L24: Mucosal Absorption

Question 1

once food is in an absorbable size, it is translocated from the lumen of the intestine to…

Answer 1

the extracellular space of the gut for further processing and distribution

Question 2

the process of translocating basic molecules from the interstitial lumen through the epithelial cells of the intestine into the vascular system

Answer 2

absorption

Question 3

T/F: the end products of carbohydrate and protein digestions are hydrophilic

Answer 3

True

Question 4

how is glucose transported across the basolateral membrane

Answer 4

by facilitated diffusion (via transport protein, GLUT-1)

Question 5

movement of glucose through the basolateral space is driven by…

Answer 5

diffusion

Question 6

what is the most important active transporter

Answer 6

Na/K pump

Question 7

what is an important secondary active transporters

Answer 7

Na/Glucose co transporter; uses the Na gradient

Question 8

transcellular absorption

Answer 8

ions follow electrochemical gradient through ion channels in the apical membrane

Question 9

paracellular absorption

Answer 9

ions follow electrochemical gradient and osmotic pressure through tight junctions

tight junctions are freely permeable to water and small ions

Question 10

facilitated diffusion

Answer 10

spontaneous passive trasnport of molecules or ions across membrane via specific membrane integral proteins

Question 11

glucose is transported across the basolateral membrane by ________ diffusion

Answer 11

facilitated via GLUT-1; dependent on glucose gradient

Question 12

the Na+ glucose coupled transport stimulates water absorption by ______

Answer 12

solvent drag

Question 13

oral rehydration salts exploit what transporter

Answer 13

SGLT-1 co transporter; remains active due to strong Na-gradient

Question 15

disorders of carbohydrate digestion and absorption are mostly due to…

Answer 15

enzyme deficiencies that prevent breakdown of carbohydrates to an absorbable form

Question 16

unabsorbed carbohydrates hold water osmotically and cause _____ diarrhea

Answer 16

osmotic
solute driven water loss

Question 18

95% of ingested fat is removed by the ….

Answer 18

small intestine

Question 19

why package lipids into small vesicles at the lumen of GI tract and inside the cell

Answer 19

hydrophobic but need to be transported in watery enviornment

Question 20

micelles enter the enterocyte cell and are repackaged into…

Answer 20

Chylomicrons: core of triglyceride and cholesterol surrounded by phospholipase and apoproteins

Question 21

what are chylomicrons

Answer 21

transport vehicles for lipids in lacteals

Question 22

water soluble chylomicrons

Answer 22

coat of phospholipids, triglycerides, proteins and contnet of triglycerides, cholesterol ester

Question 23

what is the importance of apoproteins

Answer 23

they are structural components of liporprotein particles; serve as ligands for cell surface receptors and as cofactors for enzymes

Question 24

what happens in the absence of apoproteins

Answer 24

large quantities of triglycerides accumulate in enterocytes

Question 25

chylomicrons are taken up by…

Answer 25

lacteals - lymphatic vessels in villi that take up lipids

Question 26

where do lacteals drain into

Answer 26

cisterna chyli (abdominal lymphatic duct), further into the thoracic lymphatic duct and into the internal jugular vein

Question 27

bile acids remain in the _______ lumen and are _____

Answer 27

intestinal
recycled

Question 28

where are bile acid transporters (Na-bile acid cotransporter) located

Answer 28

ileum

Question 29

bile acids are synthesized from ________ in the _________

Answer 29

cholesterol
liver

Question 30

bile acids are released into the _________ and flow through the _________ lumen where it emulsifies lipids

Answer 30

duodenum
intestinal

Question 31

lipids are primarily absorbed by ________ in the ________

Answer 31

enterocytes
jejunum

Question 32

a large % of bile acid is reabsorbed and returned to the _______ via the ______

Answer 32

liver
portal system (portal vein)

Question 33

if the liver doesn’t recycle bile acids, where will they show up

Answer 33

in the plasma

Question 34

complete or partial damage to the portal blood flow will cause _______ elevation because they bypass the liver (portosystemic shunt)

Answer 34

blood bole acid elevation

Question 35

acquired liver shunts can result from..

Answer 35

liver disease

Question 36

liver shunts can be _____ or develop from liver diseases

Answer 36

congenital

Question 36

what size and breed(s) are most susceptible to congenital extrahepatic liver shunts

Answer 36

small and toy breeds

Question 37

large breed dogs are more likely to have what kind of liver shunt

Answer 37

intra-hepatic

Question 38

accumulation of toxins and metabolic waste products from a liver shunt ca lead to hepatic _______

Answer 38

encephalopathy

Question 39

clinical signs of liver shunts

Answer 39

• poor growth / development
• neurologic & behavioral changes
• increased thirst and frequcny of urination
• vomiting
• accumulation of toxins and metabolic waste leading to hepatic encephalopathy

Question 40

in hepatic encephalopathy, gut-derived ______ substances accumulate such as _______

Answer 40

neurotoxic
Ammonia (can cross BBB)

Question 41

what is the bile acid test

Answer 41

liver function test
indicates the degree of inflammation or damage

fast for 12 hrs
collect preliminary blood sample
small meal
2 hours after meal, blood sample collected

blood samples are tested for levels of bile acids

Question 42

what would you expect to see in a normal bile acid test

Answer 42

low initial and low post meal levels of bile acids

Question 43

if a patient has an elevated resting sample from the bile acid test, what does this mean

Answer 43

bile acids are remaining in circulation –> liver disease, portosystemic shunt, impaired gall bladder, gall stones, etc

Question 44

if you do the bile acid test and get normal low resting BA levels but elevated BA levels post meal, what does this tell you?

Answer 44

bile acids are slowly reabsorbed and escape into the systemic circulation
the liver is able to handle BA between meals but not the load of substance that arrives after a meal