Absorption of Macromolecules (HDT 2-1)

What are the 3 monosaccharides? glucose fructose galactose what are the 3 disaccharides? sucrose (glucose + fructose) lactose (glucose + galactose) maltose (2 x glucose) what are the sites of polysaccharide breakdown? salivary amylase pancreatic amylase intestinal (villi) enzymes what is the site of disaccharide digestion? name the enzymes intestinal (brush border/villi) enzymes 1. maltase 2. lactase 3. sucrase summarise monosaccharide absorption: SGLT-2 - glucose + galactose into entename the transporters involved in intesti- rocyte nal monosaccharide absorption: GLUT-5- fructose into enterocyte GLUT-2 - all sugars into bloodstream what must proteins being broken down tri-peptides, di-peptides and amino acids into for intestinal absorption? what are the 2 sites of protein absorption? stomach intestine what protease enzyme is present in the stomach? pepsinogen, which is converted into pepsin in the presence of H+ what type of protein digestion occurs in the stomach? mechanical digestion where does the majority of protein digestion occur? in the intestine what are the 2 types of protease enzymes? endopeptidases and exopeptidases 1/5 endo - attack bonds in the middle of peptide changes / exo - split AAs one at a time compare endopeptidases and exopeptiendo - gastric pepsin, pancreatic trypsin/ dases: exo - pancreatic enzymes, intestinal enzymes + enterocyte cytoplasm enzymes (cellular digestion) how are amino acids absorbed into the bloodstream? what type of AAs can passively diffuse into the enterocyte? AAs with lyophilic R groups why is lipid digestion difficult? lipids are not water-soluble what is the function of bile salts? emulsify fats what is the structure of bile salts? hydrophilic head + hydrophobic tail •act as anionic surfactants bile salts + lipids = micelles, which prevent fat globules from coming together what is the shell of a micelle composed of? bile salts and phospholipids what is the core of a micelle composed FAs, MGs, cholesterol and fat soluble its. of? summarise fat absorption: thoracic duct > subclavian vein = site where lymphatic system and blood system come together, so chylomicrons can enter systemic circulation 2/5 lacteals converge into... fats absorbed in upper half of SI, wherecompare fat absorption along SI with bile as bile salts absorbed in lower half salt absorption: fat absorption in SI is passive, whereas bile salt absorption is active what is steatorrhea? fat malabsorption, resulting in fatty stools using Sudan stain on a sample of stools how can we detect steatorrhea? what is the function of Vitamin A, and what does deficiency lead to? maintains mucosal membranes + normal vision deficiency > night blindness what is the function of Vitamin D, and what does deficiency lead to? intestinal absorption of calcium + phosphorus + bone remodelling deficiency > osteomalacia (soft bones) what is the function of Vitamin E, and what does deficiency lead to? protects polyunsaturated FAs from oxidative damage deficiency > oxidative cell stress what is the function of Vitamin K, and what does deficiency lead to? formation of clotting factors deficiency > haemorrhage small intestine where is most water absorbed? how is the absorption of water linked to the absorption of Na+? 3/5 how is the absorption of water linked to food absorption? what is diarrhoea? loss of > 500 ml of water in faeces per day what are the causes of diarrhoea? what does ORT contain? sodium, glucose + chloride ions name 2 diseases that can be treated by ORT: 1. Vibrio Cholerae 2. Rotavirus How does cholera toxin work? The cholera toxin subunit stimulates formation of cAMP which opens Cl channels into the intestinal lumen. This action activates a Na pump that pumps sodium also into the lumen and water follows the Na what is dumping syndrome? delivery of a large amount of hyperosmotic chyme into the small bowel what are the 2 causes of dumping syndrome? gastric bypass/removal Zollinger-Ellison syndrome 4/5 5/5