W6 - CV Function & Growth

Question 1

Define Ejection fraction

Answer 1

Fraction of EDV that is the SV.

Question 2

Ejection Fraction at rest

Answer 2

~60-70%

Question 3

SV

Answer 3

Vol of blood expelled by the heart per beat

mL

Question 4

How is SV calculated

Answer 4

Preload-Afterload

EDV - ESV

Question 5

What does SV represent

Answer 5

Difference between the vol of blood in the ventricles before contraction + that remaining after contraction.

Question 6

When is SV greater and by how much?

Answer 6

25% greater in the supine than seated position

Question 7

Why is SV greater in a certain position above the other?

Answer 7

Consequence of venous return in the seated position.

Due to blood pooling in the lower extremities due to the effects of gravity.

• Direct comparison should only be made between data collected in similar body positions.

Question 8

Define preload

Answer 8

Vol of blood in the ventricles before contraction (EDV)

Question 9

Define after load

Answer 9

Vol of blood left in ventricles after contraction. (ESV)

Question 10

What is Resting CO closely related to?

Answer 10

O2 uptake

Question 11

What is critical for determining SV?

Answer 11

Venous return

Due to heart only being able to pump out the vol of blood it receives from the systemic circulation.

Question 12

What is the most commonly used method to remove body size, cardiac index and SV index?

Answer 12

Indexing against body surface area

Question 13

What determines HR?

Answer 13

Adrenaline

SNS

Parasympathetic NS

Question 14

Why does resting SV increase with age?

Answer 14

Due to increase in body size, not contractile function.

Question 15

What does absolute SV increase with?

Answer 15

Body size

Question 16

Absolute resting SV increases with what

Answer 16

Body mass (r=0.81)

Surface area (r=0.9-1.0)

Question 17

Absolute resting CO increases with what

Answer 17

Body mass (r=0.7)

Surface area (r=0.6-0.7)

Question 18

How is normalisation of SV most commonly done?

Answer 18

Using the ratio standard approach as body surface area as the size denominator.

Question 19

What increases HR

Answer 19

SNS

Circulating adrenaline

Question 20

What decreases HR

Answer 20

Parasympathetic NS through the release of ACh