Cardiovascular System (Exam Two) Flashcards
What is an electrocardiogram (EKG)?
Recording of the electrical activity of the heart from various views
What are the benefits of an electrocardiogram (EKG)?
- Fast
- Easy
- Painless
What are the two types of electrocardiogram (EKG)?
- 12-lead-EKG
- 18-lead-EKG
What is the cardiac conduction pathway? What affects these electrical impulses?
- Electrical impulses used to generate the heartbeat
- Affected by electrolytes (i.e. sodium, potassium, calcium, magnesium)
What is the purpose of the cardiac conduction pathway?
Stimulate the mechanical cells of the heart to contract and perfuse the body
It is vital for electrolytes to be in appropriate range for which cardiac system to run effectively?
Cardiac Electrical System/Cardiac Conduction Pathway
Name the parts of the Cardiac Conduction Pathway in order.
- Sinoatrial (SA) Node (in wall of right atrium) –>
- Interatrial Bundles –>
- Left and Right Atria begin to contract –>
- Internodal Bundles –>
- Atrioventricular (AV) Node –>
- Bundle of His –>
- Purkinje Fibers
- Right and Left Ventricles begin to contract
Where is the Sinoatrial Node (SA) located?
In the wall of the right Atrium
The rate of the Sinoatrial Node (SA) is dictated by what?
The needs of the body
Which part of the Cardiac Conduction Pathway is known as the “pacemaker” of the heart?
Sinoatrial (SA) Node
If the Sinoatrial Node fails, which part of the Cardiac Conduction Pathway will initiate a heartbeat? What is the rate?
- Atrioventricular (AV) Node
- Rate of 40 to 60 beats per minute
- The body is able to function regularly at this rate
If the Sinoatrial (SA) Node and Atrioventricular (AV) Node fails, which part of the Cardiac Conduction Pathway will initiate a heartbeat? What is the rate?
- Bundle of His (right and left)
- Rate of 20-40 beats per minute
What is the cardiac cycle? What does it consist of?
- Period from the beginning of one heartbeat to the beginning of the next
- Depolarization and repolarization
What is depolarization?
Period of contraction
What is repolarization?
Period of rest
The smallest box on an EKG represents how many millimeters/seconds?
1mm = 0.04 seconds
The largest box on an EKG represents how many millimeters/seconds?
5mm = 0.20 seconds
Within one normal cardiac cycle, there is what?
- P wave
- QRS complex
- T wave
Which wave is first in the cardiac cycle?
HINT: PQRST
P wave
What does a P wave indicate?
- The SA node is firing
- Atrial depolarization
What are the normal characteristics of a P wave?
HINT: Think of a hill
- Rounded, upright
- Occur regularly
- Should be 1 P wave for every 1 QRS complex
- Symmetrical throughout EKG
What is the PR interval? What does it identify?
- The amount of time it takes for an impulse to travel from the SA node to the AV node
- Can identify if an electrical delay is present
When do you start and finish measuring for a PR interval on an EKG?
- Begin at the peak of the P wave
- End at the trough of the QRS interval (before Q starts going in downward position)
What is the normal measurement for the PR interval?
HINT: P”R” = “Respiratory Rate”
0.12 - 0.20 seconds









