Exam 2 Review-Gas Transport

Question 1

Oxygen transport: what is O2 loading and O2 unloading.

Hint: “Pick-up at the Airport” vs. “Drop-off at the Destination”

Answer 1

Oxygen loading occurs in the lungs, where oxygen binds to hemoglobin. (Pick up)

Oxygen unloading occurs in the tissues, where oxygen is released from hemoglobin for cellular use. (Drop off)

Question 2

Discuss factors that affect oxygen loading and oxygen unloading:

Acronym: “P.C.T.A.”

Answer 2

(Pressure, CO2, Temp, Acid)

PO₂ levels (high PO₂ → more loading, low PO₂ → more unloading)

CO₂ levels (high CO₂ → more unloading)

Temperature (high temp → more unloading)

Acidity (low pH → more unloading)

Question 3

CO2 transport: discuss the three ways CO2 is transported in the blood:

Acronym: “D.B.C.”

Answer 3

(Dissolved, Bicarbonate, Carbamino)

Dissolved in plasma (~7-10%)

Bicarbonate (HCO₃⁻) (~70%)

Carbaminohemoglobin (Hb-CO₂) (~20-23%)

Question 4

Explain the Bohr Effect

Analogy: “O₂ Gets Kicked Off by CO₂ and Acid”

Answer 4

More CO₂ or H+ (acidic pH) → Hemoglobin releases O₂ more easily → Enhances O₂ unloading at tissues.

Why? CO₂ binds to Hb and changes its shape, reducing O₂ affinity.

Question 5

Explain the chloride shift and indicate where it occurs

Answer 5

Chloride Shift (Tissues) → “CO₂ to Bicarbonate”
Happens at tissues (systemic circulation).

CO₂ enters RBCs → Converts to HCO₃⁻ → HCO₃⁻ exits RBC, Cl⁻ enters to balance charge.

Purpose: Moves CO₂ in a form (HCO₃⁻) that easily travels in plasma.

Question 6

Explain the Haldane effect

Analogy: “CO₂ Rides in the Empty Seats”

Answer 6

Less O₂ → More CO₂ carried in blood (tissues)

More O₂ → CO₂ released from blood (lungs)

Why? Deoxygenated Hb binds CO₂ more easily, enhancing CO₂ transport at tissues.