First 512 words of the document:
3.1.5 The functioning of the heart plays a central role in the circulation of blood The right side pumps blood to the lungs and the left side pumps blood to the
This cycle can be represented in a pressure or a volume graph:
and relates to the level of activity of an individual. Heart disease may be linked to body, visa versa for receiving blood. On the left side, the pulmonary vein carries
factors affecting lifestyle. oxygenated blood to the heart then the aorta carries that blood to the body.
On the right side the Vena Cava carries deoxygenated blood to the heart then
Heart structure and function
the pulmonary artery carries deoxygenated blood to the lungs. Semi -lunar
The gross structure of the human heart and its associated blood vessels in relation to function. valves are present in the blood vessels carrying blood away from the heart such
as the pulmonary artery and the aorta which prevent backflow, elastic recoil of
Pressure and volume changes and associated valve movements during the cardiac cycle.
the arteries and the relaxation of the ventricles closes each valve.
Myogenic stimulation of the heart and transmission of a subsequent wave of electrical activity.
The heart is myogenic, this means that the electrical impulses are generated by
Roles of the sinoatrial node (SAN), atrioventricular node (AVN) and bundle of His. cells in the muscle and has no need of nerves. The cardiac cycle is summarized
Cardiac output as the product of heart rate and stroke volume. below:
Analyse and interpret data relating to pressure and volume changes during the cardiac cycle.
The heart is an organ that pumps blood around the body. It consists of four chambers; the left
and right atria which reside above the left and right ventricles. The atrioventricular valve sepa-
rate the atria and ventricles . The ventricles have thicker muscular walls that the atria because
whereas the atria only need to pump blood a short distance to the ventricles, the ventricles
have to pump blood a longer distance. The left ventricle has thicker walls that the right because
Or an electrocardiogram or a phonocardiagrapm:
it needs a more powerful contraction to propel blood to the rest of the body. The right only
pumps to the lungs.
Control of the Cardiac Cycle
The cardiac cycle is controlled by
the electrical impulses of the SAN
near the left atrium. It sends out
electrical impulses across to the
AVN near the top of the septum .
Then the impulse travel down
through the bundle of His to the
Pukinje fibres to the ventricular
muscles. The muscles on receiving
this signal then contract.
The P wave is the initial impulse caused by the SAN. The QRS complex is
the result of the electrical impulse reaching the AVN and travelling
down the nerve fibres. T is the depolarisation of the ventricle.