3.7 -- Cardiac Output Flashcards
What is the equation for cardiac output?
Stroke volume x heart rate
What is cardiac output?
Amount of blood ejected per minute by each ventricle
What is an intrinsic factor of heart rate?
Autorhythmic (pacemaker) activity
What is an extrinsic factor of heart rate?
Autonomic signals modulate pacemaker rate
What is an intrinsic factor of stroke volume?
Frank-Starling relationship
What is an extrinsic factor of stroke volume?
Autonomic signals – Sympathetic NS modulates contraction strength, preload (venous return and filling volume), and afterload (aortic pressure)
What do tissues care about?
Cardiac output
What is the average heart rate, stroke volume, and cardiac output? What is the average cardiac output equivalent to?
70 bpm, 70-80 ml per beat, 5,500 ml/minute which is equivalent to total blood volume
Is the cardiac output of the left ventricle equal to the right ventricle?
Yes
The lungs get 100% of the cardiac output from which ventricle while the other organs share the cardiac output of which ventricle?
Right and left
The pulmonary circulation has what flow and what pressure?
High flow, low pressure
The systemic circulation has what flow and what pressure?
Shared flow and higher pressure
What is the mean arterial pressure for the pulmonary and systemic circulations?
10-20 mmHg for pulmonary, 70-105 mmHg for systemic
Spontaneous depolarization occurs at the SA node when HCN channels open, allowing what in?
Na+ in
Channels are open due to what at the end of the preceding action potential, which is controlled by cardiac center of medulla oblongata that is affected by higher brain centers?
Hyperpolarization
Sympathetic norepinephrine/epinephrine open more HCN channels, doing what to heart rate?
Increasing heart rate
Parasympathetic acetylcholine opens K+ channels, doing what to heart rate?
Decreasing heart rate
Does the sympathetic nerve effects of the AV node increase rate of diastolic depolarization and increase cardiac rate or increase conduction rate?
Increase conduction rate
Does the sympathetic nerve effects of the SA node increase rate of diastolic depolarization and increase cardiac rate or increase conduction rate?
Increase rate of diastolic depolarization and increase cardiac rate
Electrical activity regulates what?
Contractile activity
Regulation of stroke volume is regulated by what three things?
Preload, afterload, and contractility
What does the Frank-Starling Law of the Heart say?
An increase in end-diastolic volume results in increased contraction, thus resulting in increased stroke volume
Filling the heart with more fully with blood, increased stretch of the what stretches myocytes, optimizing overlap between actin and myosin filaments, making SV increases?
Ventricles
Maximum tension is generated when muscle is between what percentage of its resting length?
100-120%
