Cardiovascular System

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If the pulmonary artery is blocked, which chamber of the heart will initially experience increased blood volume?

Left ventricle
Right ventricle (correct)
Left atrium
Right atrium

What is the correct sequence of blood flow through the heart's chambers and associated vessels?

Left atrium → pulmonary artery → left ventricle → aorta
Right atrium → pulmonary veins → right ventricle → pulmonary artery
Right atrium → right ventricle → pulmonary artery → pulmonary veins (correct)
Left ventricle → aorta → right atrium → vena cava

Which event directly follows the delivery of blood from the pulmonary veins?

Passage of blood into the aorta.
Oxygenation of the blood in the lungs.
Filling of the left atrium. (correct)
Contraction of the right ventricle.

If a patient has a damaged mitral valve (bicuspid valve), which of the following symptoms is most likely to occur?

Backflow of blood from the left ventricle to the left atrium. (B) Signup and view all the answers

What is the role of the vena cava in the cardiovascular system?

To deliver deoxygenated blood from the body to the right atrium. (C) Signup and view all the answers

According to the Frank-Starling principle, what effect would an increased end-diastolic volume (EDV) have on the stroke volume (SV), assuming other factors remain constant?

SV would increase due to more forceful contraction. (A) Signup and view all the answers

If a patient's afterload increases due to hypertension, how would this most likely affect their end-systolic volume (ESV) and stroke volume (SV)?

ESV would increase, and SV would decrease. (B) Signup and view all the answers

Which of the following scenarios would lead to a decrease in stroke volume?

Increased arterial blood pressure, increasing afterload. (A) Signup and view all the answers

A patient has an EDV of 120 ml and an ESV of 50 ml. If their heart rate is 70 beats per minute, what is their cardiac output?

4.9 L/min (C) Signup and view all the answers

How do changes in calcium levels typically affect contractility, and consequently, stroke volume?

Increased calcium levels increase contractility, which increases stroke volume. (D) Signup and view all the answers

During the plateau phase of a cardiac muscle cell action potential, which of the following ionic movements is primarily responsible for maintaining the prolonged depolarization?

Influx of calcium ions and efflux of potassium ions. (B) Signup and view all the answers

What is the primary reason the sinoatrial (SA) node initiates the heart's rhythmic contractions?

It has the fastest inherent rate of spontaneous depolarization. (A) Signup and view all the answers

Which of the following is a key difference between the action potential of a cardiac contractile cell and a neuron?

Cardiac action potentials have a longer duration due to calcium influx. (B) Signup and view all the answers

What is the role of the AV node delay in the cardiac cycle?

To allow sufficient time for atrial contraction and ventricular filling. (C) Signup and view all the answers

During which phase of the cardiac muscle action potential are voltage-gated potassium channels primarily responsible for repolarization?

Final repolarization (B) Signup and view all the answers

What would be the most likely effect of a drug that selectively blocks voltage-gated calcium channels in cardiac muscle cells?

Reduced force of contraction. (C) Signup and view all the answers

Which of the following best describes the prepotential observed in nodal cells of the heart?

A gradual depolarization toward threshold, leading to spontaneous action potentials. (B) Signup and view all the answers

If the internodal pathways between the SA and AV nodes were damaged, what would be the most likely consequence?

The timing between atrial and ventricular contractions would be disrupted. (B) Signup and view all the answers

Why is it important that the cardiac muscle has a relatively long refractory period?

To prevent tetanus and ensure alternating periods of contraction and relaxation. (D) Signup and view all the answers

During early repolarization and the plateau phase of a cardiac action potential, what is the state of the voltage-gated sodium channels?

Closed and inactivated (C) Signup and view all the answers

If the SA node's intrinsic firing rate is 80-100 action potentials per minute, why is the typical resting heart rate lower than this range?

Parasympathetic nervous system influence slows the SA node firing rate. (C) Signup and view all the answers

What does the QRS complex on an ECG represent?

Ventricular depolarization and atrial repolarization (C) Signup and view all the answers

During which phase of the cardiac cycle are all four heart valves closed, and ventricular pressure is increasing?

Isovolumetric contraction (C) Signup and view all the answers

Which of the following best describes the movement of blood during ventricular diastole?

Blood flows from the atria to the ventricles as the AV valves open passively. (D) Signup and view all the answers

The first heart sound (S1), often described as 'Lubb', is caused by what?

The recoil of blood against the closing AV valves at the start of ventricular systole. (D) Signup and view all the answers

What is the direct effect of increased resistance in blood vessels on blood flow, assuming pressure remains constant?

Decreased blood flow (B) Signup and view all the answers

How does a defibrillator work to restore a normal heart rhythm?

By delivering an electrical shock that briefly stops the heart, allowing the SA node to resume normal pacing. (A) Signup and view all the answers

During which specific phase of the cardiac cycle does isovolumetric relaxation occur?

Ventricular Diastole (C) Signup and view all the answers

If a patient's ECG shows an absent or abnormal P wave, which of the following is the most likely interpretation?

The atria are not depolarizing correctly. (D) Signup and view all the answers

In a healthy individual, which of the following has the greatest effect on blood flow?

Local changes in vessel diameter (D) Signup and view all the answers

Right Atrium

Deoxygenated blood enters here from the body via the superior and inferior vena cava.

Right Ventricle

Receives deoxygenated blood from the right atrium and pumps it to the lungs via the pulmonary arteries.