Red Blood Cell Physiology and Production/ Hemoglobin Production

Question 1

Why are RBC Metabolic Pathways mainly anaerobic?

Answer 1

Mainly anaerobic glycolysis because of the need to deliver oxygen, not consume it

Question 2

RBC metabolism is critical for maintaining

Answer 2

Hemoglobin function

Membrane integrity and deformability

Volume

Question 3

Embden-Meyerhof Glycolytic Pathway

Answer 3

Produces ATP

Anaerobic

Question 4

Hexose Monophosphate Pathway

Answer 4

G-6-PD

Protects proteins in the cell from oxidative damage

Produces NADPH

Question 5

Methemoglobin Reductase Pathway

*****1% normal more than that ind of def. of something in pathway

Answer 5

Converts methemoglobin to hemoglobin

Question 6

Rapaport-Luebering Pathway

Answer 6

Rapaport-Luebering Pathway

Question 7

Describe the shift to left and right for the O2 dissociation curve and relationship with pH, pCO, 2,3 DPG, and Temperature.

Answer 7

Shift to left (increased affinity for O2):

Increase in pH (alkalosis)
Increase in abnormal hemoglobins
Decrease in 
2,3 DPG
pCO2
Temperature

Shift to the right (decreasing affinity for O2 – reverse of the above causes)

Question 8

Why does fetal Hgb have an increased affinity for O2?

Answer 8

Because the fetus is developing in an O2 deprived environment.

Question 9

Primary function of hemoglobin?

Answer 9

Primary function is delivery and release of O2 and excretion of CO2

Allosteric movement allows for loading and unloading of oxygen and CO2

Question 10

What things are needed for adequate Hgb production?

Answer 10

Adequate iron supply and delivery

Synthesis of protoporphyrins, the precursors of heme

Adequate globin synthesis

Rate of globin synthesis is directly proportional to rate of porphyrin synthesis

Each RBC contains approximately 280 million Hgb molecules and each Hgb can bind to 4 O2 molecules

Question 11

Why can’t mature RBCs make heme?

Answer 11

No organelles

Question 12

What two parts of the cell is heme produced?

Answer 12

Cytosol
Mitochondria

***The process begins in the mitochondria, moves to the cytosol and then back to the mitochondria

Question 13

Production of globins determined by what genes?

Answer 13

Genes are on different chromosomes

Alpha and zeta on chromo 16 (2 loci)

Beta, delta, gamma and epsilon on chromosome 11 (one locus)

The production of these chains determines the type of hemoglobin molecule present at any given time during development

Question 14

Picture

Answer 14

production of globin

Question 15

Describe structure /properties of the Hgb molecule

Answer 15

Tetramer of 2 alpha and 2 non-alpha globin chains

Synthesis of globins occurs on RBC-specific ribosomes

Normal adult RBCs consist of:
95-97% is HbA
2-3% is HbA2
1-2% is HbF

Question 16

Diff types og Hgb slide

Answer 16

b

Question 17

Fetal Hgb?

Answer 17

Produced after 10 weeks gestation

Production falls after birth and is almost zero at one year

Has a higher affinity for O2

Can persist after birth in some disease states

Question 18

Name three Abnormal Hemoglobins.

Answer 18

Carboxyhemoglobin – O2 replaced with CO, 200X tighter bond than with oxygen, can be high in heavy smokers, toxic at 5.0 g.%

Methemoglobin – Fe oxidized to ferric state,

Question 19

Where are RBCs produced?

Answer 19

In the yolk sac
In the liver and spleen
In the bone marrow

Question 20

What is extramedullary hematopoiesis?

Answer 20

The production of RBCs and WBCs outside the bone marrow (in the spleen and liver) after birth

Question 21

Why is EPO produced by the kidneys?

Answer 21

Kidneys sensitive to and can change blood pressure

Question 22

Why are younger cells are larger and more basophilic?

Answer 22

they contain more organelles and RNA.

Question 23

Red Blood Cells are made in the bone marrow in response to stimulation of __________

Answer 23

erythropoietin produced by the kidneys

Question 24

Name the sequence of cells starting from immature RBCs to the final mature stage.

Answer 24

pic

Question 25

n

Answer 25

g

Question 26

n

Answer 26

g

Question 27

n

Answer 27

g

Question 28

n

Answer 28

g

Question 29

n

Answer 29

g

Question 30

Iron: Absorption, storage, and utilization by the body?

Answer 30

Absorption
stomach, intestines, bone marrow & tissues.

Storage
ferritin, hemosiderin
Utilization

Hgb formation
Fe+++ transported to RBC membrane by transferrin
Converted to Fe++ in mitochondria for insertion into protoporphyrin ring of heme

Question 31

Describe Extravascular Hemolysis.

Answer 31

pic

Approximately 90% of normal RBC degradation
Occurs in spleen: macrophages of RE system

Question 32

Describe Intravascular Hemolysis.

Answer 32

pic

Not preferred

Question 33

Importance of B12 and folate? Deficiency causes what?

Answer 33

B12 and Folic Acid necessary for synthesis of DNA, deficiency causes pernicious anemia which sometimes includes neurological symptoms

Question 34

Three phases B12 Absorption?

Answer 34

Gastric phase: released by acids and binds to R protein

Ileal phase: released from R protein and binds to intrinsic factor secreted by parietal cells of stomach, absorbed by ileum

Plasma: Transcobalamin II (TC II), deficiency causes megaloblastic anemia

Question 35

B12 and Folate Deficiency can hamper______.

What is the RBC morphology in this case?

Answer 35

Deficiency of either B12 or folate hamper RBC maturation

Megaloblasts, larger than normal immature cells, found in bone marrow

Macrocytes found in peripheral blood, can carry oxygen, but have fragile membranes and shortened life span