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Heart - BiologyMad A-Level Biology

By Alfred Pierce,2014-12-07 03:07
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Heart - BiologyMad A-Level Biology

    Heart: Pressure Changes & Exercise Questions

    1. (a) The graph shows pressure changes in the left ventricle, left atrium and aorta.

    20

    15

    R

    10QBlood

    pressure / k Pa

    5SP

    0

    5

    00.51.01.5Time / s

    Left ventricle Left atrium Aorta

    (i) Which letter on the graph corresponds to each of the following?

     Letter

    Aortic (semilunar) valve opens

    Blood starts to enter the left ventricle

    Bicuspid (atrioventricular) valve closes

    (3)

    (ii) Assuming a steady rate of beating of the heart, calculate the pulse rate per minute for this

    person.

    Answer: ................................. (1)

    (b) Contraction of the heart muscle is described as being myogenic. (i) Explain what is meant by myogenic.

    ..........................................................................................................................

    ..........................................................................................................................

    (1)

    (ii) How is contraction of muscle cells in the heart coordinated?

    ..........................................................................................................................

    .......................................................................................................................... (2)

     (Total 7 marks)

    2. A small tube called a catheter can be inserted into the blood system through a vein. It can be threaded through the vein and into and through the heart until its tip is in the pulmonary artery. A tiny balloon at the tip can then be used to measure the pressure changes in the pulmonary artery. The diagram shows a section through the heart with the catheter in place. The graph shows the pressure changes recorded in the pulmonary artery.

    X

    Pressure

    Time

(a) Name the chamber of the heart labelled P.

    .....................................................................................................................................

    (1)

    (b) Complete the table by placing ticks in the appropriate boxes to show which of valves 1 to 4 will

    be open and which closed at time X on the graph.

    Valve Open Closed

     1

     2

     3

     4

    (2)

    (c) Sketch a curve on the graph to show the pressure changes which you would expect if the

    pressure in the aorta were measured at the same time.

    (2)

    (Total 5 marks)

    3. The table shows the rate of blood flow to various parts of the body at rest and during vigorous

    exercise

    Rate of blood flowPart of body

    at restduring vigorous exercise

    Skeletal muscles100016 000

    Heart muscle2501 200

    Skin500750

    Kidneys1000300

    Liver and gut1250375

    Brain750

    (a) (i) Suggest suitable units for the rate of blood flow.

    ....................................................................................................................... (1)

    (ii) Suggest a suitable value for the rate of blood flow to the brain during vigorous exercise.

    Give a reason for your answer.

    Value ................................................................................................................

    Reason ..............................................................................................................

    ........................................................................................................................... (2)

    (b) The blood flow to the skeletal muscles changes during vigorous exercise. Describe the part

    played by each of the following in bringing about this change:

    (i) the nerves going to the sinoatrial node in the heart;

    ...........................................................................................................................

    ...........................................................................................................................

    ........................................................................................................................... (2)

    (ii) the arterioles taking blood to the skeletal muscles.

    ...........................................................................................................................

    ...........................................................................................................................

    ...........................................................................................................................

    ........................................................................................................................... (2)

    (c) Use information from the table to suggest why it is recommended that vigorous exercise should

    not be undertaken until at least two hours after a meal.

    .....................................................................................................................................

    ..................................................................................................................................... (1)

     (Total 8 marks)

    4. The graph shows changes in the volume of blood in the left ventricle as the heart beats.

    140

    A

    120

    100

    Volume /3cm

    80

    60

    00.20.40.60.81.01.21.40

    Time / s

    (a) (i) The horizontal line labelled A on the graph shows when blood is leaving the ventricle.

    Explain, in terms of blood pressure, why blood does not flow back into the atrium during

    this period.

    ...........................................................................................................................

    ...........................................................................................................................

    ...........................................................................................................................

    ...........................................................................................................................

    (2)

    (ii) Draw a horizontal line on the graph, to show the period in one cardiac cycle when the

    muscle in the wall of the ventricle is relaxed. Label this line with the letter B.

    (1)

    (b) (i) Draw a horizontal line on the graph to show one complete cardiac cycle. Label this line

    with the letter C.

    (1)

    (ii) Use line C to calculate the number of times the heart beats in one minute. Show your

    working.

    Answer ...................................

    (2)

    (c) The table shows the blood flow to different parts of the body at rest and during a period of vigorous exercise.

    3 1 Rate of blood flow/cmminutePart of the body

     at rest during exercise

    Brain 750 750

    Heart muscle 300 1 200

    Gut and liver 3 000 1 400

    Muscle 1 000 16 000

    All other organs (except lungs) 1 550 1 550

    (i) Use the figures in the table to calculate the cardiac output at rest.

    Answer ...................................

    (1)

    (ii) Give two ways in which cardiac output is increased during a period of vigorous exercise.

    1.........................................................................................................................

    ...........................................................................................................................

    2.........................................................................................................................

    ...........................................................................................................................

    (2)

    (d) Describe the parts played by the sinoatrial node (SAN) and the atrioventricular node (AVN) in controlling the heart beat.

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    .....................................................................................................................................

    .....................................................................................................................................

    .....................................................................................................................................

    (6)

    (Total 15 marks)

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