Red blood cells

Question 1

what are the 4 polypeptide chains in hemoglobin?

Answer 1

2 alpha

2 beta

Question 2

What does each polypeptide chain of hemoglobin contain?

Answer 2

each chain contains a molecule of heme.

Question 3

1. What % of RBC in blood?

2. 35% = % of ______ weight is ____

Answer 3

1. 40%

2. 35% of RBCs weight is hemoglobin

Question 4

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

Answer 4

Histidine.

Binds to iron and stabilizes the heme ring

Question 5

define oxyhemoglobin

Answer 5

Iron in hemoglobin bound to oxygen

- Bright red colour

Question 6

Define carboxyhemoglobin

Answer 6

• 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..

Question 7

Define carbaminohemoglobin

Answer 7

• Nitric oxyde bound to iron

=> vasodilator

Question 8

Methemoglobin

Answer 8

Iron oxidized to 3+

- Brown color

Question 9

Define deoxyhemoglobin

Answer 9

• No oxygen bound to iron

- Purple color

Question 10

Define fetal hemoglobin

Answer 10

• 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

Question 11

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

Answer 11

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

Question 12

Under what % of oxyhemoglobin is there an oxygen distress?

Answer 12

Under 90%

Question 13

What is the role of G6P dehydrogenase?

Answer 13

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

Question 14

Give characteristics of G6PD

Answer 14

Most common genetic disease

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

Question 15

What are the sequential changes with development of iron deficiency?

Answer 15

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

Question 16

What decreases when there is depletion of iron stores?

Answer 16

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

Question 17

What type of changes happen concerning iron transport?

Answer 17

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

Question 18

What happens to erythropoiesis when there is not enough iron?

Answer 18

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

Question 19

What are some physical symptoms of iron deficiency?

Answer 19

Less capability to transport oxygen, so:

- Tired, decrease exercise capacity

Question 20

How are erythrocytes in iron deficiency anemia?

Answer 20

• Microcytic, hypochromic erythrocytes

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

Question 21

What are 4 causes of iron deficiency?

Answer 21

• 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

Question 22

Which iron is best absorbed? At what %?

Answer 22

Heme iron (ferrous Fe2+ iron) 
25% absorbed

Question 23

What are characteristics of non-heme elemental iron?

Answer 23

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

Question 24

How is effeciency of iron absorption increased in iron defieincy?

Answer 24

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

Question 25

How do you diagnose iron deficiency anemia?

Answer 25

- 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)

Question 26

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

Answer 26

``` 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.

Question 27

What is hemochromatosis?

Answer 27

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

Question 28

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

Answer 28

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

Question 29

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

Answer 29

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

Question 30

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

Answer 30

Resistance to malaria. as in G6PD deficiency

Question 31

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

Answer 31

Biliverdin

Question 32

What happens if there is a build up of bilirubin?

Answer 32

Jaundice

Question 33

What are the 3 causes of jaundice?

Answer 33

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