Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
16 Cards in this Set
- Front
- Back
|
1. What can too high levels of CO2 at or within the tissues cause?
How can high PaCO2 affect the central respiratory centers? What happens if PaCO2 is too low? How is Ca affected by low PaCO2? |
Respiratory acidosis (hypercapnia) may result
Can acts as an anesthetic Serious acid-base and ionic disturbances will occur In high pH Ca tends to come out of solution so it precipitates uncontrolled and sustained skeletal muscle contractions occur |
|
|
2. Where does CO2 flow from?
In what three forms is CO2 transported by blood to lungs? |
Follows it pressure gradients and flows from tissues into plasma and RBCs
1. Dissolved CO2 2. Bicarbonate (HCO3) **main transport form 3. Carbaminohemoglobin **two of the three processes of CO2 transport and removal involve chemical processing by erythrocytes |
|
|
3. How is CO2 solubility?
How is diffusion of CO2? What is the amount of CO2 dissolved in plasma proportional to? |
Very soluble in tissues and plasma
Diffusion is rapid between tissues and plasma Amount dissolved in plasma is proportional to PaCO2 Amount dissolved = PaCO2 x solubility coefficient of CO2 |
|
|
4. How is the conversion of CO2 to HCO3- and why?
What is the first step in the conversion? Then what happens? (three steps) |
Very slow b/c plasma contains no carbonic anhydrase
CO2 diffuses into the RBC 1. CO2 is rapidly hydrated forming H2CO3 (carbonic acid) **carbonic anhydrase is present in large concentrations in RBC 2. H2CO3 breaks down to H+ and HCO3- w/in red cell 3. HCO3- diffuses out of RBC but H+ does not |
|
|
5. What three issues arise attributable to the breakdown of H2CO3 within erythrocytes?
|
1. HCO3- is a new osmotically active charged particle
2. Outwardly diffusion HCO3- carries a negative charge with it 3. The reaction produces H+ |
|
|
6. Why is the fact that HCO3- is a new osmotically active charge particles an issue?
|
Some of the HCO3- remains in the cell and does not diffuse out to the plasma
This increases the cell's osmolarity Some water enters cell to maintain isomotic conditions so RBC swells slightly |
|
|
7. Why does no cell lysis occur if water is entering the RBC?
|
The amount of HCO3- left behind is small so the increase in cell volume is small
|
|
|
8. How is the negative charge carried by the outwardly diffusion HCO3- replaced to maintain electric neutrality?
|
Lost negative charge is replaced by an inward diffusion of Cl- to maintain electric neutrality
(chloride shift or Hamburger shift) |
|
|
9. What can H+ cause?
How is the problem of H+ being produced and remaining in the RBC solved? |
H+ can cause intracellular acidosis and kill the cell
H+ is effectively buffered by Hb to for HHb **little intracellular pH change is noted |
|
|
10. What does the presence of H+ in the erythrocyte do to Hb's affinity for O2?
What happens to O2 release? |
Decreases Hb affinity (increase P50) for O2
**Bohr effect O2 is now more easily released **particularly in areas of high CO2 partial pressure |
|
|
11. How is carbaminohemoglobin formed?
What is the Haldane effect? What is the Bohr effect? How are both of these effects reversed? What does both of these effects do to the delivery of O2? |
Small amounts of dissolved CO2 in RBC combines w/ NH2 groups of Hb
Deoxyhemoglobin binds more CO2 than does oxyhemoglobin Increased [H+] (low pH) increases PCO2 and the rate of dissociation of O2 from Hb increases Reversed when blood re-circulates to the pulmonary vasculature Both result in more O2 delivery to metabolizing tissues |
|
|
12. How does the partial pressure of CO2 within the alveolus compare to that of the pulmonary capillary?
As a result how does CO2 diffuse? How is the RBC affected? (three things) |
Partial pressure of CO2 w/in alveolus is less than that of pulmonary capillary
CO2 diffuses from RBC & plasma into alveolus 1. Chemical rxns w/in RBC are reversed 2. Chloride exits RBC 3. H2O exist the RBC |
|
|
13. What factors determine CO2 content of whole blood?
|
1. Partial pressure of CO2
-in lung and in the tissues 2. Hematocrit -affects amount of carboamino-Hb -affects volume of HCO3- in plasma 3. Amount of deoxyhemoglobin present |
|
|
14. How are CO2 and O2 interrelated?
|
1. Tissue metabolism
2. Respiratory quotient for a tissue 3. Blood O2 content and CO2 content 4. Effect of O2 and CO2 on dissociation curve |
|
|
15. How do the blood content of CO2 and O2 compare?
What is the Haldane effect? What is the Bohr effect? |
Blood CO2 content is always higher than O2 content for any given partial pressure
CO2 content of blood is increased in presence of deoxyghemoglobin O2 dissociation from Hb is increased as PCO2 increases & pH decreases (increased [H+]) |
|
|
16. If the pH is in the abnormal ranges how are enzyme reaction dynamics upset?
|
Hypoventilation increases CO2 content
**result in respiratory acidosis Hyperventilation decreases CO2 content **results in respiratory alkalosis |
