aspects of GIT - vomiting, BER and hunger contractions.pptx

MMC, hunger contractions , vomiting, BER in brief

1. Basic Electrical Rhythm Gastric slow waves caused by slow fluctuation in RMP of GIT smooth muscle. Rhythmic depolarization + repolarization. Initiated by the Interstial cells of Cajal . Presence of food in the stomach initiates weak peristaltic constrictor waves – mixing waves. Intensity : 5 to 15mV Frequency: 3 to 12/min stomach: 3/min Duodenum: 12/min KA

2. They help in mixing the food and most of the antral contents are squeezed into the body of the stomach and not towards the pylorus. Retropulsion. After being thoroughly mixed it forms chyme that enters the intestine after staying in the stomach for 2 – 3 hrs. Gastrin, Histamine, Ach, nicotine,K + : - stimulatory Enterogastrone ( CCK and secretin), NE, Epinephrine : – inhibitory KA

3. Hunger contractions Another type of Gastric contraction Occur in the stomach when empty May experience mild pain – hunger pangs Occurs 12 – 24 hrs after the last ingestion of food. Increases in 3 – 4 days…… weakens Ghrelin a peptide hormone causes hunger contractions. KA

4. MIGRATING MOTOR COMPLEX. Initiated by Motilin . Ghrelin may play a role moves from the stomach to the intestine Regular rate ( 5 cm/min) 3 phases: Phase 1: no electrical or mechanical activity Phase 2: irregular electrical and mechanical activity Phase 3: regular electrical and mechanical activity MMC is inhibited by food. Occurs 1.5 to 2 hrs after meal There is increase secretion of bile, gastric and pancreatic juice. Helps to clear the GIT. KA

5. APPLIED PHYSIOLGY GIT KA

6. ULCER DEFINITION: : discontinuity or break in the membrane lining. An ulcer is a crater-like lesion on the skin or mucous membrane of the mouth, stomach, and other body areas PEPTIC ULCER  Is an excoriated area or is a break in the inner lining of the stomach, first part of the small intestine or sometimes the lower oesophagus. KA

7. Why does the stomach not digest itself? Surface of the mucosa lined by cells that secrete alkaline mucous Protein content of the mucus and alkalinity neutralizes H + ions. Tight Junctions Repair of damaged cells KA

8. Common sites: Lower part of esophagus Stomach Duodenum Lesion may occur in the submucosa or lamina propria , to cause bleeding. Commonly occurs in the duodenum or stomach - may also occur in the lower oesophagus due to reflux of the gastric content. Cause for peptic ulcer: So, peptic ulcer can be caused by 1. excess secretion of acid and pepsin by gastric glands. 2. diminished ability of the gastroduodenal mucosal barrier to protect against the gastric juice. KA

9. Pathophysiology KA

10. Helicobacter pylori Gram-negative,  microaerophilic  bacterium usually found in the stomach. 75% of the peptic ulcers in the lower portion of gastric mucosa and duodenum is due to H.Pylori . H.pylori is capable of penetrating the mucosal barrier and stimulate the secretion of HCl . KA

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13. NSAID’s: strong propensity to break down the gastroduodenal mucosal barrier. Smoking : increases the nervous stimulation of the gastric glands Alcohol: breaks down the mucosal barrier. Stress: increases the secretion of gastric glands. KA

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15. Treatment 1. life style modification 2. Proton pump inhibitors: - The parietal cells release H + ions (protons) during HCl production - This process is called the “proton pump” Irreversibly bind to H + /K + ATPase enzyme O meprazole ( Prilosec ), lansoprazole ( Prevacid ), rabeprazole ( Aciphex ), esomeprazole ( Nexium ) and pantoprazole ( Protonix ) KA

16. 3. H 2 blockers : Antihistaminic agents that block the stimulatory effect of histamine on gastric glands. Reduces gastric acid secretion by 70-80% ranitidine (Zantac), famotidine ( Pepcid ), cimetidine ( Tagamet ) and nizatidine KA

17. 4. Antacids: Neutralise gastric acids with antacids. Gelusil Contains Aluminium hydroxide/calcium carbonate 5. Surgery: Failure of medical treatment. Severe bleeding Gastrectomy KA

18. Zollinger – Ellison syndrome Seen in patients with gastrinomas Tumors that secrete gastrin Primary tumors may be located in the stomach, duodenum or pancreas KA

19. VOMITING (Emesis) is the involuntary, forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose 3 phases: 1. nausea 2. retching 3. vomiting KA

20. Nausea An unpleasant sensation that precedes vomiting Symptoms – Cold sweat, pallor, salivation Loss of gastric tone Reflux of intestinal contents into the stomach KA

21. RETCHING Follows nausea. Labored spasmodic respiratory movements Against a closed glottis, with contractions of abdominal muscles , diaphragm and chest wall No expulsion of gastric contents KA

22. Vomiting Begins with deep inspiration, closure of glottis to prevent vomitus into the trachea Soft palate is raised and shuts off the nasal cavity. Diaphragm contracts – descends Abdominal muscles – contracts Increases intra abdominal pressure Stomach – compressed Gastric contents forced upwards via the relaxed sphincters and esophagus Anti –peristalsis may take place in the stomach Reflex activity KA

23. Vomiting reflex STIMULI: Irritative stimuli in the GI tract Signals arising from the Chemoreceptor trigger zone for vomiting Location – area postrema – lateral walls of the 4 th ventricle. rapidly changing direction or motion Receptors in the vestibular apparatus are stimulated which send signals to vestibular nuclie , from the CRZ to the vomiting centre. increase in intracranial pressure. KA

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26. Pathway Sensory : vagus from the GI tract Nueronal pathways from the labyrinth, cortical centres , intracranial presssure receptors, chemoreceptor trigger zone. Impulses from the CTZ pass to an area in the brain stem called Vomiting center . VC – controls and integrates the visceral and somatic functions in vomiting Motor impulses are transmitted via the V, VII, IX, X, XI and XII cranial nerves from the vomiting center to the upper GI tract and through the spinal nerves to the diaphragm and abdominal muscles. KA

27. QUESTIONS Composition, functions and regulation of saliva. Describe the phases of deglutition. Mechanism of Hcl secretion from gastric glands. Discus the composition, functions and regulation of Gastric juice secretion. Explain the phases of gastric juice secretion with experimental evidences. Vomiting reflex. KA

28. Physiological basis of peptic ulcer. How do various drugs act on its treatment? Migratory motor complex Enteric nervous system Basic Electric rhythm Gastric motility KA

29. How does Gastrin effect Gastric juice secretion? Deglutition apnoea Xerostomia Gastric emptying Zollinger-Ellison syndrome Sham feeding KA

30. 36 year old software engineer ,smoker presents with complaints of : Epigastric pain, belching, worsening of pain when lying supine and sour sensation in the throat . He developed vomiting and had blood in vomitus. On Examination : Tenderness at the epigastric region . Endoscopy revealed erosion of mucus membrane of the upper duodenum. a. Identify the condition and explain the mechanism of Hcl secretion.[3marks] b. How will you treat this condition.[2marks] KA