1.2 Preload

Question 1

Congestive failure:

Answer 1

Tissue perfusion is maintained, but expense of high venous pressure.(high filling pressure)
- this leads to overwork —> heart failure

Question 2

Mitral disease:

Answer 2

Blood backs up in left ventricle —> goes to lungs —> this causes too much blood volume in lungs causing the patient to aspirate

Question 3

Clinical signs of congestive failure:

Answer 3

-Potbelly
-Panting
-Decrease in exercise

Question 4

What causes the clinical signs of congestive failure to occur?

Answer 4

• animal compensating over a long period of time
• switches on reflexes to maintain cardiac output that can drive oxygen to the tissues
• comes with expense of taking on more volume —> leads to high venous and filling pressure
• leads to high preload

Question 5

Reflexes:

Answer 5

Compensate for low, cardiac output
Ex: congestive HF = increase in blood volume
—> increase in preload

Question 6

Cardiac output:

Answer 6

Volume of blood pumped into Aorta per unit of time

Question 7

Venous output

Answer 7

Volume of blood that comes back to right atrium per unit of time

Question 8

What is stroke volume

Answer 8

Volume of blood coming out of left ventricle with each beat

Question 9

What is heart rate?

Answer 9

Number of times heart beats

Question 10

What does preload deal with?

Answer 10

Stretching of muscle

Question 11

What is preload dependent on?

Answer 11

end diastolic volume (volume in heart at the end of filling)

Question 12

When the heart contracts what happens to volume?

Answer 12

It decreases

Question 13

Ejection fraction =

Answer 13

SV/EDV
-Therapy wants to maintain ejection volume

Question 14

Ventricular end-diastolic volume:

Answer 14

Mechanical properties of cardiac muscle:
Can regulate stroke volume via:
- Increase in sympathetic activity
-Increase in hormones act in blood
Ex: adrenaline

Question 15

What effect does a sympathetic system have on the heart?

Answer 15

Makes the heart beat faster and harder

Question 16

If we can regulate stroke volume we can regulate

Answer 16

Cardiac output

Question 17

What is equation #2?

Answer 17

MAP = cardiac output X total peripheral resistance (TPR)
- This equation is dependent on cardiac output

Question 18

Preload:

Answer 18

The load of blood that is returning to fill that chamber prior chamber ejection
Ex: think about filling a balloon with water

Question 19

Central venous pressure (CVP):

Answer 19

Pressure that can be measured when all the blood is going back to right atrium
Ex: congestion/big jugular vein, = high pressure, and to high of preload

Question 20

Raised reservoir =

Answer 20

Ventricular filling increase

Question 21

What does this graph indicates?

Answer 21

That as volume/pressure increases —> work increases

Question 22

What can we measure when we go into the right side of the heart?

Answer 22

Central venous pressure
- important for regulating preload

Question 23

What two things affect central venous pressure?

Answer 23

1. Volume changes in CVP
2. Distribution of blood between arterial and venous circulation

Question 24

Increase in volume does what to pre-load?

Answer 24

Increases preload

Question 25

Decrease in volume does what to preload?

Answer 25

Decreases preload

Question 26

Distribution of blood is influenced by

Answer 26

Sympathetic nerves

Question 27

Distribution of blood example:

Answer 27

Long standing Palace guard =, decrease pre-load from lack of movement —> fainting

Question 28

What will happen if the venous system is squeezed?

Answer 28

This will encourage blood to go back to heart and increase CVP and stretch —-> increase in preload

Question 29

What influences ventricular filling??

Answer 29

1. fluid volume
2. Venous return
3. Venous tone aka squeeze
4. Stretch
5. Heart rate

Question 30

Baroreceptor reflex:

Answer 30

Regulates pressure:
- increase in volume —> increase in pressure
—>increase in baroreceptor that kicks on LARGE LOAD of reflex responses

• pressure needs to be brought down because of this

This is done via depressure reflex
- sympathetic is reduced to heart
- Decrease in SV/HR
- Decrease in CO
- less squeeze

Question 31

Parasympathetic nerve:

Answer 31

-Vagus nerve = parasympathetic nerve

Ex: supply to heart = vagus nerve, if we cut this nerve heart rate would increase

Question 32

True or false: blood volume affects blood pressure

Answer 32

True

Question 33

Renin–angiotensin–aldosterone system: decrease in volume leads to

Answer 33

Decrease in pressure = Renin produced
- Produces angiotensin II (can constrict blood vessels and increased resistance)
-This tells adrenal gland to make aldosterone (important in kidney function, retain sodium and water follows
- This leads to increase in volume and increase and prelude, which maintain CO & arterial pressure (MAP)

Question 34

What hormone regulates water balance in the body?

Answer 34

ADH

Question 35

What reflects can turn on ADH secretion?

Answer 35

Baroreceptor reflex
- Changes in baroreceptor area can affect ADH secretion, will be changing aldosterone at the same time

Question 36

Vasopressin =

Answer 36

ADH - squeezing blood vessels (vasoconstrictor molecule)

Question 37

What receptor sits in the atrial muscle

Answer 37

Atrial receptors / volume receptors

Question 38

Everything besides the ventricles has what

Answer 38

Low pressure

Question 39

Where do the baroreceptor sit? Why?

Answer 39

They sit in the arteries where the pressure is high

Question 40

Volume receptors =

Answer 40

Low pressure receptors

Question 41

Arterial volume receptors: increase in blood volume leads to increase in pressure causing reflux is to do what?

Answer 41

Reflexes will be trying to decrease the pressure:
This is done via
1. Inhibiting hormones like ADH
2. Inhibit sympathetic vasoconstrictor pathways to the kidneys leading to diuresis

Question 42

Hemorrhage =

Answer 42

Reduced preload