coordination of the heart beat Flashcards
what type of blood is passed through the right side of heart
deoxygenated blood.
what valve is in the right side of the heart
tricuspid valve.
which side ventricle is thicker and why
left-a more powerful contraction is needed to pump blood to body than lungs.
what part of the cardiac cycle shows heart relaxing/blood entering aorta.
diastole
what does the term myogenic mean
no input from nervous system and creates its own electrical impulse.
what type of polarisation cause heart to contract
depolarisation
where is the SAN found
right atria.
name the sequence of events of the heart beating .
SAN generates impulse causing atria to contract.
-impulse cannot pass directly into ventricle due to a bundle of non conductive tissue so the impulse collects in the AVN and is delayed for 0.1 s.
-impulse runs down septum in bundle of HIS.
-the impulses reach the hears apex travelling up both ventricles through purkinje fibres triggering ventricular systole and contraction of ventricles.
why is the delay required
to allow the atria to fully empty of blood and ventricles to fill before contracted.
which of the following can slow rate at which SAN generates an impulse-
1. accelerator nerve
2. Vegas nerve
3. adrenaline
- Vegas nerve
what does an ECG detect
a trace of he voltage changes in the heart during the cardiac cycle.
describe what happens during P wave on an ECG
Caused by generation of impulse by SAN. this is followed by contraction of atria
what is happening between the time between P and Q
time of wave of excitation to spread from atria to AVN.
what is happening in the QRS complex
voltage change-depolarisation resulting from spread of impulse from the AVN across ventricles , followed by contraction of ventricles.
what is happening at the T wave on an ECG
voltage changes caused by repolarisation of ventricle muscle -results in ventricular diastole.
