Git Physiology Part Ii By Dr A K Guta

FILLING OF STOMACH Food on entry into stomach arranges in different layers: b. Ist eaten food arranges against greater curvature in fundus & body of stomach c. The successive layers of food lie near the lesser curvature and the last eaten food lie at lesser curvature near UES (cardiac sphincter) d. The liquid remains near lesser curvature & flow towards pylrus along with a V shaped groove. e. The groove called magenstrasse is formed by stomach muscle

EMPTYING OF STOMACH

1.The food remains in stomach for 3 hrs. 2.Chyme is formed by its digestion. 3.With peristalsis contractions of stomach & simultaneous relaxation of pyloric sphincer slowly it is released into intestine. 4.The emptying is slow & takes 3-4 hrs. 5. Gastric emptying is influenced by following factors: a. Volume of gastric content: More the volume of gastric contents more will be gastric emptying into intestine.

APPLIED PHYSIOLOGY b. Consistency of gastric contents: liquids leave the stomach rapidly as constricted pyloric sphincter allow liquids to pass through but not solids which are allowed to pass through only on becoming semifluid. c. Chemical Composition: Carbohydrates leave stomach rapidly than proteins and proteins rapid than fats. So fatty food remains in stomach for long time. d. pH of gastric Content: Gastric Chyme with low pH leave the stomach slowly as it has to be neutralised by the lkalineintestinal juices in duodenum to prevent damage to small intestine. e. Osmolar Concentration of gastric content:

APPLIED PHYSIOLOGY

Regulation of Gastric Emptying: 2. Nervous factors: Enterogastric reflex: When the chyme enters the intestine the gastric muscle is inhibited and motility deceases to stop gastric emptying. This reflex is through vagus nerve. 3. Hormonal factors: When acid chyme enters dudenumthe duodenal mucosa release some hormones which enters blood and act on stomach to inhibit its motility. The inhibitory hormones are a. VasoactiveIntestinal Peptide (VIP) b.

APPLIED PHYSIOLOGY of stomach 1. Gastric Dumping Syndrome: Rapid gastric emptying into jejenum leading to series of upper abdominal symptoms. Occurs in those patients whose partial stomach has been surgically removed (partial gastrectomy) or have undergone gastric bypass surgery (gastro-enterostomy). The gastric emptying either occurs immediately after meal (early dumping) or about few.hrs after meal (late dumping). Causes: 5. Gastric surgery 6. Zollinger Ellison Syndrome ( Severe peptic

APPLIED PHYSIOLOGY of stomach

Symptoms of Dumping Syndrome: 2. Nausea, Vomiting 3. Feeling of abdominal fullness and tightness after meal 4. Diarrhoea- as food is not fully digested due to rapid transit in GIT. 5. Sweating & Weakness 6. Fatigue & Dizziness 7. Palpitation (feeling of heart beat).

APPLIED PHYSIOLOGY of stomach

2. Gastroparesis: A chronic disorder of delayed gastric emptying in patients with : c. Diabetes mellitus d. Post surgery e. Motility disorders f. Gastric infection g. Endocrine disorders h. Decreased myentric plexus gangle

APPLIED PHYSIOLOGY

Symptoms of Gastroparesis: 2. Early satiety (not satisfaction after eating) 3. Nausea 4. Vomiting 5. Fullness in abdomen 6. Upper abdominal discomfort.

Vomiting Vomiting is abnormal emptying of stomach and upper part of intestine via esophagus through mouth. Causes: 3. Irritation in GIT 4. Mecahnical stimulation of pharynx 5. Pregnancy 6. Alcohal 7. Stimulation of labyrinth of ear eg sea sickeness, mountain sickeness 8. Acute GI infection 9. Metabolic disorers 10.Increase Intracranial Pressure

APPLIED PHYSIOLOGY

Mechanism of Vomitting

2. Nausea: It occurs before vomiting. It is an unpleasant sensation and desire to do vomiting. In this a large amount of salive collects in mouth. 3. Retching: Strong involuntary movements of GI tract start even before actual vomiting called retching. 4. Act of Vomiting: e. Beginning of reverse peristalsis (anti peristalsis) from ileum towards mouth through intestine pushing the intestine contents into stomach within few minutes. f.

Deep inspiration followed by temporary stoppage of breathing

g. Closure of glottis h. Upward & forward movement of larynx i.

Elevation of soft palate.

j.

Contraction of diaphragm & abdominal muscles to increase intra abdominal pressure.

k. Rise in intragastric pressure due to f ABOVE.

APPLIED PHYSIOLOGY

Vomiting Reflex:

Vomiting is a reflex act. Sensory impulses arise from irritated part of GIT. Transmited to Vomiting centre in medulla oblongata of brain via vagus nerve & sympathetic afferent fibres. Efferent impulses (motor) arise from Vomiting centre & transmited via V, VII, IX & X cranial nerves to upper part of GIT and through spinal nerves to diaphgram and abdominal muscles.

Centre for Vomiting during Motion Sickness or vomiting induced by drugs like morphine: It is in floor of 4th ventricle of brain called