22 Questions
What is the effect of anemia on the oxygen content of blood?
It decreases the oxygen content, but SaO2 remains normal.
What is the effect of carbon monoxide on the oxyhemoglobin dissociation curve?
It makes the sigmoidal curve hyperbolic, leading to severe tissue hypoxia.
What is the maximum amount of oxygen that can be consumed in one minute?
VO2 max.
What is the primary factor that limits the intensity of aerobic exercise?
The amount of oxygen the muscle can consume.
Why do muscles require more oxygen during aerobic exercise?
Because muscle contraction is dependent on oxygen consumption.
What happens to the demand for oxygen from the muscle as the intensity of aerobic exercise increases?
It increases.
What is VO2 max?
The maximum rate at which oxygen can be consumed
How is relative VO2 expressed?
In milliliters of oxygen consumed per kilogram of body weight per minute
What is the rate of oxygen consumption at rest?
3.5 ml/kg/min
What happens to VO2 as an individual goes from rest to exercise?
It increases
What is Fick's Equation?
VO2 max= CO×∆𝐴 − 𝑣𝑂2 𝑑𝑖𝑓𝑓𝑒𝑟𝑒𝑛𝑐𝑒
What percentage of the body weight is made up of skeletal muscles?
50%
What percentage of oxygen consumption is accounted for by the brain?
20%
What causes a shift of the O2-Hb dissociation curve to the right?
Not specified in the text (but could be due to factors such as increased temperature, PCO2, or 2,3-DPG)
Who discovered the Bohr Effect in 1904?
Christian Bohr
What is the Bohr Effect?
The effect of CO2 on the oxyhemoglobin dissociation curve
What happens to the affinity of hemoglobin for oxygen when PCO2 levels are high and pH is low?
It decreases
What is the significance of the Bohr Effect in the tissues?
It enhances the unloading of oxygen
What is the result of CO2 diffusing out of the blood in the lungs?
A decrease in H+ concentration and a leftward shift of the O2-Hb curve
What is the Double Bohr Effect?
Reciprocal changes in acid-base balance that occur in maternal and fetal blood in transit through the placenta
What is the role of 2,3 BPG in oxygen transport?
It promotes a rightward shift and enhances oxygen unloading at the tissues
What is the chemical reaction representing the binding of 2,3 DPG to hemoglobin?
HbO2 + 2,3 DPG → Hb-2,3 DPG + O2
Study Notes
Mass Transport in Biological Systems
- The Bohr Effect, discovered by Christian Bohr in 1904, describes the effect of CO2 on the oxyhemoglobin dissociation curve.
- High PCO2 levels and low pH decrease the affinity of hemoglobin for oxygen, causing a rightward shift of the oxyhemoglobin dissociation curve.
- This occurs in tissues where high CO2 levels and acidemia contribute to the unloading of oxygen.
Implications of the Bohr Effect
- The Bohr Effect enhances oxygenation of blood in the lungs and increases the release of O2 in tissues.
- In the lungs, CO2 diffuses out of the blood, decreasing H+ concentration, which leads to a leftward shift of the oxyhemoglobin dissociation curve, increasing O2 bound to hemoglobin.
- In tissue capillaries, the increase in CO2 and H+ leads to a greater release of O2 due to less avid binding of O2 to hemoglobin.
Double Bohr Effect
- The Double Bohr Effect refers to reciprocal changes in acid-base balance that occur in maternal and fetal blood in transit through the placenta.
- Fetal blood loses CO2, leading to a rise in pH, and a leftward shift of the oxyhemoglobin dissociation curve.
- Maternal blood gains CO2, leading to a fall in pH, and a rightward shift of the oxyhemoglobin dissociation curve.
Role of 2,3 BPG (Bis-phosphoglycerate)
- 2,3 BPG tends to bind to β chains of Hb, decreasing the affinity of hemoglobin for oxygen.
- This promotes a rightward shift of the oxyhemoglobin dissociation curve, enhancing oxygen unloading at the tissues.
Effects of Anemia and CO on the Oxyhemoglobin Dissociation Curve
- Anemia: a decrease in oxygen-carrying capacity of blood, but SaO2 remains normal.
- Carbon Monoxide (CO): has a 250-fold higher affinity for Hb than O2, competing with O2 binding, leading to severe tissue hypoxia.
Oxygen Dissociation Curve: Hemoglobin vs. Myoglobin
- Hemoglobin and myoglobin have different oxygen dissociation curves, with myoglobin having a higher affinity for oxygen.
O2 Delivery During Exercise
- VO2 max is the maximal amount of oxygen that can be consumed in one minute.
- Muscle contraction depends on oxygen consumption, and the intensity of aerobic exercise is limited by the amount of oxygen available.
- VO2 max is the maximum rate at which oxygen can be consumed, expressed in relative terms (ml/kg/min).
Fick's Equation
- VO2 max = CO × Δ[A - v]O2 diff
- CO = stroke volume × Heart Rate
- Relative VO2 = VO2 / Body Weight
Organ-Specific O2 Consumption
- Heart: 0.6% of body weight, 11% of O2 consumption
- Brain: 2% of body weight, 20% of O2 consumption
- Skeletal Muscles: 50% of body weight, 27% of O2 consumption
This quiz covers the concept of mass transport in biological systems, including the Bohr Effect, and its relation to CO2 levels, pH, and hemoglobin affinity for oxygen.
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