11.04 - Heart Part 2: Crash Course

What is the primary function of CPR during cardiac arrest?

• To provide electrical stimulation to the heart

• To circulate oxygenated blood until help arrives

• To correct fibrillation

• To restart the heart immediately

What do defibrillators do to the heart?

• Provide oxygen to the heart cells

• Stop the heart to reset its rhythm

• Increase the heart rate

• Stimulate the heart to beat faster

What percentage of a cardiac cell is made up of mitochondria?

• 40 to 50 percent

• 25 to 35 percent

• 5 to 10 percent

• 10 to 15 percent

What is the role of pacemaker cells in the heart?

• To absorb excess sodium ions

• To filter blood before it is pumped

• To generate their own electrical impulses

• To pump blood throughout the body

How are cardiac cells different from skeletal muscle cells?

• Cardiac cells have multiple nuclei

• Cardiac cells do not use sliding filaments to contract

• Cardiac cells are interconnected and branched

• Cardiac cells are not striated

What triggers the action potentials in pacemaker cells?

• Neighboring cell activity

• Direct electrical shocks

• Leaky sodium and potassium channels

• External stimuli

Where are the pacemaker cells that control the heart rate located?

• In the Purkinje fibers

• In the left ventricle

• In the atrioventricular node

• In the sinoatrial node

What is the purpose of the delay at the atrioventricular node?

• To allow the ventricles to contract first

• To increase the heart rate

• To ensure the atria finish contracting before the ventricles contract

• To decrease blood pressure

What is fibrillation in the context of heart function?

• A normal heart rhythm

• A type of heart valve

• An out-of-sync heart rhythm leading to ineffective contractions

• The process of the heart pumping blood

How long does the entire process from the SA node firing to the last of the ventricular cells contracting take?

• About 100 milliseconds

• About 220 milliseconds

• About 350 milliseconds

• About 500 milliseconds