Cardiac Output

Question 1

Cardiac output

Answer 1

the amount of blood that is pumped out the heart each minute

Question 2

Easy way to calculate cardiac output

Answer 2

HR x SV

Question 3

Hard way to calculate cardiac output

Answer 3

thermal dilution

Question 4

Frank Starling Law of heart

Answer 4

as heart muscle stretches, it builds tension, allows for heart to contract more strongly when more blood is added to it, up to the point where the heart muscle dilates, and its contractility decreases which is dangerous because then blood volume into the heart is high, but the amount being pumped out is low

Question 5

How does frank starling match cardiac output to venous return

Answer 5

the more blood that comes in, the more the heart stretches, the more blood it pumps out

Question 6

How does frank starling match the cardiac output of the right heart to the cardiac output of the left heart

Answer 6

the more blood teh right heart pumps out, the more blood comes into the left heart, resulting in the left heart pumping out more blood

Question 7

How does frank starling compenstate for slight variations in the heart rate under resting conditions

Answer 7

as heart rate increases, stroke volume decreases and vice verse

Question 8

Why are there numerous frank starling curves depending on the level of sympathetic or parasympathetic stimulation

Answer 8

due to inotropic factors, force of contractino increases and decreases independent of volume, this can change stroke volume without changing the volume coming in

Question 9

negative inotropic

Answer 9

decreases force of contractions

Question 10

postivie inotropic

Answer 10

increases the force of contractions

Question 11

examples of positive inotropic agents

Answer 11

epinephrine, norepinephrine

Question 12

How does left ventricular end diastolic volume and left ventricular end systolic volume change during exercise

Answer 12

LVEDV increases and LVESV decreases, increasing SV and CO

Question 13

How does norepinephrine and epinephrine effect the heart

Answer 13

Epi and NE both stimulate beta-1 which increase heart contractility, HR, glycogenolysis and Ca++ permeability, all of these effects increase CO

Question 14

Why are ischemic hearts prone to diastolic failure

Answer 14

they are unable to actively pump Ca++ at a sufficient rate in order to relax properly, ventricular compliance will be reduced

Question 15

Mean systemic filling pressure

Answer 15

average pressure in circulation that is the driving force for venous return

Question 16

What are 3 factors that alter mean system filling pressure

Answer 16

increased blood volume, sympathetic tone, and venous massage

Question 17

How do you calculate venous return

Answer 17

mean system filling pressure - right atrial pressure