Pancreatic secretions, carbohydrate/vitamin/mineral absortion Peyer patches, bile p. 282-283 Flashcards
pancreatic secretions: what is the role of alpha-amylase?
starch digestion
pancreatic secretions: what enzyme digests starch?
alpha-amylase
pancreatic secretions: what is the role of lipase?
fat digestion
pancreatic secretions: which enzyme digests fat?
lipase
pancreatic secretions: what is the rol of trypsinogen?
converted to trypsin -> activation of other proenzymes and cleaving of more trypsinogen (positive feedback)
is alpha-amylase secreted in the active form?
yes
pancreatic secretions: what is the role of proteases?
protein digestion
name 4 types of proteases
trypsin, chymotrypsin, elastase, carboxypeptidases
how are proteases secreted (enzymes or proenzymes), and how do you call this?
proenzymes, zymogens
by which enzymes does trypsinogen get converted to trypsin?
enterokinease, enteropeptidase
where are enterokinase/enteropeptidase located? (the enzymes that convert trypsinogen into trypsin)
in the brush border of the duodenum and jejunum
what kind of saccharides are absorbed by enterocytes? poly or mono?
monosaccharides (glucose, galactose, fructose)
name 3 kinds of monosaccharides
glucose, fructose, galactose
via which transporter is fructose taken up by the enterocyte? and via what type of diffusion?
GLUT5, facilitated diffusion
via which transporter is galactose and glucose taken up by the enterocyte? and what is this dependent on (what type of transport)?
SGLT1, Na+ dependent
via what transporter are all monosaccharides (glucose, fructose, galactose) transported from the enterocyte to the blood?
GLUT2
what is the d-xylose test?
d-xylose is a simple sugar that is passively absorbed in proximal small intestine. blood/urine levels decrease with mucosal damage. (normal in pancreatic insufficieny)
vitamin and mineral deficiencies develop in patients with which conditions?
small bowel disease, bowel resection, bariatric surgery (e.g. vitamin B12 deficiency after terminal ileum resection)
small bowel disease, bowel resection, bariatric surgery. can lead to what?
vitamin and mineral deficiency
ileum resection: which deficiency?
vitamin b12
how is iron absorbed and where?
as Fe2+ in duodenum
where is folate absorbed?
small bowel
where is vitamin b12 absorbed? what does this require?
terminal ileum (along with bile salts), requires intrinsic factor
what are Peyer patches?
unencapsulated lymphoid tissue
found ileum (lamina propria and submucosa)
unencapsulated lymphoid tissue found in lamina propria and submucosa of ileum
what is this?
Peyer patches
where are Peyer patches located?
ileum (lamina propria and submucosa)
what type of specialized cells do Peyer patches contain? what do they do?
M cells (microfold cells), present antigens to immune cells
what do M cells in the Peyer patches do?
present antigens to immune cells
what do B cells inside Peyer patches differentiate into? what do they secrete? where do they reside?
plasma cells, secrete IgA, reside in lamina propria
what happens to IgA secreted by plasma cells in the lamina propria?
it gets transported into gut to deal with intraluminal antigens
mnemonic IgA in the gut?
IgA = Intra-gut-Antibody
bile: what is this composed of?
bile salts. phospholipids, cholesterol, bilirubin, water, ions
what can bile acids be conjugated to? what is the results?
glycine or taurine, makes them water soluble
what makes bile salts water soluble?
conjugation to glycine or taurine
what is the function of cholesterol 7alpha-hydroxylase ?
rate limiting step of bile acid synthesis
what are bile salts?
bile acids conjugated to taurine or glycine to make them water soluble
what are the functions of bile? (3)
- digestion/absorption of lipids and fat-soluble vitamins
- bilirubin and cholesterol excretion
- antimicrobial activity (via membrane disruption)
what is the body’s 1st means of eliminating bilirubin and cholesterol?
via bile
decreased absorption of enteric bile salts at the distal ileum.
what does this lead to? (2 things)
abnormal fat absorption, and bile acid diarrhea
decreased absorption of enteric bile salts at the distal ileum.
name 2 examples of diseases that have this decreased absorption?
short bowel syndrome, crohn
what happens with calcium/oxalate when there’s decreased fat absorption in the gut?
calcium binds normally oxalate, but now binds fat instead. oxalate absorbed by gut -> calcium oxalate kidney stones
decreased absorption of enteric bile salts at the distal ileum leads to:
1) abnormal absorption of fat
2) bile acid diarrhea
what else can happen?
calcium oxalate kidney stones
(calcium binds normally oxalate, but now binds fat instead. oxalate absorbed by gut)
