Session 6

Question 0

If TPR is constant but cardiac output decreases what happens to the pressure in arteries and veins?

Answer 0

Arterial pressure decreases

Venous pressure increases

Question 1

If TPR is constant but cardiac output increases what happens to the pressure in arteries and veins?

Answer 1

Arterial pressure increases

Venous pressure decreases

Question 2

If cardiac output is constant but TPR increases what happens to the pressure in arteries and veins?

Answer 2

Arterial pressure increases

Venous pressure decreases

Question 3

If cardiac output is constant but TPR decreases what happens to the pressure in arteries and veins?

Answer 3

Arterial pressure decreases

Venous pressure increases

Question 4

What is the ventricular compliance curve?

Answer 4

Shows the relationship between the venous pressure and ventricular volume

Question 5

What is starlings law of the heart?

Answer 5

If muscle is stretched before contracting, it contracts harder. More the heart fills up, the harder it contracts (within reason) therefore the bigger the stroke volume.

Question 6

What is the starling curve?

Answer 6

Relates stroke volume to venous pressure. The slope represents contractility.

Question 7

Define contractility

Answer 7

Ability of the heart fibres to contract

Question 8

Contraction

Answer 8

Realisation of the ability to contract

Question 9

What determines the end systolic volume?

Answer 9

How hard the hard contracts and how hard it is to eject the blood

Question 10

What factors determine the force of contraction?

Answer 10

End diastolic volume and contractility

Question 11

What is an aortic impedance?

Answer 11

Difficulty in ejecting blood from the left ventricle

Question 12

What factors affect aortic impedance?

Answer 12

Depends mainly on TPR (if TPR increases then arterial pressure increases therefore its harder to push in).

Question 13

What will the end systolic volume be if the arterial pressure is low?

Answer 13

Low. Systolic volume will be high.

Question 14

Describe what would happen to the stroke volume if the venous pressure increased and if the arterial pressure increased

Answer 14

Venous - increase in stroke volume

Arterial - decrease in stroke volume

Question 15

Where is the carotid sinus located?

Answer 15

Carotid bifurcation in carotid artery

Question 16

What does a fall in arterial pressure do?

Answer 16

Increases heart rate by decreasing parasympathetic activity and increasing sympathetic activity. Increases contractility by increasing sympathetic activity.

Question 17

What is the bainbridge reflex?

Answer 17

An increase in heart rate due to an increase in central venous pressure. Increased blood volume is detected by stretch receptors (baroreceptors) located in both atria at the venoatrial junctions.

Question 18

What can contractility be affected by?

Answer 18

Neurotransmitters, hormones or drugs acting on myocardium

Question 19

What are pre-load and after-load?

Answer 19

Pre-load - end diastolic stretch (venous pressure determines this)
After-load - when blood is expelled into arteries (force necessary to do this). Determines what happens during systole.

Question 20

If heart rate increases with no other change then what would happen?

Answer 20

Initially CO rises, but TPR stays the same. Increase in CO, decrease in venous pressure therefore stroke volume falls and CO goes back to original value.

Question 21

Describe the changes to blood supply to skeletal when exercising

Answer 21

Pre-capillary sphincters open up allowing huge amounts of blood to be available to them muscles (goes from a high TPR to low TPR). Veins surrounding the skeletal muscle become compressed.

Question 22

When is there a risk of pulmonary oedema?

Answer 22

When the output from the RHS of the heart doesn’t match the output of the LHS.

Question 23

How is overfilling of the ventricles prevented?

Answer 23

Increasing heart rate which occurs as exercise begins. Thus when venous pressure increases the heart rate is already high therefore keeping stroke volume down.

Question 24

What happens when someone stands up?

Answer 24

Blood pools in the superficial veins of the legs due to gravity therefore central venous pressure decreases. Superficial veins are affected because they are surrounded by air which is less dense than the deep veins which are surrounded by water-logged tissues.

Question 25

What is postural hypotension?

Answer 25

Decrease in blood pressure due to standing up. It occurs because of a compromise of the reflexes which keep blood pressure constant.

Question 26

What does a long term increase in blood volume do?

Answer 26

Venous pressure increases, CO increases therefore arterial pressure increases. More blood goes to tissues. Autoregulation and increased TPR therefore arterial pressure increases more.

Question 27

What is auto-transfusion?

Answer 27

Fluid tends to move from extra cellular space into circulation

Question 28

What do diuretics do?

Answer 28

Alter sodium balance by interaction with hormonal control of kidney