Lect 12 Erythrocyte Physiology Flashcards
What are the 4 functions of blood?
Deliver O2 / Nutrients
Remove wastes
Homeostasis (Thermoregulation, Hormones)
Immune Response
What is the function of RBC?
What is hematocrit?
Carry O2
% of blood that is cells (majority being RBC)
What is Erythropoiesis and where does it occur?
How does the body determine how many RBCs needed?
What happens if O2 is low? Where is EPO produced primarily?
What does EPO do?
The process of making RBCs in Bone Marrow
Amount of O2 getting to the Kidneys as sensor
HIF accumulates (normally produced but ubiquinated) and acts as TF for EPO (Kidney)
Increase SC differentiation to erythroid lineage and rate of maturation of RBCs
The acidic environment in the stomach favors which form of Iron?
How do Non-heme and Heme iron transport into Enterocyte?
How is iron extruded from cell?
What are the enzymes in the Ferroxidase family that convert Fe3+ –> Fe2+?
How is it transported in blood?
- Ferric (Fe3+)
- Iron Transport
- Non-heme –> Ferrous state and taken up via DMT1
- Heme taken up via presumed heme transporter and iron removed via enzymatic degradation
- Ferroportin
- Hephaestin or Ceruloplasmin
- Transferrin
Requirements for Adequate Erythropoiesis
How can iron deficiency occur and what is the consequence?
Why is Vit B12 & Folic Acid required?
How can Vit B12 deficiency occur and what is the consequence?
How can Folate deficiency occur and what is the consequence?
- Iron:
- Blood loss –> Microcytic Anemia
- Role in DNA synthesis
- Vit B12
- Pernicious Anemia (Loss of IF) –> Macrocytic Anemia
- Folate
- Destruction of folic acid by cooking –> Macrocytic Anemia
What is O2 Capacity and how is it calculated?
What is O2 Content and how is it calculated?
What is O2 saturation?
- Oxygen Capacity
- Amount of O2 can be carried in blood
- (1.34 mL O2 / g Hb) x (g Hb / dL blood)
- Oxygen Content
- Amount of O2 actually being carried in blood
- Oxygen Capacity x % saturation
- Oxygen Saturation
- % of available spots on heme with O2 bound to them
How is ATP produced in RBCs?
What is ATP used for?
What can happen with lack of ATP?
- Anaerobic Glycolysis
- ATP
- Maintain iron in ferrous (Fe2+) state
- Flexibility of membrane
- Ion-Transport (ATPases)
- Prevent oxidation of Hb
- No ATP
- Stiff membranes
- RBC ruptures in spleen
- Ferrous –> Ferric (altering O2)
What is the fate of old RBC?
What is the fate of Hb molecules?
Phagocytosis in spleen
Iron is recycled and heme broken down to Bilirubin
What causes anemia?
How can it occur?
What are physical consequences?
Decreased RBC count or Hb content
Folate/B12 deficiency; Iron deficiency; BM/Kidney damage
Decreased O2 capacity/content
Decreased O2 delivery to tissue
Increased work load on heart
How does Hemochromatosis occur?
What does Hepcidin normally do?
What is the effect of inadequate Hepcidin?
Inadequate production of Hepcidin
Blocks Ferroportin to reduce transfer of iron into blood
Reduced Hepcidin leads to increased Iron in the blood
What is Polycythemia?
What are the effects of this?
What is Primary Polycythemia (Polycythemia Vera)?
What is Secondary Polycythemia?
What is physiological Polycythemia?
Excess RBC
Increased O2 capacity and increased viscosity so heart has to work hard to pump blood
BM making RBC when there is no need
BM is normal and body is responding to low oxygen levels
Oxygen is low due to altitude
What does a left shift represent? What causes a left shift?
What does a right shift represent? What causes a right shift?
- Left Shift: Increase in affinity of Hb for O2 (less release)
- Low CO2; High pH; Low 2,3-BPG; Low Temperature
- Right Shift: Decrease in affinity of Hb for O2 (more release)
- High Co2; Low pH; High 2,3-BPG; High Temperature
What is methemoglobinemia?
What is the consequence of this?
Large amounts of iron in Ferric state in Heme
Unable to bind to O2 and other chains in Ferrous state have increased affinity for O2 (less release to tissues)
