Submitted Jun 20 at 8:24pm
This attempt took 2 minutes.
 
Question 1
1 / 1 pts

What are the three mechanisms that facilitate CO2 transportation in the blood, and which mechanism transports the majority of CO2 back to the lungs?

CO2 is transported from the tissues to the lungs by the following three mechanisms:

(1) CO2 is transported back to the lungs dissolved in  (~7-10% of total).

(2) CO2 is transported to the lungs bound to  (~20%).

(3) the remaining  of CO2 is transported to the lungs in the form of  because this form is much more soluble in water than a neutral gas molecule.

Answer 1:
Answer 2:
Answer 3:
Answer 4:
 
Question 2
1 / 1 pts

During respiratory distress/failure, the expiration of CO2 is impaired.

 

Therefore, as less CO2 was exhaled, the plasma PCO2 would  . About 70% of the CO2 generated by cellular metabolism would be converted to  and hydrogen ions by the enzyme carbonic anhydrase (CA). As the PCO2 continued to rise, this conversion would eventually overwhelm the buffering mechanisms that resist dramatic changes in blood pH.

This would result in a homeostatic imbalance called respiratory acidosis, in which the pH  as the hydrogen ion concentration increases. O2 transport to the tissues is vital for survival. However, if the CO2 level increases to the point that it affects the blood pH substantially, this can prove fatal.

Answer 1:
Answer 2:
Answer 3:
 
Question 3
1 / 1 pts

If the levels of CO2 rise during respiratory distress, which of the following describes how the body responds?

  
  
  
  
 
Question 4
1 / 1 pts

Consider the factors that impact how hemoglobin binds to O2 discussed last week. (we discussed these factors in the context of exercise, but remember these are factors that are true during other situations as well).

 

Which of these can impact the hemoglobin-oxygen dissociation curve?

  
  
  
  

this a tricky one! remember that CO2 pressure is directly related to blood pH because CO2 is converted to bicarbonate and hydrogen ions (H+)

 
Question 5
1 / 1 pts

In the case of respiratory distress where CO2 levels rise, what happens to the binding of oxygen to hemoglobin?

  
  
  
  
 

Now let's consider something that isn't disease related!

 

There are actually different types of hemoglobin. One that is made during adulthood (Hb) and one that you make when you are a fetus developing in the womb (fetal hemoglobin, FHb). Take a look at the following images to give you an idea of how oxygen needs to be transferred from the pregnant individual to the developing fetus:

fetal placenta oxygen transfer.jpg

Carefully looking at the placental organ, you might appreciate that the maternal blood supply is separate (but surrounds) the fetal blood vessels (you can trace these from the umbilical cord). That means maternal blood never mixes with fetal blood.

 

fetal and maternal hemoglobin.gif

Maternal hemoglobin must drop the oxygen, that oxygen crosses cells layers (called syncytiotrophoblasts) and the oxygen is picked up by FHb (fetal hemoglobin).

 

But how does the fetal hemoglobin achieve this "stealing" of maternal oxygen?

 
Question 6
1 / 1 pts

Finally, look at the hemoglobin-oxygen dissociation curves for Hb and FHb. Then, answer the question.

fetal hemoglobin dissociation curve.png

 

Carefully looking at this graph of the two curves (one for Hb and one for FHb), what can you conclude?

  
  
  
  
 
Question 7
1 / 1 pts

Last check your understanding!

 

Remember that the pressure of oxygen in the alveoli is around 100mmHg whereas in tissues is only 40mmHg. Look at the curve below and tell me how much of the oxygen (picked up in the lungs) is dropped off at the tissues?

Hb O2 dissociation.png

  
  
  
  
  
Quiz Score: 7 out of 7