The Heart and Cardiac Cycle Flashcards
What kind of muscle is the heart?
A cardiac muscle.
What does ‘myogenic’ mean?
The heart contracts rhythmically on its own.
What are interlated disks?
Help with impulse transmissions.
What ions are needed for the heart muscle to contract?
Calcium (Ca2+) ions.
The heart is also…
Striated (stripy).
What does the sinoatrial node (SAN) do within the cardiac system?
Generates a pulse of electricity that spreads across the atria causing them to contract.
What is the impulse controlled by?
The atrioventricular node (AVN).
Why can’t the impulse pass through the ventricles?
Because of non-conductive tissue.
Where does the AVN pass the impulse to?
The bundle of HIS in the septum, after receiving the impulse from the SAN.
The impulse will then pass through the…
Pukinje fibres to the apex.
Where is the impulse sent to so that it contracts?
The walls of the ventricles.
What happens when the heart muscle relaxes?
The impulse is over.
What is an echocardiogram (ECG)?
Where electrical pulses through the heart can be visualised.
What are P, QRS and T on an ECG?
P = Depolarisation of atria
QRS = Depolarisation of ventricles
T = Repolarisation
What are 2 ways pressure on the arteries affect the contracting and relaxing of the heart?
Systolic (contracts) and diastolic (relaxes/fills with blood).
