6. Digestion And Absorbtion Flashcards
How do carbohydrates digest in the digestive system?
Remember by SAM, PAM and MEG
- in salivary gland, Starch is hydrolysed by enzyme salivary Amylase into Maltose.
- in small intestine, Pancreatic Amylase hydrolyses starch into Maltose.
- in small intestine, Maltase embedded in Epithelial cells of small intestine hydrolyses maltose into Glucose.
What is the process of co transport for sodium ions and glucose?
- Na+ ions move out the epithelial cell into the blood stream by active transport.
- this lowers Na+ concentration inside cell providing a conc gradient.
- Na+ and glucose move into the epithelial cell by co transport through co transport carrier proteins
- this increase concentration glucose inside epithelial cell.
- glucose moves into the bloodstream by facilitating diffusion.
How is the ileum adapted?
Lining is folded and has microvilli to increase SA allowing more membrane bound disaccharides to fit and faster absorption of products of digestion.
Whats ficks law?
Rate of diffusion ( is directly proportional to ) ( SA x diff in conc)/ length of diffusion pathway.
What enzymes are used to digest proteins?
Begins in stomach using pepsin which is secreted with HCl which gives a pH 2. Mixture enters small intestine and is mixed with bile salts to neutralise.
Endopeptidase enzyme hydrolyses peptide bonds in the middle of polypeptide chains in the stomach to form smaller polypeptide chains with more ends. Exopeptidase enzymes hydrolyses peptide bonds at the end of polypeptide to removal terminal amino acids to form dipeptides . Dipeptidase embedded in the epithelial lining hydrolyses dipeptides into amino acids.
What enzymes are used to digest proteins?
Begins in stomach using pepsin which is secreted with HCl which gives a pH 2. Mixture enters small intestine and is mixed with bile salts to neutralise.
Endopeptidase enzyme hydrolyses peptide bonds in the middle of polypeptide chains in the stomach to form smaller polypeptide chains with more ends. Exopeptidase enzymes hydrolyses peptide bonds at the end of polypeptide to removal terminal amino acids to form dipeptides . Dipeptidase embedded in the epithelial lining hydrolyses dipeptides into amino acids.
How do amino acids get transported by co transport ?
- Na+ ions move out epithelial cell into bloodstream by active transport.
- lowers Na+ inside cell providing a concentration gradient.
- Na+ and amino acids move into cell from lumen by co transport through amino acids co transport carrier proteins.
- increase concentration amino acids in cell.
- amino acids move into bloodstream by facilitated diffusion.
How are lipids digested?
Bile salts made in liver and stored in gallbladder secreted into small intestine. Bile salt binds to large lipids to form lipid droplets ( by emulsification). Lipid droplet formation increases SA for lipase action for faster hydrolysis of triglycerides. Lipase produced by pancreas then secreted to small intestine hydrolyses ester bonds in triglycerides to produce fatty acids and monoglyceride.
What are the role of micelles in absorption of lipids?
Micelles (e.g. bile salts and fatty acids) make fatty acids more soluble. Micelles carry fatty acids to cells lining ileum. Fatty acids absorbed by diffusion.
Triglycerides reformed in cell into chylomicrons at golgi body ( combines triglycerides +proteins). Then packaged into vesicles for release by exocytosis as vesicles move to cell membrane.
How does visking tubing work?
- use it to investigate absorption of products of digestion.
-partially permeable so only allow small molecules through. - usually set up with enzyme and substrate inside tubing and incubated at specific temp for set time. Then biochemical food test completed on content in tube snd in surrounding water.
