Cardiovascular Physiology Exam Preparation Questions

What are the circuits of the heart and how do they work together?

The heart has two main circuits: the pulmonary circuit, which carries oxygen-poor blood to the lungs for oxygenation, and the systemic circuit, which delivers oxygen-rich blood to the rest of the body.

Describe the blood flow through the heart, including major vessels, chambers, and valves.

Blood flows from the body into the right atrium via the superior and inferior vena cavae, then to the right ventricle through the tricuspid valve. It is pumped to the lungs via the pulmonary arteries. Oxygen-rich blood returns to the left atrium through the pulmonary veins, moves to the left ventricle through the mitral valve, and is pumped into the aorta.

What vessels drain into the right atrium?

The superior and inferior vena cavae.

Where does blood go from the ascending aorta?

Blood from the ascending aorta is distributed to the systemic circulation through the aortic arch and descending aorta.

Which structures carry oxygen-rich blood and which carry oxygen-poor blood?

Oxygen-rich blood is carried by the pulmonary veins and aorta; oxygen-poor blood is carried by the superior and inferior vena cavae and pulmonary arteries.

Why is the left ventricular myocardium thicker than the right ventricular myocardium?

The left ventricular myocardium is thicker because it has to generate higher pressure to pump blood throughout the systemic circulation, while the right ventricle pumps to the lungs at lower pressure.

What is the function of heart valves?

Heart valves prevent the backflow of blood and ensure unidirectional flow through the heart.

How is stretching of heart valves prevented?

Stretching is prevented by fibrous rings and chordae tendineae that anchor the valve leaflets.

What are the two major types of heart valves?

The two major types are atrioventricular valves (tricuspid and mitral) and semilunar valves (pulmonary and aortic).

What are the names of the heart valves and what do they separate?

The tricuspid valve separates the right atrium and ventricle; the mitral valve separates the left atrium and ventricle; the pulmonary valve separates the right ventricle and pulmonary artery; the aortic valve separates the left ventricle and aorta.

How is cardiac muscle organized?

Cardiac muscle is organized into striated fibers that are branched and interconnected, forming a functional syncytium.

How are cardiac muscle cells connected?

Cardiac muscle cells are connected by intercalated discs, which contain gap junctions for electrical coupling.

What is a syncytium and does the heart have it?

A syncytium is a mass of cytoplasm containing multiple nuclei, formed by the fusion of cells. The heart functions as a syncytium due to the interconnections of cardiac muscle cells.

How is energy derived in cardiac muscle?

Energy is derived primarily from aerobic metabolism, utilizing fatty acids and glucose.

What are the three major action potential phases that autorhythmic cells go through?

The three phases are depolarization, repolarization, and hyperpolarization.

What part of the conduction system is considered the pacemaker?

The sinoatrial (SA) node is considered the pacemaker of the heart.

How does the autonomic nervous system control the pacemaker?

The autonomic nervous system regulates heart rate through sympathetic stimulation (increases heart rate) and parasympathetic stimulation (decreases heart rate).

Which component of the conduction system causes atrial systole?

The sinoatrial (SA) node initiates atrial systole.

Which component of the conduction system causes ventricular systole?

The Purkinje fibers cause ventricular systole.

Where is there a delay in conduction and why?

There is a delay at the atrioventricular (AV) node to allow for complete atrial contraction before ventricular contraction.

How are contractile cells stimulated?

Contractile cells are stimulated by action potentials from the conduction system, leading to depolarization.

What is the resting membrane potential of contractile cells?

The resting membrane potential of contractile cells is approximately -90 mV.

What are the four steps to a contractile cell action potential?

The four steps are rapid depolarization, plateau phase, repolarization, and resting potential.

Describe contractile cell excitation-contraction coupling.

Excitation-contraction coupling involves the influx of calcium ions during the plateau phase, which triggers further calcium release from the sarcoplasmic reticulum, leading to muscle contraction.

What causes the first heart sound and the second heart sound?

The first heart sound (S1) is caused by the closure of the atrioventricular valves; the second heart sound (S2) is caused by the closure of the semilunar valves.

What is a cardiac cycle?

A cardiac cycle is the sequence of events in one heartbeat, including contraction and relaxation of the heart chambers.

What are the five phases of a cardiac cycle?

The five phases are atrial systole, isovolumetric contraction, ventricular systole, isovolumetric relaxation, and atrial diastole.

What is cardiac output?

Cardiac output is the volume of blood pumped by the heart per minute, calculated as heart rate multiplied by stroke volume.

What is stroke volume and what is the equation to calculate it?

Stroke volume is the amount of blood ejected by the heart in one contraction, calculated as stroke volume = end-diastolic volume (EDV) - end-systolic volume (ESV).

Define end-diastolic volume (EDV).

End-diastolic volume is the volume of blood in the ventricles at the end of diastole, just before contraction.

Define end-systolic volume (ESV).

End-systolic volume is the volume of blood remaining in the ventricles after contraction.

Define total peripheral resistance (TPR) or systemic vascular resistance.

Total peripheral resistance is the resistance to blood flow offered by all of the systemic vasculature.

What are the major factors affecting stroke volume?

Major factors include preload, afterload, and contractility.

What is the relationship between end-diastolic volume and stroke volume?

Increased end-diastolic volume typically leads to increased stroke volume due to the Frank-Starling mechanism.

What is the relationship between contractility and stroke volume?

Increased contractility leads to increased stroke volume as the heart pumps more forcefully.

What is the relationship between total peripheral resistance and stroke volume?

Increased total peripheral resistance generally decreases stroke volume, as the heart must work harder to eject blood.

What is the relationship between contractility and catecholamines?

Catecholamines (like epinephrine) increase contractility by enhancing calcium availability in cardiac muscle cells.

What is the relationship between afterload and stroke volume?

Increased afterload decreases stroke volume, as it requires more force for the heart to eject blood.

Explain the Frank-Starling law of the heart.

The Frank-Starling law states that the stroke volume of the heart increases in response to an increase in the volume of blood filling the heart (preload), up to a certain limit.

What nerve innervates the ventricular myocardium?

The vagus nerve innervates the ventricular myocardium.

What division of the autonomic nervous system is responsible for innervating the ventricular myocardium?

The parasympathetic division of the autonomic nervous system.

What major structures prevent the heart from stretching beyond its optimal limits?

The fibrous skeleton of the heart and the pericardium help prevent excessive stretching.

What is a chronotropic effect?

A chronotropic effect refers to changes in heart rate.

Define positive chronotropic effect and name the nerve responsible for sending the signal.

A positive chronotropic effect increases heart rate, primarily mediated by the sympathetic nervous system via the cardiac accelerator nerves.

What are the effectors and receptors involved in a positive chronotropic effect?

Effectors include the heart's pacemaker cells, and receptors include adrenergic receptors.

Define negative chronotropic effect and name the nerve responsible for sending the signal.

A negative chronotropic effect decreases heart rate, primarily mediated by the parasympathetic nervous system via the vagus nerve.

What are the effectors and receptors involved in a negative chronotropic effect?

Effectors include the heart's pacemaker cells, and receptors include muscarinic receptors.

How do thyroid hormones affect heart rate?

Thyroid hormones increase heart rate by enhancing the heart's sensitivity to catecholamines.

What other factors affect heart rate?

Other factors include body temperature, electrolyte levels, and physical fitness.

What form of exercise promotes cardiovascular fitness?

Aerobic exercise promotes cardiovascular fitness.

What is the minimum recommendation for aerobic exercise?

The minimum recommendation is at least 150 minutes of moderate-intensity aerobic activity per week.

What does aerobic training do for heart health?

Aerobic training improves heart efficiency, increases stroke volume, and enhances overall cardiovascular health.

What are the other benefits of regular aerobic exercise?

Other benefits include improved mood, weight management, and reduced risk of chronic diseases.

Compare the heart and stroke volume of an untrained individual to a trained individual.

A trained individual typically has a lower resting heart rate and higher stroke volume compared to an untrained individual.