Carbon Dioxide Transport in the Blood

These flashcards cover key concepts related to carbon dioxide transport in blood, the role of haemoglobin, and the Hb-O2 dissociation curve.

What are the three mechanisms for the transport of CO2 in the blood?

1. Dissolved CO2 in plasma 2. Carbamino compounds (bound to proteins) 3. Bicarbonate ions (HCO3-)

According to Henry's Law, how is dissolved O2 in blood determined?

Dissolved O2 is a linear function of partial pressure of O2 (PO2), specifically 0.003 mL O2 per 100 mL blood for each mmHg PO2.

What is the key role of haemoglobin during gas exchange in the lungs?

Haemoglobin has a high affinity for O2 to ensure maximum O2 loading.

Why does oxygen bound to haemoglobin not contribute to the partial pressure of oxygen (PO2) in the blood?

Only dissolved oxygen determines the PO2 of blood; bound oxygen does not contribute to the pressure.

What happens to the Hb-O2 dissociation curve at temperatures above normal?

Increased temperature denatures the bond between Hb and O2, reducing Hb's affinity for O2.

How does the presence of 2,3-DPG affect Hb-O2 affinity?

2,3-DPG decreases Hb's affinity for O2, promoting O2 unloading in peripheral tissues.

What causes the Hb-O2 dissociation curve to shift to the right?

Increased CO2, increased H+, increased temperature, and increased 2,3-DPG cause a rightward shift, indicating decreased affinity for O2.

What is the significance of the flat upper portion of the Hb-O2 dissociation curve?

It allows for oxygen uptake at the lungs to be relatively unaffected by drops in alveolar PO2.

What promotes O2 unloading from Hb in tissues?

Factors such as increased 2,3-DPG, increased PCO2, increased H+, and increased temperature.

What occurs at a PO2 level of around 50mmHg on the Hb-O2 dissociation curve?

The amount of O2 carried by Hb increases rapidly.