10.1 Gastrointestinal Tract and Pancreatic function

What are the main organs of the GIT?

Mouth, salivary glands, stomach, pancreas, liver, gallbladder, duodenum, jejunum, ileum, colon, anus.

What is the main function of the stomach

Protein denaturation and digestion via HCL and pepsin.

What is the pH of the stomach and why is it important?

pH < 2.0; activate spepsin and denature proteins

What enzyme begins protein digestion in the stomach?

Pepsin (from pepsinogen)

What happens in the duodenum after chyme enters?

neutrlsiation by bicarbonate and activation of digestive enzymes

What is the role of bile salts?

Emulsify fats to aid lipid digestion

Where does most nutrient absorption occur?

Jejunum

What is absorbed in the SI?

Monosaccharides, amino acids, di/tripeptides, fatty aicds, monoglyceridesW

What is absorbed in the colon?

NaCl ad water

What does gastrin do?

Stimulates gastric acid (HCl) secretion and mucosal growth

Where is gastrin produced?

Gastric antrum (G cells)

What stimulates gastrin release?

Vagus nerve, gastric distension, amino acids, calcium

What hormone stimulates pancreatic enzyme secretion and gallbladder contraction?

CCK

What does secretin do?

Stimulates bicarbonate secretion and inhibits gastrin

What is the function of GIP (gastric inhibitory peptide)?

Stimulates insulin release and inhibits gastric acid

What is motilin responsible for?

Stimulating GU motility

What does VIP (vasoactive intestinal peptide) do?

Regulates GI motility and secretion

What is zollinger-Ellison syndrome (ZES)?

Gastrinoma causing excessive gastrin and acid secretion

Common symptoms of ZES?

Diarrhoea, fatty stools, abdominal pain, ulcers

How is ZES diagnosed?

Elevated serum gastrin (>1000 ng/L) and secretin test

What is gastritis?

Inflammation of the gastric mucosa

Cause of gastritis?

stress, alcohol, NSAIDs, infections (e.g., H.pylori)

What disease is H. pylori associated with?

Peptic ulcer disease

How can H. pylori be diagnosed?

• Biopsy & culture

• Stool antigen

• Serum IgG

• Urease tests

What enzyme does H. pylori produce?

Urease

What is the reaction catalysed by urease?

Urea → CO₂ + NH₃

Why does ammonia help H. pylori survive?

Raises pH of stomach mucus

What is the urea breath test measuring?

Labelled CO₂ in breath (from urea breakdown)

Why is the urea breath test useful after treatment?

Confirms eradication (IgG remains elevated long-term)

What are the endocrine functions of the pancreas?

Insulin and glucagon secretion

What are the exocrine functions of the pancreas?

Secretion of digestive enzymes and bicarbonate

What hormone stimulates bicarbonate secretion?

Secretin

What hormone stimulates enzyme secretion from pancreas?

CCK

Most common causes of acute pancreatitis?

Alcohol and gallstones

Key symptom of acute pancreatitis?

Severe abdominal pain

Main diagnostic enzyme for pancreatitis?

Pancreatic lipase

Why is lipase preferred over amylase?

More specific to pancreas

What happens in pancreatitis pathophysiology?

Enzyme release → autodigestion → inflammation → necrosis

Is amylase specific to the pancreas?

No (also from salivary glands, etc.)

What does >10× normal amylase indicate?

Acute pancreatitis

What can mildly elevated amylase indicate?

Renal failure, mumps, salivary disease

Normal range of pancreatic lipase?

~10–40 U/L

What reaction does lipase catalyse?

Triglycerides → monoglycerides + free fatty acids