Cardiac Muscle Physiology

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What happens at 0mV in terms of ion channels?

Both Ca++ and K+ channels close

Ca++ channels close and K+ channels open (correct)

Ca++ channels open and K+ channels close

Both Ca++ and K+ channels open

What slows down the repolarization phase by allowing for the plateau in cardiac action potentials?

Cl- ions

Ca++ ions (correct)

Na+ ions

K+ ions

If the SA node were not under endocrine control, how many times per minute would it fire based on the text?

Less than 10 times per minute

Over 150 times per minute

80 - 100 times per minute (correct)

20 - 30 times per minute

Which part of the heart's conduction system would fire at the slowest rate according to the text?

Purkinje fibers Signup and view all the answers

What is another name for an Electrocardiogram (ECG)?

Electrocardiograph Signup and view all the answers

What is the sound heard when the atrioventricular valves close?

S1 Signup and view all the answers

Which phase of the cardiac cycle does S2 represent?

Opening of semilunar valves Signup and view all the answers

What does S4 indicate about the heart?

Failure of left ventricle Signup and view all the answers

What is the formula for Cardiac Output (CO)?

CO = SV * HR Signup and view all the answers

What does the ejection fraction represent?

Percentage of blood pumped Signup and view all the answers

What is the function of the atria in the heart?

Collect blood and push it into lower chambers Signup and view all the answers

Where is the base of the heart located?

Superior and medial to the apex Signup and view all the answers

Which chamber of the heart connects to the pulmonary trunk?

Right ventricle Signup and view all the answers

Which artery carries deoxygenated blood in the heart?

Pulmonary artery Signup and view all the answers

What is the role of the myocardium in the heart?

Middle thickest layer with muscle cells, nerve fibers, and blood vessels Signup and view all the answers

Which layer of the heart produces lubricating fluid?

Epicardium Signup and view all the answers

What is the main purpose of AED's in the context of cardiac issues?

To deliver electrical impulses for effective heart contractions Signup and view all the answers

During which phase of the cardiac cycle does diastole occur?

When the chambers are relaxed and filling with blood Signup and view all the answers

What is the significance of the T wave in the context of cardiac muscle metabolism?

Represents repolarization of the ventricles Signup and view all the answers

What is the role of myoglobin in heart cells?

Stores oxygen in muscle cells Signup and view all the answers

Which phase of the cardiac cycle involves the semilunar valves being closed while blood flows into the atria and ventricles?

Atrial diastole Signup and view all the answers

What is the amount of blood pushed out by the ventricles known as?

Stroke volume Signup and view all the answers

What is the main function of the endothelium in the heart?

Regulating growth patterns of cardiac muscle cells Signup and view all the answers

Which structure in the heart separates the atria from the ventricles?

Septum Signup and view all the answers

What is the function of the moderator band in the heart?

Aid in cardiac conduction Signup and view all the answers

What is the primary role of semilunar valves in the heart?

Ensure unidirectional blood flow Signup and view all the answers

During which phase does the left ventricle of the heart receive oxygenated blood?

Contractile phase Signup and view all the answers

What is the function of desmosomes in cardiac muscle cells?

Prevent cardiac muscle cells from separating during contraction Signup and view all the answers

Where is the Sinoatrial (SA) node located in the heart?

Superior and posterior wall of the right atrium Signup and view all the answers

What is the role of Purkinje fibers in cardiac conduction?

Spread the impulse around the ventricles Signup and view all the answers