Gastric motility Vomiting Dr Ahrsia V F Department

Gastric motility Vomiting Dr. Ahrsia V F Department of Physiology 29/1/19

Objectives • Gastric motility • Vomiting • Applied aspects

Gastric motility • Hunger contractions • Receptive relaxation and accommodation • Mixing peristalsis and retropulsion • Gastric emptying

Hunger contractions Type I Hunger Contractions • Each contraction lasts for about 20 seconds. • The interval between contractions is about 3 to 4 seconds. • Pressure produced by these contractions is about 5 cm of H 2 O. Type II Hunger Contractions • Each of the type II contractions lasts for 20 seconds, but the pause between the contractions is decreased. • 10 to 15 cm of H 2 O. Type III Hunger Contractions • These contractions appear when the hunger becomes severe and the tone increases to a great extent. • These contractions last for 1 to 5 minutes. • 10 to 20 cm of H 2 O.

Receptive relaxation and accommodation • Bolus of food stimulates stretch receptors Distension of stomach

Mixing peristalsis and Retropulsion • 3 -4/minute. • Formation of chyme

Gastric emptying Factors Affecting Gastric Emptying 1. Volume of gastric content: gastric emptying is directly proportional to the volume. 2. Fluidity/ consistency of chyme 3. Chemical composition of the food : Carbohydrates >proteins > fats. 4. p. H of the gastric content 5. Gastrin 6. Enterogastric reflex /enterogastric hormones

Vomiting • Emesis: Causes: • Presence of irritating contents in GI tract • Mechanical stimulation of pharynx • Pregnancy • Excess intake of alcohol • Nauseating sight, odor or taste • Unusual stimulation of labyrinthine apparatus, as in the case of sea sickness, air sickness, car sickness or swinging • Drugs like antibiotics, opiates, etc. • Any GI disorder

• Vomiting reflex:

Events: • Pre-ejection phase Nausea, excessive salivation • Retching phase Contraction of abdominal , intercostal and diaphragmatic muscles • Ejection phase

Gastric Dumping Syndrome • Gastrectomy • Weakness, dizziness and sweating after meals Cause: • Sharp oscillations between hyperglycemia and hypoglycemia • Hypertonic meals in small intestine.

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