Question 1

Which of the following best describes the function of platelets in the blood?

Accepted Answer

They are essential for blood clotting and help prevent excessive bleeding.

Question 2

A patient’s complete blood count (CBC) shows a decreased hematocrit ($$Hct). $$Which of the following is the most likely cause?

Accepted Answer

Hemorrhage or chronic blood loss

Question 3

Which of the following is the correct sequence of events in the PQRST cycle of an ECG?

Accepted Answer

P wave: depolarization of atria; QRS complex: depolarization of ventricles; T wave: repolarization of ventricles

Question 4

A newborn is diagnosed with hemolytic disease due to Rh incompatibility. Which scenario is most likely responsible?

Accepted Answer

Mother is Rh-negative, fetus is Rh-positive

Question 5

Which of the following blood vessels carries oxygen-rich blood from the lungs to the heart?

Accepted Answer

Pulmonary vein

Question 6

A patient’s ECG shows a prolonged QRS complex. What does this most likely indicate?

Accepted Answer

Delayed depolarization of the ventricles

Question 7

Which formula is used to calculate heart rate ($$HR) $$from an ECG strip if the number of large boxes between two consecutive R waves is $$n$$?

Accepted Answer

$$HR = \frac{300}{n}$$

Question 8

Which of the following is NOT a component of the heart’s conduction system?

Accepted Answer

Mitral valve

Question 9

A patient presents with a high white blood cell (WBC) count. Which condition is most likely?

Accepted Answer

Leukocytosis due to infection

Question 10

Which of the following is the correct order of blood flow through the heart starting from the right atrium?

Accepted Answer

Right atrium → Right ventricle → Pulmonary artery → Lungs → Pulmonary vein → Left atrium → Left ventricle → Aorta

Question 11

Which of the following is a correct definition of hematocrit ($$Hct$$)?

Accepted Answer

The percentage of red blood cells in total blood volume

Question 12

A patient with blood type AB can safely receive blood from which of the following donors?

Accepted Answer

Any blood type (A, B, AB, O)

Question 13

Which structure prevents backflow of blood from the left ventricle to the left atrium?

Accepted Answer

Mitral (bicuspid) valve

Question 14

Which of the following is a possible consequence of a defect in the foramen ovale after birth?

Accepted Answer

Mixing of oxygen-rich and oxygen-poor blood between atria

Question 15

Which of the following arteries supplies oxygen-rich blood to the heart muscle itself?

Accepted Answer

Coronary arteries

Question 16

A patient’s blood smear shows an abnormally high number of eosinophils. Which condition is most likely?

Accepted Answer

Parasitic infection or allergic reaction

Question 17

Which of the following is the correct formula for calculating cardiac output ($$CO$$)?

Accepted Answer

$$CO = HR 	imes SV$$

Question 18

A patient with a history of deep vein thrombosis (DVT) is at risk for which of the following complications?

Accepted Answer

Pulmonary embolism

Question 19

Which of the following is a function of the pericardial sac (pericardium)?

Accepted Answer

It prevents the heart from over-expanding and reduces friction.

Question 20

A patient’s blood type is O negative. Which blood types can they safely receive in a transfusion?

Accepted Answer

O negative only

Cardiovascular System: Blood, Heart Anatomy, and ECG Interpretation

Study Guide - Practice Questions