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1 GI and liver > nitrogen balance, amino acid degradation, urea cycle, glucose-alanine cycle, lipids > Flashcards

nitrogen balance, amino acid degradation, urea cycle, glucose-alanine cycle, lipids Flashcards

1
Q

what are the 5 main roles of the liver?

A

storage

regulates hormones eg. oestrogen

immune

synthesis of proteins

digestion (produces bile)

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2
Q

what are the resident macrophages of the liver?

WBC that undergoes phagocytosis that lives in tissues of liver

A

kuppfer cells

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3
Q

what substances does the liver store?

A

fats

minerals eg. iron as ferritin

carbohydrates

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4
Q

what are the 3 types of proteins synthesised by the liver?

A

albumin (pasma proteins)

clotting factors

compliment proteins

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5
Q

what are the 2 roles of albumin?

A

to maintain oncotic pressure

carrier protein

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6
Q

what is oncotic pressure?

A

the force keeping blood in the blood vessel

achieved by albumin pressing on the walls

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7
Q

what is albumin a carrier protein for?

A

unconjugated bilirubin

insoluble, hydrophobic molecule

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8
Q

which clotting factor ISN’T produced by liver?

A

8

vonwillibrand factor

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9
Q

which clotting factors are dependent on vitamin K synthesis?

A

10,9,7,2

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10
Q

what do compliment proteins do?

A

they are involved in immune response - mark pathogens

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11
Q

what are excess proteins stored as?

A

fat

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12
Q

what are the 2 pathways for recycling faulty proteins in the liver?

ie. degrading macromolecules back into constituent AAs

A

ubiquitin dependent - protein in cytoplasm that selectively binds to protein and signals to proteases to break it down

lysosomal - Kupfer cells phagocytose the protein, and then the lysosomes of the kuppfer cells fuse and secrete enzymes that break it down

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13
Q

what is the difference between a protein, polypeptide and dipeptide?

A

depends on how many peptide bonds with the molecule

protein has 50>
polypeptide has <50 but still a lot
dipeptide has 1 (2 monomers)

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14
Q

what are the main functions of amino acids? (4)

A

1) bond via peptide bonds to form proteins and polypeptides
2) broken down to be used as intermediates in the Krebs cycle
3) form nitrogenous proteins eg. ammonia, which needs to be excreted
4) can be used to from glucose (C backbone)

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15
Q

intake of nitrogen (3)

A

diet

bodily protein (fasted state)

de novo (newly synthesised)

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16
Q

outake of nitrogen (3)

A

excreted as urine

faecel loss

skin, hair, sweat

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17
Q

what is a positive nitrogen balance?

A

when more nitrogen intake then outtake

eg. bodybuilders

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18
Q

what is a negative nitrogen balance?

A

when less intake then outtake

eg. essential amino acid deficiency

19
Q

what is transamination?

A

metabolism of amino acids to create metabolic intermediates to feed into TCA/krebs cycle

20
Q

what is the transamination reaction?

A

amino acid + alpha ketoacid → alpha keto acid + amino acid

  • swaps amine group
  • the a-kacid becomes an intermediate for Krebs
  • the aa gets NH3 removed in urea cycle
21
Q

what is the most common transamination reaction?

A

alanine + alpha-ketoglutatate → pyruvate + glutamate (aa)

22
Q

what is the catalyst for transamination reaction?

A 
alanine aminotransferease (ALT) 
with pyridoxal phosphate (PLP)
23
Q

what is pyruvate?

A

an alpha keto acid metabolic intermediate (gluconeogenesis and aerobic respiration)

produced In transamination

24
Q

what is oxidative deamination?

A
  • process to excrete toxic NH3 in urea cycle

- hydrolyses amino acid whilst preserving carbon back bone

25
Q

what are the chemicals involved in oxidative deamination?

A
  • glutamate (aa product of transamination)
  • water (because its a hydrolysis reaction)
  • glutamate dehydrogenease (catalysts)
  • alpha ketoglutemate (recycled and used in body)
  • NH3 (free ammonia, toxic, goes into urea cycle)
26
Q

what is the reaction of oxidative deamination?

A

glutamate (aa) + H20 → alpha ketoglutemate + NH3

27
Q

what is the functional use of ammonia?

A
  • product of oxidative deamination

- used in urea cycle

28
Q

why is ammonia neurotoxic?

A

it can cross the BBB and deplete alpha-ketoglutate

this impairs aerobic respiration and impacts krebbs

29
Q

what are the 3 main Amino acids to the urea cycle?

A
  1. arginine
  2. orthinine
  3. citrulline
30
Q

what are the 3 main steps of the urea cycle?

A

arginine split by arginase to form ornithine and urea (non-toxic)

ammonia and CO2 feed in and ornithine turns into citrulline

ammonia feeds in to regenerate arginine

31
Q

what is the glucose-alanine cycle?

A

cycle where liver produces glucose for energy for muscle contraction

alanine is the main amino acid involved

32
Q

what is the 1st step of the glucose-alanine cycle?

A
  1. reverse transamination in muscles to produce alanine
33
Q

what is the 2nd step of the glucose-alanine cycle?

A
  1. alanine transported to liver
34
Q

what is the 3rd step of the glucose-alanine cycle?

A
  1. transamination in liver . produces glutamate and pyruvate. glutamate undergoes oxidative deamination. pyruvate undergoes glucogensies to become glucose in the liver.
35
Q

what is the 4th step of the glucose-alanine cycle?

A
  1. glucose transported to muscle cells
36
Q

what is the 5th step of the glucose-alanine cycle?

A
  1. glycolysis of glucose to produce pyruvate for step 1
37
Q

what are lipids?

A

macromolecules

38
Q

in what form are they mainly stored in the liver as?

A

in adipocytes in white adipose tissue (some brown from brith)

39
Q

what is the main intake of lipids?

A

TAGs from diet

40
Q

what is the structure of a triglyceride?

A

1 glycerol with 3 fatty acids (ester bonds)

41
Q

lipids are also stored in the liver as phospholipids, cholesterol, and fat soluble vitamins. which are the fat soluble vitamins?

A

A
D
E
K

42
Q

what are the main functions of lipids? (4)

A
  • energy reserve (largest in body)
  • hormone metabolism
  • shock absorbant (protects liver)
  • form cell membrane components
43
Q

how do lipids relate energy?

A

fatty acid beta oxidation breaks down the FAs

releases energy

44
Q

what are the 4 biggest energy reserves in body? in order from lowest to highest

give energy in killer calories

A
  1. blood glucose 400kcal
  2. glycogen 600kcal
  3. muscle protein 30,000
  4. lipids 100,000

1 GI and liver (6 decks)

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