Lecture 5: Gas Transport and Erythrocyte Physiology

Question 1

What are the normal hematocrit levels for
Women 
Men
Newborn
2 month old

Answer 1

40%
45%
44%
35%

Question 2

Major functions of erythrocytes

Answer 2

Carry O2 from lungs to body
Carry CO2 from body to lungs
Acid/base buffer

Question 3

What is the pathway for erythrocyte maturation?

What molecule induces erythrocyte maturation?

Answer 3

HSC > reticulocyte > erythrocyte

Erythropoietin (EPO)

Question 4

What regulates the production of EPO?

Answer 4

Kidney cells sense low oxygenation > increase HIF (hypoxia inducible factor) > increase production of EPO

Question 5

What factors can decrease oxygenation?

Answer 5

Low blood volume, anemia, low hemoglobin, poor blood flow and pulmonary disease

Question 6

What is the cycle of RBCs in the body?

Answer 6

Live for 120 days > Hemoglobin broken down by macrophages in the spleen > Heme recycled in bone marrow to make more RBCs or excreted

Question 7

What is the major method of transporting O2 in the body?

Answer 7

Hemoglobin binding

Dissolved O2 is inadequate for needs

Question 8

Normal hemoglobin levels in females and males

Answer 8

F: 14
M: 15.5

Question 9

Draw the oxygen dissociation curves of O2 combined with Hemoglobin vs. Dissolved O2

Answer 9

Ok

Question 10

What does % Hb/O2 saturation mean? Normal level?

What does O2 concentration mean? Normal level?

Answer 10

• how much percentage wise of all O2 binding sites in hemoglobin has O2.
• how much O2 overall can the bloodstream carry.

Question 11

Rank these in terms of highest to lowest O2 saturation: Arteries, Veins, Tissues

What does this mean with regards to the dissociation curve?

Answer 11

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)

Question 12

If PaO2 is at least 60 mmHg, what does that tell us about O2 saturation?

Answer 12

It is at least 85% (minimal level of O2 sat before having trouble oxygenating the body)

Question 13

At what PaO2 is O2 sat down to 50%?

Answer 13

27 mmHg

Question 14

How does Hb concentration affect oxygen carrying capacity?

Does O2 Sat affect carrying capacity?

Answer 14

• 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

Question 15

What can cause left shift?

Answer 15

Polycythemia

Methemoglobinemia

Question 16

What can cause right shift?

Answer 16

CADET face right

CO2 increase/low pH
Anemia
DPG increase
Exercise
Temperature increase (bohr effect)

Question 17

How does 2,3, DPG cause a right shift?

Answer 17

Binds Hgb more than O2, so Hgb releases O2 more readily

Elevated in hypoxia/high RBC metabolism

Question 18

What is the normal oxygen capacity?

What is the normal oxygen content?

Answer 18

20. 1 mL O2/ dL blood

19. 5 mL O2/dL blood

Question 19

What is required for normal erythropoiesis?

Answer 19

Good nutrition, Vitamin B12 (cobalamin), B9 (folate) and iron

Question 20

Low folate and B12 leads to…

Low B12 absorption leads to…

Answer 20

Megaloblastic macrocytic anemia

Pernicious anemia

Question 21

What causes microcytic anemia?

What causes hypochromic anemia?

Answer 21

• iron deficiency

- transferrin not transported to erythroblast

Question 22

How does RBC perform metabolic processes if it has no mitochondria?

Answer 22

Uses ATPase and ferrous state of Fe to prevent oxidative damage

Question 23

Hemachromatosis
Cause
Clinical

Answer 23

Iron overload. Could be primary (genetic) or secondary

Liver cirrhosis, skin pigmentation, DM

Question 24

How does anemia affect blood oxygen content/capacity?

Does this affect O2 saturation?

Answer 24

Anemia = less Hgb = less blood oxygen content

No

Question 25

Polycythemia and Methemoglobinemia are associated with____

Answer 25

Left shift, due to extra RBCs

Question 26

Primary Polycythemia

Answer 26

Low EPO, bone marrow somehow makes lots of RBCs
Increased blood volume, viscosity
Normal CO

Question 27

Secondary polycythemia

Answer 27

High EPO, induces increased proliferation of RBCs

Possible normal CO

Question 28

Physiological polycythemia

Answer 28

Increase RBCs to adapt to high altitudes

Normal CO

Question 29

Methemoglobinemia
Cause
Clinical

Answer 29

Increased met-hemoglobin, which uses Ferric iron instead of ferrous
Chocolate blood, blue skin, decreased oxygen donation to tissues (left shift)

Question 30

What is A-V O2 difference?

Answer 30

PaO2 - PvO2

calculates how much blood was lost to the tissues, increases during exercise

Question 31

How do you calculate RQ?

Answer 31

Volume produced CO2/volume consumed O2 = Vdot CO2/Vdot O2

Usually 0.8 (200 ml CO2/250 mL O2)

Question 32

If your diet is …, what is the RQ?
Glucose
Fatty acid
Protein

Answer 32

1. 0
2. 7
3. 9

Question 33

How is CO2 transported in the blood?

Answer 33

Dissolved in blood

Bound to amine group of carbamino compounds or Hgb

Question 34

What is Haldane shift?

What is the chloride shift?

Answer 34

• Amine group/Hgb displaces CO2 if there is lots of O2 available
• As CO2 is converted into HCO3 in the RBC, it is pumped out for exhalation by bringing Cl- into the RBC in exchange

Question 35

What is the carbonic anhydrase equation?

Answer 35

CO2 + H2O H2CO3 <> H+ + HCO3-