milk hits epiglottis, diverts laterally down into oesophagus

Piriform fossa of larynx= guides bolus down either side of epiglottis towards oesophagus

As they grow = epiglottis pulled down = space for air to enter into the oral cavity to speak

Question 15

Outline the neural control of swallowing and its relation to the gag reflex

Answer 15

Wall of pharynx contains mechanoreceptor –> glossopharyngeal N (oropharynx) –> medulla –> vagus N –> pharyngeal constrictors, contract = push bolus inferiorly

Babies gag reflex = far more anterior

Question 16

How can stroke effect swallowing?

Answer 16

Bit of brain supplying face very close to bit of the brain supplying pharynx

Question 17

How can an oesophageal tumour effect swallowing

Answer 17

Mechanical obstruction = solid bolus, food sticking

Question 18

Describe the anatomical mechanisms that prevent gastro-oesophageal reflux

Answer 18

Thickening of smooth muscle at the lower oesophagus

Diaphragm surrounds oesophagus = pinching = stops back flow

High intra-abdo pressure = collapsing lower oesophagus preventing back flow

Mucosal rosette = fold at the bottom of the oesophagus prevent back flow

Acute angle of entry into the stomach

Question 19

Outline some of the clinical consequences of free gastro-oesophageal reflux

Answer 19

Barrett’s oesophagus

Gastroesophageal reflux disease (GERD)

Ulcers

Oesophageal cancer