Lecture 5 - Digestive Function of Pancreas

What is the function of pancreas?

Source of major enzymes required for digestion

What are proteases?

Enzymes that digest proteins into peptides and amino acids

What are amylolytic enzymes?

Digest starches into sugars

What are lipases?

Digest triglycerides into free fatty acids and monoglyceridesWh

What are nucleases?

Digest nucleic acids into free nucleotides

Where are the enzymes synthesized and storaged?

Pancreatic acinar cells synthesize and package enzymes into vesicles and stored at the apical pole until stimulus causes exocytosis

Where are most enzymes activated

In the duodenum from enterokinase. It is attached to the apical/luminal surface of epithelial cells. Cleaves trypsinogen itno trypsin (activates other enzymes)

How is autodigestion prevented?

Pancreas produces and stores proenzyme that are active at SI. It also secretes trypsin inhibitors to prevent activation and trypsin can degrade itself if activated before SI

What is chymotrypisinogen?

Endopeptidase activated by trypsin into chymotrypsin

What is pro-elastase?

Endopeptidase activated by trypsin into elastase

What is pro-carboxypeptidase A and B?

Exopeptidase activated by trypsin to carboxypeptidase A and B

What is the function of amylolytic enzymes?

Pancreatic amylase cleaves starches to sugar and end product i disaccharide, trisaccharides, maltose, maltriose, aplha-limit dextrins

What is lipase?

Lipolytic enzyme that hydrolyzes triglycerides into free fatty acids and monoglycerides

What is phospholipase A2?

Lipolytic enzyme that hydrolyzes phospholipids into free fatty acids and lysophospholipids

What is cholesterolesterase?

Lipolytic enzyme that hydrolyzes cholesterol-esters into free fatty acids and cholesterols

How are pancreatic juices regulated?

Acid entering duodenum stimulates S cells to produce secretin to stimulate release of HCO3. Digested fats/proteins enter upper SI stimulate I-cells to release CCK which gets released nto blood and acts on pancreatic duct to release enzymes

How is CCK regulated?

Stimulates gall bladder to contract and release bile acids for fat breakdown. as fats and amino acids get reasborbed, stimuli for CCK is removed

What is cystic fibrosis?

A defective chloride channel where all digestive enzymes are produced but not enough HCO3 is secreted to flush the enzymes to the stomach leading to pancreatic autodigestion and inadequate nutrients

What systems does the Liver receive blood from?

Systemic circulation and hepatic portal circulation

What is the systemic system>?

Arterial blood that is oxygen rich but nutrient poor

What is the hepatic portal circulation?

venous blood that is nutrient rich but O2 poor. COntributes to 75% of blood in liver

What is the hepatic lobule?

Functional unit of the liver with hexagonal structure that has central vein running through center and portal triad in each cornerWha

What is the portal triad

Consists of hepatic artery, portal vein, and bile duct

What are hepatocytes?

Epithelium of liver and form tube like structures call canalicular networks

What are the major functions of the liver?

Exocrine gland that forms/secretes bile, metabolizes/store nutrients, deactivation/detox, and produce circulating proteins

What are the major components of Bile?

Bile acids, cholesterol, salt, phospholipids, bile pigments, and trace mental

How does bile work with lipase?

Lipase only works on surface of small lipid droplets so bile will emulsify large lipids and prevent them re-aggregatin using amphiphatic heads and phospolipids

What is a micelle?

Polar head groups facing outside and non-polar facing inside to form a hollow ball and allows lipase to breakdown triglycerides within the ball to create monoglycerides and fatty acids for digestion