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level: Cardiac Function

Questions and Answers List

level questions: Cardiac Function

QuestionAnswer
Describe the cardiac cycleSystole - Blood flows passively from the atria to ventricles (Early Filling), followed by an atrial contraction (Late Filling). Diastole - The pulmonic and aortic valves open topermit blood flow from the ventricles into the pulmonary and systemic circulation. For there to be a cardiac output, the Left Ventriclemust develop enough pressure to open the aortic valve.
What is the formula for cardiac output?Formula: Cardiac output = stroke volume x heart rate Cardiac output = blood ejected from the left ventricle each minute Stroke volume = blood ejected from the left ventricle with each cardiac cycle.
What is the control of cardiac output?Most healthy individuals can increase their cardiac output 4 to 6-fold such as during exercise. Increases in cardiac output can be achieved through Intrinsic cardiac regulation of the output. Changes in heart rate via autonomic nervous system control.
What is the Frank-Sterling Mechanism and how does it relate to intrinsic cardiac regulation of output?Simply put: the greater the return of venous blood to the heart, the greater the subsequent output that can be achieved. Note: a useful addition to the effect of venous return on cardiac output is a reflex known as the Bainbridge Reflex, which stimulates an increase in HR with increased atrial stretch.
What is arterial pressure?Blood pressure therefore influenced by altered cardiac output and changes in vascular resistance. A major contributor of peripheral vascular resistance is sympathetic vasoconstrictor nerves Arterial pressure controlled acutely through baroreflex.
What is the formula for arterial pressure?Formula - Ohm’s Law: (Δ) Pressure = Flow x Resistance
Describe the cardiac responses to physiological stressors such as exercise.During exercise HR increases in proportion to metabolic demand. Stroke volume increases with the onset of exercise but plateaus after ~50% of peak workload Net effect is an increase in cardiac output in proportion to the degree of O2 demand.