Lecture 14 - CO, BP, VR

Question 1

cardiac output is equal to what

Answer 1

heart rate x stroke volume

Question 2

cardiac index is equal to what

Answer 2

cardiac output / BSA

Question 3

stroke volume is determined by

Answer 3

preload, contractility, afterload

Question 4

what are the 4 determinants of cardiac output

Answer 4

1. heart rate
2. preload
3. contractility
4. afterload

Question 5

describe preload

Answer 5

all factors contributing to passive ventricular wall stress or tension at the end of diastole

Question 6

what is the most important factor in stretching cardiac muscle

Answer 6

venous return

Question 7

what are the 3 outcomes of the frank-starling mechanism

Answer 7

1. regulating moment to moment changes in SV
2. responsible for balancing outputs of L and R ventricles
3. prevents “back-up” of blood on one side of the heart

Question 8

Venous return is equal to

Answer 8

the difference in mean systemic filling pressure and right atrial pressure

Question 9

increased venous return will ____ ventricular filling and ____ stronger contractions

Answer 9

increase; increase

Question 10

what 4 factors influence venous return

Answer 10

1. blood volume
2. venous compliance
3. skeletal muscle pump
4. respiratory pump

Question 11

T/F: an increase in venous return will increase cardiac output

Answer 11

TRUE

Question 12

what are 4 things used to estimate preload

Answer 12

1. venous return
2. hydration/dehydration
3. pressure in atria/ventricle
4. central venous pressure

Question 13

what is compliance

Answer 13

relationship of V / P and the distensibility of ventricles

Question 14

T/F: a compliant ventricle is stiff

Answer 14

FALSE - easily stretched

Question 15

why would ventricles lose compliance

Answer 15

1. ischemia
2. age
3. heart disease
4. infiltrative disease

Question 16

if a ventricle is ______ it will require higher pressure to fill

stiff or compliant

Answer 16

stiff

Question 17

describe afterload

Answer 17

• tension generated in ventricular myocardium for ejection
• inversely proportional to stroke volume

Question 18

how is the afterload estimated

Answer 18

1. ventricular myocardial wall tension
2. systemic vascular resistance
3. diastolic BP

Question 19

T/F: systolic arterial BP is a good index of afterload

Answer 19

FALSE

Question 20

define contractility

Answer 20

the speed with which myocytes would contract if no load were placed on the heart

Question 21

contractility will increase due to the increase in what

Answer 21

calcium

Question 22

stroke volume and contractility are ____ related

Answer 22

directly; increase/decrease with each other

Question 23

B1 adrenergic receptors

Answer 23

• binds epinephrine and norepinephrine
• increases intracellular calcium

Question 24

decreased contractility is a mark of

Answer 24

cardiac disease (DCM, myocarditis)

Question 25

contractility is estimated by

Answer 25

1. LV ejection fraction
2. LV change in diameter

Question 26

T/F: heart rate and pulse rate are different

Answer 26

TRUE

Question 27

T/F: acetylcholine causes a negative chronotropic effect

Answer 27

TRUE

Question 28

pressure drop across the vascular bed is

Answer 28

the product of cardiac output and systemic vascular resistance

Question 29

systolic BP

Answer 29

highest pressure during ventricular systole

Question 30

diastolic BP

Answer 30

the lowest pressure during ventricular diastole

Question 31

Mean arterial pressure

Answer 31

organ perfusion pressure; correlates with diastolic value

Question 32

normal blood pressure in dogs

Answer 32

120/80 (90)

Question 33

what must be the mean arterial pressure to maintain organ perfusion

Answer 33

60 mmHg

Question 34

what are the determinants of blood pressure

Answer 34

1. cardiac output
2. peripheral vascular resistance
3. blood volume
4. blood viscosity
5. elastic or arterial walls

Question 35

how is BP directly measured

Answer 35

arterial catheter

Question 36

how is BP indirectly measured

Answer 36

doppler flow
oscillometric BP