CHOUD BSC 1-24

Question 1

What is the major product of nitrogen metabolism

Answer 1

urea

Question 2

What is the ornithine cycle

Answer 2

urea cycle

Question 3

where is ammonia from

Answer 3

aa catabolism

Question 4

intracellularly what sequesters ammonia,

Answer 4

glutamic acid to form glutamine

Question 5

where is the urea cycle

Answer 5

in the liver, and some in kidney

Question 6

what transports glutamate from muscles

Answer 6

alanine

Question 7

What organ produces alot of ammonia

Answer 7

brain

Question 8

how is ammonium released from glutamine

Answer 8

glutamine–>glutamate–>alphaketoglutarate. each step releases an ammonium

Question 9

how do we measure blood ammonium

Answer 9

BUN, nitrogen levels

Question 10

In which organelle does urea cycle start

Answer 10

mitchondria

Question 11

deficiency in carbamoyl phosphatase 1 will lead to what

Answer 11

high levels ammonium in blood= bad

Question 12

what forms citrulline and why

Answer 12

carbamoyl and ornithine form citrulline so can be shuttle out of mitochondria into cytosol of lvier

Question 13

What are the 5 steps urea cycle

Answer 13

carbamoyl phosphate combine with ornithine to form citrulline
citrulline converted to arginino-succinate
argininosuccinate cleaved f=to fumurate and arginine
urea and ornthinite formed
formation urea

Question 14

What combines carbamoyl phsophate and ornithine to make citrulline

Answer 14

ornithine transcarbamoylase

Question 15

What can result from elevated NH4 in blood

Answer 15

hyperammonemia–>toxic in brain, cerebral edema, convulsions, coma and death

Question 16

What is the role of glutaminase synthetase

Answer 16

combines nitrogen and glutamate to make glutamine

Question 17

What is the role of glutaminase

Answer 17

deaminates glutamine to glutamate and NH3

Question 18

What 5 enzymes are important in urea cycle

Answer 18

carbamoylphosphate synthetase I
ornithine transcarbamylase
argininosuccinate synthetase
argininosuccinate lyase
arginase

Question 19

What is the pacemaker enzyme of urea cycle

Answer 19

carbamoyl phosphate synthase I to keep cycel running

Question 20

activity of CPS I is dictated by what

Answer 20

rate of synthesis from aCoA and glutamate because increases Nacetyl glutamateNAG

Question 21

Why does starvation increase CPS I activity

Answer 21

increased production of ammonia from increased protein digestion

Question 22

What causes citrullinemia

Answer 22

deficiency of argininosuccinic acid synthase

Question 23

all (but one) urea cycle disorders are autosomal recessive. which one is not

Answer 23

ornithine transcarbomylase deficiency is X linked dominant- mitochondria

Question 24

infant is vomiting drowsy increased temp and HR, hepatomegaly, high glutamine and uracil
what does this suggest

Answer 24

hyperammonemia- impaired urea formation
Probably ornithinine transcarbamoylase because increased uracil (orotic acid)
transamination enzymes are fine because glutamine is being made

Question 25

Tx for ornithine transcarbomoylase deficiency?

Answer 25

give less protein in diet | supplemental dietary arginine

Question 26

``` PTT that does not get better with Vit K bilirubin in urine high liver enzymes hypocalcemia low BUN what does this suggest? ```

Answer 26

chronic hepatitis B- end stage liver disease Vit K no response shows liver is unable to synthesize the PT protein cofactors II VII IX and X hypocalcemia because no albumin low BUN-->liver

Question 27

ALT is higher than AST in what pahtology

Answer 27

acute hepatitis

Question 28

hypoabluminemia and prolonged PTT are markers for what

Answer 28

severe liver disease since liver synthesizes the proteins

Question 29

macrocytic anemia suggests what

Answer 29

folate deficiency or B12 deficiency

Question 30

Extreme levels of plasma ammonium in an infant usually means what

Answer 30

OTC deficient-- x linked | CPS I affected

Question 31

infants with urea cycle disorders present how

Answer 31

normal initially and rapidly develop cerebral edema, lethargy, anorexia, hyperventilation etc.

Question 32

normal urea level

Answer 32

20-40 mg/dL

Question 33

high glutamine and orotic acid in urine as well as low BUN is what disorder

Answer 33

mitochondrial OTC

Question 34

HArtnup disease patients don't become deficient in aa because what

Answer 34

PepT1