List and describe the steps in coordinating the heartbeat/ describe how the electrical signal moves through the heart to control heartbeat rates.

1.    List and describe the steps in coordinating the heartbeat/ describe how the electrical signal moves through the heart to control heartbeat rates. 

2.    Why is it essential that there is a delay between activation of the sinoatrial node and activation of the atrioventricular node. 


3.    What is the lumen of a blood vessel? How about the endothelium? 


4.    Complete the following sentence about exchange in the capillaries. At the arteriole end of the capillary bed there is a net transport of materials (into/ out of <— select one) the capillaries, and toward the venule end there is a net transport of materials (into/ out of <— select one) the capillaries. 

5.    What forces drive the direction of transport at the arteriole and venule ends of the capillary bed? 


6.    What is the composition of blood? What is plasma? What is the function of white blood cells (leukocytes)? What is the function of erythrocytes? (Also what are erythrocytes?) What is the function of platelets? 


7.    How do partial pressures of oxygen and CO2 vary around the body and how does this affect exchange (i.e.) direction of movement of gases in different parts of the body (lung capillary beds vs. systemic capillary beds) 


8.    From the list in question 11, know which of those structures would contain deoxygenated blood and which would contain oxygenated blood. 


9.    Briefly describe the structure of hemoglobin. What metal is found in the center of the heme group in hemoglobin? 


10. When O2 binds to one subunit of hemoglobin, it causes the others to change shape slightly, which increases their affinity for O2. What does it mean to say that the affinity for O2 has increased? When 4 O2 molecules are bound and one subunit unloads its O2 this causes the other 3 to change shape and unload more readily by lowering the affinity for O2. What does it mean to say that the affinity for O2 has decreased? 


11. Why is the oxygen dissociation curve for hemoglobin sigmoidal in shape rather than a gradually increasing straight line? Make sure you feel comfortable reading those diagrams. 


12. Would you expect fetal or maternal hemoglobin to have a higher affinity for oxygen? 

13. How does pH influence the binding or release of oxygen from hemoglobin? Why is this effect of pH useful for the body? 

14. How is carbon dioxide transported through the blood? (Which forms does it take?)