Flashcards in Control Of Cardiac Output Deck (24)
If cardiac output is fixed and total peripheral resistance falls, what will happen to arterial and venous pressure?
Arterial will fall and venous will rise.
If cardiac output is fixed and total peripheral resistance rises, what will happen to arterial and venous pressure?
Arterial will rise and venous will fall.
If total peripheral resistance is fixed and cardiac output falls, what will happen to arterial and venous pressure?
Arterial pressure falls and venous pressure rises
If total peripheral resistance is fixed and cardiac output rises, what will happen to arterial and venous pressure?
Arterial pressure rises and venous pressure falls.
What changes total peripheral resistance?
Extra point - how does it signal this?
A change in metabolism.
Extra point - in the form of arterial and venous pressure.
What is demand led pumping?
The heart responds to a decrease I'm arterial pressure and an increase in venous pressure by pumping more blood.
The higher the venous pressure, the more the heart fills. Why is this?
Extra point - what is this called?
In diastole the ventricle is connected to the veins only. This fills until the walls stretch enough to make the intra ventricular pressure = venous pressure.
Extra point - known as ventricular compliance curve.
What does Starings law state about the strength of heart contraction?
The more the muscle is stretched before contraction, the harder it will contract.
If the heart contracts harder, what happens to the stroke volume?
It will increase.
What does a rise in venous pressure do to the stroke volume?
What does the Starling curve relate to one another?
Stroke volume to venous pressure. (Known as contractility of ventricle)
What does the end systolic volume rely on?
How much the ventricle empties which depends on how hard it contracts and how difficult it is to eject the blood.
What does the force of contraction depend on?
Which branch of the ANS increases this?
The end diastolic volume and contractility.
Extra point - this is increased by sympathetic activation.
What is aortic impedance?
The difficulty of ejecting blood.
What does aortic impedance depend on?
Mainly on the total peripheral resistance.
If it easier to eject blood will more come out in systole or diastole?
Systole. *If arterial pressure falls, the end systolic volume will fall and stroke volume will rise*
What is the effect of an increased venous pressure on stroke volume?
The stroke volume will rise.
What is the effect of decreased arterial pressure on stroke volume?
Stroke volume will increase.
How is the autonomic outflow of the heart controlled?
By signals from Baroreceptors.
What senses arterial pressure?
The carotid sinus.
If there is a fall in arterial pressure, how is the heart rate increased?
By reducing parasympathetic activity and increasing sympathetic activity.
If there is a fall in arterial pressure, how is the contractility increased?
By increasing sympathetic activity.
If venous pressure rises, what is the effect on cardiac output?
It will rise.