Human Circulatory System

Biology, HSSC-Punjab First Year. This chapter is split into 23 topics and has 590 practice questions. The topics covered are listed below, followed by 10 free sample questions from the chapter.

Topics in this chapter

1. Blood vessels: arteries, veins and capillaries 25 questions
2. Heart sounds, heartbeat rate and cardiac output 27 questions
3. Capillary exchange, blood flow and velocity 25 questions
4. Cardiovascular disorders and their treatment 25 questions
5. Regulation of heartbeat and the ECG 25 questions
6. Pericardium and the heart wall 25 questions
7. Chapter review: circulatory system (end-of-chapter exercise focus) 28 questions
8. The lymphatic system 25 questions
9. Circulatory system overview and structure of the heart 25 questions
10. Blood pressure and its measurement 25 questions
11. Circulatory routes: pulmonary, systemic, coronary, hepatic portal and renal 25 questions
12. Heart chambers, valves and the cardiac cycle 30 questions
13. Congenital heart problems: blue babies and heart murmurs 20 questions
14. ECG waves, intervals and conduction pathway (Figures 11.4 and 11.5) 24 questions
15. Cardiac cycle and cardiac output: timing and calculations 23 questions
16. Blood vessels, capillary flow and velocity: figures and calculations 24 questions
17. Circulatory pathway figures 11.13 to 11.16 and routes traced 21 questions
18. Blood pressure: readings, Figure 11.17 and regulation scenarios 30 questions
19. Atherosclerosis, hypertension and cardiovascular risk factors 30 questions
20. Angiography, angioplasty and stenting in detail 21 questions
21. Thrombosis, heart attack and bypass surgery 30 questions
22. Lymph, lymph nodes, spleen and lymphoid organs (Figures 11.21 to 11.23) 30 questions
23. Chapter exercise: structured answers on the circulatory system 27 questions

Sample questions: Human Circulatory System

10 sample questions with the correct answer and an explanation. Try to answer each one before reading the explanation.

Q1. When blood pressure falls, baroreceptors in the carotid arteries and aortic arch trigger which of the following responses?

• A. Secretion of ANH by the right atrium
• B. Increased urine output and reduced blood volume
• C. Decreased heart rate and vasodilation in arterioles
• D. Increased rate and force of heart contraction and vasoconstriction in arterioles(correct answer)

Answer: D.When blood pressure falls, baroreceptors activate sensory neurons that send information to the brain; the control centre increases the rate and force of heart contraction and causes vasoconstriction in arterioles, restoring blood pressure.

Q2. A patient can still develop new blockages of coronary arteries after successful coronary bypass surgery because the surgery:

• A. Permanently prevents the formation of new thrombi
• B. Does not cure the underlying disease process, such as atherosclerosis(correct answer)
• C. Removes all fatty deposits from the patient's arteries
• D. Repairs the heart valves that caused the blockages

Answer: B.Coronary bypass surgery does not cure the underlying disease process, i.e. atherosclerosis or coronary artery disease; lifestyle changes such as smoking cessation are crucial to reduce the chance of future blockages and heart attacks.

Q3. Arrange the steps of angioplasty in the correct order: (1) Balloon advanced over the wire into the narrowed section (2) Dye injected to confirm successful dilatation (3) Catheter passed through the narrowed coronary artery under X-ray guidance (4) Balloon inflated to dilate the narrowed section

• A. 3 -> 4 -> 1 -> 2
• B. 1 -> 3 -> 2 -> 4
• C. 3 -> 1 -> 4 -> 2(correct answer)
• D. 1 -> 4 -> 2 -> 3

Answer: C.During angioplasty the catheter is first passed through the narrowed coronary artery under X-ray guidance, the balloon is then advanced into the narrowed section and inflated to dilate it, and finally a small amount of dye is injected to confirm successful dilatation.

Q4. Assertion (A): Prolonged hypertension can lead to congestive heart failure. Reason (R): Hypertension weakens cardiac muscles, so the heart is unable to pump effectively and blood may be retained in the heart and lungs.

• A. Both A and R are true, but R is not the correct explanation of A
• B. Both A and R are true and R is the correct explanation of A(correct answer)
• C. A is true but R is false
• D. A is false but R is true

Answer: B.Hypertension weakens cardiac muscles; if it is prolonged, the heart cannot pump effectively and blood flow cannot meet the needs of tissues, so blood may be retained in the heart and lungs, a condition called congestive heart failure.

Q5. Assertion (A): When the metabolic activity of a tissue increases, blood flow through its arterioles and capillaries increases. Reason (R): When metabolic activity increases, carbon dioxide decreases and oxygen increases in the interstitial fluid.

• A. Both A and R are true, and R is the correct explanation of A
• B. A is true, but R is false(correct answer)
• C. A is false, but R is true
• D. Both A and R are true, but R is not the correct explanation of A

Answer: B.When metabolic activity rises, oxygen decreases and carbon dioxide increases in the interstitial fluid; this relaxes the arteriolar circular muscles (vasodilation) and increases blood flow, so the assertion is true but the reason is false.

Q6. During increased metabolic activity in a tissue, which of the following correctly links the events in sequence?

• A. Carbon dioxide increases → circular muscles of arterioles relax → vasodilation → blood flow increases → more oxygen supplied and more carbon dioxide removed(correct answer)
• B. Carbon dioxide decreases → circular muscles of arterioles contract → vasodilation → blood flow increases
• C. Carbon dioxide increases → circular muscles of arterioles contract → vasoconstriction → blood flow decreases
• D. Oxygen increases → circular muscles of arterioles relax → vasodilation → blood flow decreases

Answer: A.With increased metabolic activity, carbon dioxide increases and oxygen decreases in the interstitial fluid; the circular muscles relax (vasodilation), blood flow increases, and more oxygen is supplied while more carbon dioxide is removed.

Q7. Assertion (A): The pulmonary arteries carry deoxygenated blood to the lungs. Reason (R): The pulmonary veins return oxygenated blood from the lungs to the left atrium.

• A. A is true but R is false.
• B. A is false but R is true.
• C. Both A and R are true, and R is the correct explanation of A.
• D. Both A and R are true, but R is not the correct explanation of A.(correct answer)

Answer: D.Both statements are true, but the return of oxygenated blood through the pulmonary veins does not explain why the pulmonary arteries carry deoxygenated blood; the pulmonary trunk receives deoxygenated blood from the right ventricle.

Q8. Assertion (A): In the renal circulation, blood passes through two sets of capillaries arranged one after the other before it reaches the renal vein. Reason (R): The capillaries of glomeruli unite to make the efferent arteriole, which divides to make the peri-tubular capillaries and the vasa recta.

• A. Both A and R are true, and R is the correct explanation of A.(correct answer)
• B. A is false but R is true.
• C. A is true but R is false.
• D. Both A and R are true, but R is not the correct explanation of A.

Answer: A.Blood flows from the glomerular capillaries into the efferent arteriole, which forms the second capillary set (peri-tubular capillaries and vasa recta); these drain into venules, smaller veins and finally the renal vein, so R explains A.

Q9. A drop of blood is in the right ventricle of the heart. Which of the following correctly traces its path until it reaches the left atrium?

• A. Right ventricle → pulmonary trunk → lung capillaries → pulmonary arteries → pulmonary veins → left atrium
• B. Right ventricle → pulmonary arteries → pulmonary trunk → pulmonary arterioles → pulmonary venules → left atrium
• C. Right ventricle → pulmonary trunk → pulmonary arteries → pulmonary arterioles → lung capillaries → pulmonary venules → pulmonary veins → left atrium(correct answer)
• D. Right ventricle → pulmonary trunk → pulmonary veins → lung capillaries → pulmonary arterioles → left atrium

Answer: C.The pulmonary trunk carries blood from the right ventricle, divides into right and left pulmonary arteries, and the blood passes through pulmonary arterioles, lung capillaries, pulmonary venules and pulmonary veins to reach the left atrium.

Q10. Which of the following sequences correctly describes the events that restore blood pressure when it falls?

• A. Fall in blood pressure → control centre activated → vasoconstriction in arterioles → baroreceptors activated → heart rate decreased
• B. Fall in blood pressure → baroreceptors activated → sensory neurons send information to the brain → control centre increases heart rate and force of contraction and causes vasoconstriction in arterioles(correct answer)
• C. Fall in blood pressure → sensory neurons activated directly → vasodilation in arterioles → heart rate increased
• D. Fall in blood pressure → posterior pituitary secretes ADH → baroreceptors activated → vasoconstriction in arterioles

Answer: B.When blood pressure falls, baroreceptors activate sensory neurons that send information to the brain; the control centre then increases the rate and force of contraction of the heart and causes vasoconstriction in arterioles, restoring blood pressure.