digestion and absorbtion Flashcards
6 basic functions of GI
- movement
- secretion of digestive juices
- digestion
- absorption
- circulation - of blood through system
- control of processes
2 main structures involved in digestion
- luminal tract (tube from top to bottom)
2. accessory organs - teeth, pancreas, liver stc
3 main roles of stomach
- break down food mechanically
- secrete acid/enzymes
- kill bacteria
role of SI
digestion and absorbtion
how is SI surface are increaed
microvillae
4 sources of luminal enzymes and what they are
- salivary glands - amylase, lipase
- stomach - pepsin, lipase
- pancreas - anylase, trypsin, lipase
- SI - enterokinase, dissacharidase, pepsidase
what happens to proteins in stomach
broken into polypeptides by gastirc acid and pepsin
what happens to proteins in SI
polypeps broken into smaller polypeps using panc. enzymes (trypsin, chymotripsin)
what removes AAs from polypeps
carboxypolypesdiases
how does AA enter system
brush border pulls in di, tri AAs and and these are transported into cell via Na co-transporter
what happens to AA in cell
broken into smaller AAs so can enter the blood
what happens to fat ins stomach and mouth
breakup of 10% of TGs into MG and FFAs by acid resistant lipase
what happens to fat in SI
bile salts emulsify
what is eumlsification
bile salts align to make fat hydrophillic
what happens to fat with bile salts
along with lipase, broken down further into micelle
why are micelles important
allow it to cross H2O layer before brush border of cell
what happens to fats within cell (2)
- MG and FFA reesterify into TG in ER of cell
2. apoproteins attached in golgi to make chilomicron
why is apoprotein important
allows CM to leave cell
what can cause intraluminal malabsorbtion (3)
- lipase defic - pancreatitis
- impaired micelle formation - no bile salts - liver probs
- pH probs - H excess via gastroma, HCO3 via CF
2 problem occuring with mucosa
- impaired uptake - celiacs, fistula
2. impaired CM formation - abetalipoprotenemia
what happens to starch in mouth
amylase breaks it down into maltose
what happens to starch in stomach
salivary amylase continues to break into maltose, HCl only allows 35%
what happens to starch in SI
pancreatic amylase (stronger) breaks it down to maltose
what happens to maltose in SI
disaccaridases at brush border break disacs into monosacs
how does glucose get in
Na/glucose pump pulls it in + also solvent drag
how does fructose get in
via facilated diffusiton
what happens to fructose in cell
some turned into glucose
where is bile salts resabsorbed
illeum
where is B12 absorbed
activated in duod, but absorbed in illeum
