Which of the Following is Most Likely to Increase Ejection

Question

Which of the following is most likely to increase ejection fraction?
A) Activation of beta1-adrenergic receptors
B) Vagal discharge
C) Blockade of beta1-adrenergic receptors
D) Activation of the muscarinic receptors

Accepted Answer

Activation of beta1-adrenergic receptors is most likely to increase ejection fraction because it leads to increased contractility of the heart muscle. This can improve the ability of the heart to pump blood out of the left ventricle and increase the ejection fraction, which is the percentage of blood that is pumped out of the ventricle with each beat.