Heart Anatomy and Circulation Quiz

Questions and Answers

What is the primary function of the pulmonary circuit?

Transport deoxygenated blood to the lungs for oxygenation. (correct)

Remove waste products from the blood.

Deliver oxygenated blood to body tissues.

Supply nutrients to cardiac muscle cells.

Which structure of the heart is responsible for separating the left atrium from the left ventricle?

Pulmonary arteries

Pulmonary semilunar valve

Aortic semilunar valve

Left AV valve (correct)

Which of the following correctly describes the flow of blood through the heart?

Pulmonary veins → left atrium → left AV valve → left ventricle. (correct)

Inferior vena cava → right atrium → pulmonary veins → lungs.

Right atrium → right AV valve → left ventricle → pulmonary arteries.

Superior vena cava → left atrium → left ventricle → aorta.

What unique characteristic of cardiac muscle cells facilitates fast communication during contraction?

Intercalated disks Signup and view all the answers

What is the primary difference between conducting cells and contractile cells in the heart?

Conducting cells initiate the heartbeat while contractile cells facilitate contraction. Signup and view all the answers

What is the role of the SA node in the cardiac conduction system?

Acts as the 'pacemaker' of the heart Signup and view all the answers

During the cardiac cycle, what occurs in the diastole phase?

Blood moves from high to low pressure areas Signup and view all the answers

Which interval on an electrocardiogram (ECG) represents the signal conduction through the AV node?

PR interval Signup and view all the answers

What describes the 'funny current' during spontaneous depolarization?

Sodium influx occurs slowly Signup and view all the answers

Which of the following correctly describes a stage of cardiac muscle contraction?

Rapid depolarization involves sodium flooding in Signup and view all the answers

What component of the cardiac conduction system follows the AV node?

Bundle of His Signup and view all the answers

What primarily causes the prolonged depolarization in contractile cardiac muscle?

Slow calcium influx through calcium channels Signup and view all the answers

Which wave on an ECG corresponds to ventricular repolarization?

T wave Signup and view all the answers

What determines whether the AV valves are open?

When the pressure in the atria is greater than the pressure in the ventricles Signup and view all the answers

Which statement is true regarding isovolumetric contraction?

Ventricular pressure is increasing with no change in volume Signup and view all the answers

What event occurs during ventricular ejection?

Semilunar valves open and blood is ejected into the aorta Signup and view all the answers

What primarily causes heart sounds during the cardiac cycle?

Blood turbulence hitting the walls of the heart Signup and view all the answers

How is cardiac output (CO) calculated?

By multiplying stroke volume by heart rate Signup and view all the answers

Which factor does NOT affect heart rate (HR)?

Cardiac output from the previous minute Signup and view all the answers

What is the formula to calculate stroke volume (SV)?

End diastolic volume minus end systolic volume Signup and view all the answers

Which of the following factors does NOT regulate stroke volume?

Heart rate, the number of beats per minute Signup and view all the answers

Study Notes

Circulatory Systems

Pulmonary Circuit: Transports deoxygenated blood to the lungs for oxygenation and CO2 removal.
Systemic Circuit: Delivers oxygenated blood and nutrients to body cells while removing waste.

Heart Structure

Pericardium: Protective sac surrounding the heart.
Myocardium: Middle layer of heart muscle with intercalated discs for connectivity and contraction.
Heart Chambers: Comprises two atria (left and right) and two ventricles (left and right), equipped with AV and semilunar valves.
Major Vessels: Includes vena cavas, pulmonary arteries, pulmonary veins, and aorta.

Blood Flow Through the Heart

Pathway: Superior/inferior vena cava → right atrium → right AV valve → right ventricle → pulmonary semilunar valve → pulmonary trunk → pulmonary arteries → lungs → pulmonary veins → left atrium → left AV valve → left ventricle → aortic semilunar valve → aorta → systemic circulation.

Cardiac Muscle Characteristics

Structure: Features intercalated discs, desmosomes, and gap junctions for efficient contraction.
Metabolism: Primarily aerobic, rich in mitochondria, and mainly fueled by fatty acids.

Conducting vs. Contractile Cells

Conducting Cells: Initiate electrical depolarization; includes SA node; characterized by spontaneous depolarization via sodium and calcium influx.
Contractile Cells: Responsible for heart muscle contraction; features a lengthy depolarization process involving rapid sodium influx, plateau phase due to calcium, and repolarization through potassium outflow.

Cardiac Conduction System

SA Node: Acts as the heart's pacemaker, generating 80-100 bpm.
AV Node: Delays ventricular contraction to allow atrial filling, maximum rate of 230 bpm.
AV Bundle, Bundle Branches, Purkinje Fibers: Conduct impulses to the apex and ventricles.

Electrocardiogram (ECG) Interpretation

P Wave: Represents atrial depolarization.
PR Interval: Indicates signal transmission through the AV node.
T Wave: Reflects ventricular repolarization.
QRS Interval: Associated with atrial repolarization and diastole duration.
Segments: PQ segment marks atrial systole; ST segment indicates ventricular systole and blood ejection.

Cardiac Cycle Phases

Systole: Refers to heart contraction and blood expulsion.
Diastole: Involves relaxation and chamber filling from high to low pressure.
Phases:
- Ventricular Filling: Occurs during diastole with AV valves open.
- Isovolumetric Contraction: Begins ventricular systole, raises pressure without volume change.
- Ventricular Ejection: Ventricular systole with semilunar valves opening at peak pressure.
- Isovolumetric Relaxation: Early diastole, low chamber pressure with closed valves.

Heart Sounds

S1 (Lub): Caused by the closing of AV valves.
S2 (Dub): Resulting from the closing of semilunar valves.

Wiggers Diagram Interpretation

ECG Events: P wave marks atrial depolarization; QRS wave corresponds to ventricular depolarization, with AV valve closure producing a heart sound.
Pressure Changes: Green line indicates pressure in the aorta; red line shows ventricular pressure drop as semilunar valves close.

Cardiac Output Calculation

Formula: CO = HR x SV, representing blood ejected per minute.
Example: CO = 70 bpm x 70 mL = 4900 mL = 4.9 L.
Regulators: Influenced by heart rate (hormonal and neural inputs) and stroke volume changes (preload, afterload, contractility).

Stroke Volume Calculation

Formula: SV = End Diastolic Volume - End Systolic Volume, measuring blood volume ejected per heartbeat.

Factors Regulating Stroke Volume

Preload: Volume of blood in the ventricles prior to contraction affects SV.
Afterload: The resistance the heart must overcome to eject blood.
Contractility: The intrinsic ability of cardiac muscle to generate force during contraction.

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Description

Test your knowledge on the structure and functions of the heart, including the distinctions between the pulmonary and systemic circuits. This quiz covers the major components of the heart's anatomy, such as the pericardium and myocardium, and their roles in circulation.