Oxygen is added to blood as it flows through the ________ circuit.

Which one of the following blood vessels carries oxygenated blood:

If the pacemaker cells in the SA note become more permeable to potassium ions, the

In response to hemorrhage, there is

The pulmonary arteries carry blood to the

An increased firing of the parasympathetic nervous system causes increased cardiac output.

Figure 20-2 Cardiac Cycle Use Figure 20-2 to answer the following questions: What occurs at the area labeled “B” on the graph?

The mitral valve is normally closed:

The _____ _____ normally establish the rate of contraction

Generalized vasoconstriction occurs as a result of: