Describe internal structure of the heart?
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.
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
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
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
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
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
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
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
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