1. Describe briefly the sources of gastric innervation.

• Extrinsic supply: from the sympathetic and parasympathetic systems

• Intrinsic supply: from the enteric nervous system

2. What is the autonomic supply?

• Sympathetic: from the coeliac plexus. Reduces gastric motility

• Parasympathetic: from the vagus nerve – causing increased motility

3. What is the storage capacity of the stomach?

1–2L.

4. How does the stomach accommodate this volume without painful distension?

It undergoes the process of receptive relaxation. This is a vagally mediated reflex where the fundus and the body relax when distending with food.

5. Apart from receptive relaxation, name some other important gastric reflexes.

• Peristalsis: the basic electrical rhythm of the stomach generates slow waves that pass from inflow to outflow segments, propelling food

• Retropulsion: when chyme is pushed backwards and forwards in the lumen. This helps to break up boluses

• Emptying

• Vomiting reflex

6. List the hormones which stimulate gastric emptying.

• Gastrin: released from the gastric G-cells

• CCK: from the duodenum

• Secretin: also from the duodenum

7. What happens to the stomach during the process of vomiting? Outline the steps.

• The process begins with a deep inspiration

• This is followed by closure of the glottis

• There is diffuse contraction of the abdominal and thoracic muscles. This elevates the pressures of both compartments. The intra-abdominal pressure may rise to 800 mm Hg

• Simultaneously, there is relaxation of the lower oesophageal sphincter

• There is a large retrograde contraction of the stomach, forcing the contents into the oesophagus following relaxation of the cricopharyngeus muscle

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