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Cardiovascular System: Practice Questions on Heart Rate, Blood Flow, and Blood Pressure, Exercises of Law

Katholieke Hogeschool LeuvenLaw

Practice questions related to the cardiovascular system, covering topics such as heart rate control, stroke volume, veins, and blood flow. Students can test their understanding of these concepts through the provided questions and answers.

Typology: Exercises

2021/2022

Uploaded on 08/05/2022

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CHAPTER 1: THE CARDIOVASCULAR SYSTEM
Practice questions - text book pages 26 - 27
1) Heart rate is controlled by the cardiac conduction system.
Which one of the following is the order of the cardiac conduction system?
a. atrioventricular node, sinoatrial node, bundle of His, Purkinje fibres.
b. atrioventricular node, sinoatrial node, Purkinje fibres, bundle of His.
c. sinoatrial node, atrioventricular node, bundle of His, Purkinje fibres.
d. sinoatrial node, atrioventricular node, Purkinje fibres, bundle of His.
Answer: c.
Explanation:
• The sinoatrial node (SA node) is the pacemaker located in the right atrial wall just inferior to the entrance of the superior vena
cava.
• The SA node generates impulses which travel across the atria (followed by atrial systole) and then pause (0.1s) at the
atrioventricular node (AV node, sited at the superior part of the inter-ventricular septum) and then to the bundle of His located
between the ventricles, splitting into right and left branches down the inter-ventricular septum towards the heart apex, and out to
the Purkinje fibres which turn superiorly into the ventricular walls (followed by ventricular systole).
2) According to the Frank-Starling law, stroke volume increases as a function of:
a. increasing heart rate.
b. decreasing heart rate.
c. increasing end-diastolic volume.
d. increasing venous return.
Answer: c.
Explanation:
• Frank–Starling law states that the stroke volume of the heart increases in response to an increase in the volume of blood filling
the heart (the end diastolic volume) when all other factors remain constant.
3) Which statement does not accurately describe veins?
a. have less elastic tissue and smooth muscle than arteries.
b. contain more fibrous tissue than arteries.
c. most veins in the extremities have valves.
d. always carry deoxygenated blood.
Answer: d.
Explanation:
• This is because the pulmonary vein carries oxygenated blood from the lungs to the left ventricle.
4) The amount of blood pumped by one ventricle in one minute is called:
a. stroke volume.
b. end-diastolic volume.
c. ejection fraction.
d. cardiac output
Answer: d.
Explanation:
• Cardiac output is a combination of stroke volume and heart rate. Stroke volume is the volume of blood pumped by the left
ventricle of the heart per beat. Heart rate is the number of beats of the heart per minute (bpm).
5) Why is atherosclerosis especially dangerous when found in coronary arteries?
a. it can cause a heart attack.
b. it can restrict blood flow to the heart muscle.
c. It can lead to coronary heart disease.
d. all of the above options are correct.
Answer: d.
Explanation:
• Atherosclerosis is a disease of the arteries characterised by the deposition of fatty material on their inner walls that can lead to a.
b. and c.
1Answers
QUESTIONS AND ANSWERS
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CHAPTER 1 : THE CARDIOVASCULAR SYSTEM

Practice questions - text book pages 26 - 27

  1. Heart rate is controlled by the cardiac conduction system. Which one of the following is the order of the cardiac conduction system? a. atrioventricular node, sinoatrial node, bundle of His, Purkinje fibres. b. atrioventricular node, sinoatrial node, Purkinje fibres, bundle of His. c. sinoatrial node, atrioventricular node, bundle of His, Purkinje fibres. d. sinoatrial node, atrioventricular node, Purkinje fibres, bundle of His. Answer : c. Explanation :
  • The sinoatrial node (SA node) is the pacemaker located in the right atrial wall just inferior to the entrance of the superior vena cava.
  • The SA node generates impulses which travel across the atria (followed by atrial systole) and then pause (0.1s) at the atrioventricular node (AV node, sited at the superior part of the inter-ventricular septum) and then to the bundle of His located between the ventricles, splitting into right and left branches down the inter-ventricular septum towards the heart apex, and out to the Purkinje fibres which turn superiorly into the ventricular walls (followed by ventricular systole).
  1. According to the Frank-Starling law, stroke volume increases as a function of: a. increasing heart rate. b. decreasing heart rate. c. increasing end-diastolic volume. d. increasing venous return. Answer : c. Explanation :
  • Frank–Starling law states that the stroke volume of the heart increases in response to an increase in the volume of blood filling the heart (the end diastolic volume) when all other factors remain constant.
  1. Which statement does not accurately describe veins? a. have less elastic tissue and smooth muscle than arteries. b. contain more fibrous tissue than arteries. c. most veins in the extremities have valves. d. always carry deoxygenated blood. Answer : d. Explanation :
  • This is because the pulmonary vein carries oxygenated blood from the lungs to the left ventricle.
    1. The amount of blood pumped by one ventricle in one minute is called: a. stroke volume. b. end-diastolic volume. c. ejection fraction. d. cardiac output Answer : d. Explanation :
  • Cardiac output is a combination of stroke volume and heart rate. Stroke volume is the volume of blood pumped by the left ventricle of the heart per beat. Heart rate is the number of beats of the heart per minute (bpm).
    1. Why is atherosclerosis especially dangerous when found in coronary arteries? a. it can cause a heart attack. b. it can restrict blood flow to the heart muscle. c. It can lead to coronary heart disease. d. all of the above options are correct. Answer : d. Explanation :
  • Atherosclerosis is a disease of the arteries characterised by the deposition of fatty material on their inner walls that can lead to a. b. and c.

Answers 1

QUESTIONS AND ANSWERS

  1. Figure 1.18 shows a diagrammatic picture of the cardiac impulse. Using the information in this diagram, describe the flow of blood during the specific stages of the cardiac cycle in relation to the cardiac impulse. In your answer explain how the heart valves help control the direction of blood flow. 8 marks Answer : Atrial and ventricular diastole:
  • During atrial and ventricular diastole there is no electrical impulse from the SA node.
  • And so relaxed heart muscle chambers (atria and ventricles) fill with blood.
  • From the venae cavae (on the right hand side of the heart).
  • And the pulmonary veins (on the left hand side of the heart).
  • As the cuspid valves open and the semi-lunar valves close. Diastole is followed by systole consisting of two distinct phases: Atrial systole:
  • The SA node creates an electrical impulse.
  • This causes a wave-like contraction over the atria myocardium.
  • Forcing the remaining blood from the atrial chambers.
  • Past the cuspid valves.
  • Into the ventricles. Ventricular systole:
  • The impulse reaches the AV node.
  • The cuspid valves close during ventricular systole.
  • The impulse travels down the bundle of His to the Purkinje fibres.
  • Across ventricular myocardium.
  • Which then contracts as the semi-lunar valves open.
  • Blood is forced out of the ventricles.
  • Into the aorta (left hand side).
  • And the pulmonary arteries (right hand side).
  • Myocardial contractions, during systole, are said to be myogenic or under involuntary nervous control.
    1. Q

= SV x HR. Explain the meaning of this equation and give typical resting values that you would expect in an endurance-based athlete. 6 marks Answer :

  • Q

represents cardiac output – is defined as the volume of blood pumped by the left ventricle in one minute.

  • And is a combination of SV – stroke volume is defined as the volume of blood pumped by the left ventricle of the heart per beat.
  • x HR – heart rate is defined as the number of beats of the heart per minute (bpm).
  • Typical resting values for an endurance-based athlete: Q

= SV x HR 5.6 litres min-1^ = 110ml x 51 (or same values in dm^3 min-1).

THE CARDIOVASCULAR SYSTEM

SECTION 1

CHAPTER 1

SAnode AV node bundle of His myogenic Purkinje fibres figure 1.18 – the cardiac impulse

  1. Jodie Swallow is a top class female British Triathlete, and has a resting heart rate of 36 bpm. Give reasons why such an athlete might have a low resting heart rate. 4 marks Answer :
  • Due to bradycardia or slow heart beat.
  • Effects of an aerobic endurance-based triathlete training programme is to produce cardiac hypertrophy i.e. heart becomes bigger and stronger (mainly left ventricle).
  • Producing an increase in stroke volume (SV).
  • And decrease in resting heart rate (HRrest).
  • A reduced resting heart rate allows for an increase in diastolic filling time.
  • The net effect is that the heart does not have to pump as frequently for the same given resting oxygen consumption.
    1. Explain what is meant by the term ‘cardiovascular drift’. 3 marks Answer :
  • Cardiovascular drift is characterised by a decrease in stroke volume and a parallel increase in heart rate to maintain a constant cardiac output.
  • This results in a decrease in pulmonary arterial pressure and reduced stroke volume.
  • And an increase in heart rate.

THE CARDIOVASCULAR SYSTEM

SECTION 1

CHAPTER 1

  1. A Level Regular aerobic exercise results in significant benefits to the heart and vascular system. What are these benefits and how do they contribute to a ‘healthier lifestyle’? 15 marks Answer :

- Stamina-building activities such as jogging, cycling and swimming will improve the efficiency of cardiac tissue and blood circulation. - Resting heart rate reduces as stroke volume increases to give the same resting cardiac output. - This is because the heart becomes bigger and stronger. - Improved coronary blood flow will reduce myocardial demands as the heart becomes more efficient. - Therefore less likely to suffer angina and/or coronary heart disease. - Resting blood pressure^ is lowered and the balance of^ cholesterol^ and^ triglycerides^ (can create fatty deposits that obstruct arteries) is improved. - Thereby reducing the risks of hypertension and atherosclerosis respectively. - There is an increase in blood volume and blood cell count. - Hence an^ increase in^ V

O2max.

- Increased elasticity and thickness of smooth walls of arterial muscle makes walls tougher and less likely to stretch under pressure. - Thereby reducing arteriosclerosis and hypertension. - Regular exercise will reduce the risk of potential blood clots. - Thereby reducing risk of coronary thrombosis. - All these aerobic adaptive responses will enable the individual to sustain physical activity for longer and be able to increase work load intensities. - Within an ageing population,^ V

O2max and physical strength can be maintained at a much higher level.

- Therefore greater and better life expectancy. - Reduction in obesity, as weight decreases due to regular aerobic exercise, puts less strain on the heart and so benefits from decreased risk of cardiovascular for all age groups. - The impact of a fitter population reduces the strain on NHS. - A physicallly active population has long-term mental and social well-being as individual fitness copes with the demands of everyday life. QUESTIONS AND ANSWERS

Answers 5

  1. Table 1.4 shows the rate of blood flow (in cm^3 per minute) to different parts of the body in a trained male athlete, at rest and while exercising at maximum effort on a cycle ergometer. Table 1.4 – estimated blood flow at rest and during maximum effort organ or system estimated blood flow in cm^3 min- at rest during max effort skeletal muscle 1000 26400 coronary vessels 250 1200 skin 500 750 kidneys 1000 300 liver & gut 1250 375 other organs 1000 975 Study the data carefully before answering the following questions. a) The rate of blood flow to the ‘entire body’ increases significantly during exercise. Explain briefly how the heart achieves this. 2 marks Answer :
  • Increased heart rate.
  • Increased stroke volume.
  • Therefore increased cardiac output. b) What percentage of the total blood flow is directed to the skeletal muscle at rest and during maximum effort? Show your calculations. 3 marks Answer : The percentage of total blood flow directed to skeletal muscle at rest is:
  • 1000 x 100 = 20%. 5000 The percentage of total blood flow directed to skeletal muscle during maximal effort is:
  • 264000 x 100 = 88%. 30000 c) How is blood flow to various regions of the body controlled? 4 marks Answer :
  • Achieved through vasomotor control.
  • Which creates the vascular shunt.
  • This is vasodilation, which is the expansion of arteries and arterioles, and relaxation of precapillary sphincters to increase blood flow to active muscle tissue.
  • This is in response to a cessation of neural signals to the smooth muscle walls of these blood vessels.
  • Also vasoconstriction, which is the restriction of arteries and arterioles, and contraction of precapillary sphincters to decrease blood flow to non-active tissue.
  • This is a response to increased neural signals from baroreceptors which detect changes in cardiac output.
  • These neural signals go to the smooth muscle walls of these particular blood vessels. QUESTIONS AND ANSWERS

Answers 7

  1. a) What is meant by the concept ‘venous return mechanism’? 2 marks Answer :
  • Venous return is the transport of blood from the capillaries, through venules, veins and venae cavae to the right atrium of the heart. b) Describe how it is aided during physical activity when a person is exercising in an upright position. 3 marks Answer :
  • Venous return is aided by exercise due to increased actions of skeletal muscle and respiratory and cardiac pumps and limited action of venoconstriction of veins.
  • Increased activity in skeletal muscle results from contracting and relaxing squeezing sections of veins.
  • Therefore causing increased blood flow back towards the heart.
  • Blood cannot flow the opposite way because of pocket valves placed every so often in each vein. c) Explain the importance of the skeletal muscle pump mechanism during an active cool-down. 2 marks Answer :
  • Skeletal muscles continue to contract to squeeze vein walls, forcing blood back towards the heart.
  • Thereby preventing blood pooling and an associated sudden drop in blood pressure.
  • And removing of waste products such as carbon dioxide and lactic acid. d) What effect does enhanced venous return have upon cardiac output and stroke volume? 3 marks Answer :
  • Stroke volume is dependent on the amount of venous return.
  • Up to 70% of the total volume of blood is contained in the veins at rest.
  • Increased venous return will cause myocardial tissue to be stretched even further.
  • And so contract more forcibly.
  • To increase stroke volume (Starling’s Law of the heart).
  • Cardiac output is a combination of SV and HR.
  • Therefore an increased stroke volume will create an increased cardiac output.

THE CARDIOVASCULAR SYSTEM

SECTION 1

CHAPTER 1