Hemodynamics (Assignment)

Question 1

Define cardiac output

Answer 1

The amount of blood pumped by the heart per minute.

Question 2

Define blood flow

Answer 2

The volume of blood flowing through a given tissue at any period of time (mL/min).

Question 3

What does cardiac output equal?

Answer 3

Cardiac Output = Total Blood Flow

Question 4

Calculate cardiac output

Answer 4

Cardiac Output = Heart Rate x Stroke Volume

Question 5

What are the two factors that cardiac output depend on?

Answer 5

Pressure difference and resistance

Question 6

What generates blood pressure?

Answer 6

Contraction of the ventricles

Question 7

Where does blood flow?

Answer 7

From an area of high pressure to an area of low pressure.

Question 8

What is blood pressure?

Answer 8

The hydrostatic pressure exerted on the walls of blood vessels.

Question 9

What determines blood pressure?

Answer 9

Cardiac output
Blood volume
Vascular resistance

Question 10

Remember…

Answer 10

Blood pressure drops as blood moves further from the heart.

Question 11

Define mean arterial pressure (MAP)

Answer 11

The average blood pressure in an artery.

Question 12

How can MAP be calculated?

Answer 12

MAP = Diastolic + 1/3 x (Systolic - Diastolic)

Question 13

Calculate CO using MAP

Answer 13

CO = MAP/Resistance

Question 14

Calculate MAP using CO

Answer 14

MAP = CO x Resistance

Question 15

CO increases, what does MAP do (provided resistance remains steady)?

Answer 15

Increases

Question 16

CO decreases, what does MAP do (provided resistance remains steady)?

Answer 16

Decreases

Question 17

Blood volume decreases modestly, what does blood pressure do?

Answer 17

A modest decrease can be compensated for by homeostatic mechanisms.

Question 18

Blood volume decreases due to a haemorrhage, what does blood pressure do?

Answer 18

Decreases because there is less blood flowing through the arteries per minute (decreased CO).

Question 19

Blood volume increases due to water retention, what does blood pressure do?

Answer 19

Increases (consider increased CO).

Question 20

Define vascular resistance

Answer 20

The opposition to blood flow due to friction between the blood and the walls of the blood vessels.

Question 21

What does vascular resistance depend on?

Answer 21

• Blood vessel lumen
• Blood viscosity
• Total blood vessel length