Cardiac Physiology Review

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Questions and Answers

During which phase of the cardiac action potential does the cell membrane return to its resting potential?

Hyperpolarization
Repolarization (correct)
Automaticity
Depolarization

What is the primary role of intercalated discs in myocardial cells?

To anchor the actin and myosin filaments, enabling force generation during contraction.
To store calcium ions necessary for muscle contraction.
To facilitate rapid electrical communication between cells, allowing the heart to contract as a coordinated unit. (correct)
To provide structural support and prevent overstretching of muscle fibers.

Which component of the troponin complex binds to calcium ions, initiating the process of myocardial contraction?

Troponin T
Tropomyosin
Troponin C (correct)
Troponin I

How do sympathetic nerves influence heart action?

By increasing heart rate and contractility through the release of norepinephrine. (B) Signup and view all the answers

What is the significance of L-type calcium channels in myocardial contraction?

They regulate the influx of calcium into myocardial cells during the plateau phase of the action potential, which is crucial for excitation-contraction coupling. (B) Signup and view all the answers

Assuming normal cardiac function, which pressure gradient would be most indicative of healthy ventricular filling during diastole?

Right atrial pressure of 10 mm Hg, right ventricular end-diastolic pressure of 2 mm Hg (B) Signup and view all the answers

A patient's cardiac catheterization reveals a pressure of 20 mm Hg in the right ventricle during systole. According to normal values, this finding suggests:

Normal right ventricular systolic function (A) Signup and view all the answers

Following a myocardial infarction in the inferior wall of the heart, which coronary artery is most likely to be affected?

Right coronary artery (C) Signup and view all the answers

Which of the following accurately describes the function of the left heart?

Pumping blood through the body's systemic circulation. (D) Signup and view all the answers

Which sequence accurately describes the path of an electrical impulse through the heart's conduction system?

SA node → AV node → Bundle of His → Bundle branches → Purkinje fibers (D) Signup and view all the answers

If a patient's ECG shows signs of impaired conduction through the Bundle of His, which of the following would be the most likely consequence?

Delayed or uncoordinated ventricular contraction (B) Signup and view all the answers

A patient is diagnosed with pericarditis. Which layer of the heart is directly affected by this condition?

Epicardium. (A) Signup and view all the answers

During which phase of the cardiac cycle do the ventricles fill with blood?

Diastole (C) Signup and view all the answers

Which valve prevents backflow of blood from the aorta into the left ventricle?

Aortic semilunar valve (A) Signup and view all the answers

A cardiologist is examining a patient with mitral valve prolapse. Which of the heart's chambers is directly affected by the malfunctioning of this valve?

Left atrium & left ventricle (B) Signup and view all the answers

Following a car accident, a patient experiences trauma to the mediastinum. Which organ is most likely to be directly affected?

Heart (A) Signup and view all the answers

Deoxygenated blood enters the heart through which of the following?

Venae cavae (D) Signup and view all the answers

The Right ventricle pumps blood into which of the following?

Pulmonary artery (B) Signup and view all the answers

According to Starling's law of the heart, what is the relationship between preload and stroke volume?

Stroke volume is directly proportional to preload, up to a physiological limit. (C) Signup and view all the answers

A patient's end-diastolic volume has increased significantly. Which of the following best describes the direct effect of this increase on cardiac performance?

Increased preload, leading to a potentially stronger contraction. (D) Signup and view all the answers

If a drug increases myocardial contractility without changing preload or afterload, what is the most likely effect on stroke volume?

Stroke volume will increase. (B) Signup and view all the answers

A patient is diagnosed with increased systemic vascular resistance. What will be the effect on the heart?

Left ventricle will be required to pump harder. (A) Signup and view all the answers

Which of the following changes would increase resistance to blood flow, according to Poiseuille’s law?

Decreased blood vessel diameter. (D) Signup and view all the answers

What is the primary function of baroreceptors in the circulatory system?

Monitor blood pressure and signal the cardiovascular center. (C) Signup and view all the answers

In a healthy individual at rest, which type of blood flow is most commonly observed in large arteries?

Laminar flow (C) Signup and view all the answers

How do arterial chemoreceptors primarily influence cardiovascular function?

By detecting changes in blood pH, $CO_2$, and $O_2$ levels and influencing ventilation and vasomotor tone. (C) Signup and view all the answers

What is the primary function of the right heart?

Pumping blood through the pulmonary circulation. (B) Signup and view all the answers

Which layer of the heart wall is primarily responsible for the heart's contractile function?

Myocardium (A) Signup and view all the answers

What is the role of the pericardial fluid?

To lubricate the surfaces of the pericardium, reducing friction. (A) Signup and view all the answers

Which valves prevent backflow of blood from the ventricles into the atria?

Atrioventricular valves (C) Signup and view all the answers

What is the destination of blood that passes through the pulmonic semilunar valve?

Pulmonary artery (D) Signup and view all the answers

Which great vessel carries oxygenated blood from the lungs to the heart?

Pulmonary veins (C) Signup and view all the answers

During which phase of the cardiac cycle do the ventricles contract, ejecting blood into the pulmonary artery and aorta?

Systole (D) Signup and view all the answers

Why is the left ventricle more muscular than the right ventricle?

The left ventricle pumps blood through the systemic circulation at higher pressure. (A) Signup and view all the answers

A patient's cardiac catheterization reveals a right atrial pressure of 10 mm Hg. Based on the provided pressure ranges, what condition might this indicate?

Elevated right atrial pressure, potentially indicating a cardiovascular issue. (D) Signup and view all the answers

Following a blockage in the circumflex artery, which area of the heart is MOST likely to experience ischemia?

Posterior wall of the left ventricle and left atrium. (D) Signup and view all the answers

Which of the following statements BEST describes the relationship between the sinoatrial (SA) node and the atrioventricular (AV) node in normal cardiac function?

The SA node initiates the electrical impulse, which then travels to the AV node. (B) Signup and view all the answers

A patient's ECG shows a prolonged PR interval. This finding suggests a MOST LIKELY delay in the electrical impulse at which location?

Atrioventricular (AV) node. (B) Signup and view all the answers

If a patient has a significantly elevated end-diastolic volume (EDV) but a normal ejection fraction, which compensatory mechanism is MOST likely at play?

Increased contractility to maintain stroke volume despite the high EDV. (B) Signup and view all the answers

Following a period of intense exercise, the heart rate typically decreases due to increased parasympathetic activity. Which of the following mechanisms primarily mediates this effect?

Increased release of acetylcholine acting on muscarinic receptors in the sinoatrial (SA) node. (A) Signup and view all the answers

A researcher is investigating the effects of a new drug on myocardial oxygen consumption. If the drug increases both the heart rate and the afterload, which of the following is the MOST likely effect on myocardial oxygen consumption?

Myocardial oxygen consumption will increase due to increased cardiac workload. (A) Signup and view all the answers

In an experiment, cardiac muscle cells are treated with a substance that selectively blocks L-type calcium channels. Which of the following effects would be MOST expected?

Reduced influx of calcium during the plateau phase of the action potential, weakening myocardial contraction. (A) Signup and view all the answers

A patient's ECG shows a prolonged PR interval, indicating a first-degree AV block. This delay is MOST likely due to impaired conduction through which structure?

AV node. (A) Signup and view all the answers

How does the presence of intercalated discs affect the function of the heart?

They speed up the transmission of action potentials throughout the heart. (D) Signup and view all the answers

According to Laplace's Law, which of the following scenarios would result in increased ventricular wall tension?

Increased ventricular pressure and increased ventricular radius (B) Signup and view all the answers

How do arterial chemoreceptors respond to a decrease in blood oxygen levels to maintain cardiac performance?

By increasing sympathetic nervous system activity, leading to increased heart rate and vasoconstriction (A) Signup and view all the answers

A patient with hypertension has an elevated afterload. Which compensatory mechanism will the heart employ, according to Starling's law, to maintain cardiac output?

Increase myocardial contractility to enhance stroke volume (D) Signup and view all the answers

If a patient's end-systolic volume (ESV) increases while end-diastolic volume (EDV) remains constant, how is the ejection fraction affected?

Ejection fraction decreases. (B) Signup and view all the answers

Which of the following best explains the role of the tunica media in maintaining blood pressure?

It contains circularly arranged smooth muscle fibers that regulate vessel diameter. (C) Signup and view all the answers

How does laminar flow differ from turbulent flow in blood vessels, and what is its primary advantage?

Laminar flow is streamlined and orderly, reducing resistance and promoting efficient blood flow. (A) Signup and view all the answers

How do inotropic agents affect cardiac performance?

They influence myocardial contractility, altering the force of cardiac muscle contraction. (D) Signup and view all the answers

A researcher is studying the effects of different blood vessel diameters on resistance to blood flow. According to Poiseuille's law, what change in vessel radius would have the greatest impact on reducing resistance, assuming all other factors remain constant?

A doubling of the radius. (B) Signup and view all the answers

Flashcards

Cardiac Action Potential Propagation

The electrical activity sequence in the heart: resting membrane potential, depolarization, repolarization, and hyperpolarization.

Electrocardiogram (ECG/EKG)

A recording of the electrical activity of the heart over time.