Cardiac output and venous return

Question 1

What are the 3 definitions or caridac output?

Answer 1

1. quantity of blood pumped into the aorta each minute by the heart
2. quantity of blood that flows through the circulation
3. sum of all the blood flows to all of the tissues of the body

Question 2

How would you define cardiac index?

Answer 2

Cardiac output per square meter of body surface

Question 3

What is the relationship between cardiac index and age?

Answer 3

Cardiac index peaks around 10 yrs and begins to decline as one ages

Question 4

What is the relationship between cardiac output, cardic index, and oxygen consumption during exercise?

Answer 4

They all increase relative to the amount of work/exercise you are doing

Question 5

Why would you uses the Fick principle of blood flow?

Answer 5

To calculate blood flow through an organ.

Question 6

According to the Fick principle of blood flow, what equation would you use to calculate cardiac output?

Answer 6

Cardiac output = O₂ Consumption / [O₂] _{pul vein} - [O₂] _{pul art}

• Measure oxygen consumption for the whole body
• measure pulmonary vein [O2] in systemic arterial blood
• measure pulmonry artery [O2} in systemic mixed venous blood

Question 7

How are cardiac output, stroke volume, and heart rate related?

Answer 7

CO = SV x HR

Question 8

What is the determining factor that controls how much blood the heart pumps out?

Answer 8

• Venous return
• it is the amount of blood returning to the heart that determines how much blood the heart pumps out

Question 9

The cardiovascular system consists of two pumps and two circuits that are connected in ________?

Answer 9

Series

Question 10

What are the 2 pumps of the cardiovascular system?

Answer 10

The left and right ventricles

Question 11

Name the two the circuits of the cardiovascular system.

Answer 11

1. Pulmonary circuit
2. Systemic circuit

Question 12

Because the 2 circuits of the cardiovascular system are in series what must be true about flow in the 2 circuits?

Answer 12

Flow must be equal in the 2 circuits

Question 13

Because the 2 circuits of the cardiovascular system are in series, what is the relationship between cardiac output and flow of the 2 systems?

Answer 13

Cardiac output and rate of the 2 systems of the two circuits are equal

Question 14

Because the 2 circuits of the cardiovascular system are connected in series, what relationship exists between the pressures of the 2 circuits?

Answer 14

All pressures are higher in the systemic circuit

Question 15

Because the 2 circuits of the cardiovascular system are in series, the chemical composition os pulmonary venous blood is similar to that of _________ _________ blood?

Answer 15

Systemic arterial

Question 16

Because the 2 circuits of the cardiovascular system are in series, the chemical composition of venous blood entering the right atrium is the same as the composition of _______ ________ blood?

Answer 16

Pulmonary arterial

Question 17

Name 3 of the 4 factors that directly affect cardiac output.

Answer 17

1. Basic level of body metabolism
2. Whether the person is exercising
3. Age
4. Size of the body

Question 18

What are the normal cardiac output values for healthy young men, women, and the resting adult?

Answer 18

• healthy young men- 5.6 L/min
• Women - 4.9 L/min
• Resting adult 5.0 L/min

Question 19

Summarize the Frank-Starling law of the heart

Answer 19

The heart autoomatically pumps whatever amount of blood that flows into the right atrium.

Question 20

Stretching of the heart causes the heart to pump ______?

Answer 20

Faster

Question 21

Stretching of the right atrium initates nervous reflex called what?

Answer 21

The Bainbridge reflex (increases heart rate)

Question 22

Under most normal non-stressull conditions, the cardiac ouput i controlled almost entirly by _________ factors that determine _______ ________?

Answer 22

Peripheral, venous return

Question 23

What are the most imortant controllers of cardiac output?

Answer 23

Peripheral factors

Question 24

How does Ohm’s law summarize the control of cardiac output?

Answer 24

Anytime the long-term level of total peripheral resitance changes (but no other functions of the circulation change), the cardiac output changes qantitatively in exactly the opposite direction

20-4

Question 25

What two reflexes control heart rate?

Answer 25

1. The bainbridge reflex 2. The baroreceptor relex

Question 26

How are the Bainbridge reflex and the barorecepto reflex different from each other?

Answer 26

* Bainbridge reflex (atrial stretch)---responds to changes in blood volume as detected by stretch receptors in the right atrium * Baroreceptor reflex--- responds to changes in arterial pressure

Question 27

As total peripheral resistance increases cardiac output \_\_\_\_\_\_\_\_?

Answer 27

decreases 20-4

Question 28

How are cardiac output, arterial pressure, and total peripheral resistance related?

Answer 28

Cardiac output = Arterial pressure / Total peripheral resistance 20-4

Question 29

As arterial pressure increases cardiac output \_\_\_\_\_\_\_\_\_?

Answer 29

increases

Question 30

List 2 of the 3 factors that cause a hyperefective heart

Answer 30

1. Nervous stimulation 2. Hypertrophy of the heart 3. Exercise via the nervous system

Question 31

Summarize why exercise via the nervous system causes a hypereffective heart?

Answer 31

* Intense increase in metabolism in active skeletal muscle causes the muscle arterioles to relax * This allows more blood into these arterioles * The brian sends motor signals to the muscle and to the ANS centers of the brain to excite circulatroy activty * This causes large vein constrictiono * This leads to increased heart rate, and increased contractility of the heart

Question 32

Name 4 of the 7 factors that cause a hyporeffective heart

Answer 32

1. increased arterial pressure (hypertension) 2. inhibition of nervous excitation of the heart 3. pathological factors causing abnormal heart rythm/rate 4. coronary artery blockage 5. valvular heart disease 6. congenital heart disease 7. cardiac hypoxia 20-5

Question 33

List 3 of the 5 factors that cause decreased cardiac output.

Answer 33

1. severe blood vessel blockage----\>myocardial infarction 2. severe valvular disease 3. myocarditis 4. cardiac tamponade 5. cardiac metabolic arrangements

Question 34

Beriberi causes a(n) _________ cardiac output as the result of _________ total peripheral resitance?

Answer 34

increased, reduced (chronically)

Question 35

An arteriovenous (AV) fistula (shunt) causes _________ cardiac output as a result of _________ total peripheral resistance?

Answer 35

Increased, reduced (chronically)

Question 36

Hyperthyroidism causes ________ cardiac output as a result from _________ total resistance?

Answer 36

Increased, reduced (chronically)

Question 37

Anemia causes __________ cardiac output as a result of ________ total peripheral resistance?

Answer 37

increased, reduced (chronically)

Question 38

Decreased skeletal muscle mass causes __________ cardiac output as a result from decreased ________ \_\_\_\_\_\_\_\_\_?

Answer 38

decreased, venous return

Question 39

Decreased metabolic rate (hypothyroidism) causes decreased ________ \_\_\_\_\_\_\_\_ as a result from ________ venous return?

Answer 39

cardiac output, decreased

Question 40

Name 3 of the 5 NON-CARDIAC factors that cause a decreased cardiac output

Answer 40

1. Decreased blood volume 2. acute venous dilation 3. obstruction of large veins 4. decreased tissue mass (especially muscle mass) 5. decreased metabolic rate of tissues

Question 41

The greater the difference betweeen the mean systemic filling pressure and the _______ \_\_\_\_\_\_\_ pressure, the greater the venous return

Answer 41

right atrial

Question 42

What is the difference between the mean systemic filing pressure and the right atrial pressure?

Answer 42

Pressure gradient for venous return

Question 43

About 2/3 of the resistance to venous return is determined by ________ \_\_\_\_\_\_\_\_?

Answer 43

venous resistance

Question 44

About 1/3 of the resistance to venous return is determined by ________ and _______ \_\_\_\_\_\_\_ resistance?

Answer 44

arteriolar, small artery

Question 45

What equation would you use to calculate venous return?

Answer 45

venous return = (systemic filling pressure - right atrial pressure) / Resistance to venous return VR= (Psf-PRA) / RVR

Question 46

Name 4 of the 6 chemicals that are responsible for stimulating large blood flow by dilating muscle arterioles during skeletal muscle activity

Answer 46

1. reduction in O2 2. adenosine 3. potassium ions 4. ATP 5. Lactic acid 6. Carbon dioxide