Lecture 6 Flashcards
Can polysaccharides be digested as is?
Nope, gotta be monosaccharides
What digests proteins
Pepsin
What converts trypsinogen into trypsin
Membrane bound enteropeptidase
What convertes chymotrypsinogen into chymotrypsin
Trypsin
What converts procarboxypeptidase into carboxypeptidase
Trypsin
How does pepsin digest proteins
It cleaves bonds with tyrosine and phenylalanine
Pepsin hydrolyzes what percent of ingested protein
10-15
What are the two sources for carboxypeptidase
brush border
pancreas
What enzyme chews one amino acid from the carboxyl end
Carboxypeptidase
What enzyme chews an amino acid frm the amine region
Aminopeptidase
What enzyme chews an amino acid at both ends
Dipeptidase
What breaks protein into large polypeptides
Pepsin
What breaks proteins from large polypeptides to small polypeptides
Pancreatic enzymes
What breaks small protein polypeptides into amino acids
Brush border enzymes
Aminopeptidase, Carboxypeptidase, and Dipeptidase are what kind of enzymes
Brush border
Trypsin, chymotrypsin and carboxypeptidase are what kind of enzymes
Pancreatic enzymes
What is a triglyceride
a neutral fat
how does glycerol turn into a triglyceride
loses an h20 and binds with two other gycerols
What is the only significant site of fat digestion
small intestine
what do lipases cleave triglycerides into
fatty accids and glycerol/2-monoglycerides
How are nucleic acids digested
pancreatic nucleases reduce rna and dna to consistent nucleotides
what reduces nucleotides to free bases, pentose sugars and phosphate ions
intestinal brush border
nucleosidases
phosphatases
How many L of chyme reach the LI per day
0.5-1
What is the ileums primary function
recycle bile salts via portal circulation to the liver
What valve does the leftover foodstuff pass through to the large intestine from the ileum
Ileocecal valve
whose primary function is it to recycle bile salts via portal circulation to the liver
Ileum
Intestinal cells are joined at luminal surfaces by what
tight junction
How are lipid digestion products absorbed by the SI
passive diffusion
How are most nutrients absorbed
active transport
Carbs have to be ______ to be digested
monosaccharides
How are carbs absorbed into epithelial cells
Secondary active transport
How are carbs absorbed into blood capillaries
diffusion through intercellular clefts
What is the only monosaccharide that doesnt need ATP to be absorbed
fructose
The carb absorption used the _____ concentration gradient in the basolateral membrane
Sodium
The protein absorption used the _____ concentration gradient in the basolateral membrane
sodium
How do amino acids get into capillaries
Diffusion
are monoglycerides, glycerol and ffa water soluble or insoluble
Insoluble
What is a micelle
a very small emulsion droplet
What two things associate to create a micelle
Bile salts
lecithin
Can micelles diffuse across the lipid bilayer
Yes
Once micelles diffuse into the cell, what happens to ffa and glycerol
they get resynthesized into triglycerides
what are chylomicrons
proteins, triglycerides, phospholipids and cholesterol
How do chylomicrons empty into the venous blood
they enter the lymphatic systme and are emptied into the thoracic duct
how are triglycerides hydrolyzed in circulation
by lipoprotein lipase
lipid absorption is usually complete by the _____
Ileum
What happens to lipid digestion if bile is missing
You can’t absorb it, so you just have fatty stools
what type of vitamins are absorbed as part of the micelles
fat soluble vitamins
What are the fat soluble vitamins we learned
A D E K
what are the water soluble vitamins we learned
B C
what type of vitamins are absorbed easily
water soluble
what is the water soluble vitamin that cannot be absorbed easily
Vitamin B12
sodium absorption is coupled to that of ____ and ______
glucose and amino acids
anions primarily follow the electrical gradient established by ______
sodium
do chloride ions transport actively or passively
actively
How is potassium absorbed
simple diffusion - osmotic gradient
how is iron absorbed
it’s actively transported into mucosal cells and binds to ferritin
How is iron transported in bloud
Bound to transferrin
what is the absorption of calcium related to
blood levels of ionic calcium
what does PTH trigger
activation of vitamin D by idneys, to increase uptake of calcium by the SI
What triggers secretion of PTH
low plasma calcium
most of the water is absorbed by ______
osmosis
How long does the leftover foodstuff spend in the LI
12-24 hours
What is the major function of the large intestine
Defecation
What causes gases
Fermentation in the LI (ie of cellulose)
What vitamins are synthesized in the LI
B and K
how often are haustral contractions
every 30 mins
what does a haustral contraction move the contents to
the next haustrum
what is the gastrocolic reflex
Long, slow and powerful mass movements in the LI
How often does the gastrocolic reflex occur in a day
3-4 times
What can occur when you have too little fiber
pressure on walls increases; can lead to diverticulosis
What is diverticulosis
small herniations of the LI mucosa
What can diverticulosis lead to
Diverticulitis
Whats more serious, diverticulosis or diverticulitis
diverticulitis
What does fiber do
increases strength of colon contractions and softens stools
what is valsalvas maneuver
the closing of glottis, contracting diaphragm and ab muscles
