Vascular Control I & II

Question 1

The cardiovascular system is a ______ system.

Answer 1

closed

Question 2

Blood input should ____ output or in other words venous return should _____ cardiac output (since this is a closed system) in a steady state. These both have the units of _______. For instance, is cardiac output increases during a marathon, venous return must ______ also.

Answer 2

Blood input should equal output or in other words venous return should equal cardiac output (since this is a closed system) in a steady state. These both have the units of volume/min. For instance, is cardiac output increases during a marathon, venous return must increase also.

So on graphs, when I see venous return, think Cardiac Output.

Question 3

Describe cardiac preload & afterload

Answer 3

Preload is the pressure due to the amount of stretch at the end of inflow in the ventricle (starlings law). It is determined by ventricular end diastolic volume. Preload is directly proportional to stroke volume. Preload = central venous pressure.

Afterload is the pressure needed to be generated by the ventricle to eject blood. It is the end systolic ventricular pressure

Question 4

What is the function of the arterioles in the body?

Answer 4

They determine systemic vascular resistance (they have the highest resistance) & afterload.

Question 5

What is the function of the capillaries in the body?

Answer 5

Diffusion of nutrients, O2, ATP, glucose, etc.

Question 6

What is the function of the venous 2 compartments in the body?

Answer 6

1) The central venous compartment determines preload.
2) The peripheral venous compartment holds the most blood, due to its increased compliance.

Functionally, you can think of them as 2 diff systems because if pressure is greater in one of them, flow will follow in that direction.

Question 7

The function of arteries is to act as ______ for the blood.

Answer 7

conduits

Question 8

The central venous compartment consists of

Answer 8

the heart.

Whatever comes into the central venous compartment, must come out as CO.

Question 9

The peripheral venous compartment consists of

Answer 9

venous system after the capillaries & before the heart

Question 10

If the heart is not beating, most of the blood will _______ in the venous circulation, due to its _____ compliance.

Answer 10

pool

increased

Question 11

Right atrial pressure is the same as

Answer 11

central venous pressure

Question 12

Jugular venous pressure from the _______ can help us determine ______. If jugular venous pressure is high then ____ & ____ is also high.

Answer 12

external jugular

preload & central venous pressure

central venous pressure

left ventricular end diastolic volume & pressure

It is preferable to examine the internal rather than external jugular veins since the internal jugular veins are in a direct line with the superior vena cava and right atrium whereas the external jugular veins are not in a direct line with the superior vena cava and connect with it after negotiating two almost 90 degree angles

Question 13

If you are hypotensive, the jugular veins will be

Answer 13

flat & non-distende–since the barometer (external jugular) is low

Central venous catheters can get central venous pressure also via the internal jugular (medicine can be given through it too).

Question 14

If the central venous pressure is equal to the peripheral venous pressure, what would happen?

Answer 14

No flow would occur due to no pressure gradient

Question 15

What are the typical pressures in the central & peripheral venous compartments? With these values, what is the venous return?

Answer 15

Peripheral = 7mmHg

Central = 0mmHg

venous return = 7 L/min (from graph)
- See pg. 8

Question 16

Mean arterial pressure or MAP is typically?

Answer 16

100 mmHg

Question 17

If we stop someones heart, their MAP will _______ 0mmHg because _________. Therefore the MAP will be ________.

Answer 17

not equal

there is a reservoir of blood in the veins (& other vessels) giving a BP

7mmHg due to the peripheral venous pressure being this value = mean systemic filling pressure

Question 18

1) Define mean systemic filling pressure.
2) Therefore, if I remove blood from a patient, their mean systemic filling pressure will _______. Conversely, if I give them blood their mean systemic filling pressure will _______, even if their heart is not beating.

Answer 18

1) The pressure that is exerted by the total body volume that is in the circulatory system. Mean systemic filling pressure is defined as the pressure in the blood vessels during cardiac arrest. It is an important determinant for venous return to the heart and thus for cardiac output.
2) Therefore, if I remove blood from a patient, their mean systemic filling pressure will decrease. Conversely, if I give them blood their mean systemic filling pressure will increase, even if their heart is not beating.

Question 19

If we decreased a patient’s central venous pressure (by taking blood from their peripheral venous compartment) to 4 mmHg, what would happen? How would the curve initially shift?

Answer 19

NOTE: by taking blood from the peripheral venous compartment there is a decrease in the pressure gradient into the central venous compartment. Therefore, the flow & venous return decreases.

The venous return would initially decrease & shift the curve left because the peripheral venous compartment pressure would decrease. If the X axis decreases so does the y axis.

See pg. 9

Question 20

If you are losing blood, the body will adjust by _______ venous tone, which increases venous return to the heart & it will shift the curve _____.

Answer 20

increasing

right

See pg. 9

Question 21

If you increase the blood volume or venous tone on the curve on pg. 9 the curve shifts _____, & if you decrease blood volume or venous tone you shift it to the _____.

Answer 21

If you increase the blood volume or venous tone on the curve on pg. 9 the curve shifts right, & if you decrease blood volume or venous tone you shift it to the left.

Question 22

The arterioles regulate the circulatory system & the ______ circulation.

Answer 22

The arterioles regulate the circulatory system & the venous circulation.

Question 23

Arteriolar vasoconstriction ______ venous return & arteriolar vasodilatation ______ venous return with ______ in mean systemic filling pressure. If you _____ your arterioles, you increase stroke volume.

Answer 23

decreases

increases

no change

vasodilate

Mean systemic filling pressure does not change in vasodilation or vasoconstriction because it is only shifting or redistributing blood & no blood is being lost. Mean systemic filling pressure only changes when there is an increase or decrease in blood volume. Therefore, if I remove blood from a patient, their mean systemic filling pressure will decrease.

Question 24

The units for CO & venous return are

Answer 24

liters/ min, since it is a flow

Question 25

1) Stroke volume =

2) If you increase end systolic volume, what happens to stroke volume

Answer 25

end diastolic volume - end systolic volume

1) SV = EDV - ESV
2) it decreases

Question 26

If you vasodilate the arterioles, it is _____ for the left ventricle to pump against the new lower resistance so the ESV ______ & afterload _______. Therefore, stroke volume ______ & cardiac output ______.

Answer 26

If you vasodilate the arterioles, it is easier for the left ventricle to pump against the new lower resistance so the ESV decreases & afterload decreases. Therefore, stroke volume increases & cardiac output increases.

SV = EDV - ESV

CO = HR x SV

Afterload is the pressure needed to be generated by the ventricle to eject blood. It is the end systolic ventricular pressure

see pg. 14

Question 27

Arteriolar vasoconstriction or vasodilation _______ change peripheral venous compartment volume or Mean systemic filling pressure since ______.

Answer 27

does not

Mean systemic filling pressure = peripheral venous compartment

Question 28

Describe the Frank Starling curve

Answer 28

If you increase filling pressure & stretch the myocytes, you have greater cardiac output. In other words, if preload is high, you have a greater stroke volume & cardiac output.

See figure on pg. 10

Question 29

Describe the equillibrium point between the Starling curve & the venous function curve: It is the equilibrium that the body goes to so that cardiac output or venous return is _____ & @ rest, central venous pressure is ______.

Answer 29

It is the equilibrium that the body goes to so that cardiac output or venous return is 5 L/min & @ rest, central venous pressure is 2mmHg.

See figure on pg. 10

Question 30

Increased contractility via sympathetic activity (norepi) shifts the starling curve ______ & decreased contractility shifts the starling curve to the _____.

Answer 30

left & up

right & down

See figure on pg. 11

Question 31

If someone has an MI, the Starling or normal cardiac function curve shifts ____.

Answer 31

right & down

A person with heart failure’s cardiac output will decrease to shift down

To keep central venous pressure, the curve will also shift right. They try to increase venous return to increase cardiac output.

See figure on pg. 10 & starling curve in problems folder

Question 32

Analyze figure on pg. 11

Answer 32

-

Question 33

Dr Dhamoon has been called in for an emergency and WILL NOT be presenting his lecture at 9am today. This lecture is officially CANCELLED. As a consequence, we will limit the number of unit exam questions for Vascular Control I&II to a total of 2 only (not 4).

Answer 33

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