Fyllingsfase

Fyllingsfase refers to a stage in the cardiac cycle known as ventricular filling. This is the period when the ventricles of the heart relax and expand, drawing blood from the atria into their chambers. This process is crucial for preparing the heart to pump blood efficiently.

The fyllingsfase is further divided into two main parts. The first part is passive filling, where blood flows from the atria into the ventricles primarily due to the pressure gradient created by atrial relaxation. This occurs without active atrial contraction. The second part is active filling, or atrial kick, which is initiated by the contraction of the atria. This atrial contraction pushes a final volume of blood into the ventricles, ensuring they are adequately filled before ventricular contraction begins.

Several factors influence the rate and volume of filling during the fyllingsfase. Heart rate plays a significant role; at higher heart rates, the time available for filling decreases, potentially reducing stroke volume. Conversely, at slower heart rates, there is more time for passive filling. Venous return, the rate at which blood returns to the heart, also directly impacts the amount of blood available to fill the ventricles. Conditions that affect venous return, such as blood volume or the tone of blood vessels, can therefore alter the fyllingsfase. The elasticity of the ventricular walls and the pressure within the atria also contribute to the efficiency of ventricular filling.