Stroke Volume Influences
What is preload?
The volume of blood in the ventricle at the end of diastole and primarily reflects venous return.
What is the pressure under which a ventricle fills called?
Preload
Blood Pressure is defined as?
The pressure that the blood exerts against the walls of the arteries as it passes through them.
What is cardiac output by definition?
The amount of blood that is pumped by the ventricles in one minute.
What is Heart Rate by definition?
The number of cardiac contractions per minute (pulse rate)
What is afterload?
The force against which the ventricles must contract to eject blood.
True or False: The ventricles are never completely emptied of blood with any single heartbeat?
True
Measuring blood pressure is one method to evaluate the effectiveness of?
Cardiac Output
What is stroke volume by definition?
The amount of blood pumped out by either ventricle in a single contraction (heartbeat)
What is the ml range for a healthy adult, blood pumped out in a single beat?
60-100 ml
What is stroke volume directly influenced by?
Preload, afterload, and the contractile state (contraction or relaxation) of the myocardium.
When cardiac muscle is stretched, it contracts with a greater force, up to a limit- a property called?
Frank Starling mechanism or Starlings Law
What is systemic vascular resistance?
The resistance to blood flow within all blood vessels except the pulmonary vessels.
What is the normal cardiac output for an average adult?
5-6 liters/minute
What is ejection fraction?
The percentage of blood the leaves the heart each time it contracts.
What is afterload directly influenced by?
Arterial BP, arterial distensibility, and arterial resistance.
Which system regulates the contractility of the heart from heartbeat to heartbeat?
The nervous system.
What determines the resistance to the flow of blood?
The diameter of the blood vessel and the tone (the normal state of balanced tension in body tissues) of the vascular musculature. "Think widened or narrowed"
What equation equals cardiac output?
Stroke Volume x heart rate.
Which Ventricle is the primary pump for the heart?
The left ventricle.
What is arterial distensibility?
The stretching ability of the arteries.
The Frank Starling system is under nervous system control, true or false?
False, this mechanism is an intrinsic property of heart muscle making it not under nervous system control.
What is the normal ejection fraction range of the left ventricle in an adult?
55-70%
Cardiac Output math- If SV is 70ml and HR is 80 beats/min, what is Cardiac Output?
5.6 liters/minute.
The heart must be able to increase its output in response to changes in the body's demand for oxygen. What is one activity that increases & one activity that decreases the body's demand for O2?
Exercise would increase and sleep would decrease.