W3-L4: Respiratory System 2 Flashcards
What is The Bohr Effect?
- Any increase in plasma acidity (including CO2 concentration) and temperature causes the oxyhemoglobin dissociation curve to shift downward and to the right
- Indicates that [H+] and CO2 alter hemoglobinʼs molecular structure to decrease its O2 -binding affinity
- The reduced effectiveness of hemoglobin to hold O2 occurs in the PO2 range of 20 to 50 mm Hg
- The Bohr effect predominates during intense exercise as more O2 releases to tissues from associated increases in metabolic heat, CO2, and acidity from blood lactate accumulation
What is Arteriovenous Oxygen Difference
(a-vO2 diff)?
The a-vO2 difference describes the difference between oxygen content of arterial blood and mixed-venous blood
- Averages 4 to 5 mL O 2 /dL blood at rest
O2 release from Hb can occur without any increase in local tissue blood flow
- Amount of O2 released to muscles in vigorous exercise increases by three times the resting level
Whole Body Arteriovenous Oxygen Difference at Rest and During Intense Aerobic Exercise
What limits aerobic capacity?
An active muscle’s uncompromising capacity to use available oxygen in its large blood flow supports the position that oxygen supply, not muscle oxygen use, limits aerobic capacity
on arterial side start with 20 mL of O2 for 100 mL of blood, less )2 coming back to lung
Where does red blood cell get energy?
A red blood cell derives its energy solely from the anaerobic reactions of glycolysis because they contain no mitochondria
What do RBC produce?
- Red blood cells produce 2,3-diphosphoglycerate
- 2,3 DPG binds loosely with Hb subunits reducing its affinity for oxygen
- This causes a greater oxygen release to the tissues for a given decrease in PO2, so it aid in the O2 transfer to muscles
What is Myoglobin, the Muscle’s Oxygen Storage? (2)
How does it differ from Hb? (2)
- An iron-containing globular protein in skeletal & cardiac muscle fibers
- Provides for intramuscular O2 storage
- 240x greater affinity for O2 than Hb
- each molecule contains 1 iron atom while Hb contains 4
How is Carbon Dioxide Transported in the Blood?
3
Once CO2 forms, diffusion and subsequent transport in venous blood is the only means for its “escape” through the lungs
The blood carries CO2 in three ways:
1. In physical solution in plasma
2. Combined with hemoglobin within red blood cells
3. As plasma bicarbonate
How is CO2 transported in physical solution?
- 5% of CO2 formed during energy metabolism moves into physical solution in the plasma as free CO2
- The random movement of this small quantity of dissolved CO2 molecules establishes the PCO2 of the blood
How is CO2 transported as bicarbonate?
- CO2 in solution combines with H2O to form carbonic acid
- Once carbonic acid forms in tissues, most of it ionizes into H+ and bicarbonate
- 60-80% of the total CO2 exists as plasma bicarbonate
Hows is CO2 transported as carbamino compounds?
- At a tissue level, carbamino compounds form when CO2 reacts directly with the amino acid molecules of blood proteins
- Globin portion of Hb, which carries about 20% of the body’s CO2 form a carbamino compound
How does the Haldene affect play a role?
The Haldane effect states that in the lungs, a decrease in plasma PCO₂ reverses carbamino formation, causing CO₂ to dissolve into the plasma and enter the alveoli. As hemoglobin becomes oxygenated, its ability to bind CO₂ decreases, facilitating CO₂ release.
Transport of CO2
