Lecture 14: Cardiac output and blood flow in muscle tissues

Question 1

Coronary artery blood flow during diastole

Answer 1

Cardiac muscle relaxes and no longer obstructs blood flow through the left ventricular capillaries

Question 2

Non cardiac factors causing decreased cardiac output

Answer 2

Decreased blood volume
Acute venous dilation
Obstruction of large veins
Decreased tissue mass
Decreased metabolic rate of tissues

Question 3

Factors that cause hypoeffective heart

Answer 3

Increased arterial pressure
Inhibition of nervous excitation of heart
Pathological factors causing abnormal heart rate
Coronary artery blockage
Valvular heart disease
Congenital heart disease
Cardiac hypoxia

Question 4

Primary controller of coronary flow

Answer 4

Local muscle metabolism

Question 5

What increases vascular volume

Answer 5

Infusion of blood or activation of renal-angiotensin-aldosterone system

Question 6

Cardiac index equation

Answer 6

Cardiac output/body surface area =3L/min/m2 usually

Question 7

Stroke volume equation

Answer 7

Cardiac output/heart rate

Question 8

Venous return equation

Answer 8

Mean systemic filling pressure - right atrial pressure/ resistance to venous return

Question 9

Sympathetic vasoconstrictor nerves do what

Answer 9

Secrete norepinephrine

Can decrease blood flow through resting muscle to as little as one half to one third normal

Question 10

Bainbridge reflux

Answer 10

Atrial stretch reflex

Responds to changes in blood volume as detected by stretch receptors in right atrium

Question 11

Mean circulatory filliing pressure =__ when blood volume is 4L, and when 5L

Answer 11

0 when 4L

7mm Hg when 5L

Question 12

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

Answer 12

The amount of blood returning to the heart

Question 13

Maximal sympathetic stimulation does what to cardiac output and venous return

Answer 13

Increases both

Question 14

What increases venous compliance

Answer 14

Inhibit sympathetics
Alpha block
Venodilators
Standing upright

Question 15

What decreases venous compliance

Answer 15

Sympathetic stimulation
Muscle pump
Exercise
Laying down

Question 16

Increase in blood volume would shift the vascular function curve to the ____, cardiac output and right atrial pressure would both _____

Answer 16

Right- both cardiac output and right atrial pressure are increased

Question 17

What decreases the vascular volume

Answer 17

Hemorrhage
Burn trauma
Vomiting
Diarrhea

Question 18

Mass discharge of the sympathetic nervous system causes

Answer 18

Heart rate increases
Most peripheral arteries are strongly contracted BESIDES coronary/cerebral arteries
Muscle walls of veins are contracted- increases mean systemic filling pressure

Question 19

Decrease/increase in resistance do what to venous return

Answer 19

Decrease in resistance increases venous return

Increase in resistance decreases venous return

Question 20

Pressure gradient for venous return is

Answer 20

The difference between the mean systemic filling pressure and the right atrial pressure

Question 21

Factors that affect venous return to the heart from systemic circulation – what curve are these 3 factors quantitatively expressed in

Answer 21

Right atrial pressure
Mean systemic filling pressure
Blood flow resistance b/w peripheral vessels and right atrium

Expressed in venous return curve

Question 22

Strong sympathetic stimulation or inhibition do what to mean systemic filling pressure

Answer 22

Increases with sympathetic stimulation

Decreased with sympathetic inhibition

Question 23

Coronary artery blood flow during systole

Answer 23

Coronary blood flow in the left ventricle falls to a low vaue

Question 24

Spinal anesthesia does what to cardiac output and venous return

Answer 24

Decreases venous return and cardiac output

Question 25

Factors causing hypereffective heart

Answer 25

Nervous stimulation Hypertrophy of the heart Excercise

Question 26

Venous return =__ when right atrial pressure is 7

Answer 26

0

Question 27

The highest level that the right atrial pressure can rise is

Answer 27

Equal to the mean systemic filling pressure

Question 28

Cardiac output equation

Answer 28

O2 consumption/ Systemic arterial [O2] - systemic mixed venous [O2]

Question 29

If right atrial pressure reaches -2, venous return..

Answer 29

Reaches a plateau, caused by collapse of veins entering chest

Question 30

Large blood flow during skeletal muscle activity is due mainly to

Answer 30

Chemicals that act directly on muscle arterioles to dilate them Reduction in oxygen ATP CO2

Question 31

Increasing mean systemic filling pressure does what to vascular return curve

Answer 31

Shifts it to the right

Question 32

The greater the difference between _____________, the greater the venous return

Answer 32

Difference between the mean systemic filling pressure and right atrial pressure

Question 33

Ways to increase mean systemic filling pressure

Answer 33

Increase vascular volume | Decrease venous compliance

Question 34

Coronary artery occlusion causes death by

Answer 34

Decreased cardiac output Damming of blood in pulmonary vessel and death resulting from pulmonary edema Fibrillation of heart Rupture of heart

Question 35

Cardiovascular system is connected in series which means

Answer 35

Flow must be equal in the two circuits Cardiac output and rate of two circuits are equal All pressures are higher in the systemic circuit

Question 36

Frank starling law

Answer 36

Heart automatically pumps whatever amount of blood that flows into the right atrium

Question 37

Factors that directly affect cardiac output

Answer 37

Basic level of body metabolism Whether the person is exercising Age Size of body

Question 38

Ohms law

Answer 38

Any time the long term level of total peripheral resistance changes, the cardiac output changes quantitatively in the exact opposite direction

Question 39

Cardiac factors causing decreased cardiac output

Answer 39

``` Severe blood vessel blockage-->myocardial infarction Severe valvular disease Myocarditis Cardiac tamponade Cardiac metabolic derangements ```

Question 40

Mean systemic filling pressure equals

Answer 40

Right atrial pressure when there is no flow in the cardiovascular system

Question 41

Under most normal non-stressful conditions, the cardiac output is controlled by

Answer 41

Peripheral factors that determine venous retrun