Mixing of venous blood with arterial blood (a right-to-left ...

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Mixing of venous blood with arterial blood (a right-to-left shunt) occurs normally because of which of the following? 1. Congenital cardiac defects 2. Bronchial venous drainage 3. Thebesian venous drainage in the heart
 
  a. 1, 2, and 3
  b. 2 and 3 only
  c. 1 only
  d. 2 only

Question 2

Before draining into the right atrium, where do the large veins of the coronary circulation gather together?
 
  a. Coronary sinus
  b. Left posterior coronary vein
  c. Right coronary sulcus
  d. Thebesian veins

[briseldagonzales]

Answer to Question 1

ANS: B
Because the thebesian veins bypass, or shunt, around the pulmonary circulation, this phenomenon is called an anatomical shunt. When combined with a similar bypass in the bronchial circulation (see Chapter 7), these normal anatomical shunts account for approximately 2 to 3 of the total cardiac output.

Answer to Question 2

ANS: A
These veins gather together into a large vessel called the coronary sinus, which passes left to right across the posterior surface of the heart. The coronary sinus empties into the right atrium.