CVS Session 6 (Lecture 6.1)

Question 1

What factors increase arterial pressure and determine it?

Answer 1

Increased cardiac output and increased TPR

Question 2

What factors determine pressure in veins?

Answer 2

Rate at which blood enters and rate at which heart pumps it out

Question 3

What occurs if CO remains constant and TPR falls to arterial and venous pressure?

Answer 3

AP - Falls

VP - Increases

Question 4

What occurs if CO remains constant and TPR rises to arterial and venous pressure?

Answer 4

AP - Increases

VP - Falls

Question 5

What occurs if TPR remains constant and CO rises to arterial and venous pressure?

Answer 5

AP - Increases

VP - Falls

Question 6

What occurs if TPR remains constant and CO falls to arterial and venous pressure?

Answer 6

AP - Falls

VP - Increases

Question 7

What is TPR inversely proportional to?

Answer 7

Body demand for blood

Question 8

What is meant by demand-led pumping? How is it expressed?

Answer 8

If the body needs more blood, the heart pumps more to meet the demand.

Expressed as changes in arterial and venous pressure

Question 9

What is stroke volume the difference between?

Answer 9

End diastolic volume - End systolic volume

remember heart fills in diastole

Question 10

What is the intra-ventricular pressure equal to? Explain?

Answer 10

Equal to venous pressure as during diastole the ventricles fill, so are reliant on the venous pressure. The higher the venous pressure the more the heart fills.

Question 11

Describe the ventricular compliance curve? Draw it out.

Answer 11

Relationship between venous pressure and ventricular volume.

Question 12

What is Starling’s law?

Answer 12

The more the heart fills in diastole, the harder it contracts so the bigger the SV as the ventricular walls are stretched.

Rises in VP lead to increased SV

Question 13

What is the Starling curve? Draw it

Answer 13

Relates SV to venous pressure

Slope is the contractility of the ventricle (not same as FOC)

Question 14

What occurs at the top, flat portion of the graph?

Answer 14

Heart cannot stretch anymore due to pericardium holding the heart in place. This decreases the FOC

Question 15

What affects the end systolic volume?

Answer 15

How hard the heart contracts

How hard it is to eject

Question 16

What determines the FOC? How is contractility increased?

Answer 16

End diastolic volume and contractility

Increased by sympathetic activity

Question 17

If it is harder to eject blood into the arteries what will the AP do?

Answer 17

Rise

Question 18

If it easier to eject blood in systole, what occurs to AP, ESV and SV

Answer 18

AP - falls
ESV - falls (systolic volume)
SV - increases

Question 19

What occurs to SV if VP rises or AP falls?

Answer 19

Increases (VP is the dominant variable)

Question 20

Where is the carotid sinus? What exists there and where does it sends signals to?

Answer 20

At the bifurcation between the internal and external carotid arteries.
Baroreceptors to medulla controlling HR

Question 21

If arterial pressure falls how does the carotid sinus respond?

Answer 21

Senses fall in AP therefore increases HR by increasing sympathetic and decreasing parasympathetic sactivity to the heart.

Increases contractility by increasing sympathetic activity.

Question 22

If venous pressure falls how does the heart respond?

Answer 22

Increased VP
Sensed in RA
Lead to reduced PS activity
Rise in HR
Bainbridge reflex