3. RBCs Continued

Question 1

CO2 transport:

Answer 1

-moves through tissues by simple diffusion (high to low concentration)

Question 2

3 forms of CO2:

Answer 2

1. Dissolved in solution (CO2=highly soluble)
2. Reversible reactions in plasma
3. Reversible reactions in RBCs

Question 3

Reversible reactions in plasma:

Answer 3

-combine with terminal amino groups in plasma proteins
-CO2+H20 to H2CO3 to H+ and HCO3-

Question 4

Reversible reactions in RBCs:

Answer 4

-combine with terminal amino groups in Hb
-CO2+H20 to H2CO3 to H+ and HCO3-
>catalyze by carbonic anhydrase, more efficient

Question 5

CO2 transport by Hb and Cl shift in capillaries:

Answer 5

1. Bicarbonate production
2. Chloride shift
3. H+ ions are trapped intracellularly and can protonate the Hb

Question 6

Bicarbonate production: CO2 transport by Hb

Answer 6

-majority of CO2 in circulation is converted into bicarbonate within the erythrocytes

Question 7

Chloride shift: CO2 transport by Hb

Answer 7

-RBCs utilize Cl- anion transport pumps to exchange HCO3- for Cl-
>HCO3- out, Cl- into RBC

Question 8

Haldane effect:

Answer 8

*Hb’s impact on CO2 transport in RBCs

Question 9

Haldane effect: histidine and O2 coordination

Answer 9

-histidine coordinates O2 binding Fe2+
-can be pronated or deprotonated’

Question 10

Haldane effect: effect of O2 binding

Answer 10

-O2 binding leads to histidine deprotonation
>arterial blood

Question 11

Haldane effect: effect of O2 unbinding

Answer 11

-O2 unbinding results in histidine protonation
>venous blood

Question 12

Gas exchange of CO2 at respiring tissues:

Answer 12

-low pO2, shifts the carbonic anhydrase (CAH) equilibrium towards H2CO3 formation (goes to HCO3- and H+)
>O2 goes into the tissues and H+ protonates the Hb
>favours CO2 into RBC

Question 13

Gas exchange of CO2 at lungs (alveoli):

Answer 13

-high pO2, shifts CAH equilibrium towards CO2 formation
>Hb is being deprotonated from O2 binding
>favours CO2 leaving the RBC

Question 14

RBC as buffer:

Answer 14

-carbonic acid system
-Hb
>all proteins have buffering capacity

Question 15

Buffering capacity:

Answer 15

-chemical groups that accept and donate protons

Question 16

Hemopoiesis:

Answer 16

-process of blood cell formation
-happens in the bone marrow within the medullary canals of long bones (red bone marrow)

Question 17

Hemopoiesis in younger animals:

Answer 17

-primary sites are large long bones
Ex. tibia and femur

Question 18

Hemopoiesis in older animals:

Answer 18

-primary sites are the vertebra, sternum and rib bones

Question 19

Sinusoids:

Answer 19

-small irregular shaped blood vessels found in certain organs
Ex. in red bone marrow

Question 20

All blood cells originate from:

Answer 20

-pluripotent hemopoietic stem cells

Question 21

2 major lines of hemopoietic stem cells:

Answer 21

1. Myeloid progenitor
2. Common lymphoid progenitor

Question 22

Erythropoiesis:

Answer 22

-production of erythrocytes (RBCs) from hemopoietic stem cell to mature circulating erythrocytes
*regulated by erythropoietin (EPO)

Question 23

Sites of erythropoiesis:

Answer 23

-in bone marrow
>mostly in long bones
>vertebrae
>pelvis
>sternum
>ribs

Question 24

Erythropoiesis stages:

Answer 24

1. Rubriblast
2. Prorubricyte
3. Rubricyte
4. Metarubricyte
5. Polychromatophilic erythrocyte
6. Erythrocyte

Question 25

Rubriblasts:

Answer 25

-precursors for erythrocytes
-nucleated cells
-NO Hb

Question 26

Rubricytes

Answer 26

-abundance of polyribosomes
-active Hb production

Question 27

As erythropoiesis progresses:

Answer 27

-EP receptors decrease
-transferring receptors increase
>need more iron to make Hb

Question 28

Metarubricyte:

Answer 28

-mitosis stops
-hemoglobinization nears completion
-nucleus condenses
-at end of stage: nucleus is expelled

Question 29

Polychromatophilic erythrocyte:

Answer 29

-polychromatophilic staining due to residual rRNA
-present in small amount (less than 1% in dogs) under normal conditions in most species
>except horses

Question 30

Horses and erythrocytes:

Answer 30

-don’t have polychromatophilic erythrocytes
*never release immature erythrocytes

Question 31

Reticulocytes:

Answer 31

-essentially polychromatophilic cells, but stained differently
-a more accurate number
>give insight into bone marrow activity

Question 32

Erythropoiesis: steady state process

Answer 32

-when tissue O2 is adequate, RBC productions balances with RBC turnover
-regulated by erythropoietin
>90% made in kidneys
*pathological conditions will lead to abnormal RBC production (ex. hypoxia, renal diseases)

Question 33

Erythropoietin:

Answer 33

-produced in kidneys
*why cats in renal failure develop anemia

Question 34

Factors that lead to decreased oxygenation: hypoxia

Answer 34

-low blood volume
-anemia
-low Hb
-poor blood flow
-pulmonary disease

Question 35

Heme formation:

Answer 35

-Fe2+ and protoporphyrin IX
>ring like structure

Question 36

Hb synthesis:

Answer 36

1. 2 succinyl-CoA + 2 glycine forma pyrrole
2. 4 pyrrole form protoporphyrin XI
3. Fe2+ + protoporphyrin IX form heme
4. Heme + polypeptide form hemoglobin chain (alpha or beta)
5. 2 alpha chains + 2 beta chains =hemoglobin a

Question 37

Nutrients required for erythropoiesis:

Answer 37

1. Iron: tends to be the limiting one
2. Folic acid (vitamin B9)
3. Vitamin B12
4. Vitamin B6
5. Riboflavin, nicotinic acid, pantothenic acid, thiamine, biotin, ascorbic acid
6. Copper
7. Cobalt

Question 38

Folic acid and vitamin B12:

Answer 38

-DNA synthesis
>purine and pyrimidine synthesis
-synthesis of molecules important for survival (myelin maintenance/production, NTs)