Unit 1 - CV System The Heart PART G

Question 1

Cardiac Output

Answer 1

Volume of blood ejected by each ventricle over time (i.e. rate at which each ventricle pumps blood)

Question 2

What is cardiac output determined by?

Answer 2

Determined by the rate at which the ventricles contract (HEART RATE) and the volume of blood pumped per contraction (STROKE VOLUME).

Question 3

If average heart rate at rest is 72 beats/min and average stroke volume at rest is 70 mL/beat, then average cardiac output is:

Answer 3

5040 mL/min or ~5.0 L/min

Question 4

During exercise, cardiac output can increase up to ____

Answer 4

5x

Question 5

Cardiovascular athletic training/exercise can further increase cardiac output (up to ______

Answer 5

40 L/min).

Question 6

What does Cardiovascular athletic training/exercise do?

Answer 6

Training increases heart muscle mass (which increases stroke volume), and decreases resting heart rate (maximal heart rate stays the same). Overall training increases the difference between resting and exercise values of both heart rate and stroke volume, resulting in higher cardiac output during exercise

Question 7

What is cardiac output a measure of?

Answer 7

cardiac performance

Question 8

How do you measure cardiac output?

Answer 8

Heart rate x Stroke volume = cardiac output

Question 9

Cardiac output is the SAME for BOTH ventricles. BUT, if 1 side of the heart begins to fail (unable to pump efficiently), CO becomes mismatched. So…

Answer 9

blood pools in the circulation behind the WEAKER side of the heart

Question 10

Stroke Volume =

Answer 10

EDV - ESV

Question 11

End Diastolic Volume (EDV) =

Answer 11

amount of blood in each ventricle at the end of the ventricular relaxation period and, just prior to the start of ventricular contraction. On average, at rest = 135mL.

AKA volume of blood BEFORE contraction

Question 12

What is End Diastolic Volume (EDV) on average, at rest?

Answer 12

On average, at rest = 135mL.

Question 13

End Systolic Volume (ESV) =

Answer 13

amount of blood left in each ventricle just after ventricular ejection. On average, at rest = 65 mL.

AKA volume of blood AFTER contraction

Question 14

What is End Systolic Volume (ESV) on average, at rest?

Answer 14

On average, at rest = 65 mL.

Question 15

Therefore average resting stroke volume =

Answer 15

135 mL – 65 mL = 70 mL

Question 16

During the cardiac cycle, the EDV is the _______ ventricular volume, and ESV the _______ ventricular volume.

Answer 16

MAXIMUM

MINIMUM

Question 17

The precise values of these maxima and minima can vary depending on conditions (e.g. during exercise…

Answer 17

EDV stays the SAME or INCREASES; and ESV DECREASES, allowing for at least the maintenance or an increase in stroke volume at higher heart rates).

Question 18

Both stroke volume and heart rate are variable and can be modified by both the nervous and endocrine systems and other mechanisms. As a result,…

Answer 18

the body can adjust cardiac output by changing either the heart rate or stroke volume (or both) to respond to the body’s needs

Question 19

Ejection fraction

Answer 19

the volume of blood ejected from the ventricle in 1 contraction = ejection fraction (% of EDV ejected with 1 contraction (STROKE VOLUME/EDV)

Ex:
EDV = 70 mL
SV = 135 ml
therefore, 70/135 = 52% –> ventricle is ejecting 52% of the blood that was in it @ the end of relaxation & filling