Digestion Flashcards
where does most digestion take place?
small intestine
what sphincter controls the common bile duct?
sphincter of oddi
In pancreas, what cell produces the primary secretion?
What cell modify the secretion?
What is HCO3- exchanged with? What happens in cystic fibrosis, and what’s the effect of this?
Acinar cells
duct cells
CL-
Cl- ion channel is absent in cystic fibrosis - causes malabsorption disorders in CF sufferers
3 functions of bicarbonate activity?
digestive enzyme activity
micelle formation (fat absorption)
protecting duodenal mucosa
what enzyme digests carbohydrates in the mouth and small intestine?
alpha-amylase
what linkage is broken by the amylase?
alpha-1,4-glycosidic linkages
Why is energy needed to absorb glucose?
to create a sodium gradient to drag glucose along with Na+ to epithelial cells for breakdown
What are the products of breakdown of lactose, maltose, and sucrose? Enzymes that do the breakdown?
lactose-galactose and glucose
maltose- glucose and glucose
sucrose- glucose and fructose
lactase, maltase, sucrase
what are the 2 classes of pepsin and what do they do?
Why is pepsin activity halted?
endopeptidases - cleave interior peptide bonds
exopeptidases - cleave external peptide bonds
by alkaline pancreatic scretions
what enzyme converts the zymogens into peptidases?
Where are peptidases also located to assist in digestion of proteins?
trypsin
brush border epithelium
Is absorption of di- and tri-peptides passive or active? At what point are they converted into amino acids?
passive diffusion or faciliated transport
when broken down by intracellular peptidases
where are bile salts produced and stored? What do they do? What enzyme (produced by what) breaks down fats?
liver
congeals it to aid digestion
pancreatic lipase
Explain how bile salts work
Bile salts will incorporate the fats – and forms a micelle
For fats to be absorbed, what needs to be formed? How?
triglyuceride combined with protein, cholesterol and phospholipids to form a chylomicron which can then pass around the body in a lacteal and into the lymphatic system. Chylomicron too big to pass into capillary. Then goes to blood via the thoracic duct
what is secretin and where is it released from? What does cholecystokinin do?
secretin (released in response to acid in duodenum) stimulates HCO3- production - potentiated by ACh
cholycystokinin (CCK) stimulates enzyme rich secretion (released in response to presence of fat and protein in duodenum)
