Heart Structure and Function
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Questions and Answers

What is the primary function of the heart?

  • To pump blood throughout the body (correct)
  • To produce electrical signals
  • To filter blood and remove waste
  • To facilitate gas exchange in the lungs

Which of the following structures prevents blood from flowing backward into the left ventricle?

  • Bicuspid valve
  • Pulmonary vein
  • Aortic semilunar valve (correct)
  • Coronary artery

What is the sequence of the cardiac cycle?

  • Atria fill, ventricles contract, blood leaves heart (correct)
  • Ventricles contract, atria relax, blood returns to heart
  • Atria contract, ventricles relax, blood flows in
  • Ventricles contract, atria empty, valves close

Which part of the heart serves as the primary pacemaker?

<p>Sinoatrial (SA) node (C)</p> Signup and view all the answers

What happens during the diastole phase of the cardiac cycle?

<p>Atria fill with blood and ventricles relax (A)</p> Signup and view all the answers

What is the role of the coronary arteries?

<p>To provide blood supply to the heart muscle (D)</p> Signup and view all the answers

What sound is produced by the closing of the atrioventricular valves?

<p>Lup (D)</p> Signup and view all the answers

What can a blockage in the coronary arteries lead to?

<p>Myocardial infarction (A)</p> Signup and view all the answers

What is the role of the Purkinje fibers in the heart?

<p>To conduct electrical impulses to the ventricles (C)</p> Signup and view all the answers

Which layer of the heart is responsible for muscle contraction?

<p>Myocardium (D)</p> Signup and view all the answers

What is the main function of the right atrium in the heart?

<p>To receive deoxygenated blood from the superior and inferior vena cavae (A)</p> Signup and view all the answers

Why is the wall of the right side of the heart thinner than the left side?

<p>It pumps blood to the lungs, which are closer to the heart (B)</p> Signup and view all the answers

What is the role of the tricuspid valve in the heart?

<p>To prevent backflow of blood from the right ventricle to the right atrium (B)</p> Signup and view all the answers

Which structure receives deoxygenated blood from the heart itself?

<p>Coronary sinus (B)</p> Signup and view all the answers

What is unique about the heart's muscle structure?

<p>It is asymmetrical to accommodate different pumping distances (B)</p> Signup and view all the answers

How does blood flow from the right ventricle to the lungs?

<p>Via the pulmonary arteries without passing through a valve (D)</p> Signup and view all the answers

Which valve is located on the left side of the heart?

<p>Bicuspid (mitral) valve (D)</p> Signup and view all the answers

What happens to prevent blood from flowing back into the right ventricle after passing through the pulmonary arteries?

<p>The right semilunar valve closes (A)</p> Signup and view all the answers

What is the size of an average human heart?

<p>About the size of a clenched fist (B)</p> Signup and view all the answers

What is the primary division of the circulatory system associated with the heart's function?

<p>Pulmonary and systemic circuits (C)</p> Signup and view all the answers

What is the main distinction between the right and left sides of the heart?

<p>The left side is larger and pumps blood to the entire body. (B)</p> Signup and view all the answers

What type of blood does the right atrium receive?

<p>Deoxygenated blood from the systemic circulation. (B)</p> Signup and view all the answers

Why is the wall of the right ventricle thinner than the left ventricle?

<p>It needs to generate low pressure to pump blood to the lungs. (A)</p> Signup and view all the answers

What is the function of the tricuspid valve in the heart?

<p>To prevent backflow of blood into the right atrium. (B)</p> Signup and view all the answers

What distinguishes coronary circulation from the pulmonary and systemic circulation?

<p>It does not involve oxygen exchange. (C)</p> Signup and view all the answers

What is the flow of blood after it passes through the right ventricle?

<p>To the pulmonary arteries for re-oxygenation. (C)</p> Signup and view all the answers

Which set of structures increases the efficiency of blood flow in the heart?

<p>Valves and chambers. (C)</p> Signup and view all the answers

How does the structure of the heart reflect its function?

<p>The asymmetrical muscle structure allows for different pressures in pulmonary and systemic circulation. (D)</p> Signup and view all the answers

What feature helps prevent the backflow of blood after leaving the right ventricle?

<p>The semilunar valve. (D)</p> Signup and view all the answers

What causes the heartbeat to initiate?

<p>Spontaneous pulses from the sinoatrial node (A)</p> Signup and view all the answers

Which layer of the heart is primarily responsible for pumping blood?

<p>Myocardium (B)</p> Signup and view all the answers

What is the primary role of the coronary veins?

<p>Carry deoxygenated blood back to the right atrium (A)</p> Signup and view all the answers

What is characteristic of cardiomyocytes compared to other muscle cells?

<p>They beat rhythmically and involuntarily (B)</p> Signup and view all the answers

Which heart condition is caused by the complete blockage of the coronary arteries?

<p>Myocardial infarction (D)</p> Signup and view all the answers

What is the function of the aortic semilunar valve?

<p>Prevent blood from flowing back into the left ventricle (D)</p> Signup and view all the answers

During which phase of the cardiac cycle do the ventricles contract?

<p>Systole (B)</p> Signup and view all the answers

What sound is produced by the closing of the semilunar valves?

<p>Dupp (D)</p> Signup and view all the answers

How does the electrical impulse travel from the AV node to the ventricles?

<p>Via the bundle of His and Purkinje fibers (C)</p> Signup and view all the answers

What is a key function of the pericardium?

<p>Allow for free movement of the heart while preventing friction (B)</p> Signup and view all the answers

Flashcards

Coronary Circulation

The system of blood vessels that deliver blood to the heart muscle.

Pulmonary Circulation

The system of blood vessels that transport blood between the heart and lungs, responsible for oxygenating blood.

Systemic Circulation

The system of blood vessels that transport blood from the heart to the rest of the body, delivering oxygenated blood and nutrients.

Left Ventricle Thickness

The left ventricle pumps blood to the rest of the body in the systemic circulation, requiring more pressure and a thicker muscle wall.

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Right Ventricle Thickness

The right ventricle pumps blood to the lungs in the pulmonary circulation, which is a shorter distance, requiring less pressure.

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Atria

Two chambers of the heart responsible for receiving blood.

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Ventricles

Two chambers of the heart responsible for pumping blood out.

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Tricuspid Valve

Valve separating the right atrium and right ventricle. It prevents blood from flowing back into the atrium.

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Bicuspid (Mitral) Valve

Valve separating the left atrium and left ventricle. It prevents blood from flowing back into the atrium.

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Pulmonary Valve (Semilunar Valve)

Valve located between the right ventricle and the pulmonary artery. It prevents blood from flowing back into the ventricle.

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Cardiac Cycle

In the heart, the process of the chambers filling and emptying with blood, controlled by electrical impulses that cause the heart muscle to contract and relax.

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Epicardium

The outer layer of the heart, composed of a membranous layer called the pericardium, which protects and surrounds the heart.

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Myocardium

The middle layer of the heart, composed of the heart muscle cells (cardiomyocytes) responsible for the heart's pumping action.

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Endocardium

The inner layer of the heart, lining the chambers and valves.

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Bicuspid Valve (Mitral Valve)

The valve between the left atrium and left ventricle, responsible for preventing backflow of blood into the atrium during ventricular contraction.

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Aortic Semilunar Valve (Aortic Valve)

The valve between the left ventricle and the aorta, preventing backflow of blood into the ventricle after it's pumped out.

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Intercalated Disks

The special junction between cardiac muscle cells that allow for rapid and coordinated electrical and mechanical communication.

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Sinoatrial (SA) Node

The natural pacemaker of the heart, located in the right atrium, responsible for initiating the electrical impulses that control heartbeat.

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Atrioventricular (AV) Node

The node located between the atria and ventricles, responsible for delaying the electrical impulse to allow the atria to fully empty before the ventricles contract.

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Electrocardiogram (ECG)

A recording of the electrical activity of the heart, showing the electrical impulses that control its contractions and relaxations.

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Right Ventricle Size

The right ventricle is smaller and thinner because it pumps blood only to the lungs (short distance).

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Left Ventricle Size

The left ventricle is thicker and stronger because it pumps blood to the entire body (long distance).

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Atria (plural)

Chambers of the heart that receive blood from the body or lungs.

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Ventricles (plural)

Chambers of the heart that pump blood out to the body or lungs.

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Pulmonary Valve

Valve located between the right ventricle and the pulmonary artery, preventing backflow of blood.

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What regulates the heart's rhythm?

The heart's rhythmic beating is regulated by its internal pacemaker, known as the sinoatrial (SA) node. This node initiates electrical impulses that spread through the heart, causing the chambers to contract in a coordinated manner.

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Explain the cardiac cycle.

The heart's four chambers work together in a coordinated sequence called the cardiac cycle. During this cycle, the heart contracts (systole), pushing blood out, followed by relaxation (diastole), where the heart fills with blood.

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Describe the layers of the heart.

The heart is made up of three layers: the epicardium (outermost), the myocardium (middle layer containing heart muscle cells), and the endocardium (inner lining).

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How does the heart get its own blood supply?

The heart requires a constant supply of oxygen-rich blood to function. This is provided by the coronary arteries, which branch off the aorta and encircle the outer surface of the heart.

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What is atherosclerosis and how does it affect the heart?

A condition called atherosclerosis occurs when fatty plaques build up in the arteries, narrowing them and restricting blood flow. This can severely affect the coronary arteries, potentially leading to heart attack.

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What is an electrocardiogram (ECG)?

When the heart's electrical impulses are measured on the skin, the resulting recording is called an electrocardiogram (ECG). This diagnostic tool measures electrical activity, revealing how well the heart is functioning.

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What are cardiomyocytes and how are they unique?

Cardiac muscle cells, also known as cardiomyocytes, have striated features like skeletal muscle but beat rhythmically and involuntarily like smooth muscle. Their unique structure includes intercalated disks, which facilitate the rapid and coordinated communication between cells.

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Why is there a delay at the AV node?

The atrioventricular (AV) node is located between the atria and ventricles. Electrical impulses from the SA node reach the AV node, where they are briefly paused before continuing to the ventricles. This delay allows the atria to empty completely before the ventricles contract.

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What is the role of the left ventricle?

The left ventricle is responsible for pumping oxygenated blood to the rest of the body through the aorta. It requires more pressure and strength than the right ventricle, which pumps blood to the lungs.

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What is the function of the aortic semilunar valve?

The aortic semilunar valve (or aortic valve) is located between the left ventricle and the aorta. It prevents blood from flowing back into the ventricle when the ventricle relaxes.

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Study Notes

Heart Structure and Function

  • The heart pumps blood through three circuits: coronary (heart's own vessels), pulmonary (heart to lungs), and systemic (heart to body). Coronary circulation receives blood directly from the aorta.
  • The right ventricle pumps blood to the lungs, a shorter distance, hence a thinner wall compared to the left ventricle needing higher pressure to circulate blood to the entire body. This asymmetry stems from the varied distances blood must travel in the respective circuits.
  • The heart is roughly fist-sized and divided into four chambers (two atria, two ventricles).
  • Atria receive blood; ventricles pump blood.
  • The right atrium receives deoxygenated blood from the superior and inferior vena cava (from body) and coronary sinus (from heart). This includes blood from the jugular vein (brain), arm veins, and veins from lower organs/legs (inferior vena cava).
  • Deoxygenated blood passes through the tricuspid valve to the right ventricle.
  • The right ventricle pumps blood to the lungs via pulmonary arteries (past pulmonic valve) to receive re-oxygenation.
  • Lungs re-oxygenate blood, and it returns to the left atrium via pulmonary veins.
  • Oxygenated blood passes through the mitral (bicuspid) valve to the left ventricle.
  • The left ventricle pumps blood to the body via the aorta (past aortic valve).

Heart Valves

  • Valves ensure one-way blood flow.
  • Tricuspid valve (right side): prevents backflow from the right ventricle to the right atrium.
  • Mitral/bicuspid valve (left side): prevents backflow from the left ventricle to the left atrium.
  • Pulmonary valve (right side): prevents backflow from the pulmonary artery to the right ventricle. Closing prevents backflow into the Right ventricle.
  • Aortic valve (left side): prevents backflow from the aorta to the left ventricle. Closing prevents backflow into the left ventricle.

Heart Wall Structure

  • The heart wall has three layers: epicardium (outer), myocardium (middle, muscle), and endocardium (inner).
  • Epicardium is a membranous layer (pericardium) that protects, reduces friction, and allows for vigorous pumping while keeping the heart in place.
  • Myocardium is the heart muscle tissue.
  • Endocardium lines the inner chambers.

Coronary Circulation

  • Coronary arteries supply blood to the heart muscle.
  • Coronary arteries branch from the aorta, forming a network of capillaries for oxygen supply.
  • Coronary veins collect deoxygenated blood and return it to the right atrium.
  • Heart muscle needs a constant blood supply to avoid death.
  • Atherosclerosis (build-up of fatty plaques in coronary arteries) can cause reduced blood flow (angina) or complete blockage (heart attack/myocardial infarction).

Cardiac Cycle

  • The heart's repeating pumping sequence is the cardiac cycle.
  • The cycle involves the coordination of filling and emptying heart chambers using electrical signals.
  • Heart contracts (systole) to pump; relaxes (diastole) to fill with blood.
  • Atrial contraction forces blood into ventricles. Closing of atrioventricular valves makes the "lub" sound.
  • Ventricular contraction forces blood into the aorta and pulmonary artery. Closing of semilunar valves makes the "dub" sound.
  • Heart beats over 100,000 times a day.

Heart Muscle and Electrical System

  • Cardiomyocytes (heart muscle cells) are striated and involuntary.
  • Connected by intercalated disks.
  • Self-stimulation.
  • Electrical signals regulate contractions through the heart's internal pacemaker.
  • Sinoatrial (SA) node is the heart's natural pacemaker.
  • Electrical signals through the SA node, AV node, bundle of His, bundle branches, and Purkinje fibers coordinate contraction. The AV node introduces a delay allowing the atria to fully empty before contraction.
  • Electrocardiogram (ECG) measures electrical activity in the heart.

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Description

Explore the anatomy and physiology of the heart in this quiz. Learn about the heart's chambers, blood circulation, and the roles of the atria and ventricles. Test your knowledge on how the heart pumps blood through various circuits.

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