CVS- Control of Cardiac Output Flashcards
What is pressure in the veins a balance of?
Rate at which blood enters veins
Rate at which heart pumps blood out
What is arterial pressure determined by?
Cardiac output
Total peripheral resistance
What happens to arterial and venous pressure if TPR falls?
Arterial pressure falls
Venous pressure rises
What happens to arterial and venous pressure when cardiac output increases?
Arterial pressure rises
Venous pressure falls
What is TPR inversely proportional to?
The body’s need for blood
What do the pressure changes in the arteries and veins bring about?
Changes to cardiac output
What is cardiac output the product of?
Stroke volume and heart rate
What is stroke volume?
The difference between end diastolic pressure and end systolic pressure,
When to the ventricles stop filling in diastole?
Until the walls stretch to produce an intraventricular pressure equal to venous pressure.
What makes the contraction of the ventricles stronger?
Ventricular muscle stretching
What is starlings law?
The more the heart fills the harder it contracts
‘More is equal to more’
What is the slope of starlings law known as?
Contractility
What is the relationship contractility demonstrates?
Venous pressure vs stroke volume
Where does contractility level out?
At high venous pressure once the ventricle can’t fill anymore.
What is the force of contraction determined by!
End diastolic volume
Contractility
What increases contractility?
Sympathetic activity
What does the ability to eject blood mainly depend on?
TPR
What happens to stroke volume if arterial pressure falls?
The end systolic volume falls and stroke volume rises
How is autonomic flow to the heart controlled?
By baroreceptors in the carotid sinus
What do baroreceptors do?
They sense arterial pressure and send signals to the medulla
What is the bainbridge reflex?
Rises in venous pressure detected in the right atrium leads to reduced PS activity and so a rise in HR,
Describe what happens when eating a meal
Increased activity of the gut leads to vasodilation
Total peripheral resistance falls
Venous pressure rises –> rise in cardiac output
Arterial pressure falls –> boosted by CO.
