Transport of Oxygen and Carbon Dioxide in Blood Quiz

Oxygen Transport

• Oxygen diffuses from the alveoli into the pulmonary capillary blood in the lungs due to the higher oxygen partial pressure (PO2) in the alveoli.
• In the tissues, oxygen diffuses from the capillary blood into the surrounding cells due to the higher PO2 in the capillary blood compared to the tissues.
• Oxygen is carried in the blood by binding loosely and reversibly with the heme portion of hemoglobin.
• When PO2 is high, oxygen binds with hemoglobin, but when PO2 is low, oxygen is released from hemoglobin.

Carbon Dioxide Transport

• Carbon dioxide diffuses from the tissues into the blood due to the higher PCO2 in the tissues.
• In the lungs, CO2 diffuses from the pulmonary capillary blood into the alveoli due to the higher PCO2 in the pulmonary capillary blood.
• CO2 is carried in the blood in three forms: bicarbonate ions (HCO3-), bound to hemoglobin, and dissolved in plasma.
• The enzyme carbonic anhydrase speeds the breakdown of carbonic acid (H2CO3) in red blood cells.

External Respiration

• External respiration is the exchange of gases between air in the alveoli and blood in the pulmonary capillaries.

Internal Respiration

• Internal respiration is the exchange of gases between the blood and the tissues.

Altitude Sickness and Acclimatisation

• Altitude sickness is caused by acute exposure to low partial pressure of oxygen at high altitude.
• The body compensates for altitude sickness through altitude acclimatisation, which involves producing more red blood cells.

Tissue Hypoxia and Cyanosis

• Tissue hypoxia occurs when the amount of oxygen available for cellular metabolism is inadequate.
• Hypoxia leads to anaerobic mechanisms that produce lactic acid and decrease blood pH.
• Cyanosis is a purplish discoloration seen on the mucous membranes, fingertips, and toes when the blood in these areas is hypoxemic.

Polycythemia

• Polycythemia occurs when pulmonary disorders produce chronic hypoxemia, leading to an increased level of RBCs.
• The hormone erythropoietin stimulates the bone marrow to increase RBC production in response to hypoxemia.
• Polycythemia is an adaptive mechanism designed to increase the oxygen-carrying capacity of the blood.

Test your knowledge on the transport of oxygen and carbon dioxide in blood, including the processes of diffusion of O2 and CO2 in the lungs, capillaries, and tissues. Understand how gases move between the respiratory system and body cells.