Digestive Disorders — Classification, Cause, and Key Features — Summary

Disorder	Classification	Primary Cause	Key Clinical Features	NEET Tip
Kwashiorkor	Protein-Energy Malnutrition	Severe protein deficiency (calories may be adequate)	Oedema, distended belly (ascites), skin lesions, growth retardation, fatty liver	Oedema = defining feature; caused by hypoalbuminaemia
Marasmus	Protein-Energy Malnutrition	Total calorie + protein deficiency	Extreme wasting, emaciation, shrunken limbs, NO oedema	Wasting = defining feature; no oedema
Jaundice	Hepatobiliary	Excess bilirubin (liver failure or bile duct obstruction)	Yellow skin + sclera (icterus), dark urine (obstructive)	Bilirubin = haemoglobin breakdown product; liver processes it
Vomiting	Reflex disorder	Medullary vomiting centre activation (toxins, motion, gastric irritation)	Forceful expulsion of stomach contents through mouth	Controlled by MEDULLA OBLONGATA
Diarrhoea	Motility/secretory	Infection, food intolerance, excess secretion	Frequent watery stools, dehydration	Water absorption failure in large intestine; ORS treatment uses SGLT
Constipation	Motility	Low fibre diet, dehydration, reduced GI motility	Hard, infrequent, difficult-to-pass stools	Excess water absorbed from colon → hard faeces
Indigestion (dyspepsia)	Functional	Overeating, spicy/fatty food, anxiety (vagal stimulation → HCl ↑), enzyme deficiency	Bloating, burning sensation, stomach discomfort	Gut-brain axis: stress → vagus → increased HCl
Hiatal hernia	Structural	Stomach protrudes through oesophageal hiatus of diaphragm	Acid reflux (GERD), heartburn (worse lying down, better standing)	LOS incompetence → acid + no oesophageal mucus protection
Acute pancreatitis	Inflammatory	Premature intrapancreatic proenzyme activation (gallstones, alcohol)	Severe abdominal pain, elevated serum amylase/lipase, haemorrhage, fat necrosis	Autodigestion: elastase → haemorrhage; lipase → fat necrosis
Peptic ulcer	Mucosal breakdown	H. pylori infection OR NSAID use → disrupted mucus protection + excess HCl	Epigastric pain, bleeding	Mucus layer failure → acid and pepsin attack gastric/duodenal wall
Lactose intolerance	Enzyme deficiency	Lactase deficiency (brush border)	Bloating, gas, diarrhoea after dairy consumption	Undigested lactose → colonic bacterial fermentation