Gas Transport In Blood And Tissues Flashcards
What are the two ways that oxygen is carried through the body?
Oxygen is carried through haemoglobin and plasma, where haemoglobin is the primary method of transportation. 97% ~196ml/L
1g of haemoglobin can carry 1.34ml of O2. Knowing that the body has 150g of Hb, at 100% saturation how much oxygen is bound to haemoglobin?
196ml/L
How does the composition of alveolar air affect the other partial pressures?
Because the alveolar air has more water vapour and carbon dioxide there is less oxygen due to the partial pressures adding up and having to be 760mmHg.
The higher concentration of water vapour and carbon dioxide will dilute the oxygen’s partial pressure
What is the shunt and dead space effect? How is it represented in ratio of alveolar ventilation (Va) and cardiac output (Q)?
The shunt effect is where Va/Q1. Where the work of breathing is wasted.
What determines when oxygen binds or is released from haemoglobin?
The partial pressure pO2 of oxygen determines the release and binding of oxygen. When pO2 is low in the tissues, oxygen will be released and vice versa.
The Bohr effect is a group of factor that affects oxygen unloading at the tissues AND lungs. What are the three factors?
Because oxygen unloading apart from partial pressure is affected by pH, the Bohr effect is eesntially the factors that can affect the pH.
Temperature, hydrogen ion concentration, carbon dioxide concentration.
When the pH increases, the unloading increases
Why does the Bohr effect affect oxygen loading with different degrees in the lungs and in the tissues?
This is because the O2-Hb curve is sigmoidal and the curve shifts to the right with the Bohr effect.
When the curve shifts to the right, there is a smaller difference in Hb saturation at the top where the curve plateaus.
There is a larger difference in Hb saturation at the middle where the curve is near vertical and a shift to the right brings about greater change.
What are the 3 chemical forms in which CO2 is transported?
- Dissolved in plasma (8-10%)
- As bicarbonate ions HCO3- (60-88%)
- Chemically bound to Hb (5-30%)
How does CO2 react to form bicarbonate ions as a means of transport?
Carbon dioxide reacts with water to form bicarbonate ions
CO2+H2OH2CO3H+ + HCO3-
How does the RBC maintain electrical neutrality through carbon dioxide release at the TISSUES? What is the result of the venous blood thereafter?
When carbon dioxide is being transported in the RBC as bicarbonate ion, it leaves the RBC, and the result of this is that there is the Chloride shift, where Chloride ions move into the RBC to maintain electrical neutrality as the Bicarbonate ions move out.
The result is also that the venous blood as chloride content.
A byproduct of Carbon dioxide unloading at the tissues through the bicarbonate pathway is that there is a buildup of H+ at the end of the reaction chain. However, this does not limit the reaction (and prevent it from going backwards). Why?
The reason that the H+ ions are bound to the Hb (that has already released the oxygen) and there is no buildup of H+ ions to limit the step.
CO2+H2O–>H2CO3–>HCO3- +H+
This H+ joins with Hb to become HHb
What is the haldane effect and how does oxygen in the lungs affect the carbon dioxide?
The haldane effect describes the oxygen binding affinity to Hb.
At the lungs: Oxygen loading reduces affinity for Hb and CO2. Thus, CO2 will unload easier.
At the tissues: Oxygen unloading increases affinity between Hb and CO2. Thus, CO2 will load easier.
