Oxygen Transport to the Tissues

Flashcards review the key concepts of oxygen transport, hemoglobin binding, and factors influencing oxygen release at tissues.

What percentage of total oxygen is transported dissolved directly in blood plasma?

Roughly 2% of oxygen travels dissolved in plasma.

To which molecule does the majority (≈98%) of oxygen bind for transport in blood?

Hemoglobin, specifically the iron atom in each heme group.

What drives oxygen movement from alveoli into pulmonary blood plasma?

A partial-pressure gradient (higher PO₂ in alveoli than in blood).

After leaving blood plasma at the tissues, where does oxygen go next?

Directly into tissue cells to support cellular respiration.

How does an increased partial pressure of CO₂ in tissues affect hemoglobin’s affinity for oxygen?

Higher PCO₂ decreases hemoglobin affinity, stimulating O₂ release (Bohr effect).

What is the effect of decreased pH (increased acidity) on oxygen release from hemoglobin?

Lower pH promotes oxygen unloading from hemoglobin.

How does temperature influence oxygen unloading from hemoglobin?

Increased temperature at metabolically active tissues encourages O₂ release.

Which glycolytic intermediate enhances oxygen release from hemoglobin, especially during anaerobic metabolism?

2,3-bisphosphoglycerate (2,3-BPG).

Why do metabolically active tissues promote oxygen unloading?

They raise CO₂, lower pH, increase temperature, and may elevate 2,3-BPG—each of which lowers hemoglobin’s O₂ affinity.

Approximately what proportion of blood oxygen is bound to hemoglobin versus free in plasma?

About 98% bound to hemoglobin, 2% free in plasma.

Through which lung structures does oxygen enter the bloodstream?

Alveolar air sacs into surrounding pulmonary capillaries.

State the cellular respiration equation emphasized in the lecture.

Glucose + O₂ → CO₂ + H₂O + heat + ATP.

How is 2,3-BPG production linked to oxygen availability?

Low O₂ increases anaerobic glycolysis, raising 2,3-BPG, which promotes O₂ release from hemoglobin.

Outline the path of oxygen from the atmosphere to tissue cells.

Atmosphere → alveoli → blood plasma → red blood cells (bound to hemoglobin) → blood plasma (at tissues) → tissue cells.