Lecture 15: Regulation of Cardiac Output (Hayward)

Question 1

cardiac output =

Answer 1

flow. L/min CO = SV * HR **MEMORIZE

Question 2

parasympathetic or sympathetic input to heart is more quickly reversed?

Answer 2

parasym.

Question 3

Increases in HR are coupled with changes in :

Answer 3

ventricular function

Question 4

Positive lusitropic effects –> HR and rate of relaxation

Answer 4

increases both

Question 5

chronotropic effect

Answer 5

changes HR. Positive chronotropic effect = increased HR

Question 6

lusotropic effect relates to

Answer 6

contractility

Question 7

inotropic effect

Answer 7

regulates myocardial performance.

Intrinsic regulation via cardiac muscle
Extrinsic regulation via external force (hormones, sympathetic innervation, pH, etc.)

Question 8

Actin and myosin interact during

Answer 8

muscle contraction

Question 9

functional unit of a muscle

Answer 9

sarcomere

Question 10

How does stretch in cardiac tissue prior to systole impact contractility?

Answer 10

SOME stretch increases capacity to generate force, but too much stretch generates less force

Question 11

Active tension in cardiac muscle is dependent on:

Answer 11

starting length of the sarcomeres at the time of activation

Question 12

Total tension +

Answer 12

passive + active tension

Question 13

preload

Answer 13

the stretch on the cardiac muscle that occurs during the relaxed state. Determines the force generated by the cardiac muscle for the subsequent contraction (length-tension relationship)

Question 14

afterload

Answer 14

P in the outside of the system that heart must work against (i.e. aortic pressure)

Question 15

end-diastolic volume

Answer 15

volume load during diastole

Question 16

Frank-Starling effect

Answer 16

relationship between muscle length and force generated. Uses the intrinsic properties of the muscle w/o any outside influence. Important mech. for equalizing outputs between R and L ventricles

Question 17

main force ventricles have to overcome during volume ejection (isotonic contraction phase)

Answer 17

aortic pressure

Question 18

isotonic contraction

Answer 18

muscle shortens when total muscle force exceeds external load

Question 19

increased aortic pressure –> stroke volume ?

Answer 19

decreases

Question 20

end-systolic length of muscle after contraction is directly related to –>

Answer 20

AFTERLOAD and contractility (not preload!)

Question 21

decreased aortic pressure –> stroke volume?

Answer 21

increases

Question 22

contractility

Answer 22

performance of the heart at a given preload and afterload. Determined by changes in intracellular Ca and rate of contractile protein interaction

Question 23

inotropic changes ***

Answer 23

changes in contractility **

Question 24

Increased NE –> contractility

Answer 24

increases (because more Ca is released) INOTROPIC EFFECT

Question 25

ischemia

Answer 25

lack of perfusion

Question 26

Thyroid hormone —> Ca reuptake and hypertrophy

Answer 26

Enhances both

Question 27

Increased CO2 –:> myocardial performance

Answer 27

declines (due to lower pH)