Exam 3, L3

Question 1

What is the solubility coefficient of oxygen in blood?

Answer 1

0.003 mL O₂/mmHg per deciliter.

Question 2

How much dissolved oxygen is in arterial blood with a PO₂ of 100 mmHg?

Answer 2

0.3 mL O₂/dL (100 × 0.003)

Question 3

Is dissolved oxygen sufficient to meet metabolic demand?

Answer 3

No — we need hemoglobin to meet the ~250 mL/min O₂ demand.

Question 4

How much oxygen can 1 gram of hemoglobin carry?

Answer 4

1.34 mL O₂

Question 5

How much oxygen can 15 g/dL of hemoglobin carry at 100% saturation?

Answer 5

20.1 mL O₂/dL

Question 6

What is normal arterial O₂ content?

Answer 6

~20.4 mL O₂/dL (bound + dissolved)

Question 7

What is normal venous O₂ content?

Answer 7

~15 mL O₂/dL

Question 8

What percent of O₂ is unloaded at the tissues?

Answer 8

About 25% (from 100% to ~75% saturation)

Question 9

What chains make up adult hemoglobin (HbA)?

Answer 9

2 alpha and 2 beta chains

Question 10

What chains make up fetal hemoglobin (HbF)?

Answer 10

2 alpha and 2 gamma chains

Question 11

Why does HbF have a higher affinity for oxygen?

Answer 11

To extract O₂ from maternal blood during gestation

Question 12

What is myoglobin’s role?

Answer 12

It facilitates O₂ delivery to skeletal muscles and has a higher affinity than adult Hb.

Question 13

How does CO affect hemoglobin?

Answer 13

It binds tighter than O₂ and reduces both O₂ carrying capacity and release.

Question 14

How does CO shift the oxyhemoglobin curve?

Answer 14

Left shift — increased O₂ affinity, less unloading

Question 15

What is the P₅₀ value for adult hemoglobin?

Answer 15

~26.5 mmHg — the PO₂ required to saturate Hb 50%

Question 16

What causes a right shift of the curve?

Answer 16

↑CO₂, ↑H⁺ (↓pH), ↑Temperature, ↑2,3-BPG

Question 17

What does a right shift mean?

Answer 17

↓Affinity → more O₂ unloading to tissues

Question 18

What causes a left shift of the curve?

Answer 18

↓CO₂, ↓H⁺ (↑pH), ↓Temp, ↓2,3-BPG, CO, HbF

Question 19

What does a left shift mean?

Answer 19

↑Affinity → less O₂ unloading (e.g., in lungs)

Question 20

What is typical arterial O₂ saturation?

Answer 20

~97–100%

Question 21

What is typical venous O₂ saturation?

Answer 21

~70–75%

Question 22

What is venous O₂ saturation in the coronary sinus?

Answer 22

~25% — heart extracts ~75% of O₂

Question 23

What is 2,3-BPG?

Answer 23

A byproduct of metabolism that reduces O₂ affinity

Question 24

How does 2,3-BPG shift the O₂ curve?

Answer 24

Right shift — promotes unloading at tissues

Question 25

What does increased temperature do to hemoglobin's O₂ affinity?

Answer 25

Causes a right shift → enhanced unloading

Question 26

What does decreased temperature do?

Answer 26

Causes a left shift → less unloading

Question 27

What are the 3 forms of CO₂ in blood?

Answer 27

Dissolved (5%), carbamino compounds (5%), bicarbonate (90%)

Question 28

What is the solubility of CO₂ in blood?

Answer 28

0.06 mL CO₂/mmHg per dL

Question 29

How much CO₂ is dissolved in arterial blood (PCO₂ = 40)?

Answer 29

2.4 mL/dL (0.06 × 40)

Question 30

How much CO₂ is in venous blood (PCO₂ = 45)?

Answer 30

2.7 mL/dL (0.06 × 45)

Question 31

Why does deoxygenated Hb carry more CO₂?

Answer 31

Deoxy-Hb buffers H⁺ and exposes amine groups for CO₂ binding

Question 32

What enzyme accelerates CO₂ to HCO₃⁻ conversion?

Answer 32

Carbonic anhydrase

Question 33

What is the Bohr effect?

Answer 33

↑CO₂ or ↓pH causes Hb to release more O₂ (right shift)

Question 34

What is the Haldane effect?

Answer 34

Deoxygenated Hb binds and carries more CO₂

Question 35

Why does the CO₂ curve have to use multiple lines?

Answer 35

Because CO₂ content depends on Hb oxygenation — use different curves for arterial vs. venous samples

Question 36

What is average arterial CO₂ content?

Answer 36

~48 mL/dL

Question 37

What is average venous CO₂ content?

Answer 37

~52.5 mL/dL