Md2 Block4 Biochem L 40 Metabolism Of Amino Acids Conversion Part B

Front 1

Heme is degraded in two steps =

Back 1

-Bilirubin,
then conjugated to ...
-Glucuronic acid .......
excreted.

Front 2

Bilirubin is highly lipid _______

Back 2

soluble

Front 3

What labs are used in the differential diagnosis of hyperbilirubinemia.

Back 3

Indirect bilirubin values

Direct bilirubin values

Front 4

Is Heme reutilized?

Back 4

No
it must be
degraded
excreted.

Although heme is not recycled, its iron is conserved.

Front 5

hemolysis occurs, hemoglobin (with its iron) is released into the .

Back 5

plasma

Possible causes of hemolysis include: =
3ct

Hint 5

- erythrocyte fragility
-thermal burns
-erythroblastosis fetalis

Front 6

In the plasma, oxyhemoglobin dissociates into alpha-beta dimers, which can escape through the glomerular filtration system of the kidney to appear in the urine.

To prevent this, there is a plasma protein, ______ , which binds the dimer and:

Back 6

haptoglobin

delivers it to the reticuloendothelial system for processing
activates the heme to prepare it for degradation

Front 7

______ , then transports it to the liver for degradation.

Back 7

hemopexin


The first reaction is cleavage of the heme ring by a microsomal heme oxygenase. The substrates for this reaction are: =
3ct

Hint 7

heme
three molecules of oxygen
NADPH

Front 8

biliverdin
produces what dangerous gas =

Back 8

CO
(this is the only endogenous source of CO)
Fe2+
NADP+

Front 9

In the second reaction
biliverdin reductase
reduces the central methene bridge of biliverdin, producing _______ =.

Back 9

bilirubin

Front 10

Bilirubin must be conjugated to a water-soluble substance :

The substrates are:
bilirubin
(or bilirubin monoglucuronide)
UDP-glucuronic acid

Back 10

The major product is =

Hint 10

bilirubin diglucuronide.

Front 11

The clinical determination of plasma bilirubin distinguishes between =

Back 11

conjugated (direct) and unconjugated (indirect) bilirubin.


The reaction, called the ***___ ____ reaction, is a coupling of bilirubin with a diazonium salt to form a ***___ _____

Hint 11

van den Bergh

coloured complex.

Front 12

the INDIRECT bilirubin.
define =

Back 12

Total bilirubin =
direct bilirubin
+
indirect bilirubin

i

Hint 12

Only conjugated bilirubin is water soluble and reacts directly. This is called the DIRECT bilirubin.


To measure the unconjugated bilirubin bound to albumin, alcohol is added to release it into solution, where it can now react with the van den Bergh reagent.

Front 13

Several diseases are associated with hyperbilirubinemia.
Direct and indirect bilirubin values are used in the differential diagnosis of hyperbilirubinemia. =

Back 13

Hyperbilirubinemia could be caused by:

Hint 13

- increased bilirubin production
- decreased uptake into the liver cells
- impaired conjugation
- interference with the secretion of conjugated bilirubin

Front 14

Hemolytic jaundice

results from increased production of bilirubin
=

Back 14

- increased bilirubin in bile,
- increased urobilinogen,
- urine urobilin,
- unconjugated bilirubin increases in blood

Hint 14

Front 15

preemies especially may have low
___ ____ ____ activity for first two weeks of life

Back 15

bilirubin glucuronyl transferase

bilirubin can diffuse into___ ___ and cause encephalopathy

Hint 15

basal ganglia

blue fluorescent light converts bilirubin into more polar compound that can be excreted in bile without the need for conjugation

Front 16

Synthesis of creatine


Excretion of creatine is in proportional to__ ___

Back 16

muscle mass.

Hint 16

Front 17

Synthesis of histamine

Back 17

histamine is a chemical messenger
A powerful ________
The reaction requires ___ ___

Hint 17

vasodilator

pyridoxal phosphate.

Front 18

Synthesis of serotonin

Back 18

Serotonin: performs :
- pain perception
--- regulation of : 3ct
-sleep,
-temperature
-blood pressue

Mainly found in the =
3ct

Derives from =

Hint 18

Intestine
platelets
CNS.

tryptophan

Front 19

Synthesis of catecholamines

Nm the Catecholamines: =
3ct

Back 19

-dopamine,
-epinephrine
-norepinephrine

Derived from =.

Hint 19

tyrosine

Dopamine and norepinephrine are neurotransmitters in the brain and autonomic nervous system.

Epinephrine and norepinephrine are synthesized by adrenal medulla in response to
fright,
cold
low levels of glucose.

Front 20

Degradation of catecholamines

Back 20

Inactivated by
oxidative deamination
catalyzed by
monoamine oxidase (MAO)
or
Inactivated by
O-methylation

catalyzed by catenol-O-methyl-transferase (COMT).

The metabolic products of these reactions are excreted in the urine.

Hint 20

Front 21

Synthesis of melanin

Back 21

Pigment in the skin, hair and eye. It protect cells from harmful effects of sunlight.

Two common forms:
_______ (black-brown)
and
________ (red).

Derives from ________; synthesized by melanocytes.

Hint 21

eumelanin
pheomelanin

tyrosine

Front 22

Synthesis of melanin
Two major steps :

Back 22

-first step is catalyzed by the copper-containing enzyme =

(Refer to catecholamines).

-Second major step:
formation of the pigment; involves several smaller steps.

Hint 22

tyrosine hydroxylase
(or tyrosinase)