6 Control of Cardiac Output and Responces of the System Flashcards
What happens arterial and venous pressure when cardiac output INCREASES?
Venous pressure falls
Arterial pressure rises
What is the relationship between TPR and the body’s blood needs?
Inversely proportional
The more the body needs blood, the lower the TPR
What happens to the TPR after a meal is eaten?
After a meal, more blood is needed in the gut. Local vasodilators dilate the arterioles causing the TPR to fall.
What is ‘stroke volume’?
The difference between the end diastolic volume and the end systolic volume
What does the ventricular compliance curve show?
The relationship between venous pressure and the amount the heart fills in diastole.
What is Starlings Law?
The more the heart fills, the harder it contracts so the larger the stroke volume.
What does the Starling curve show?
What is the slope known as?
The relationship between stroke volume and venous pressure
The slope is known as the contractility of the ventricle
Where are rises in venous pressure detected?
The right atrium- leads to reduced parasympathetic activity- increases heart rate
Bainbridge reflex
List 3 things that happen to the CVS during exercise
Increase in demand
Muscle pumping compresses veins- increased venous pressure
Arterial pressure falls
What happens if the venous pressure increases too quickly?
The heart is overfilled. The right side pumps more than the left side causing fluid to accumulate in the lungs. Fluid is pushed into the surrounding tissues- pulmonary oedema.
How is overfilling of the ventricles prevented?
Rise in heart rate driven by the brain
What happens to central venous pressure when you stand up?
Pressure decreases
Blood pools in the superficial veins in the legs due to gravity
On standing up, both arterial and venous pressure drops. How is this corrected?
Baroreceptors detect the fall of arterial pressure which raises the heart rate.
The TPR is increased to keep arterial pressure to the skin and the gut.
What happens to the CVS when a patient haemorrhages?
Which areas are at risk?
The blood volume decreases so venous pressure falls. Cardiac output and arterial pressure also fall.
Heart rate and TPR are increased. This makes the problem worse.
Risk to the brain and kidneys
What happens when there is a long term increase in blood volume?
Venous pressure increases. Cardiac pressure increases. Arterial pressure rises.
TPR increases to compensate
