Digestion and absorption of carbs Flashcards
Monosaccharide found in table sugar
glucose
Monosaccharide found in fruits
fructose
Monosaccharide found in “milk sugar”
galactose
Sucrose bond and 2sugars
alpha-1,2. glucose and fructose
Lactose bond and 2sugars
beta-1,4. glucose and galactose
Maltose bond and 2sugars
alpha-1,4. glucose and glucose
2 components of starch and where found
amylose and amylopectin. storage in plant cells
glycogen found in
animal cells
cellulose aka ___ found where
fiber. found in plant cell walls
amylose bond
alpha 1,4
amylopectin bond
alpha 1,4 and alpha 1,6
glycogen bond
alpha 1,4 and alpha 1,6
cellulose bond
beta 1,4
which is more branched? glycogen or amylopectin
glycogen
which polysaccharide can humans NOT break down and why
cellulose. cannot break down beta 1,4 linkages
what is the function of gastrointestinal organs?
digestion and absorption
alpha amylase breaks down what linkages
alpha 1,4 found in starch
what is alpha amylase considered and where is it found
endoglycosidase found in saliva and pancreatic juice
what are the products after alpha amylase is used in starch
maltose, maltotriose, and alpha dextrins (shortened polysaccharide chains)
what epithelium releases the enzymes lactase, sucrase, and alpha glucosidases
intestinal
what are the two alpha glucosidases and what do they cleave
maltase cleaves alpha 1,4. isomaltase cleaves alpha 1,6
what is the most commonly deficient enzyme
lactase
what does the drug Acarbose do and how does it do it
blocks activities of pancreatic alpha amylase and brush border alpha glucosidases.
Used to treat Type 2 diabetes.
Reduces the rate at which ingested carbs reach bloodstream after a meal
Facilitative glucose transporters are
GLUT 1-5
Na+ dependent transporters are
SGLT1 and SGLT2
SGLT1 is found in
intestine
SGLT2 is found in
kidney
Mutations in SGLT1 cause
malabsorption of Glc and Gal
Mutations in SGLT2 cause
familial renal glycosuria
how do Glifozins work and what do they treat
inhibitors of SGLT2 transporters. inhibit reabsorption of glucose which allows for more to be excreted in urine. helps with type 2 diabetes
GLUT2 where is it found and what does it do
found in pancreatic beta cells.
- receptor takes in glucose
- allows for ATP to be broken down in mitochondria
- this breakdown of ATP closes K+ channel which allows for K+ to stay in and depolarization of cell
- change in membrane polarization opens voltage gated calcium channel allowing calcium to enter
- increased calcium leads to insulin being released
GLUT4 where is it found and what does it do
found in muscle and adipose tissue.
- stimulated by insulin which causes GLUT4s which were in membrane to fuse with plasma membrane.
- the more GLUT4s attach the more glucose can be taken in by the cell
when are GLUT4’s recruited to membrane in muscles?
during exercise
what mediates the uptake of GLUT4 in muscles during exercise
AMP-dependents protein kinase (AMPK).
What gene is mutated in neonatal diabete
KCNJ11 gene
what does the KCNJ11 gene code for and what disease process is relevant
encodes subunit for K+ATP channel. Neonatal diabetes
What does KCNJ11 gene mutation do in neonatal diabetes?
eliminates ATP-dependent regulation of the channel and results in always open channel. Inability to close prevents release of insulin in beta pancreatic cells
what drug can be used to treat neonatal diabetes
sulfonylureas
how does sulfonyureas work and what does it treat
stimulates release of insulin by closing ATP-sensitive K-channels in beta cells. treats neonatal diabetes
what GLUT is responsible for sending glucose across blood brain barrier
GLUT1
GLUT1 deficiency causes
decreased glucose transport into the cerebrospinal fluid and brain. patients suffer with seizures in infancy and developmental delays
What GLUTs control BBB
GLUT 1 and GLUT3
symptoms of hypoglycemia like light-headedness or dizziness are relevant with what GLUT transporters
GLUT 1 and GLUT3
