The Mouth and Oesophagus L2

Question 1

Digestion ?

Answer 1

• The process of digestion is the
  conversion of dietary nutrients into a
  form that the small intestine can
  absorb.
• Digestion starts in the oral cavity

Question 2

The mouth

Answer 2

• The mouth is lined by
  mucous membranes-oral
  mucosa.
• Secretions in the mouth are
  saliva, salivary amylase,
  mucus and lysozyme

Question 3

The Teeth

Answer 3

Mastication: chewing food
* Function: decrease particle size
(larger surface area)
* Larger surface area in the food
allows better action of the digestive
enzymes.

Question 4

Tongue

Answer 4

• taste : the papillae contain taste
  buds that has gustatory cells (taste
  receptors)
• Prepares food for swallowing –
  cohesive bolus

Question 5

Saliva

Answer 5

Saliva contains water (99.5%), electrolytes, mucus, amylase,
lysozymes
* It plays a major role in motility, taste and cleaning the mouth.
* There are 3 pairs of salivary gland innervated by the
parasympathetic autonomic nervous system

Question 6

Salivary gland

Answer 6

The salivary gland is an exocrine gland. This
means that it contains branched ductal
system used to release secretory productssaliva.
* The salivary gland gives two types of
secretions: serous (protein) and mucous
(lubricant).
* Acinar cells produce enzymes, and the
ductal cells produce mucous.

Question 7

Salivary gland - acinar cells

Answer 7

Produces saliva by transporting
ions (Na, K, Cl) across cell
membranes.
* They also secrete enzymes,
proteins and other substances.
* Saliva is hypotonic and alkaline.

Question 8

Salivary gland - goblet ( ductal ) cells

Answer 8

• Lubrication
• Hydration: Keeps the oral
  mucosa moist and prevents
  dehydration and cell death
• Cytoprotection: Protects oral and
  oesophageal mucosa from
  damage

Question 9

Salivary gland diseases

Answer 9

Sjögren’s syndrome
* Autoimmune condition that
affects salivary and tear glands
which results in dry mouth and
eyes
* Associated with rheumatoid
arthritis; commonly affects
women

Mumps virus (parotitis)
* Mumps is a viral infection that
causes parotitis
* The most common sign of
mumps is the swelling of the
parotid gland (bilateral)
* MMR vaccine

Question 10

The Oesophagus

Answer 10

• A muscular tube that connects the
  pharynx to the stomach.
• The main secretion in the pharynx and
  oesophagus is mucus
• The upper third of the oesophagus
  contains striated muscle, the lower third
  contains smooth muscle, and the
  middle third contains a mixture of both

Question 11

The process of swallowing

Answer 11

1. Oral Preparatory Phase - food is manipulated in the mouth
   and masticated to reduce to a consistency which can be
   swallowed
2. Oral Transport Phase - the tongue propels food posteriorly
   until the pharyngeal swallow is triggered
3. Pharyngeal Phase - once the pharyngeal swallow is
   triggered, the bolus is transported through the pharynx with
   coordinated closure of the glottis via movement of the
   epiglottis and cessation of breathing and relaxation of the
   upper oesophageal sphincter (UOS)
4. Oesophageal Phase - oesophageal peristalsis carries the
   bolus from the UOS through the oesophagus to the Lower
   oesophageal Sphincter

Question 12

Gastro-oesophageal reflux disease (GORD)

Answer 12

• A disorder where acid from the stomach
  leaks into the oesophagus
• Common causes are obesity, hiatus
  hernia, drugs that lower tone at LOS (anti
  cholinergic, beta agonist,
  benzodiazapenes), pregnancy, Zollinger
  Ellison syndrome and gastrin secreting
  tumour

-Sliding hernia (80%)– the GOJ, the abdominal part of
the oesophagus, and frequently the cardia of the
stomach slides upwards through the diaphragmatic
hiatus into the thorax.

-Rolling hernia (20%) – an upward movement of the
gastric fundus occurs to lie alongside a normally
positioned GOJ, which creates a ‘bubble’ of stomach
in the thorax.

Question 13

Outcome of GORD

Answer 13

Effects
1. Oesophagitis
2. Stricture
3. Barrett’s metaplasia (BM)
4. Oesophageal adenocarcinoma (OAC)

Question 14

Barrett’s metaplasia

Answer 14

Metaplasia: ‘change of epithelial type in response to environmental stress’.
* 10% of patients with GORD develop Barrett’s metaplasia (BM)
* BM is considered a pre-malignant condition for oesophageal adenocarcinoma

Question 15

Treatment

Answer 15

CONSERVATIVE
Weight loss
Avoid food/alcohol close to bedtime
Decrease alcohol
Raise head of bed 20-30cm

MEDICAL
Decrease acid
Proton pump inhibitors
H2 blockers
Antacids increase pH
Alginates (Gaviscon)

SURGICAL
Anti reflux surgery ‘fundoplication’
Repair hiatus hernia
(historic note: Vagotomy – decreases acid
production)

Question 16

Achalasia

Answer 16

• Achalasia – dramatic reduction in the number of neuronal
  cells in the lower oesophageal segment.
• It makes it difficult for food to pass from the oesophagus
  into the stomach due to impaired oesophageal peristalsis.
• Progressive degeneration of myenteric neurons prevents
  the lower oesophageal sphincter from relaxing. This
  results in dilation of the oesophagus.
• Symptoms: difficulty swallowing (dysphagia),
  regurgitation of undigested food, pain
• Diagnosis: barium swallow test, endoscopy
  (rule out GE junction tumors, esp. age>60),
  oesophageal manometry (absent peristalsis,
   LES relaxation, & resting LES >45 mmHg)
• Treatment: focus on relieving symptoms
  (medications: nitrates and calcium blockers),
  decrease pressure of LES (pneumatic
  dilation, botulinum toxin injections).