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Flashcards in Iron metabolism Deck (31):
1

How is iron transported in the blood?

it is bound to transferrin (as Fe3+)

2

How is iron stored in cells?

It is stored in cells bound to ferritin in hemosiderin

3

Iron is absorbed as ___ and converted to ___ by ceruloplasmin.

Fe2+,
Fe3+

4

How do we measure iron status?

Serum ferritin (Levels below 15 mg/mL indicate iron deficiency)

5

Heme synthesis

First step: ALA produced by gamma-ALA synthase (amino acid decarboxylation reaction)
Requires pyridoxal phosphate
negatively regulated by heme

Second step: 2 gamma-ALA react to form porphobilinogen. Gamma-ALA dehydratase is zinc enzyme sensitive to lead inhibition.

6

Elevation of gamma-ALA in the absence of elevation of porphobilinogen is diagnostic for ___.

lead poisoning

7

Erythropoeitic protoporphyria

Ferrocheletase deficiency protoporphyrin accumulates, causes photosensitivity

8

Porphyria cutanea tarda

URO decarboxylase deficiency accumulates uroporphyrinogen III and causes photosensitivity

9

Wilson Disease

Excess copper
Inability to export copper from the liver to bile (excretion pathway) and incorporate into ceruloplasmin (major plasma copper carrier)
Copper accumulates in liver, brain, kidneys, cornea
Severe liver damage: cirrhosis, jaundice, hepatomegaly
Caused by mutation in ATP7B (ATPase membrane transporter) Causes accumulation, then damage to hepatocytes. Leaks out of hepatocytes and accumulates in other tissue

Symptoms: Kayser-Fleischer rings (opthalmologic), tremor (neurological), maybe renal

10

Enzymes with copper

lysyl oxidase, cytochrome C oxidase, superoxide dismutase, and dopamine beta-hydroxylase

11

True or False: Type I fibers are slow twitch.

True

12

True or False: Type I fibers appear white.

False, they appear red.

13

Cardiac injury markers

Troponin (MI), Creatinine kinase (CK-MB abundant in heart, B dimer in brain, M dimer is muscle isoform) (CK-MB peaks 12-24 hours after AMI, returns to normal in 3-4 days)

14

Things to remember about muscle metabolism

Uses GLUT4 receptor to taken in glucose
PFK-2 is not regulated by phosphorylation in muscles
Glycogen does not respond to glucagon (no receptors)
Uses Acetyl Coa Carboxylase 2
Malonyl CoA regulates fatty acid oxidation
AMP protein kinase is an important regulator
FA preferred fuel under rest, fasting, or starved condition
Use branched chain amino acids for fuel in amino acid metabolism
Creatine phosphate used for short term energy needs

15

PFK-2 regulation

ATP and citrate levels inhibit glycolysis in skeletal muscles
In cardiac muscle, PFK-2 is phosphorylated and activated by insulin-dependent kinase cascade. Phosphorylation activates PFK-2 kinase activity
(In liver, phosphorylation of PFK-2 inhibits activity)

16

Activation of ___ inhibits ATP-requiring pathways and stimulates ATP-producing pathways.

AMP-PK

17

AMP-PK induces insulin-independent recruitment of ____ receptors in active skeletal muscle (Skeletal muscle makes up for 70% of plasma glucose uptake)

GLUT4

18

AMP-PK phosphorylation ____ acetyl-CoA carboxylase and ___ malonyl-CoA decarboxylase lowering malonyl CoA, resulting in ____.

inactivates,
activates,
increased mitochondrial fatty acid beta-oxidation

19

ACC

Acetyl Coa Carboxylase

20

ACC1

Acetyl Coa Carboxylase 1:
located in liver and adipose tissue
biosynthesis of fatty acids

21

ACC2

Acetyl Coa Carboxylase 2:
located in muscle
regulatory purpose - forms malonyl CoA
little biosynthesis of fatty acids

22

Malonyl CoA

Relieves inhibition of CPT-1 by Malonyl CoA when phosphorylated by AMP-PK; muscles

23

____ stimulates glycogenolysis in muscle.

Epinephrine

24

Epinephrine activates ____.

Adenylate cyclase

25

AMP activates ____ in muscle.

phosphorylase b and PFK-1

26

2 ADP are converted to ___ and ___ by ____ during muscle contraction.

ATP and AMP
by adenylate kinase
(Increases AMP concentration, which activates glycogenolysis)

27

___ can be used to generate ATP in muscles.

Creatine phosphate

28

Creatine synthesis

Glycine converted to Guanidinoacetate in the kidney (also converting arginine to ornithine). Guanidinoacetate is converted to Creatine using SAM in the liver. It then travels to the brain, heart, and skeletal muscle

29

True or false: Lactate is used by skeletal muscle.

False

30

True or false: Lactate can be used by cardiac muscle.

True

31

Difference between creatine and creatinine

Creatinine is formed when creatine phosphate cyclizes. Creatinine is cyclic.