Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
18 Cards in this Set
- Front
- Back
What does alpha amylase do?
|
Cleaves starch only at 1,4 linkages(NOT at 1,6 or at the ends) so that no free glucose is made from starch digestion
Maltose, maltotriose, or limit dextrin is made |
|
True/False: Starch is broken down in the brush border.
|
FALSE: It is broken down in the lumen by free alpha amylase(LUMINAL DIGESTION)
|
|
Where are the disaccharides resulting from starch digestion broken down?
|
In the brush border
|
|
How are simple sugars absorbed?
|
GLT1 sodium co-transporter(glucose/galactose) or through the GLUT5(fructose)
|
|
Glucose and galactose enter enterocytes how?
|
Using the sodium gradient set up by the Na/K ATPase in the apical membrane--they are secondarily actively transported into the cell through the GLUT1
|
|
How do all sugars leave enterocytes?
|
Through the GLUT2 transporter
|
|
Trypsinogen is activated by what? What does it do?
|
Enterokinase cleaves trypsinogen into trypsin--this cleaves all other pancreatic enzymes except pepsin
|
|
What are the three methods for protein absorption?
|
Secondary active transport coupled with sodium(may be multiple AA or just one type)
PepT1 Oligopeptide Transporter--this is the fastest and transports two to three AA peptides(KINETIC ADVANTAGE) Endocytosis into enterocytes and M cells to present to lymphocytes in the lamina propria |
|
All protein transport types are in what class of cell transportation?
|
Facilitated diffusion
|
|
Which protein transport method is the best?
|
Oligopeptide transport through the PepT1 transporter
|
|
What is the process for fat absorption?
|
Fat droplets in the stomach are coated in phospholipids and bile salts grab on them in the duodenum--The bile salts attract lipases which need bile salt and COLIPASE to stay attached--Lipase begins chewing off FFA and those are formed into lamellar vesicles which are bile salt coated and contain cholesterol, phospholipid, and FFA in the center--the lamellar vesicles attract more bile salts to become micelles--the micelles bump into enterocytes and their FFA are protonated--the protonated FFA's are taken up by the cell and the bile salts are reabsorbed in the ileum
|
|
What is the order of fat objects in absoprtion?
|
Emulsified droplet--Lamellar vesicle--Micelle--FFA in cell
|
|
What happens once the FFA's are in the cell?
|
FABP binds them and they are resynth. into TG's in the smooth ER
FA + CoA w/ ATP-->Acyl CoA + Monoglyceride = Diglyceride + Acyl CoA = TG |
|
What does lipase do?
|
Breaks up TG into FFA
|
|
What are cholymicrons and how are they made?
|
Phospholipids, TG's, and cholesterol are packaged together and coated in apoproteins
|
|
Where is cobalamin absorbed?
|
ONLY IN THE ILEUM
|
|
What is the process for Fe absorption?
|
Heme oxygenase breaks down the heme in the enterocytes to yield free Fe--biliverdin(byproduct) is converted into bile salts and bilirubin--Mobilferrin takes up free Fe and exits at the BL membrane to bind TRANSFERRIN--transferrin is taken to the liver(it is also in the gut and grabs Fe and then is endocytosed in vesicles)
|
|
What is DCT1 and what can it cause?
|
DCT1 works with a PROTON gradient to facilitate Fe/H+ cotransport--hemachromatosis is caused by upreg of this transporter and is treated by phlebotomy
|