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Physiology Exam 2: Lectures 8-16 > Lecture 14: Cardiac Output and Blood Flow in Muscle Tissues > Flashcards

Lecture 14: Cardiac Output and Blood Flow in Muscle Tissues Flashcards

1
Q

What is cardiac output?

A

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

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2
Q

What is cardiac index?

A

cardiac output per square meter of body surface

normal human cardiac index: 3 L/min/m^2

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3
Q

What is the flick principle of blood flow?

A

used to calculate blood flow through an organ

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4
Q

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

A

heart is demand pump
heart pumps out whatever blood comes back into it from venous system
amount of blood returning to the heart that determines how much blood the heart pumps out

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5
Q

What are the two pumps in the cardiovascular system?

A

left and right ventricles

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6
Q

What are the two circuits in the cardiovascular system?

A

pulmonary and systemic

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7
Q

_____ must be equal in the two circuits

A

flow, cardiac output and rate

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8
Q

All pressures are higher in the ________ circuit

A

systemic

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9
Q

Chemical composition in the pulmonary venous blood is similar to that of _______

A

systemic arterial blood

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10
Q

Chemical composition of venous blood entering the right atrium is the same as the composition of ____

A

pulmonary arterial blood

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11
Q

What factors directly affect cardiac output?

A

basic level of body metabolism
whether the person exercises
age
size of body

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12
Q

What is the normal cardiac output for men?

A

5.6 L/min

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13
Q

What is the normal cardiac output for women?

A

4.9 L/min

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14
Q

What is the normal cardiac output for a resting adult?

A

5 L/min

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15
Q

Under most normal non stressful conditions, cardiac output is controlled almost entirely by _____

A

peripheral factors that determine venous return

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16
Q

What is the Bainbridge reflex?

A

the atrial stretch reflex, responds to changes in blood volume as detected by stretch receipts in the right atrium

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17
Q

What do baroreceptors respond to?

A

changes in arterial pressure

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18
Q

What reflexes control heart rate?

A

bainbridge and baroreceptor

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19
Q

What factors causes hypereffective heart?

A

nervous stimulation
hypertrophy of heart
exercise via nervous system

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20
Q

what factors cause hypo effective heart?

A

increased arterial pressure
inhibition of nervous excitation of heart
pathological factors causing abnormal heart rhythm/rate
coronary artery blockage
valvular heart disease
congenital heart disease
cardiac hypoxia

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21
Q

What are the cardiac factors that can cause decreased cardiac output?

A 
severe blood vessel blockage--myocardial infarction
severe valvular disease
myocarditis
cardiac tamponade
cardiac metabolic derangement
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22
Q

What are the non cardiac factors that can cause decreased cardiac output?

A 
decreased blood volume
acute venous dilation 
obstruction of large veins
decreased tissue mass
decreased metabolic rate of tissues
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23
Q

What are factors that affect venous return to the heart from the systemic circulation?

A

right atrial pressure

degree of filing of systemic circulation

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24
Q

What is the mean systemic filling pressure?

A

venous return—0 when right atrial pressure— +7 mmHG

25
Q

If right atrial pressure is -2 mmHg, venous return reaches a ______ and is caused by ______

A

plateau, collapsed of veins entering chest

26
Q

When the heart pumping stops what happens?

A

all blood flow ceases, pressures everywhere in body become equal

27
Q

What is mean circulatory filing pressure

A

when pressures everywhere in body become equal,
= 0 when blood volume =4 L
=7 mmHg when blood volume = 5L

28
Q

The greater the difference between men systemic filing pressure and the right atrial pressure, the ________ the venous return

29
Q

The difference between the man systemic filling pressure and right atrial pressure = _______

A

pressure gradient for venous return

30
Q

What are the factors that affect venous return to the heart from the systemic circulation?

A

resistance to blood flow

venous return

31
Q

About ___ of the resistance to venous return is determined by venous resistance
About ___ of the resistance to venous return is determined by arteriolar and small artery resistance

32
Q

What is the equation for venous return?

A

(mean systemic filling pressure - right atrial pressure) / resistance to venous return

33
Q

What are factors that affect venous return?

A

right atrial pressure
mean systemic filling pressure
blood flow resistance between peripheral vessels and right atrium

34
Q

How does right atrial pressure affect venous return?

A

impedes flow of blood from veins into right atrium

35
Q

How does mean systemic filling pressure affect venous return?

A

forces systemic blood toward heart

pressure when arterial and venous pressures come to equilibrium and systemic circulation flow comes to a stop

36
Q

Decreases in resistance allows _______ while an increase in resistance ______

A

more blood to flow; has the opposite affect

37
Q

The highest level to which right atrial pressure can rise is equal to the

A

mean systemic filling pressure

38
Q

What can increase systemic filling pressure?

A

increase vascular volume

decrease venous compliance

39
Q

How can you increase vascular volume?

A

infusion or activation of renal-angiotensin-aldosterone system

40
Q

How do you decrease venous compliance?

A

sympathetic stimulation
muscle pump
exercise, lying down

41
Q

What does increasing systemic filling pressure result in?

A

shift in the vascular return curve to the right, enhances filling of the ventricles

42
Q

How do you decrease systemic filling pressure?

A

decrease vascular volume

increase venous compliance

43
Q

How do you decrease vascular volume?

A

hemorrhage
burn trauma
vomiting
diarrhea

44
Q

How do you increase venous compliance?

A

inhibit sympathetics
alpha block
venodilators
standing upright

45
Q

What happens when you decrease systemic filling pressure?

A

shift in vascular return curve to left

reduces filling of ventricles

46
Q

What is the positive inotropic effect?

A

equilibrium shifts to a higher cardiac output and a correspondingly lower right atrial pressure

47
Q

What is the negative inotropic effect?

A

equilibrium shifts to a lower cardiac output and a correspondingly higher right atrial pressure

48
Q

What are local controls that regulate blood flow to skeletal muscles?

A 
blood flow mainly due to chemicals that act directly on muscle arterioles to dilate them:
reduction in oxygen
adenosine 
potassium ion
ATP 
lactic acid
carbon dioxide
49
Q

What are nervous controls that regulate blood flow to skeletal muscles?

A

sympathetic vasoconstrictor nerves

adrenal medulla

50
Q

What does sympathetic vasoconstrictor nerves do?

A

secrete norepinephrine

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

51
Q

What does the adrenal medulla do?

A

secrete norepinephrine and epinephrine

52
Q

What does exercise do to blood flow to skeletal muscles?

A

mass discharge of sympathetic nervous system
heart rate increases
most perisperhal arteries are strongly contracted
muscles walls of veins are contracted

53
Q

during systole, coronary blood flow in the left ventricle ______

A

falls to a low value

54
Q

During diastole, cardiac muscles realize and no longer _______ through the left ventricular capillary

A

obstructs blood flow

55
Q

What is the primary controller of coronary flow?

A

local muscle metabolism

56
Q

Coronary flow increases in ______ proportion to additional metabolic consumption of oxygen by heart

57
Q

Direct ANS stimulation acts on ______

A

blood vessels

58
Q

Indirect ANS stimulation is on the ______ tissue and indirectly on the ______ via local control mechanisms

A

cardiac muscle; coronary vessels

59
Q

What causes death after acute coronary occlusion?

A

decreased cardiac output
damming of blood in pulmonary blood vessels and death resulting from pulmonary edema
fibrillation of heart that leads to rupture of heart and death

Physiology Exam 2: Lectures 8-16 (9 decks)

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