FILLING OF STOMACH

Food on entry into stomach arranges in different layers:a. Ist eaten food arranges against greater curvature in fundus & body

of stomachb. The successive layers of food lie near the lesser curvature and the

last eaten food lie at lesser curvature near UES (cardiac sphincter)c. The liquid remains near lesser curvature & flow towards pylrus along

with a V shaped groove. d. 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 PHYSIOLOGYb. 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 lkaline intestinal juices in duodenum to prevent damage to small intestine.e. Osmolar Concentration of gastric content: Isotonic gastric contents leave rapidly than hypotonic or hypertonic contents.

APPLIED PHYSIOLOGYRegulation of Gastric Emptying:1. 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.

2. Hormonal factors: When acid chyme enters dudenum the duodenal mucosa release some hormones which enters blood and act on stomach to inhibit its motility. The inhibitory hormones are

a. Vasoactive Intestinal Peptide (VIP) b. GIP c. Secretin d. Somatostatin e. Peptide YY.

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:1. Gastric surgery 2. Zollinger Ellison Syndrome ( Severe peptic ulcers and

gastrin secreting Pancreatic tumor)

APPLIED PHYSIOLOGY of stomach

Symptoms of Dumping Syndrome:1. Nausea, Vomiting2. Feeling of abdominal fullness and tightness after

meal3. Diarrhoea- as food is not fully digested due to

rapid transit in GIT.4. Sweating & Weakness5. Fatigue & Dizziness6. Palpitation (feeling of heart beat).

APPLIED PHYSIOLOGY of stomach

2. Gastroparesis:A chronic disorder of delayed gastric emptying in patients with :a. Diabetes mellitusb. Post surgeryc. Motility disordersd. Gastric infectione. Endocrine disordersf. Decreased myentric plexus gangle

APPLIED PHYSIOLOGY

Symptoms of Gastroparesis:1. Early satiety (not satisfaction after eating)2. Nausea3. Vomiting4. Fullness in abdomen 5. Upper abdominal discomfort.

Vomiting

Vomiting is abnormal emptying of stomach and upper part of intestine via esophagus through mouth.Causes: 1. Irritation in GIT2. Mecahnical stimulation of pharynx3. Pregnancy4. Alcohal5. Stimulation of labyrinth of ear eg sea sickeness, mountain sickeness6. Acute GI infection7. Metabolic disorers8. Increase Intracranial Pressure

APPLIED PHYSIOLOGYMechanism of Vomitting1. 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.2. Retching: Strong involuntary movements of GI tract start even before actual

vomiting called retching. 3. Act of Vomiting: a. Beginning of reverse peristalsis (anti peristalsis) from ileum towards mouth

through intestine pushing the intestine contents into stomach within few minutes.

b. Deep inspiration followed by temporary stoppage of breathingc. Closure of glottisd. Upward & forward movement of larynxe. Elevation of soft palate.f. Contraction of diaphragm & abdominal muscles to increase intra abdominal

pressure.g. Rise in intragastric pressure due to f ABOVE.h. Relaxation of lower esophageal sphincter and upper esophageal sphincter.i. Forceful expulsion of gastric contents through esophagus,pharynx and mouth.

APPLIED PHYSIOLOGYVomiting 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 Chemoreceptor Trigger Zone. Afferent impulses reach here during travel from labyrinth & vestibular apparatus of ear & reach vomiting centre via this zone.