Pancreas Enzymes and Pancreatitis

Pancreas

• Amilase pancreas breaks down polysaccharides into oligosaccharides, which are further broken down by oligosacaridase on the brush border of the small intestine.
• Lipase pancreas hydrolyzes triglycerol, cholesterol ester, and phospholipase A2.
• Ribonuclease and deoxyribonuclease are also present in the pancreas.

Pancreatic Insufficiency

• Causes steatorrhea.

Pancreatitis

• Caused by heavy alcohol intake, biliary tract obstruction, or insufficient trypsin inhibitor.
• Pancreatic cells release trypsin, which digests pancreatic cells.

Regulation of Pancreatic Secretion

• Mainly hormonal:
  • Secretin stimulates secretion of pancreatic juice rich in water and HCO3-, but poor in enzymes, in response to acid chyme in the duodenum.
  • CCK stimulates secretion of pancreatic juice rich in enzymes, in response to digestive products of proteins and fats in the duodenum.
• Nervous control: parasympathetic impulses along vagus nerves stimulate secretion of pancreatic enzymes.

Biliary System

• Includes the liver, gallbladder, and associated ducts (hepatic, cystic, and common bile ducts).

Functions of Liver

• Synthesizes and secretes bile.
• Performs metabolic processes (e.g., gluconeogenesis, glycogenolysis).
• Performs detoxification and degradation (e.g., of drugs and hormones).
• Synthesizes plasma proteins (e.g., albumin, clotting factors).
• Stores nutrients (e.g., Na+).

Absorption of Nutrients

• Na+: diffusion, cotransport, or active transport, stimulated by aldosterone.
• Ca2+: active transport, stimulated by calcitriol and PTH.
• K+: diffusion.
• Mg2+, Fe2+: active transport.
• PO43-, SO42-, Cl-, I-, HCO3-: diffusion or carrier-mediated transport.
• Water-soluble vitamins: diffusion.
• Fat-soluble vitamins: diffusion, absorbed from micelles.
• Vit B12: active transport, must be bound to intrinsic factor.

Vomiting

• Definition: ejection of stomach contents through the mouth.
• Stimuli: tactile stimulation of the back of the throat, irritation or distension of the stomach and duodenum, elevated intracranial pressure, rotation/acceleration, chemical agents, and psychogenic factors.
• Process: nausea, palpitation, sweating, pupil dilation, and belching, followed by contraction of the abdominal muscles and diaphragm, relaxation of the upper esophageal sphincter, and closure of the glottis and epiglottis.

Gall Bladder

• No digestive role.
• Stores bile.
• Concentrates bile.
• Empties during meals.
• Secretes mucus.

Regulation of Bile Secretion and Gall Bladder Emptying

• Chemical: bile salts stimulate bile secretion by liver cells.
• Hormonal: secretin and CCK stimulate bile secretion and gall bladder contraction.
• Neural: vagal stimulation increases bile secretion and causes weak contraction of the gall bladder.