Intestinal Transport & Liver Physiology Flashcards
The enterosystemic fluid cycle is what?
daily exchange of several times total volume of water
- net movement both into and out of the intestinal lumen every 24 hours
Why is the enterosystemiic fluid cycle important?
to reabsorb secretions delivered to proximal part of the small intestine
What has a substantial fraction of ECF volume?
secretory fluids from accessory organs
stomach and intestine itself
In the enterosystemic fluid cycle, there are larger volumes of secretions in [carnivores/omnivores/herbivores]
herbivores
Where are major reabsorptive sites regarding the enterosystemic fluid cycle?
distal small intestine
large intestine
Epithelial cells lining intestinal crypts secrete _____ & ______
fluid
electrolytes
During intestinal secretions, the apical membrane has what kinds of channels?
Cl-
What does the basolateral membrane have in epithelial cells of the intestinal crypt?
Na+/K+ ATPase
Na+/K+/2Cl co-transporter
Cl- channels of the epithelial cells of the crypts are usually [open/closed], but will open to response to _____ and ________ binding the basolateral membrane
closed
hormones
neurotransmitters
What does the cholera toxin cause? What does it do?
chloride channels to open
dumps lots of Cl-, Na+, and water
Which routes are there for fluid and electrolyte absorption
transcellular
paracellular
If the junction is tight, it tends to go the [transcellular/paracellular] route
transcellular
Where are there tight junctions?
stomach
colon
If the junction is leaky, it tends to go the [transcellular/paracellular] route
paracellular
Where are there leaky junctions?
duodenum
jejunum
What is special about the jejunum with intestinal absorption?
major site for Na+ absorption
Intestinal absorption occurs via what transporters on the apical membrane? Na+ transporters are coupled with what?
monosaccharides
amino acids
Na+/H+ exchanger
The ileum also absorbs ______
Na+
What transporters are on the apical membrane in the ileum?
Na+/sugar or amino acid
Cl-/HCO3-
Na+/H+ exchanger
In the ileum, there is an overall net absorption of ______
NaCl
What channels are there in the apical membrane of the colon?
Na+ and K+
The synthesis of Na+ channels is induced by ______
aldosterone
Diarrhea is due to an increase loss of [Na+/K+] due to an [increased/decreased] flow rate of intestinal fluid
K+
increased
The colon helps to excrete which ion?
K+
What are some issues and losses associated with severe diarrhea?
hypercholemic metabolic acidosis with normal anion gap
You lose a lot of ____ from the GIT which signals the kidneys to reabsorb ______
HCO3-
NaCl
What does losing HCO3- from the GIT stimulate?
Na+/H+ exchanger
kidneys start to excrete more H+, need more NH3 for buffering
What causes diarrhea?
decreased surface area for absorption
osmotic diarrhea
secretory diarrhea
The liver receives portal blood from which organs?
stomach
small intestine
large intestine
pancreas
spleen
What produces and exerts bilirubin?
liver
Bilirubin production and excretion has which type of system?
mononuclear phagocyte
Hemoglobin is degraded to ______ then _______
biliverdin
bilirubin
Bilirubin binds to _____ in [blood/lumen/colon]
blood
After bilirubin binds to albumin in blood and transports to liver, it is conducted to _____, which results in _______
glucoronic acid
detoxification/degradation in liver
Conjugated bilirubin is excreted in ___ AND secreted in ______
urine
bile - SECRETED!!
If secreted in bile, conjugated bilirubin travels to where to become deconjugated?
terminal ileum
colon
What is conjugated bilirubin deconjugated to?
urobilinogen
urobilin + stercobilin
What is jaundice?
accumulation of free or conjugated bilirubin
What does jaundice result in?
destruction of red blood cells
destruction of bile ducts
liver disease
Can conjugated bilirubin be excreted?
NO
shows up in circulation
What aa does gluconeogenesis use to synthesize glucose after glycogen is depleted? This is in [ruminants/nonruminants]
glycerol
glycogenic aa
non-ruminants
How do ruminants do gluconeogenesis?
continuous process of converting propionate to glucose
Glycogenesis are highly branches chains of stored _____ and occurs [before/after] a meal
glucose
AFTER
What is glycogenolysis?
break down glycogen to release glucose
What stimulates glycogenolysis?
glucagon
epinephrine
What are the metabolic functions of the liver?
carbohydrate metabolism
protein metabolism
lipid metabolism
Protein metabolism in the liver does what?
synthesizes non-essential amino acids
modifies amino acids
synthesizes plasma proteins (albumin)
converts ammonia to urea
What happens in lipid metabolism in the liver?
fatty acid oxidation
synthesizes lipoproteins, cholesterol, phospholipids, and bile acids
