How can the heart increase cardiac output?
Cardiac Output (CO) is represented as :
Stroke Volume (SV) x Heart Rate (HR).
So increased SV or HR or both will increase CO.
Cardiac output is amount of blood pumped by each ventricle per minute.
Several factors control heart rate including neurotransmitters and hormones. Physical exercise, emotional shock, etc. always lead to an increase in heart rate. Increased heart rate means an increase in cardiac output.
Amount of stroke volume is determined by amount of blood coming inside heart during diastole. According to Frank-Starling law larger the end diastolic volume of heart, more is the force of contraction to pump blood out. Hence more input means more output.