Solutions
A first-degree block is caused by __________. Correct Answers
delay of the action potential between the SA and subendocardial
conducting network (Purkinje fibers)
Action potentials received directly from the __________
stimulate the papillary muscles to contract, allowing for the
proper __________ of the AV valves. Correct Answers
subendocardial conducting network (Purkinje fibers); closing
An ECG tracing from someone with a third-degree AV block is
best described as a tracing with a __________. Correct Answers
2:1 ratio of P waves to QRS complexes
An individual with high blood pressure (hypertension) is
expected to benefit from the administration of __________
inotropic drugs that __________ the hearts workload. Correct
Answers negative; decrease
An instrument called the electrocardiograph ____________
these signals and produces a record on a moving paper chart.
Correct Answers Amplifies
As exercise progresses, muscular activity __________ venous
return. This increases the __________ on the right ventricle.
Correct Answers increases; period
Classify the following images into the phase of the cardiac cycle
they represent. Correct Answers
, Classify whether each given factor would increase or decrease
heart rate. Correct Answers Increased: Cutting the vagus nerve,
exercise, sympathetic stimulation, psychological stress
Decreased: Vagal tone, SA node damage, bundle branch block,
calcium channel blockers
Complete each sentence by dragging the labels to the
appropriate blanks. Then place each sentence in a logical order
beginning with blood entering the right side of the heart.
Correct Answers 1. The contraction of the heart begins with
autorhythmic depolarization of the sinuatrial node located in the
superior portion of the posterior atrial wall.
2. From the pacemaker, the wave of depolarization disperses
through the myocardium of the atria.
3. Depolarization then arrives at the atrioventricular node
located in the inferior interatrial septum.
4. The AV node fires causing the signal to travel into the AV
bundle branches as it passes through the interventricular septum.
5. Making a U-turn at the apex of the heart, the signals are then
carried by the subendocardial conducting network through the
exterior walls of the ventricles.
Complete each sentence by dragging the labels to the
appropriate blanks. Then place each sentence in a logical order
beginning with cardiomyocytes in a resting state. Correct