The component of the conduction system referred to as the ...

[chads108]

The component of the conduction system referred to as the pacemaker of the heart is the:
 
  a. Atrioventricular (AV) node.
  b. Sinoatrial (SA) node.
  c. Bundle of His.
  d. Bundle branches.

Question 2

When assessing a newborn infant who is 5 minutes old, the nurse knows which of these statements to be true?
 
  a. The left ventricle is larger and weighs more than the right ventricle.
  b. The circulation of a newborn is identical to that of an adult.
  c. Blood can flow into the left side of the heart through an opening in the atrial septum.
  d. The foramen ovale closes just minutes before birth, and the ductus arteriosus closes immediately after.

[macybarnes]

Answer to Question 1

ANS: B
Specialized cells in the SA node near the superior vena cava initiate an electrical impulse. Because the SA node has an intrinsic rhythm, it is called the pacemaker of the heart.

Answer to Question 2

ANS: C
First, approximately two thirds of the blood is shunted through an opening in the atrial septum, the foramen ovale, into the left side of the heart, where it is pumped out through the aorta. The foramen ovale closes within the first hour after birth because the pressure in the right side of the heart is now lower than in the left side.