Heart and cardiovascular system Flashcards

Question

Answer 1

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A. Superior to the diaphragm, between the lungs, within the mediastinum

The heart is located in the mediastinum, a central region of the thoracic cavity. It is flanked by the lungs, rests superior to the diaphragm, and is protected by the sternum and ribs.

Answer 2

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C. Myocardium

The myocardium is the thick, muscular layer responsible for pumping blood. It is composed of cardiac muscle tissue, which contracts rhythmically to circulate blood throughout the body. The epicardium is the outermost layer, and the endocardium lines the heart chambers.

Answer 3

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C. Right atrium

Deoxygenated blood from the body returns via the superior and inferior vena cavae to the right atrium. From there, it passes through the tricuspid valve into the right ventricle, which pumps it to the lungs for oxygenation.

Answer 4

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D. Mitral (bicuspid) valve

The mitral valve (bicuspid) separates the left atrium and left ventricle. It prevents backflow of oxygenated blood as the left ventricle contracts to pump blood through the aortic valve into systemic circulation.

Answer 5

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B. Transports oxygen-poor blood to the lungs for gas exchange

The pulmonary circuit carries deoxygenated blood from the right ventricle to the lungs via the pulmonary arteries. In the lungs, gas exchange occurs, and oxygenated blood returns to the left atrium via the pulmonary veins.

Answer 6

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C. It carries oxygen-rich blood to body tissues and returns oxygen-poor blood to the heart

The systemic circuit begins at the left ventricle, which pumps oxygen-rich blood through the aorta to body tissues. Deoxygenated blood returns via the venae cavae to the right atrium, completing the circuit.

Answer 7

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B. To maintain unidirectional blood flow and prevent backflow

Heart valves ensure one-way blood flow. The atrioventricular (AV) valves (tricuspid and mitral) prevent backflow into the atria, while the semilunar valves (pulmonary and aortic) prevent backflow into the ventricles.

Answer 8

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B. Pulmonary and aortic valves

During ventricular contraction (systole), the pulmonary valve allows blood to enter the lungs, and the aortic valve allows blood to enter systemic circulation. The AV valves (tricuspid and mitral) close to prevent back flow into the atria.

Answer 9

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C. Coronary arteries

The coronary arteries branch off from the ascending aorta, providing oxygen and nutrients to the myocardium. A blockage can lead to myocardial infarction (heart attack) due to lack of oxygen.

Answer 10

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B. Myocardial infarction

A myocardial infarction (heart attack) occurs when coronary arteries are blocked, preventing oxygen delivery to the heart muscle. This leads to tissue death and impaired heart function.

Answer 11

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C. Sinoatrial (SA) node

The SA node, also known as the pacemaker of the heart, is located in the right atrium and generates the electrical impulse that spreads through the heart, initiating each heartbeat. The impulse then travels to the AV node, Bundle of His, bundle branches, and Purkinje fibers, ensuring coordinated contraction. Damage to the SA node can lead to arrhythmias and may require a pacemaker to regulate heart rhythm.

Answer 12

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A. SA node → AV node → Bundle of His → Purkinje fibers

The impulse starts at the SA node, travels to the AV node, then moves through the Bundle of His, and finally spreads via Purkinje fibres to trigger ventricular contraction.

Answer 13

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B. The heart muscle contracts

Systole is the contraction phase, where the ventricles eject blood into the aorta and pulmonary arteries.

Answer 14

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B. The volume of blood pumped by each ventricle per beat

Stroke volume (SV) is the amount of blood ejected per heartbeat (average = 70 mL). It contributes to cardiac output (CO = HR × SV).

Answer 15

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B. Decreases heart rate

The vagus nerve (parasympathetic system) slows heart rate by reducing SA node activity, promoting rest and digestion.

Answer 16

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B. Increases heart rate

Epinephrine (adrenaline) is a sympathetic hormone that increases heart rate and contractility, preparing the body for “fight or flight.”

Answer 17

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C. Inferior vena cava

The inferior vena cava collects deoxygenated blood from the lower body and returns it to the right atrium.

Answer 18

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B. To provide alternate pathways for cerebral circulation

The Circle of Willis is a ring of arteries at the base of the brain that ensures continuous blood supply even if one artery is blocked, reducing the risk of stroke.

Answer 19

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B. To transport nutrient-rich blood from digestive organs to the liver

The hepatic portal vein carries nutrient-rich blood from the small intestine, stomach, pancreas, and spleen to the liver, where it is processed before entering general circulation.

Answer 20

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A. Stroke

Chronic high blood pressure (hypertension) can damage blood vessels, increasing the risk of stroke, heart attack, kidney failure, and aneurysms.

Answer 21

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B. Diffusion

Oxygen, carbon dioxide, and nutrients passively diffuse across capillary walls from areas of high concentration to low concentration.

Answer 22

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B. Hydrostatic pressure

Hydrostatic pressure (blood pressure within capillaries) pushes fluid out at the arterial end, while osmotic pressure pulls fluid back in at the venous end.

Answer 23

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B. To prevent backflow of blood

Heart valves ensure unidirectional blood flow through the heart. The atrioventricular (AV) valves (tricuspid and mitral) prevent blood from flowing back into the atria, while the semilunar valves (pulmonary and aortic) prevent backflow into the ventricles. Valve dysfunction can lead to murmurs, heart failure, or inefficient circulation.

Answer 24

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B. Atrioventricular (AV) node

The AV node is located between the atria and ventricles. It slows the electrical impulse from the SA node, giving the atria time to contract before the ventricles contract. Without this delay, the heart would not effectively pump blood. Damage to the AV node can cause heart blocks, requiring pacemaker intervention.