Quiz- 3.1 ( The electrocardiogram)

What electrical event is occurring in the heart during the portion of the ECG tracing shown below indicated by the letter B?

ventricular repolarization

What is the function of the valve indicated by the letter B?  In other words,

why do we need to have the structure indicated by the letter B in our heart and why would our heart not work properly if this structure were removed?

it prevents blood from flowing from the left ventricle to the left atrium during ventricular systole

The structure in the heart's conducing system that transmits the electrical signal from the atria to the ventricles (through the cardiac skeleton) is called the

atrioventricular bundle (a.k.a. bundle of His)

The structure in the heart's conducting system that normally sets the heart rate is called the

sinoatrial node (a.k.a. SA node)

The structure in the heart's conducting system that slows the electrical signal so the ventricles have time to fill before they contract is called the

atrioventricular node (a.ka. AV node)

What part of the cardiac cycle is occurring during the portion of the ECG tracing shown below indicated by the letter B?

ventricular systole

The portion of the ECG tracing shown below indicated by the letter A is best described as the __________ and during this portion of the ECG tracing, the electrical signal is spreading through the ____________.

PR segment; AV node

The ECG tracing labeled A (on the top) represents was recorded from a normal healthy individual.  

What condition best describes the patient from whom the ECG tracing labeled B (on the bottom) was recorded?

second degree heart block

Recall that in PhysioEx Exercise 6, a hook was inserted through the apex of the frog's heart so that the frog's heart pulled on the hook when the heart contracted.

In these activities.

_______ was plotted on the x-axis.

_______ was plotted on the y-axis.

X: Time

Y: Tension (force)

Recall that in PhysioEx Exercise 6, a hook was inserted through the apex of the frog's heart so that the frog's heart pulled on the hook when the heart contracted.

1. In these experiments, the heart does not experience tetanus because ____________

2. It is important that the heart does not experience tetanus because _____________

1. the absolute refractory period of cardiac muscle cells is very long.

2. the heart must relax so the ventricles can fill with the volume of blood that will be pumped into arteries during the next heartbeat.

Answer each question by choosing the correct division of the autonomic nervous system (ANS).

For the Following:

Which division of the ANS has more control over heart rate when the body is resting?

parasympathetic division

- Which division of the ANS has more control over heart rate during exercise?

-Sympathetic division

Input to the heart from which division of the ANS causes heart rate to increase?

Sympathetic Division

Input to the heart from which division of the ANS causes heart rate to decrease?

Parasympathetic Division

Input from which divsion of the ANS reaches the heart via the vagus nerve?

Parasympathetic division

Excessive input to the heart from which division of the ANS can stop the heart?

Parasympathetic division

Input to the heart from which division of the ANS can cause vagal escape if the haert has stopped?

Sympathetic division

The ECG tracing labeled A (on the top) represents was recorded from a normal healthy individual.  

What condition best describes the patient from whom the ECG tracing labeled B (on the bottom) was recorded?

first degree heart block