Ventricular ejection

Definition

Ventricular ejection is the phase of the cardiac cycle during which blood is expelled from the ventricles into the arteries. This process occurs after the ventricles have filled with blood and contracted, generating enough pressure to open the semilunar valves and propel blood into the pulmonary artery and aorta. It is crucial for maintaining circulation and ensuring that oxygenated blood reaches the body while deoxygenated blood is sent to the lungs for oxygenation.

5 Must Know Facts For Your Next Test

1. Ventricular ejection occurs during the late stage of systole, following the isovolumetric contraction phase where pressure builds up in the ventricles.
2. The ejection fraction, which measures how much blood is pumped out of the ventricles relative to their total capacity, is a key indicator of heart function during this phase.
3. During ventricular ejection, blood is pushed into two major arteries: the aorta from the left ventricle and the pulmonary artery from the right ventricle.
4. This process is influenced by factors such as preload (the degree of stretch of cardiac muscle fibers) and afterload (the resistance the heart must overcome to eject blood).
5. Proper functioning during ventricular ejection is essential for maintaining adequate blood pressure and ensuring efficient circulation throughout the body.

Review Questions

• How does ventricular ejection relate to other phases of the cardiac cycle, particularly systole?
  • Ventricular ejection is a crucial part of systole, specifically occurring after isovolumetric contraction. During systole, the ventricles contract to increase pressure, leading to ventricular ejection when this pressure exceeds that in the arteries. This relationship highlights how effective contraction during systole enables efficient blood flow to both systemic and pulmonary circuits.
• Discuss how factors like preload and afterload affect ventricular ejection and its efficiency.
  • Preload refers to the amount of blood in the ventricles before contraction, which influences how much can be ejected during ventricular ejection. A higher preload usually increases stroke volume due to more significant stretching of cardiac fibers. Afterload, on the other hand, is the resistance against which the ventricles must work to eject blood. High afterload can reduce the efficiency of ventricular ejection by making it harder for the heart to pump effectively, impacting overall cardiac output.
• Evaluate how measuring stroke volume and ejection fraction can provide insights into cardiac health related to ventricular ejection.
  • Stroke volume and ejection fraction are critical metrics for assessing cardiac health, especially concerning ventricular ejection. Stroke volume quantifies how much blood is pumped with each heartbeat, while ejection fraction represents this volume as a percentage of total ventricle capacity. Analyzing these values can reveal issues like heart failure or valve problems; for instance, a reduced ejection fraction may indicate that the heart isn't pumping effectively, prompting further investigation into underlying conditions affecting ventricular performance.

Related terms

systole:

The phase of the cardiac cycle when the heart muscle contracts, resulting in the pumping of blood from the chambers.

diastole: The phase of the cardiac cycle when the heart muscle relaxes, allowing the chambers to fill with blood.

stroke volume:

The amount of blood pumped by the left ventricle of the heart in one contraction, which is significantly influenced by ventricular ejection.