Lecture 2 : Mouth and Esophagus

Question 1

The Mouth

Answer 1

• Beginning of digestion
• Site of secretions

Question 2

Teeth and Tongue

Answer 2

• Teeth masticate, ie. Break down food
• Decrease particle size, larger SA, better enzyme action
• Tongue tastes via papillae, enables swallowing by pushing food to back of throat

Question 3

Salivary Gland

Answer 3

• Exocrine gland
• 2 types of secretions : serous (proteins) and mucous (lubricant)

Acinar Cells
- secrete enzymes
- Produces saliva by transport of ions across membranes
- Saliva is hypotonic and alkaline

Goblet Cells
- Provide lubrication
- Keeps oral mucosa hydrated
- Secretes mucus which protects mucosa in mouth and esophagus from damage

Question 4

Sjogren’s syndrome and Mumps virus (parotitis)

Answer 4

Sjorgren
- Autoimmune condition where salivary and tear glands don’t secrete enough fluid, so eyes and mouth become dry
- Associated with rheumatoid arthritis

Mumps (parotitis)
- Mumps is viral infection causing parotitis, saliva gland is blocked, dry mouth, swelling, pain
- Swelling of parotid gland is common symptom
- Cured with MMR Vaccine

Question 5

Esophagus

Answer 5

• Only secretion is mucus
• Upper third contains striated muscle, middle third mixture of striated muscle and smooth muscle, lower third just smooth muscle

Question 6

Process of swallowing

Answer 6

1. Oral Preparatory Phase
   - Food masticated
   - SA reduced
   - Consistency of food safe enough for swallowing
2. Oral Transport Phase
   - Tongue propels food posteriorly til pharyngeal swallow is triggered
3. Pharyngeal Phase
   - Food Swallowed
   - Bolus travels through pharynx
4. Oesophageal Phase
   - Peristalsis carries bolus to lower oesophageal sphincter

Question 7

Gastro-oesophageal reflux disease

Answer 7

• When acid from stomach leaks into oesophagus
• Causes are obesity, hernia, drugs, pregnancy (Sometimes)

Question 8

Achalasia

Answer 8

• Less neuronal cells in lower oesophageal segment
• So passing food through oesophagus is more difficult due to impaired peristalsis
• Difficulty swallowing

Question 9

Barret’s Metaplasia

Answer 9

When normal squamous epithelium of lower esophagus is replaced by columnar epithelium due to chronic acid reflux