Heart and Conduction Flashcards

Flashcards about the heart and circulatory system

What is the typical size of the heart and how does it differ between males and females?

About the size of a large fist, with males having slightly larger hearts (280-340 grams) than females (230-280 grams).

What is the primary function of the heart?

Pumping blood to the lungs and around the body.

What type of muscle is the heart made of?

Cardiac muscle or myocardium.

What is the difference in function between the right and left sides of the heart?

The right heart pumps deoxygenated blood to the lungs, while the left heart pumps oxygenated blood to the rest of the body.

What are the four chambers of the heart?

Left and right atria and left and right ventricles.

How many valves separate the heart chambers?

Four valves.

What is the protective covering surrounding the heart?

Pericardium.

What are the two layers of the pericardium?

Fibrous pericardium and serous pericardium, with fluid in between to reduce friction.

What is the myocardium?

The muscular wall of the heart, forming the atria and ventricles.

Is the myocardium under voluntary or involuntary control?

Involuntary.

What is the endocardium?

The innermost lining of the heart chambers and valves, made of simple squamous endothelium.

Where is the heart located?

Located within the thoracic cavity in the anterior portion of the mediastinum, just left of center, within the pericardial sac.

Describe the location of the base and apex of the heart.

The apex is at the bottom (around the fifth intercostal space) and the base is at the top (around the third costal cartilage).

What is the approximate height of the heart?

About 12.5 centimeters.

What is the role of the right atrium?

The right atrium receives deoxygenated blood from the superior and inferior vena cava and pumps it to the right ventricle.

What is the role of the right ventricle?

The right ventricle receives deoxygenated blood from the right atrium and pumps it to the pulmonary artery to the lungs.

What is the role of the left atrium?

The left atrium receives oxygenated blood from the pulmonary veins and pumps it to the left ventricle.

What is the role of the left ventricle?

The left ventricle receives oxygenated blood from the left atrium and pumps it into the aorta to the rest of the body.

What is the function of the superior vena cava?

Drains blood from the head, neck, and arms into the right atrium.

What is the function of the inferior vena cava?

Drains blood from the chest down (abdomen, legs, etc.) into the right atrium.

What is the function of the pulmonary trunk?

Takes blood from the right ventricle to the lungs.

What is the function of the pulmonary veins?

These carry oxygenated blood from the lungs to the left atrium.

What is the function of the aorta?

Distributes blood through the arterial system around the body.

What are the two main types of heart valves?

Atrioventricular valves (between atria and ventricles) and semilunar valves (between ventricles and aorta/pulmonary trunk).

What are atrioventricular valves?

Located between the atria and ventricles.

What are semilunar valves?

Located between the ventricles and the aorta or pulmonary trunk.

What is the right atrioventricular valve?

Also called the tricuspid valve, it allows blood to flow from the right atrium to the right ventricle.

What is the left atrioventricular valve?

Also called the bicuspid or mitral valve, it allows blood to flow from the left atrium to the left ventricle.

What is the aortic valve?

Allows blood to flow from the left ventricle to the aorta.

What is the pulmonary valve?

Allows blood to flow from the right ventricle to the pulmonary arteries.

What are chordae tendineae?

These anchor the valve leaflets to the papillary muscle, preventing the valves from flying open and causing regurgitation.

What are papillary muscles?

These anchor the chordae tendineae to the heart wall and contract when the ventricle contracts to pull the valves closed.

What happens if papillary muscles rupture?

Rupture of papillary muscles can cause valve malfunction and regurgitation.

What is the pulmonary circuit?

The right side of the heart receives deoxygenated blood and pumps it to the lungs.

What is the systemic circuit?

The left side of the heart receives oxygenated blood from the lungs and pumps it to the rest of the body.

Why is the left side of the heart thicker than the right side?

The right side has thinner walls because it only needs to pump blood to the adjacent lungs, while the left side needs to pump blood to the entire body.

What is the coronary circulation?

Supplies the heart muscle with blood and is divided into right and left coronary arteries.

Where does the heart drain blood into?

Coronary veins drain into the coronary sinus, which drains into the right atrium.

What happens when there is a blockage of coronary arteries?

Can lead to angina and heart attack, compromising blood flow to the heart itself.

Describe the pathway of blood flow through the heart.

Blood drains into the right atrium via the superior and inferior vena cava, flows through the tricuspid valve into the right ventricle, then through the pulmonary valve into the pulmonary trunk to the lungs. Oxygenated blood returns via the pulmonary veins to the left atrium, flows through the mitral valve into the left ventricle, then through the aortic valve into the aorta to the body.

What is the cardiac cycle?

Coordinated contraction and relaxation of the heart muscle.

What is systole?

Contraction of the heart chamber, decreasing its volume and increasing pressure.

What is diastole?

Relaxation of the heart chamber, increasing its size and decreasing pressure.

What is the fundamental rule that drives blood flow through the heart?

Fluid will naturally move from a region of high pressure to low pressure.

What is end diastolic volume (EDV)?

Volume of blood in the ventricle at the end of diastole (filling).

What is end systolic volume?

Volume of blood left in the ventricle after the heart has contracted.

What is stroke volume?

Amount of blood ejected per heartbeat from each ventricle.

What are the two heart sounds and what causes them?

The first sound (lub) is the closure of the atrioventricular valves and is best heard at the apex of the heart. The second sound (dub) is the closure of the semilunar valves and is best heard toward the base of the heart.

Where are the best locations to hear the closure of each of the heart's four valves?

The bicuspid valve is best heard at the apex of the heart, the tricuspid valve at the left sternal border, the aortic valve between the second and third right intercostal space, and the pulmonary valve between the second and third left intercostal space.

How is the electrical activity of the heart generated?

The heart generates its own electrical rhythm, exciting itself and setting its own pace.

What is the SA node?

Specialized pacemaker cells within this structure generate the sinus rhythm, the normal rhythm of the heart.

What are the components of the electrical network of the heart?

Sinoatrial node (SA node), atrioventricular node (AV node), bundle of His, bundle branches, and Purkinje fibers.

Why does the heart contract from the apex up?

It allows the heart to expel as much blood as possible out into those arteries.

Describe the pathway of electrical activation through the heart.

The SA node triggers the sinus rhythm, stimulating the atrial muscle to contract. The signal travels to the AV node, then to the bundle of His, dividing into bundle branches and innervating the myocardium via Purkinje fibers from the apex up.

What is an electrocardiogram (ECG)?

Measures the electrical activity of the heart and can detect abnormalities in heart function.

What are the different waves on the ECG and what do they represent?

P wave, QRS complex, and T wave, each relating to a specific chamber or action within the heart.

What does the P wave represent?

This represents atrial depolarization.

What does the QRS complex represent?

This is representing ventricular depolarization.

What does the T wave represent?

This is representing ventricular repolarization.

What is bradycardia?

A slow heart rate (under 60 beats per minute).

What is tachycardia?

A fast heart rate (more than 100 beats per minute).

What is fibrillation?

Loss of sequential and coordinated depolarization.

What is atrial fibrillation?

Inappropriate contraction of the atria.

What is ventricular fibrillation?

Inappropriate and inconsistent contraction of the ventricles.