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Seminar On

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Introduction Stomach is a hollow

muscular organconsisting of

following parts1. Fundus2. Body

3. Pyloric part

Body

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Physiologically stomach is devidedinto two parts

1. Orad portion

2. Caudad portion

Orad

Caudad

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Rugae In the empty state the

stomach is contractedand its mucosa and

submucosa arethrown up into distinctfolds called rugae

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Motor function of stomach Storage of food Mixing of food with gastric secretion

Slow empting of stomach

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Storage function of stomach

1. Food enter in stomach and formconcentric circle of food in orad portion of stomach

2. Newest food lying closest to theoesophageal opening

3. Oldest food lying nearest the outer wallof the stomach

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Vagovagal reflex This reflex also known as receptive

relaxation Reflex start from stomach to the brain

stem and then back to the stomach this isvagovagal reflex

This reflex reduces tone in muscular wall

of the body of stomach Normal capacity of relaxed stomach is 0.8-

1.5 liter

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Mixing of food with gastricsecretion

Basic electricalrhythm It is electrical slow

wave It Initiate peristaltic

constrictor wave ingut wall

00 252015105 45403530

-40mV

-80mV

Time (sec)

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Weak peristaltic constrictor wave It is mixing wave Start in mid to upper

portion of stomach walland move towardsantrum in every 15 - 20sec.

constrictor wave processfrom body of stomach into antrum

It become extreemlyintense and providepowerful peristaltic actionpotential.

Grinding

Relaxation

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Retropulsion A wave of contraction closes the distal

antrum thus as the caudad stomachcontracts. Food is propelled back into thestomach to mixed

It is an important mixing movementmechanism in the stomach

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Chyme After food in the stomach has become

thoroughly mixed with the stomachreaction the resulting, murky semifluidmixture called chyme

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Slow emptying of stomach Stomach emptying

promoted by intenseperistaltic contraction

or pyloric pump Emptying of stomach

opposed byresistance to passageof chyme at thepylorus

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Pyloric pumpor

Intense Peristaltic Contraction Intense peristaltic wave force up to several

ml of chyme into duodenum This wave causing mixing in the stomach

also provide pumping action called pyloricpump

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Role of Pylorus in controllingstomach emptying

Distal opening of stomach is pylorus thereis a circular muscle called pyloric sphincter

Pylorus usually open enough for water andother fluid to empty from stomach intoduodenum

Constriction usually prevent passage of food particles until they have becomemixed in the Chyme

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Regulation of stomach emptying Stomach empties is regulated by signal from

both stomach and duodenum controlling theemptying of chyme into duodenum at a rate

no greater than the rate at which the chymecan be digested an absorbed in the smallintestine

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Factor which promote emptying Gastrin hormone Gastric food volume

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Vomiting Vomiting is a forceful expulsion of contents

of the stomach and often the smallintestine