hjärtförloppet

Hjärtförloppet refers to the complete cardiac cycle, encompassing all the events that occur from the beginning of one heartbeat to the beginning of the next. It involves a coordinated sequence of electrical and mechanical events that allow the heart to pump blood efficiently throughout the body.

The cardiac cycle is divided into two main phases: diastole and systole. Diastole is the relaxation phase, during which the heart chambers fill with blood. This phase includes isovolumetric relaxation, where the ventricles relax and the pressure drops, followed by ventricular filling, where blood flows from the atria into the ventricles.

Systole is the contraction phase, during which the heart pumps blood out. It begins with isovolumetric contraction, where the ventricles contract with all valves closed, building pressure. This is followed by ejection, where the semilunar valves (aortic and pulmonary) open, and blood is pumped into the aorta and pulmonary artery.

The electrical activity of the heart, originating from the sinoatrial (SA) node, initiates and coordinates these mechanical events. Impulses spread through the atria, causing them to contract, then through the atrioventricular (AV) node and down the Bundle of His and Purkinje fibers, causing the ventricles to contract. The rhythmic and sequential nature of hjärtförloppet ensures effective circulation of oxygenated and deoxygenated blood.