GI 2 Flashcards
what binds carbohydrates together
condensation
process for digestion of fats, carbs, and proteins
hydrolysis
disaccharide found in milk
lactose
large polysaccharide present in almost all nonanimal foods (poatoes)
starch
what secrets ptyalin
parotid gland
what starch is hydrolyzed to via ptyalin
maltose
digestive enzyme of saliva (alpha-amylase)
ptyalin
digestion is active or inactive with pH less than 4
inactive
amount of starches digested into maltose in stomach
30-40%
main enzyme for digestion of carbs in small intestine; more powerful than salivary amylase
pancreatic amylase
enzymes that digest sugars in small intestine
lactase, sucrase, maltase, alpha-dextrinase
what lactose splits into
galactose and glucose
what sucrose splits into
fructose and glucose
what maltose and other small glucose polymers split into
glucose
more than 80% of final products of carb digestion
glucose
important peptic enzyme of stomach (digestion of protein); can also digest collagen
pepsin
pH of this makes pepsin most active
2/3/2015
pepsin represents this amount of total protein digestion
10-20%
where protein digestion mostly occurs
upper small intestine
pancreatic proteolytic enzymes
trypsin, chymotrypsin, carboxypolypeptidase, proelastase
where digestion of proteins in enterocytes of villi occurs (last stage of protein digestion)
duodenum and jejunum
99% of final protein digestive products are absorbed as these
amino acids
most abundant fats of the diet
triglycerides
digests small amount of triglycerides in the stomach (less than 10%)
lingual lipase
where almost all of the fat digestion occurs
small intestine
where emulsification of fat begins…and where it occurs primarily (under influence of bile)
stomach, duodenum
phospholipid that is important in emulsification process of fats (present in bile)
lecithin
surface area of small intestine
250 m2
most important enzyme for digestion of triglycerides
pancreatic lipase
lipase in enterocytes for digestion of TG (not as significant as pancreatic)
enteric lipase
product of TG digestion
free FA and 2MG
remove 2MG and free FA from vicinity of digesting fat globules (so they do not block further digestion)
bile salts
what bile salts accumulate as
micelles
transport medium for 2MG and free FA to brush border of intestinal epithelial cells
bile salt micelles
site of bile salt reabsorption
ileum
cholesterol with one fatty acid
cholesterol ester
enzymes that hydrolyze cholesterol and phospholipids (other than lipases)
cholesterol ester hydrolase and phospholipase A2
total amount of fluid reabsorbed by intestines each day (from ingestion and GI secretions)
8.5
amount of liquid that is left to be absorbed in proximal colon
1.5
lipid-soluble substances that can be absorbed in stomach (otherwise poor absorption)
alcohol, aspirin
increase the mucosal absorptive area by nearly 1000 fold
folds of Kerckring, villi, and microvilli
project 1 mm above surface of mucosa; increase absorptive area by 10 fold
villi
from epithelial cell body into each microvillus of brush border…causes continual movement keeping them exposed to new fluid
actin filaments
typical absorption in small intestine for carbs, fat, amino acids and ions, water
several hundred g; 100 g; 50-100 g; 7-8 L
absorptive capacity for normal small intestine…for carbs, fat, proteins, and water
several KG, 500 g, 500-700 g, 20 L or more
when these kinds of solutions are released from stomachs to duodenum, water transferred to the chyme by osmosis (to make isosmotic)
hyperosmotic
amount of Na typically consumed in a day; amount of Na secreted in intestinal secretions each day
5-8g; 20-30g
typical sodium concentration in chyme
142 mEq/L
sodium cotransported through brush border membrane via these carrier proteins (last is exchange)
Na-glucose, Na-amino acid, Na-H
hormone that is secreted during dehydration…enhances Na absorption
aldosterone
aldosterone causes secondary increase of absorption of these
Cl and water
where Cl absorption occurs
proximal small intestine, also Cl-HCO3 in ileum and colon
where HCO3 is secreted (via pancreatic secretions and bile)
duodenum
amount of water and NaCl secreted as diarrhea each day due to cholera toxin (increases epithelial fold secretion…greater than what can be reabsorbed)
5-10 L
where Ca is absorbed
duodenum
what activates vitamin D (which increases Ca absorption)
parathyroid hormone
how all carbs in food are absorbed
monosaccharides
80% of carb calories absorbed as this
glucose
20% of absorbed monosaccharides composed of this
galactose and fructose
absorption of glucose occurs via this
Na-Glucose co-transport
how fructose is transported through intestinal epithelium
facilitated diffusion
energy for transport of di/tripeptides in protein absorption comes from this
Na co-transport
monoglycerides and free FA become dissolved in the central lipid portions of these (essential for 2MG and FA absorption)
bile micelles
with micelles, only this percentage of fat is absorbed
40-50%
what length of FA are more water-soluble? not converted into TG by ER (allows for direct diffusion from intestinal epithelial cells into capillary blood of intestinal villi)
short
amount of Na and Cl typically left in feces
1-5 mEq
in colon absorption…helps neutralize acidic end products of bacterial action in large intestine
bicarbonate
amount colon can absorb of fluid and electrolytes
5-8 L
bacteria in colon can aid in absorption of these vitamins
K, B12, thiamine, riboflavin
derivatives of bilirubin that cause brown color of feces
stercobilin and urobilin
bacterial byproducts that cause odor of feces
sindole, skatole, mercaptans, hydrogen sulfide
