The diagram shows the external structure of the human heart.
Which part is blocked in coronary heart disease?
▶️ Answer/Explanation
Ans: B
Coronary heart disease (CHD) occurs when coronary arteries (B) are blocked by fatty deposits (atherosclerosis). These arteries supply oxygenated blood to the heart muscle, and their blockage can lead to angina or heart attacks.
A (Pulmonary artery) carries blood to the lungs, C (Vena cava) returns blood to the heart, and D (Aorta) distributes blood to the body. None of these are directly affected in CHD, making B the correct answer.
The diagram shows the human heart.
What are the semilunar valves?
A) W and X
B) W and Z
C) X and Y
D) Y and Z
▶️ Answer/Explanation
Ans: A
The semilunar valves are located at the exits of the heart’s ventricles, preventing backflow of blood into the heart. In the diagram, they are represented by W (pulmonary valve) and X (aortic valve).
Option B (W and Z) includes a non-valve structure, while options C (X and Y) and D (Y and Z) incorrectly identify atrioventricular valves (Y and Z). Since semilunar valves are specifically W and X, the correct answer is A (W and X).