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FOM: Nutrition > Nitrogen > Flashcards

Nitrogen Flashcards

1
Q

primary source of nitrogen

A

dietary proteins = primary source of nitrogen metabolized in the body

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2
Q

amino acids absorbed through

A

intestinal epithelial cells

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3
Q

nitrogen balance during periods of growth vs starvation

A

during growth nitrogen balance positive

– growing weight

during starvation nitrogen balance negative

– weakness and anemia

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4
Q

carbon skeletons of amino acids serve as

A

source of energy

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5
Q

amino acids can only be oxidized after

A

the nitrogen (amino group) is removed

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6
Q

what is the product of nitrogen removal

A

toxic ammonia

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7
Q

organ responsible for producing urea

A

liver

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8
Q

uric acid

A

produce of purine degradation

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9
Q

creatine formed from

A

when creatine phosphate and ammonia are released from glutamine in the kidneys

– here it helps puffer the pH of urine

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10
Q

bilirubin

A

nitrogen containing degradation product

– excreted primarily as feces

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11
Q

major nitrogen excretory products

A

urea

NH4+

creatine

uric acid

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12
Q

digestive enzymes produced as

A

zymogens to prevent damage to enzyme secreting cells

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13
Q

pepsinogen

A

cleaved by pepsin in highly acidic environment

– pepsin secreted due to HCl secretion from gastric parietal cells

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14
Q

acetocholine

A

major neurotransmitter for stimulating enzyme and electrolyte secretion throughout the GI tract

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15
Q

histamine

A

stimulates HCl secretion

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16
Q

tryspinogen

A

zymogen form of tyrpsin

– activated upon by pancreatic enzyme, enteropeptidase, which is secreted by brush border cells of the small intestine

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17
Q

enteropeptidase

A

is secreted by brush border cells of the small intestine

activates trypsinogen and

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18
Q

serotonin

A

stimulates intestinal NaCl secretion

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19
Q

amino acid active transport in small intestine

A

Na+

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20
Q

dipeptide active transport in small intestine

A

H+

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21
Q

transamination reactions

A

produces alpha keto acids and glutamate from amino acids and alpha-ketoglutarate

– B6 (pyridoxal phosphate) is a required cofactor for aminotransferases

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22
Q

ALT vs AST

A

both aminotransferases

ALLT - alanine aminotransferase

AST- asparatate aminotransferase

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23
Q

which two amino acids do not participate in amino transferase reactions

why?

A

Threonine and Lysine

– both are exceptions: they lose their amino group by deamination

– aka they do not TRANSFER their amino group

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24
Q

urea cycle in liver vs kidnsey

A

in liver - GDH releases ammonia from glutamate; this reaction occurs in kidney too but ammonia can be excreted directly (imp for buffering pH of urine)

kidney does not have enzyme arginase (converts arginine + water to urea)

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25
Q

glucose alanine cycle

A

pyruvate can be converted back to glucose = can enter the blood and be delivered to muscle

they cycling of glucose and alanine between muscle and liver known as glucose-alanine cycle

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26
Q

what two amino acids used for transport of amino groups

A

glutamine

alanine

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27
Q

how many ATP’s are required for each molecule of urea produced

A

3 ATPs

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28
Q

rate limiting step of urea cycle

activator?

A

CPS I (converts NH3 + CO2 + 2ATP] to carbamoyl phosphate

– activated by N-acetylglutamate (NAG)

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29
Q

amino acids that may become essential

– under what conditions?

A

tyrosine and cysteine = may become essential in cases of metabolic enzyme deficiencies

arginine = may become essential in certain urea cycle deficiencies or during periods of growth

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30
Q

which two amino acids do not get recycled back into GNG (gluconeogenesis)

A

leucine

lysine

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31
Q

what is the main glucogenic amino acid converted to pyruvate

A

alanine

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32
Q

molecules synthesized from tyrosine

A

monoamine neurotransmitters (by decarboxylation of tyrosine)

DOPA (by tyrosine hydroxylase)

melanin (tyrosinase in melanocytes)

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33
Q

molecules synthesized from tryptophan

A

serotonin (5-hydroxytrypatmine)

Melatonin (synth from serotonin)

NAD, NADH

^^ B6 & FAD required for synthesis of niacin

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34
Q

molecules synthesized from histidine

A

histamine (decarboxylation of histidine)

^^ involved in allergic and inflammatory response

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35
Q

molecules synthesized from arginine and glycine

A

creatine phosphate (high energy compound that maintains energy levels during intense exercise)

phosphorylation by creatine kinase - uses SAM as a cofactor

36
Q

creatine

A

excreted in the urine

creatine levels in the urine stay almost constant

decreased creatinine content indicates muscle loss

increased creatine content indicates kidney malfunction

37
Q

molecules synthesized from glycine and succinyl coa

A

heme

38
Q

molecules synthesized from aspartate, glycine, and glutamine

A

purines

39
Q

molecules synthesized from aspartate and glutamine

A

pyrimidines

40
Q

Pyridoxal Phosphate

Pathways Involved in, Deficiency

A
41
Q

NAD, NADP

Pathways Involved in, Deficiency

A
42
Q

tetrahydrofolate

Pathways Involved in, Deficiency

A
43
Q

methyl-cobalamin

Pathways Involved in, Deficiency

A
44
Q

SAM

Pathways Involved in, Deficiency

A
45
Q

thiamine pyrophosphate

Pathways Involved in, Deficiency

A
46
Q

tetrayhydrobiopterin

Pathways Involved in, Deficiency

A
47
Q

coenzyme A

Pathways Involved in, Deficiency

A
48
Q

Biotin

Pathways Involved in, Deficiency

A
49
Q

FAD

Pathways Involved in, Deficiency

A
50
Q

bases vs nucleoside vs nucleotide nomenclature

A

base = guanine

nucleoside = base + sugar (ribose/ deoxyribose)

nucleotide = nucleoside + phosphate (mono, di, or tri)

51
Q

pathways that intersect with nucleotide metabolism

A
  1. pentose phosphate pathway (produces ribose-5-phosphate)
  2. amino acid metabolism (contributes, Asp, Glu, Gly, Gln)
  3. TCA cycle (intermediate fumarate produced in purine synth)
52
Q

nucleotide degradation produces

A
  1. ammonia
  2. ribose-5-phosphate
  3. purine/pyrimidine bases
53
Q

how are nucleotide bases recycled

A
  1. recycled to new nucleotides (salvage pathway: purines/ thymine)
  2. converted to uric acid and excreted (purines)
  3. catabolized into B-amino acids, CO2 and H2O (pyrimidines)
54
Q

nucleotide dipphosphates

A

made from nucleotide kinases that are specific to each nucleotide type

ex: adenylate kinase, guanylate kinase, thymidylate kinase

55
Q

nucleotide triphosphate synthesis

A

generic nucleotide diphosphate kinase on NDP’s using ATP

56
Q

ribonucleotide reductase

A

synthesize deoxynucleotide diphosphates

ribose → deoxyribose

inhbibited by dATP

57
Q

during fasting what are free amino acid levels like

A

large free amino acid pool

58
Q

amino acid pool provides

A

liver and other cell types fuel for gluconeogenesis

59
Q

branched chain amino acids are oxidized mainly in

A

skeletal muscle

60
Q

glutamine - role in urea cycle

A

carries ammonia to kidney = ultimately helps balance the pH of urine

61
Q

after high protein meal

– how will body react

A

gut and liver = use most of the absorbed amino acids

glucagon is released = stimulates uptake of amino acids and GNG

insulin levels increase enough for BCAA to be absorbed in muscle but not enough to inhibit GNG

62
Q

ingestion after mixed protein/ carb meal

– how will body react

A

insulin levels rise = amino acids shifted into biosynthetic pathway

– includes synthesis of acetyl-coa from pyruvate and citrate which leads to FA

63
Q

fasting state

– early

– 1 to 2 days

– prolonged

– very prolonged

A

early: blood sugar levels drop = muscle and liver use fatty acids as fuel rather than glucose

– diminished use of glucose allows glycogenolysis to restore blood glucose lvels

1-2 days: glycogen stores diminished

– lypolysis and hydrolysis of muscle protein = provide net carbons for gluconeogen

prolonged starvation: fuel used shifts to fatty acids and ketone bodies

– no excess protein stores left

TG stores diminished: protein degradation accelerates and death inevitably results from loss of heart, liver, or kidney function

64
Q

high protein low carb diet

A

based on premise that circulating insulin levels remain low which prevents energy storage = release of glucagon will mobilize fatty acid oxidation

65
Q

what results in a negative nitrogen balance

A

surgery

trauma

burns

sepsus

66
Q

LAT transporter

A

uptake of large neutral amino acids

– can be inhibited by excess plasma and brain phenylalanine

(it’s why in PKU = fatigue because phenyalinine is “hogging” the LAT transporter)

67
Q

adenosine deaminase deficiency

A

used in purine degradation pathway

cause of SCID = immune deficiency (involved both T and B cells_

68
Q

myoadenylate deaminase

A

deficiency = most common in white populations

involved deficiency in the purine nucleotide cycle = negatively impacts energy levels in exercising muscles

69
Q

purine nucleotide phosphorylase

A

involved in purine degradation (breaks down guanine)

affects T-cell function

70
Q

cystic fibrosis

A

autosomal recessive – involves transmembrane Cl- ion channel

result is diminished NaCl and fluid secretion = increased viscosity of mucous secretion

– one of the main causes of pancreatitis and exocrine pancreatic dysfunction in children

== maldigestion, malabsorption, and fatty stool (steatorrhea) occur

71
Q

cystinuria

A

disorder cusaed by inadequate amino acid transport systen

kidney stone and elevated dibasic amino acids in urine

72
Q

hartnup disease

A

caused by a defect in transport of neutral aa (LAT?) in kidney and tubules and intestinal cells

symptoms mild but pellagara may occur dude to def in Trp

73
Q

pernicious anemia

A

maladsorption of dietary cobalamin (b12)

74
Q

PEM

A

protein energy malnutriton

PEM defined as BMI < 16 kg/m2

75
Q

kwashiorkor

A

intake of carbs greater than intake of proteins

– fatty acid build up in the liver

– decreased albumin synthesis

– fluid build up in peritoneal cavity → distended abdomen

– edema in ankles

76
Q

marasmus

A

total calorie deprivation in protein and carbs

extreme muscle wasting occurs due to breakdown for energy

– wizened appearance and no body fat

77
Q

secondary PEM

A

occurs in elderly

– similar sypmtoms to maramus + edema similar to kwashiorkor

78
Q

cachexia

A

Secondary PEM

symptoms in cancer/ aids patients

increased expenditure of resting energy

79
Q

Wernick-Korsakoff syndrome

A

thiamine deficiency

80
Q

megaloblastic anemia

A

decrease in purine and thymine syntehsis associated with THF def

B12 = recycle folate pool

B12 = involved in BCAA degradation (can also result in methylmalonic aciduria)

81
Q

neurlogical disease

A

folate deficiency

affect SAM = impaired methylation and myleination and DNA synth

82
Q

adult vs child neurolgical def

A

adult = result of B12 def

child = result of BH4 synthesis

83
Q

acquired hyperammonemia

A

sign of liver disease

caused by envio factors (liver infection or alcohol disease)

associated with leaking enzymes → AST/ ALT

84
Q

secondary goat

A

caused by diet high in red meat/ cured meat (rich in purine)

can result from radiation = tumor lysis syndrome

85
Q

tumor lysis syndrome

A

occurs from radiation

results in gout

86
Q

lead poisoning

A

inhibits ALA dehydrogenase

= accumulated ALA → increased serum iron and ferritin

FOM: Nutrition (3 decks)

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