DLA 16 and Lecture 27+28 Flashcards

1
Q

digestion in the mouth

A

carbohydrate digestion by salivary alpha amylase

this enzyme cleaves alpha 1,4 bonds of starch and glycogen and forms branched oligosaccharides

lingual lipase for lipid digestion
released in the mouth but mainly swallowed

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2
Q

digestion in the stomach

A

gastrin

leads to HCl release from parietal cells
release of pepsinogen and gastric lipase from chief cells.

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3
Q

role of HCl in the stomach

A

HCl denatures food; leads to quicker digestion

destroys fungi and bacteria

alters the conformation of pepsinogen to pepsin; autocatalytic activation

pepsin cleaves peptide bonds within the protein (endopeptidase)

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4
Q

acidic chyme in the stomach

A

stops carb digestion… salivary amylase is denatured

protein digestion starts from pepsin

breakdown of TAGs

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5
Q

role of secretin and CCK

A

when the acidic chyme reaches the duodenum, these enzymes are released to assist with neutralizing the pH

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6
Q

role of CCK and digestion

A

release of bile from gallbladder
activation of enteropeptidase enzyme
secretion of pancreatic enzymes

inhibition of gastric motility; allows pH change

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7
Q

role of enteropeptidase

A

activates zymogens:

trypsinogen to trypsin
chymotrypsinogen to chymotrypsin
proelastase to elastase
procarboxypeptidases to carboxypeptidases

for lipids:
prophospholipase A2 to phospholipase A2
procolipase to colipase

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8
Q

lactose intolerance

A

pain, nausea, flatulence, and diarrhea after the consumption of lactose

suppose to be broken down by lactase

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9
Q

lactase synthesis

A

The LCT gene for lactase is generally less expressed after infancy (lactase non-persistence phenotype)

The gene expression is controlled by MCM6

inherited changes to this leads to prolonged synthesis of lactase (lactase persistence phenotype)

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10
Q

abnormal lactose metabolism

A

lactase deficiency will lead to lactose reaching the large intestine.

the gut bacteria degrade the lactose to osmotically active compounds and thus lead to symptoms

osmotic diarrhea- water entering the lumen from cells

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11
Q

treatment of lactose intolerance

A

diet low in lactose
lactose free products
lactase pill

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12
Q

forms of lactose intolerance

A
  1. lactase non-persistence or primary lactose intolerance

lactase is strongly reduced after age 7
adult hypolactasia

  1. disaccharide deficiency - secondary lactose intolerance

all disaccharides are affected, but lactase is the first activity lost
can occur due to food poisoning
rotavirus
celiac disease

  1. congenital lactase deficiency (most severe and most rare form )

symptoms as a baby
need lactose free formula

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13
Q

activation of trypsin

A

trypsinogen is released into the duodenum by the pancreas

activated when it reaches the lumen; due to it being a powerful enzyme

activated by enteropeptidase

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14
Q

once trypsin is activated what does this enzyme activate

A

chymotrypsin
elastase
carboxypeptidase

phospholipase A
colipase

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15
Q

where does trypsin cleave

A

after arginine or lysine

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16
Q

where does chymotrypsin cleave

A

after bulky and aromatic residues

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17
Q

where does elastase cleave

A

glycine, alanine, and serine

18
Q

where does carboxypeptidase cleave

A

cleave from the carboxy-end

19
Q

absorption of AA’s

A

done mainly by secondary active transport with the co-transport with Na

the release of AA’s into the portal vein is by facilitated diffusion

20
Q

absorption of monosaccharides

A

dietary fructose enters the intestinal cell via facilitated transport via GLUT 5

dietary glucose and galactose will enter the intestinal cell via SGLT-1
secondary active transport with Na

all three monosaccharides are released via facilitated transport by GLUT-2 into the portal vein

21
Q

function of bile salts?

A
  1. transportation of free cholesterol and conjugated bilirubin from the liver to duodenum
  2. emulsify dietary lipids for digestion
  3. form mixed micelles for the uptake of lipids into the mucosal cells
22
Q

colipase action?

A

The protein colipase pushes bile salts away from TAGs and anchors pancreatic lipase to the lipid droplet.

23
Q

pancreatic lipase function

A

cleaves TAGs only to MAG’s

24
Q

Orlistat

A

a drug used to inhibit pancreatic lipase for weight loss treatment

25
end product of nucleic acids
uric acid that is released into the urine
26
possible causes of steatorrhea
1. lack of conjugated bile salts due to liver damage, bile duct obstruction, and/or pancreatic tumor 2. defects related to pancreatic secretions deficiency in enzymes 3. defective intestinal cells or shortened bowl
27
what reactions require BH4 as a cofactor
phenylalanine hydroxylase (Phe to Tyr) tyrosine hydroxylase (Tyr to DOPA) tryptophan hydroxylase (Trp to 5-hydroxy tryptophan)
28
PKU II or malignant PKU
deficiency of BH2 or dihydrobiopterin reductase much more severe CNS symptoms: decreased neurotransmitter synthesis (serotonin, dopamine, Epi, and Norepi) treatment includes Phe diet restriction and providing dietary biopterin treatment can also be saproterin or an analogue of BH4
29
biochemical defect of PKU II
No BH2 and/or no dihydrobiopterin reductase deceased melanin synthesis and decreased neurotransmitter synthesis tyrosine becomes essential AA increase in phenylpyruvic acid
30
Tetrahydrobiopterin deficiency
results in hyperphenylalaninemia and decrease synthesis of neurotransmitters results in intellectual disability and seizures management: provisional neurotransmitters dietary restriction of phe
31
S-adenosyl methionine (SAM)
synthesized from methionine A methyl group donor in many reactions after the donation of the methyl group SAM is converted to homocysteine homocysteine may be converted to cysteine by transsulfuation pathway (need PLP or B6) or conversion back to methionine by B12 and methylfolate
32
importance of 1-carbon pool
products formed are purines and pyrimidines required for DNA and RNA synthesis (cell division)
33
folate deficiency
reduction in 1-C donors, thus reduced synthesis of purines and pyrimidines delay in DNA synthesis, thus reduced rates of cell division effects on RBC formation- see macrocytes and megaloblasts decrease in hemoglobin concentration polysegmented neutrophils
34
who is at risk for folate deficiency?
those who are pregnant (neural tube defects) chronic alcohol consumption those who do not eat vegetables (green, leafy)
35
histamine load test????
used to determine folate deficiency in folate deficiency, it is seen that histamine metabolism is limited and FIGLU accumulates more FIGLU in the urine
36
Vitamin B12 deficiency
macrocytic anemia and neurological features (tingling in hands/feet, inability to walk, psychiatric, and urinary incontinence) usually absorbed in the terminal ileum with intrinsic factor (released by parietal cells) have increased levels of methylmalonate in circulation and in urine elevated homocysteine levels have normal levels of un-usable folate (methyl THF form)
37
functions of B12
animal sources are rich in vitamin B12 needed for methionine synthase needed for methylmalonyl CoA mutase
38
reactions that need B12?
conversion of homocysteine into methionine via methionine synthase conversion of methylmalonyl CoA to succinyl CoA via methylmalonyl CoA mutase
39
folate trap
when one does not have correct levels of vitamin B12 the cellular folate is stuck in the methyl-THF form cannot be converted back bc the reaction is not reversible
40
who is at risk for B12 deficiency
Vit. B12 is stored in the liver, so it takes some time to develop a lack of B12 usually seen in vegans or failure to absorb B12 due to atrophic gastritis pernicious anemia disease of the ileum
41
diff between folate and B12 deficiency
In vitamin B12 deficiency one will see neurological manifestations and an increase in methylmalonate