physiology of gi disorders

8/8/2019 Physiology of Gi Disorders

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DR MOHAMMAD NASIR

MBBS(AMC)

LECTURERPHYSIOLOGY DEPARTMENT


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PHYSIOLOGY OF GI DISORDERS


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DISORDERS OF OESOPHAGUS

PARALYSIS OF SWALLOWING MECHANISMS:

CAUSES:

Damage to 5th 9th and 10th cranial nerve

Poliomyelitis

Encephalitis

Muscle dystrophy Myasthenia gravis

Botulism

anesthesia


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EFFECTS:

No swallowing

Food enter lungs Food enter posterior naries

ACHALASIA AND MEGA OESOPHAGUS:

Failure of lower oesophageal sphinctor torelax


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CAUSE:

Non functioning of the myenteric plexus in

lower third of oesophagus

MEGAOESOPHAGUS:

Distended oesophagus associated withachalasia


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DISORDERS OF THE STOMACH

GASTRITIS:

Inflammation of the gastric mucosa

TYPES:

Acute and chronic

Superficial and deep


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CAUSES

Chronic bacterial infections

Alcohol Aspirin

CONCEPT OF GASTRIC BARRIER:

Consist of mucus cell and their tightjunctions


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GASTRIC ATROPHY:

CAUSES:

Chronic gastritis Autoimmune

EFFECTS OF GASTRIC ATROPHY:

Hypochlorhydria Achlorhydria

Pernicious anemia


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PEPTIC ULCER

Excoriated are of mucosa caused mainly

by gastric juices

COMMONLY EFFECTED AREAS:

First few cms of duodenum

Lesser curveture Gastroesophageal sphinctor


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BASIC PHYSIOLOGY OF PEPTIC ULCERATION:

Imbalance between rate of secretion and degree ofprotection

PROTECTIVE FACTORS:

Mucus production

Bicarbonates of pancreatic juices

Bile from the liver

Reverse enterogastric reflex

secretin


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CAUSES OF PEPTIC ULCERS:

H pylori

Alcohol

Smoking

Aspirin

MARGINAL ULCER: Ulcer after gastroduodenostomy of

gastrojejunostomy


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PHYSIOLOGFY OF TREATMENT

OF PEPTIC ULCER MEDICAL: Antibiotics

H2 receptor blockers

PPIS

Mucaine sucralfates etc

SURGICAL: Vagotomy

Removal of portion of stomach


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DISORDERS OF SMALL

INTESTINE ABNORMAL DIGESTION OF FOOD BY THE

SMALL INTESTINE:

Failure of the pancreas to secrete pancreatic

juices

OCCURS IN:

Pancreatitis:acute and chronic Pancreatic duct blokage by gallstone

Pancreas removal


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MALABSORBTION BY SMALL

INTESTINE-SPRUE NONTROPHICAL SPRUE:

Celiac disease or gleuten enteropathy

CAUSE:

Toxic effects of gluten present in wheat and rye

EFFECTS:

Direct destructive effects on microvilli and villi


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TROPHICAL SPRUE:

Occurs in trophical areas

CAUSE:

Infectious agent and treated with antibiotics

MALABSORBTION IN SPRUE:

Fats called steatorrhea

Proteins vitamins

EFFECTS: Nutriional deficency,osteomaslacia and anemia


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DISORDERS OF LARGE

INTESTINE CONSTIPATION:

HIRSCHPRUNG DISEASE:

DIAHORREA: Enteritis

Psychogenic diahorrea

Ulcerative colitis and crohn disease


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OTHER GI DISORDERS

VOMITING:

The process by which the GIT get rid of itscontent when almost any part of the upperGI become excessively irritated overdistended or over excitable.

TRANSMISSION OF IMPULSES:

AFFARENT IMPULSES: from vagus andsymphathetic nerves bilateralvomiting centre of medulla


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EFFERENT IMPULSES:

Vomiting centre 5th,7th,9th,10th and

12th

upper GI Vomiting centre spinal nerves

diaphram and abdominal muscles


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Connections of vomiting centre


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ANTIPERISTALSIS:

The start of vomiting

THE VOMITING ACT: Deep breath

Upper oesophageal sphinctor open

Glottis closed

Posterior nares closed

Diaphram and abdominal muscles contract


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CHEMORECEPTOR TRIGGER ZONE:

Area located bilaterally on the floor of fourth

ventricle

Its excitation cause vomiting

EXCITING FACTORS:

Electrical

Drugs like opiods Motion sickness


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MOTION SICKNESS:

Vomiting due to rapidly changing

directions MECHANISM:

Labyrinthine receptors vestibular

nuclei cerebellum CTZVomiting centre

physiology of gi disorders

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