Lecture 5: Gas Transport and Erythrocyte Physiology Flashcards
What are the normal hematocrit levels for Women Men Newborn 2 month old
40%
45%
44%
35%
Major functions of erythrocytes
Carry O2 from lungs to body
Carry CO2 from body to lungs
Acid/base buffer
What is the pathway for erythrocyte maturation?
What molecule induces erythrocyte maturation?
HSC > reticulocyte > erythrocyte
Erythropoietin (EPO)
What regulates the production of EPO?
Kidney cells sense low oxygenation > increase HIF (hypoxia inducible factor) > increase production of EPO
What factors can decrease oxygenation?
Low blood volume, anemia, low hemoglobin, poor blood flow and pulmonary disease
What is the cycle of RBCs in the body?
Live for 120 days > Hemoglobin broken down by macrophages in the spleen > Heme recycled in bone marrow to make more RBCs or excreted
What is the major method of transporting O2 in the body?
Hemoglobin binding
Dissolved O2 is inadequate for needs
Normal hemoglobin levels in females and males
F: 14
M: 15.5
Draw the oxygen dissociation curves of O2 combined with Hemoglobin vs. Dissolved O2
Ok
What does % Hb/O2 saturation mean? Normal level?
What does O2 concentration mean? Normal level?
- how much percentage wise of all O2 binding sites in hemoglobin has O2.
- how much O2 overall can the bloodstream carry.
Rank these in terms of highest to lowest O2 saturation: Arteries, Veins, Tissues
What does this mean with regards to the dissociation curve?
Arteries > Veins > Tissues
At arteries, Hgb’s affinity is high (left shift)
At the tissues, Hgb’s affinity for O2 is much lesser (right shift)
If PaO2 is at least 60 mmHg, what does that tell us about O2 saturation?
It is at least 85% (minimal level of O2 sat before having trouble oxygenating the body)
At what PaO2 is O2 sat down to 50%?
27 mmHg
How does Hb concentration affect oxygen carrying capacity?
Does O2 Sat affect carrying capacity?
- Since Hb is the main method of carrying O2 in the blood, they are directly proportional to each other. More Hgb = more O2 blood can carry.
- Not directly
What can cause left shift?
Polycythemia
Methemoglobinemia
What can cause right shift?
CADET face right
CO2 increase/low pH Anemia DPG increase Exercise Temperature increase (bohr effect)
How does 2,3, DPG cause a right shift?
Binds Hgb more than O2, so Hgb releases O2 more readily
Elevated in hypoxia/high RBC metabolism
What is the normal oxygen capacity?
What is the normal oxygen content?
- 1 mL O2/ dL blood
19. 5 mL O2/dL blood
What is required for normal erythropoiesis?
Good nutrition, Vitamin B12 (cobalamin), B9 (folate) and iron
Low folate and B12 leads to…
Low B12 absorption leads to…
Megaloblastic macrocytic anemia
Pernicious anemia
What causes microcytic anemia?
What causes hypochromic anemia?
- iron deficiency
- transferrin not transported to erythroblast
How does RBC perform metabolic processes if it has no mitochondria?
Uses ATPase and ferrous state of Fe to prevent oxidative damage
Hemachromatosis
Cause
Clinical
Iron overload. Could be primary (genetic) or secondary
Liver cirrhosis, skin pigmentation, DM
How does anemia affect blood oxygen content/capacity?
Does this affect O2 saturation?
Anemia = less Hgb = less blood oxygen content
No
