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NUTR 307 > Red blood cells > Flashcards

Red blood cells Flashcards

1
Q

what are the 4 polypeptide chains in hemoglobin?

A

2 alpha

2 beta

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2
Q

What does each polypeptide chain of hemoglobin contain?

A

each chain contains a molecule of heme.

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3
Q
  1. What % of RBC in blood?

2. 35% = % of ______ weight is ____

A
  1. 40%

2. 35% of RBCs weight is hemoglobin

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4
Q

What amino acid is really important in RBC? What odes it do?

A

Histidine.

Binds to iron and stabilizes the heme ring

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5
Q

define oxyhemoglobin

A

Iron in hemoglobin bound to oxygen

- Bright red colour

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6
Q

Define carboxyhemoglobin

A
  • CO bound to iron
  • Carbon monoxyde poisoning… CO binds more tighly to iron than oxygen… more red then oxy hemoglobin, but cannot tell posonning just by color..
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7
Q

Define carbaminohemoglobin

A
  • Nitric oxyde bound to iron

=> vasodilator

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8
Q

Methemoglobin

A

Iron oxidized to 3+

- Brown color

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9
Q

Define deoxyhemoglobin

A
  • No oxygen bound to iron

- Purple color

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10
Q

Define fetal hemoglobin

A
  • 2alpha and 2 gama chains
  • More efficient at picking up oxygen
  • Getting oxygen from maternal blood
  • Needs pick up oxygen more efficiently from maternal blood red cells. In the fallowing months of baby’s birth, will switch to 2 alpha to beta chains
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11
Q

true or false, if you have 97% oxyhemoglobin in blood , you are healthy

A

False, can still be anemic and not have enough hemoglobin.

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12
Q

Under what % of oxyhemoglobin is there an oxygen distress?

A

Under 90%

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13
Q

What is the role of G6P dehydrogenase?

A

Convert G6P to pentose phosphate, but also generate NADPH, and regenerate GSH (glutathione, an anti-oxidant agent).

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14
Q

Give characteristics of G6PD

A

Most common genetic disease

  • X linked recessive, many SNPs
  • 400 million people, 4000 deaths…
  • Gives protection against malaria
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15
Q

What are the sequential changes with development of iron deficiency?

A
  1. Depletion of iron stores
  2. Changes in iron transport
  3. defective erythropoiesis
  4. Iron deficiency anemia
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16
Q

What decreases when there is depletion of iron stores?

A

Decrease ferritin. Ferritin=> how iron is stored in liver.

17
Q

What type of changes happen concerning iron transport?

A
  • Increase absorption efficiency
  • Increase transferrin iron binding capacity
  • Increase transferrin receptors
  • decrease transferin saturation %
18
Q

What happens to erythropoiesis when there is not enough iron?

A
  • formation of erythrocyte protoporphyrin
  • no heme
  • No iron, no functional capability of transporting oxygen.
  • Structure and fct of RBC is being compromised => become smaller
19
Q

What are some physical symptoms of iron deficiency?

A

Less capability to transport oxygen, so:

- Tired, decrease exercise capacity

20
Q

How are erythrocytes in iron deficiency anemia?

A
  • Microcytic, hypochromic erythrocytes

Hypochromic=> decreased hemoglobin (about color…)
Microcytic => small RBCs (size..)

21
Q

What are 4 causes of iron deficiency?

A
  • Decreased dietary iron intake (can be because vegetarian, or less absorption)
  • Inhibition of absorption
  • Increase red cell mass (pregnancy)
  • Increased losses (hemolysis => could be due to G6PD, GI bleeding, heavy menstruation
22
Q

Which iron is best absorbed? At what %?

A 
Heme iron (ferrous Fe2+ iron) 
25% absorbed
23
Q

What are characteristics of non-heme elemental iron?

A
  • absorption highly variable (1-50% absorbed, average < 10%)
  • Released from ligands by gastricl HCl
  • Absorbed as FERROUs (Fe2+) iron and not FERRIC (Fe3+) iron
24
Q

How is effeciency of iron absorption increased in iron defieincy?

A

Efficiency increased by increasing synthesis of intestinal reductase, divalent metal transporter (brush boarder) and ferroportin (basolateral )

25
Q

How do you diagnose iron deficiency anemia?

A
  • Hemoglobin concentration (<140 mg/L in men, <120 mg/L in women)
  • Defective hematopoiesis (free erythrocyte protoporphyrin)
  • Decreased transport ( decreased transferrin saturation)
  • Decreased stores (decreased ferritin)
26
Q

What is responsible for increase efficiency of iron absorption in iron defieciency? What does it do?

A 
Hormone Hepcidin (peptide hormone produced by liver)
- Hepcidin is responsible for inhibiting ferroportin (transporter between enterocytes and blood vessels and in liver too...)
  • When deficiency => less hepcidin secretion, so less ferroportin inhibition, so more absorption.
27
Q

What is hemochromatosis?

A

Chronic iron overload with tissue damage

  • Defective regulation of hepcidin synthesis (so decreased hepcidin)
  • Very efficient Iron absorption.
  • Iron deposition as hemosiderin - Cirrhosis
  • Genetic disease
28
Q

What are 2 important enzymes in heme synthesis, what happens if deficiency of these enzymes?

A

PGB deaminase:

  • Deficiency results in acute intermediate porphyria
  • Result in increase of precursor
  • Neurological and psychological disturbance

UPG decarboxylase:

  • Deficiency results in porphyria cutanea tarda
  • Skin problems, blisters, when contact with light
  • Can have darker pigmentation
  • People tend to avoid day light
  • Paler skins, hairy body
  • People tending to stay in cloudy climate
29
Q

What is the amino acid substitution of hemoglobin in sickle cell anemia?

A

There is a valine in the sequence, instead of glutamic acid

30
Q

What is an advantage of heterozygote sickle cell anemia? As in what other genetic disease?

A

Resistance to malaria. as in G6PD deficiency

31
Q

What is the intermidate between heme and bilirubin in heme degradation?

A

Biliverdin

32
Q

What happens if there is a build up of bilirubin?

A

Jaundice

33
Q

What are the 3 causes of jaundice?

A

Pre-hepatic:

  • A lot of bilirubin because of increase RBC production
  • Peharps because of malaria or G6P deficiency

Hepatic:
- Liver disease=> disease of hepatocytes or problem with bile flow

Post-hepatic - bile removal

  • Linked with bile removal, due to bile flow
  • Cholestasis, biliary atresia
  • Pale feces, dark urine
  • Urine is dark because bilirubin excreted in urine

Neonates

NUTR 307 (5 decks)

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