chapter 18

Compared to skeletal muscle, cardiac muscle ________.

•  

  lacks striations

  
  

•  

  has more nuclei per cell

  
  

•  

  cells are larger than skeletal muscle cells

  
  

•  

  has gap junctions that allow it to act as a functional syncytium

  
  

Heart contraction is the systole.

• True

• False

Which of the following is NOT an age-related change affecting the heart?

•  

  thinning of the valve flaps

  
  

•  

  fibrosis of cardiac muscle

  
  

• atherosclerosis

•  

  decline in cardiac reserve

  
  

Norepinephrine acts on the heart by ________.

•  

  causing a decrease in stroke volume

  
  

•  

  causing threshold to be reached more quickly

  
  

•  

  decreasing heart contractility

  
  

•  

  blocking the action of calcium

  
  

The myocardium receives its blood supply from the coronary arteries.

• True

• False

Which is NOT a vessel that brings blood directly into the right atrium?

•  

  superior vena cava

  
  

•  

  coronary sinus

  
  

•  

  pulmonary vein

  
  

•  

  inferior vena cava

  
  

Damage to the ________ causes heart block.

•  

  atrioventricular (AV) node

  
  

•  

  atrioventricular (AV) valves

  
  

•  

  atrioventricular (AV) bundle

  
  

•  

  sinoatrial (SA) node

  
  

Which chambers of the heart contain oxygenated blood?

•  

  right and left ventricles

  
  

•  

  right and left atria

  
  

•  

  right atrium and ventricle

  
  

•  

  left atrium and ventricle

  
  

Normal heart sounds are caused by which of the following events?

•  

  closure of the heart valves

  
  

•  

  opening of the heart valves

  
  

•  

  friction of blood against the chamber walls

  
  

•  

  excitation of the sinoatrial (SA) node

  
  

The semilunar valves are responsible for preventing blood flow back into the atria.

• True

•  

  False