Gas Transport

What are the two ways oxygen is transported in the blood?

98% bound to hemoglobin (HbO₂), 2% dissolved in plasma.

What is oxyhemoglobin (HbO₂)?

Hemoglobin with oxygen bound to its iron atoms.

What is deoxyhemoglobin (HHb)?

Hemoglobin without bound oxygen.

Why is hemoglobin essential for oxygen transport?

Oxygen has a low solubility in plasma, so hemoglobin carries most of it.

What is the oxygen reserve?

Oxygen still bound to hemoglobin after passing through systemic circulation, available during increased demand.

What are the three ways carbon dioxide is transported in the blood?

7% dissolved in plasma, 23% bound to hemoglobin (HbCO₂), 70% as bicarbonate (HCO₃⁻).

What is carbaminohemoglobin (HbCO₂)?

Hemoglobin with carbon dioxide bound to the globin portion.

What enzyme catalyzes the conversion of CO₂ and H₂O into carbonic acid?

Carbonic anhydrase.

What is the chloride shift?

Exchange of bicarbonate out of erythrocytes and chloride ions in, to maintain charge balance.

What three substances can hemoglobin transport?

Oxygen (to iron), carbon dioxide (to globin), and hydrogen ions (to globin).

What is the Bohr effect?

H⁺ binding to hemoglobin reduces its affinity for oxygen, promoting oxygen release.

How does temperature affect oxygen release from hemoglobin?

Increased temperature decreases hemoglobin’s affinity for oxygen, enhancing release.

What is 2,3-BPG and its role in oxygen transport?

A molecule in erythrocytes that binds hemoglobin and promotes oxygen release; stimulated by hormones like epinephrine and thyroid hormone.

What is cooperative binding in hemoglobin?

Each bound O₂ increases hemoglobin’s affinity for the next O₂ molecule.

What causes a right shift in the oxygen-hemoglobin saturation curve?

Increased temperature, H⁺, CO₂, or 2,3-BPG → more O₂ released.

What causes a left shift in the curve?

Decreased temperature, H⁺, or CO₂ → more O₂ retained.

What is the typical hemoglobin saturation at rest after systemic circulation?

About 75% (25% of O₂ released to tissues).

How does vigorous exercise affect hemoglobin saturation?

Drops to about 35% due to increased O₂ demand.