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Carriage of Oxygen and Carbon Dioxide in the Blood

• The transportation of gases in the body occurs through the cardiovascular system via diffusion, which is driven by random, elastic collisions between gas molecules and establishes equilibrium within 1 second.
• Oxygen is transported in the blood in two ways: physically dissolved in plasma (~2%) and chemically bound to the haemoglobin molecule (~98%).
• Haemoglobin is a heterotetramer consisting of 4 subunits and each haem iron atom molecule contains one oxygen molecule, allowing for the reversible binding of oxygen to be carried from the respiratory organs to the rest of the body.
• The position of the oxyhaemoglobin dissociation curve is not fixed and can vary depending on factors such as pH, temperature, and concentration of 2,3-diphosphoglycerate (2,3-DPG).
• The Bohr effect states that haemoglobin’s oxygen binding affinity is inversely related to both acidity and PCO2, facilitating O2 release from Hb at tissues.
• Haemoglobin F binds O2 better than haemoglobin A because 2,3-DPG binds poorly to the gamma chains of haemoglobin F, improving O2 transfer across the placenta.
• Anemia reduces the O2 carrying capacity of the blood, while carbon monoxide poisoning forms carboxyhaemoglobin which does not bind O2 and shifts the oxyhaemoglobin dissociation curve to the left, leading to severe tissue hypoxia.
• Cyanosis is a blue colouration of the skin and mucous membranes due to arterial blood desaturation or reduced tissue blood flow.
• Carbon dioxide is transported in the blood in three ways: physically dissolved (5%), combined with Hb as carbaminohaemoglobin (3%), and chemically combined as bicarbonate ion (92%).
• Carbonic anhydrase is an enzyme present in red blood cells that accelerates the formation of carbonic acid from water and CO2 over 1000 times, allowing for continued uptake of carbon dioxide into the blood as bicarbonate.
• The chloride shift at tissues and reverse chloride shift at lungs ensure ionic and electrical stability of the RBC during the transport of carbon dioxide.
• Hyperventilation causes respiratory alkalosis, and hypoventilation causes respiratory acidosis.

Carriage of Oxygen and Carbon Dioxide in the Blood

• The transportation of gases in the body occurs through the cardiovascular system via diffusion, which is driven by random, elastic collisions between gas molecules and establishes equilibrium within 1 second.
• Oxygen is transported in the blood in two ways: physically dissolved in plasma (~2%) and chemically bound to the haemoglobin molecule (~98%).
• Haemoglobin is a heterotetramer consisting of 4 subunits and each haem iron atom molecule contains one oxygen molecule, allowing for the reversible binding of oxygen to be carried from the respiratory organs to the rest of the body.
• The position of the oxyhaemoglobin dissociation curve is not fixed and can vary depending on factors such as pH, temperature, and concentration of 2,3-diphosphoglycerate (2,3-DPG).
• The Bohr effect states that haemoglobin’s oxygen binding affinity is inversely related to both acidity and PCO2, facilitating O2 release from Hb at tissues.
• Haemoglobin F binds O2 better than haemoglobin A because 2,3-DPG binds poorly to the gamma chains of haemoglobin F, improving O2 transfer across the placenta.
• Anemia reduces the O2 carrying capacity of the blood, while carbon monoxide poisoning forms carboxyhaemoglobin which does not bind O2 and shifts the oxyhaemoglobin dissociation curve to the left, leading to severe tissue hypoxia.
• Cyanosis is a blue colouration of the skin and mucous membranes due to arterial blood desaturation or reduced tissue blood flow.
• Carbon dioxide is transported in the blood in three ways: physically dissolved (5%), combined with Hb as carbaminohaemoglobin (3%), and chemically combined as bicarbonate ion (92%).
• Carbonic anhydrase is an enzyme present in red blood cells that accelerates the formation of carbonic acid from water and CO2 over 1000 times, allowing for continued uptake of carbon dioxide into the blood as bicarbonate.
• The chloride shift at tissues and reverse chloride shift at lungs ensure ionic and electrical stability of the RBC during the transport of carbon dioxide.
• Hyperventilation causes respiratory alkalosis, and hypoventilation causes respiratory acidosis.