What is the main function of the pancreas in digestion?
Produces enzymes for digestion of carbs, proteins, fats, and nucleic acids
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| Term | Definition |
|---|---|
What is the main function of the pancreas in digestion? | Produces enzymes for digestion of carbs, proteins, fats, and nucleic acids |
What happens without the pancreas? | Starvation would occur |
What do proteases digest? | Proteins into peptides and amino acids |
What do amylolytic enzymes digest? | Starch into sugars |
What do lipases digest? | Triglycerides into free fatty acids and monoglycerides |
What do nucleases digest? | Nucleic acids into nucleotides |
Where are pancreatic enzymes stored before secretion? | Zymogen granules in acinar cells |
In what form are most pancreatic enzymes secreted? | Inactive proenzymes |
Where are pancreatic enzymes activated? | In the duodenum |
What enzyme activates trypsinogen? | Enterokinase |
What does trypsin do? | Activates other proteases |
How does the pancreas prevent autodigestion? | Inactive enzymes, trypsin inhibitors, trypsin self-degradation |
What are the major pancreatic proteases? | Trypsin, chymotrypsin, elastase, carboxypeptidase |
What type of enzyme is trypsin? | Endopeptidase |
What type of enzyme is carboxypeptidase? | Exopeptidase |
What does pancreatic amylase produce? | Maltose, maltotriose, α-limit dextrins |
What does pancreatic lipase produce? | Free fatty acids and monoglycerides |
What hormone is released in response to fat/protein in SI? | CCK |
What does CCK stimulate? | Pancreatic enzyme secretion and gallbladder contraction |
What hormone is released in response to acid in duodenum? | Secretin |
What does secretin stimulate? | HCO3- secretion from pancreas and liver |
What is the major phase of pancreatic secretion? | Intestinal phase |
What stimulates the cephalic phase? | Sight, smell, taste (parasympathetic) |
What stimulates the gastric phase? | Stomach distension |
What happens in cystic fibrosis in the pancreas? | Reduced HCO3- secretion → enzymes not flushed → autodigestion |
What are the major functions of the liver? | Bile production, metabolism, detoxification, protein synthesis |
What does bile contain? | Bile acids, cholesterol, salts, phospholipids, bilirubin |
What is the role of bile in fat digestion? | Emulsifies fat into smaller droplets |
What are bile acids? | Amphipathic molecules |
What is a micelle? | Soluble cluster with nonpolar core and polar exterior |
What is the function of micelles? | Transport fatty acids and monoglycerides to enterocytes |
What happens to lipids after absorption? | Reformed into triglycerides and packaged into chylomicrons |
Where do chylomicrons enter circulation? | Lymphatic system |
What enzyme breaks down chylomicrons in blood? | Lipoprotein lipase |
How is iron absorbed? | Fe2+ transported into enterocyte → stored as ferritin or transported via transferrin |
What transporter brings iron into enterocytes? | DMT-1 |
What transporter exports iron to blood? | Ferroportin |
What happens when iron stores are high? | Reduced absorption (↑ ferritin) |
What is iron deficiency anemia? | Low RBC number/size causing fatigue |
How much fluid enters GI tract daily? | 8–9 L |
Where is most water absorbed? | Small intestine |
What drives water absorption? | Na+ gradients |
What transporter is involved in glucose absorption? | SGLT |
What transporter moves glucose into blood? | GLUT |
What drives water secretion in intestine? | Cl- secretion via NKCC1 and CFTR |
What is segmentation? | Mixing contractions in small intestine |
What is the MMC? | Migrating myoelectric complex (clears intestine between meals) |
What causes lactose intolerance? | Lack of lactase enzyme |
What are symptoms? | Gas, diarrhea, bloating |
What causes cholera diarrhea? | Increased cAMP → Cl- secretion → water follows |
What are functions of the large intestine? | Water absorption, storage, bacterial metabolism |
What is unique about large intestine structure? | No villi, only crypts |
What bacteria do in large intestine? | Produce vitamins (K) and SCFAs |
What triggers defecation? | Rectal distension |
What happens during defecation reflex? | Internal sphincter relaxes, external controlled voluntarily |
What are the sections of small intestine? | Duodenum, jejunum, ileum |
Where are bile acids absorbed? | Ileum |
Where is most digestion/absorption? | Duodenum and jejunum |
What is a brush border enzyme? | Enzyme on microvilli for final digestion |
What breaks starch into glucose? | Amylase + brush border enzymes |
What breaks sucrose? | Sucrase |
What breaks lactose? | Lactase |
How are amino acids absorbed? | Na+-dependent transport |
How are small peptides absorbed? | H+-dependent transport |
Where are peptides broken into amino acids? | Inside enterocytes |