Phys 4 Flashcards
What is the major mxn for uptake of protein and fats into the enterocytes?
pinocytosis
What are the layers to go from the lumen to the blood?
unstirred layer of fluid –> glycocalyx –> apical membrane
–> cytoplasm of cell –> basolateral membrane –> basement membrane –> wall of capillary or lymph vessel
Maltose
maltose–> glucose and glucose
Trehalose
trehalase –> glucose and glucose
Lactose
lactase–> glucose and galactose
Sucrose
sucrase–> glucose and fructose
Starch
alpha amylase –> alpha dextrin -alpha dextrinase-> glucose
alpha amylase –> maltose -maltase-> glucose
alpha amylase –> maltotriose -sucrase-> glucose
CHO Testing
a. D-xylose levels above 4 g: you’re good
b. D-xylose levels below 4 g: you have an absorption problem
*urine collected continuously over 5 hours
What are the endopeptidases we learned?
trypsin, pepsin, chymotrypsin, elastase –> make small polypeptides
What are the exopeptidase we learned?
carboxypeptidases A and B –> cleaves AA into carboxyl ends
What ion is associated with AA take up? di/tri peptides?
- Na+
- H+
- each type of AA has it’s own transporter
- *Na/K establishes Na+ gradient
What can CF lead to protein absorption problems?
CFTR is blocked, so Cl- isn’t gonna want to go into the cell, which means the transporter with HCO3- isn’t doing too hot… can lead to pancreatitis, and an inflamed pancreas isn’t gonna wanna make all them enzymes we need
*steatorrhea think CF
Triglyceride
—-lingual, gastric, pancreatic lipase—> monoglyceride + FA + FA
Cholesterol ester
—cholesterol ester hydrolase–> cholesterol + FA
Phospholipid
–phospholipase A2—> lysolecithin + FA
What are the five steps in FA absorption?
- Solubilization by micelles
- Diffusion of micellar content across apical membrane
- Re-esterification
- Chylomicron formation
- Exocytosis of chylomicron into lymphatics
How are fat soluble vitamins absorbed? water soluble?
- same way as lipids
2. Na+ co transporter (except B12)
What are some side effects of B12 deficiency?
demyelination of the large nerve fibers of the SC; diminished RBC synthesis
What can cause the body to not produce enough IF?
- AI diseases (immune system attacks IF or parietal cells)
- Atrophic gastritis (destruction of parietal cells)
- Gastrectomy: loss of parietal cells
- Gastric bypass: exclusion of stomach, duodenum, and proximal jejunum alters absorption
What does the liver secrete into bile to help with iron absorption?
apotransferrin –> binds with free iron to make transferrin —> which binds to Rs on epi cells and absorbed via pinocytosis
What is needed for uptake of nonheme iron?
calcium
What is absorbed in the proximal SI? middle? distal? all three?
- sugars, peptides/aas, Ca, iron, folate, fat
- sugars, peptides/aas, Ca, (especially Na+
- bile acids, B12
- Water, electrolytes
