Human biology 1.2.1 the heart

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Describe internal structure of the heart?

(http://upload.wikimedia.org/wikipedia/commons/thumb/e/e0/Heart_diagram-en.svg/350px-Heart_diagram-en.svg.png)

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Describe cardiac cycle?

diastole- heart muscle is relaxed 

atrial systole- atrias fill with blood which pushes open the atrio-ventricular valves and causes muscular walls of atria to contract known as atrial systole, then blood starts to enter ventricles

ventricular systole- blood enters the ventricles and muscular walls contract and as theres greater pressure in ventricles than atria the atrio-ventricular valves and forced shut. the pressure pushes blood out of right ventricle into pulmonary artery through semi-lunar valves to be carried to the lungs and blood out of left ventricle through semi-lunar valves to aorta.

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What is chordae tendinde?

tendons attached to the wall of the ventricles which prevents the av valves from going inside out by becoming tense during ventricular systole which pulls the flaps and holds them in a closed position

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Outline how an ECG is used?

technician asks paitent to remove clothes from waist upwards

places electrodes on arms,chest and legs

ECG cream is used between electrodes and skin

paitent asked to lay down and remain completely still as any movement interfers with recording

machine records for 5 minutes and gives recording from each electrode

P- represents atria deploraise impulse sent from san to av node

Q,R,S- impulse down bundle of his and purkyne tissue

T- ventria replorize- ventricles recover

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Explain how heart action is initiated?

- sino-atrial node in right atrium (pacemaker) sends electrical impulse across atria walls through branched cardiac muscles which causes atrial systole

-impulse then passes to atrio-ventricular node where the impulse gets delayed to allow the atria to empty

-impulse then passes down septum of ventricles through bundle of his

- impulse reaches apex of the heart and spreads through purkyne tissues causes ventricular systole

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Explain what cardiac output is and how its calcula

Cardiac output- volume of blood pumped out the left ventricle per minute

Stroke volume x heart rate = cardiac output

stroke volume- volume of blood pumped out left ventricle in cardiac cycle

heart rate-how many pulses are felt in an artery per minute

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Explain why trained athletes have high stroke volu

Strenous exercise streches the heart muscle making it contracts more strongly meaning that a greater volume of blood returning to the right atrium

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Why is it beneficial to have high stroke volume?

Atheletes heart rate doesnt increase as much so atheletes can exercise more strenously and for longer periods of time

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Why do athletes have a low resting heart rate?

training has lead to increase thickness in heart muscle so stroke volume at rest will be higher so this means the heart has less beats needed to generate the same cardiac output

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Describe how pulse rate can be measured?

- find position of radial artery- wrist

- place second and third fingers on artery and press firmly

- count how many pulses in 1 minute or 30 secs and times by two

athelete- 60/80 bpm

10+ and adult- 60-100 bpm

1-10 60-140 bpm]

0-12 months 100-160 bpm

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