c1-human heart
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8/7/2019 C1-human heart
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³The future depends on what we do in the present.´
5. There are four structures involved in the beating of the heart: sinoatrial node (SAN),
atrio-ventricular node (AVN), bundle of His and Purkinje fibres. State the functions of
the SAN and AVN.
(Tip: The two nodes act like batteries and generate electrical impulses that cause thecardiac muscles to contract)
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6. The pacemaker of a patient's heart fails to function. An electronic pacemaker is used to
replace the original pacemaker . Explain how this works.
(Tip: Think about the function of the SAN - the electronic pacemaker has the samefunction)
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7. Compare the rate of blood flow in blood vessels A and D.
(Tip: Which of the blood vessels is an artery or a vein? Which undergoes more pressure?
So, in which of them will blood flow more and at a greater speed?)
o A, the aor ta,
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o D, the vena cava,
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