Heart structure and function iGCSE

Which diagram shows the human double circulatory system?

• A

• B

• C

• D

Answer explanation

Diagram D accurately represents the human double circulatory system, which consists of two circuits: the pulmonary circuit for oxygenation and the systemic circuit for delivering oxygenated blood to the body.

How often must a blood cell in the renal artery pass through the heart before it again reaches the renal artery?

• once

• twice

• three times

• four times

Answer explanation

A blood cell in the renal artery must pass through the heart twice: first, it goes from the right atrium to the lungs for oxygenation, and then from the left atrium back to the systemic circulation, including the renal artery.

The diagram shows a double circulatory system. Which vessels carry oxygenated blood?

• 1 and 2

• 1 and 4

• 2 and 3

• 2 and 4

Answer explanation

In a double circulatory system, oxygenated blood is carried by the pulmonary veins and the aorta. Therefore, vessels 2 (pulmonary vein) and 4 (aorta) carry oxygenated blood, making the correct answer 2 and 4.

The diagram shows the circulatory system of a mammal.

What describes the blood in vessels X and Y?

• X: deoxygenated

  Y: deoxygenated

• X: deoxygenated

  Y:oxygenated

• X:oxygenated

  Y: deoxygenated

• X: oxygenated

  Y: oxygenated

Answer explanation

In mammals, blood in vessels X and Y is oxygenated after passing through the lungs. Therefore, both X and Y carry oxygen-rich blood, making the correct choice: X: oxygenated, Y: oxygenated.

Which chamber of the heart has the most muscular wall?

• left atrium

• left ventricle

• right atrium

• right ventricle

Answer explanation

The left ventricle has the most muscular wall because it needs to generate enough force to pump oxygenated blood throughout the entire body, unlike the other chambers which pump blood to nearby areas.

The diagram shows a cross-section through a human blood vessel.

Which type of blood vessel does the diagram show?

• an artery

• a capillary

• a vein

• a ventricle

Answer explanation

The diagram shows an artery, which has thick, muscular walls to withstand high pressure from the heart. This distinguishes it from veins and capillaries, which have thinner walls and different functions.

What happens when the left ventricle contracts?

• atrioventricular valves: closed

  semilunar valves: closed

• atrioventricular valves: closed

  semilunar valves: open

• atrioventricular valves: open

  semilunar valves: closed

• atrioventricular valves: open

  semilunar valves: open

Answer explanation

When the left ventricle contracts, it generates pressure that closes the atrioventricular valves to prevent backflow into the atria and opens the semilunar valves, allowing blood to flow into the aorta.

The diagram shows the directions of blood flow through a heart.

Which chamber of the heart receives blood directly from the lungs?

• A

• B

• C

• D

Answer explanation

The chamber that receives blood directly from the lungs is the left atrium, which is represented by choice B. It collects oxygenated blood from the pulmonary veins.

What is structure B?

• Left atrium

• Right atrium

• Left ventricle

• Right ventricle

Answer explanation

Structure B is the left atrium, which receives oxygenated blood from the lungs. It is one of the four chambers of the heart, playing a crucial role in the circulatory system.

What is structure D?

• Left atrium

• Right atrium

• Left ventricle

• Right ventricle

Answer explanation

Structure D refers to the right ventricle, which is responsible for pumping deoxygenated blood to the lungs for oxygenation. It is located on the lower right side of the heart, distinguishing it from the left atrium and left ventricle.