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Physiology > [2] Lecture 13: CO And Blood Flow In Muscle Tissues > Flashcards

[2] Lecture 13: CO And Blood Flow In Muscle Tissues Flashcards

1
Q

Quantity of blood pumped into the aorta each minute but the heart.

Quantity of blood that flows through the circulation

Sum of all the blood flows to all of the tissues of the body

A

Cardiac output

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2
Q

Cardiac output per sq. Meter of body surface

A

Cardiac index

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3
Q

Calc norm cardiac index

A

70 kg
Body surface area: 1.7 sq. m
CO: 5L

5L /1.7 =3L min/m^2

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4
Q

Through life, cardiac index increases til about age _____ and decreases from there on

A
  1. Indicative of declining muscle mass and/ or activity w/ age
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5
Q

Increasing levels of execise:

A

Increase oxygen consumption and CO and CI

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6
Q

Used to calc blood flow through an organ

A

Flick principle of blood flow

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7
Q

Flick principle formula:

A

CO= O2 consumption / [O2] pul.vein - [O2] pul.artery

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8
Q

Patient has a resting O2 consumption of 250 mL/min
Systemic arterial O2 content of 0.20 mL O2 /mL of blood Systemic mixed venous O2 content of 0.15 mL O2 /mL of blood Heart rate of 72 beats/min

CO?
SV?

A

5L;

70 ml

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9
Q

Determining factor controlling how much heart pumps out?

A

Based on ‘demand’

Pumps out what is pumped in

Amt. blood returning to heart determines how much is pumped out

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10
Q

CV system:

A

2 pumps and 2 circuits

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11
Q

What are the 2 CV pumps?

A

L and r side of heart

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12
Q

What’re the 2 circuits of CV system?

A

Pulmonary and systemic circuits

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13
Q

The CV circuits are connected in :

A

Series

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14
Q

2 things same and 1 different in pul. And systemic Circuits of CV system:

A

Flow and CO is equal

Pressures are different…higher in systemic

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15
Q

Chemical composition of Paul. Venous blood and systemic arterial is

A

Similar,

Same venous blood entering r atrium is same as Pul. Arterial blood

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16
Q

Factors affecting CO (4):

A

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

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17
Q

WNL CO values:

A

Young healthy men: 5.6 L/min

Women: 4.9L/min

Resting adult: 5L/min

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18
Q

Heart automatically pumps whatever amt. of blood that flows into R atrium

A

Frank-starling law

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19
Q

What initiates bainbridge reflex?

A

Stretched R atrium

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20
Q

Strecthing heart causes:

A

Heart to pump faster

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21
Q

Most important factors in controlling heart:

A

Peripheral system factors primarily control CO

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22
Q

Anytime a long-term level of TPR changes CO changes quantitatively in exactly the oppo direction

A

Ohm’s law

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23
Q

MOst important controller of CO:

A

Peripheral factors

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24
Q

2 reflexes that control heart rate

A

Bainbridge and baroreceptor reflexes

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25
Q

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

A

Bainbridge reflex

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26
Q

Respond to changes in arterial pressure

A

Baroreceptors

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27
Q

After birth, what happens to mother who recently delivered baby:

A

Tachycardia, b/c of blood return form uteroplacental return that activates bainbridge reflex

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28
Q

Is bainbridge considered detrimental to humans?

A

No, its not significant in humans

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29
Q

Formula for CO:

A

CO = Art. Pressure / TPR

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30
Q

Factors casing hypereffective heart:

A

Nervous stimulation
Hypertrophy
Exercise via the NS

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31
Q

Hyper effective heart:

A

Too effective

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32
Q

Exercise effect on CV:

A

Increase in metabolism=arterioles relax;
Allows more blood into these arterioles;
Brain sends motor signals to the muscles and ANS centers of the brain to excite circulatory activity;
Causes large vein constriction;
Leads to increased HR and contractility

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33
Q

Factors to hypoeffective heart:

A 
Increased arterial pressure;
Inhibition of NS excitation;
Pathological factors causing abnormal HR;
CAD blockage;
Valvular heart Dz;
Congenital heart Dz; 
Cardiac hypoxia
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34
Q

As ventricles fill in response to higher atrial pressures,e ach ventricular volume and stretch of cardiac muscle contraction also increases in CO….what is this called?

A

Ex of frank-starling mechanism

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35
Q

Factors decreasing CO

A 
Severe vessel blockage- MI
Severe valvular Dz
Myocarditis
Cardiac tamponade
Cardiac metabolic arrangements
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36
Q

Non-cardiac factors leading to decreased CO

A 
Decreased blood volume
Acute venous dilation
Obstruction of large veins 
Decreased tissue mass (muscle mass)
Decreased metabolic rate of tissues
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37
Q

what is req’d to maintain CO?

A

Nervous control/maintenance

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38
Q

Factors that affect venous return to heart from systemic circulation:

A

Right atrial pressure

Degree of filing of systemic circulation

Resistance to blood flow

39
Q

When venous return is 0 (mean systemic filling pressure)

A

This is when right atrial pressure =+7 mm Hg

40
Q

Pressures everywhere in the body become equal

A

Mean circulatory filling pressure

41
Q

The greater the difference btw the mean systemic filling pressure and right atrial pressure:

A

The greater the venous return

42
Q

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

A

Pressure gradient for venous return

43
Q

Mean systemic filing pressure - R atrial pressure

/
Resistance to venous return

=

A

Venous return

44
Q

2/3 of resistance to venous return is determined by venous resistance b/c of

A

Vein distensibility. There is little rise in venous return

45
Q

About 1/3 of the resistance to venous return is determined by arteriolar and small artery resistance d/t

A

Accumulation of blood overcomes Munich of the resistance

46
Q

Impedes flow of blood from veins into r atrium

A

R atrial pressure

47
Q

Forces systemic blood toward heart

Pressure when atrial and venous pressure come to equilibrium and systemic circulation flow comes to a stop (=7mm Hg)

A

Mean systemic filling pressure

48
Q

Thiamine deficiency. Reduced peripheral resistance

This causes heart failure by means of high cardiac output

A

Beriberi

49
Q

fusion of artery and vein leads to a lowering in peripheral resistance….causes increased CO

A

Atriovenous fistula

50
Q

Elevated levels of hormone induces vasodilation of circulatory beds supplying muscle and skin.

Reduced peripheral resistance

This leads to an increase in CO

A

Hyperthyroidism

51
Q

This decrease causes a lowered afterload effect

Reduced peripheral resistance

This increases CO

A

Anemia

52
Q

The loss of this tissue req’s less circulation b/c there is less tissue

This decreases CO

A

Decreased skeletal muscle mass

53
Q

This condition req’s less nutrient transportation to tissues leading to decrease in CO

A

Decreased metabolic rate

54
Q

Where R atrial pressure = mean systemic filling pressure, venous return =

A

0

55
Q

What does the plateau of venous return graph signify?

A

Caused by collapse of large veins entering chest when R atrial pressure < ATM pressure

This is good b/c it is maximizing CO @ approx. -2 mm Hg

56
Q

What constricts all the systemic and pulmonary blood vessels and the chambers of the heart and leads to increased mean circulatory filling pressures?

What kind of shift is this?

A

Strong sympathetic stimulation

This is a shift to the left?

57
Q

What relaxes all the systemic and pulmonary blood vessels and the chambers of the heart and leads to decreased mean circulatory filling pressures.

A

Complete sympathetic INHIBITION

This causes a shift to the Right

58
Q

What happens to venous return when R arterial pressure increases?

A

Venous return decreases

59
Q

What happens w/ blood flow (venous return) when resistance decreases?

A

More venous return

60
Q

What is the highest level to which the R atrial pressure can rise is

A

Equal to the mean systemic filling pressure

61
Q

As resistance decreases= venous return __________

A

Increases

62
Q

What function is shown as the cardiac output curve?

A

Ventricular function

63
Q

What does the point at which venous return curve and CO curve insect signify?

A

The amount of blood pumped is = the amt. of blood returned.

64
Q

Measured when the heart is stopped experimentally

R atrial pressure when there is “no flow” in the CV system

CO and venous return= 0

Pressure is equal throughout the CV system

A

Mean systemic filling pressure

65
Q

what effect does increased blood volume have on mean systemic pressure ?

What shift happens on vascular function curve?

What does this do to CO and R atrial pressure?

A

Increases

Shifts to the right

Increases CO and R atrial pressure

66
Q

A decrease in blood volume has what effect on mean systemic pressure?

What type of shift in vascular function curve?

What is the effect on CO and R atrial pressure?

A

Decreases mean systemic pressure

Shifts the vascular function curve to the left

Decreases CO and R atrial pressure

67
Q

How to increase vascular volume:

A

Infusion

Activation of renin-aldosterone system

68
Q

Ways to decrease venous compliance (3):

A

Sympathetic stimulation

Muscle pump exercise

Lying down

69
Q

What could cause decrease in vascular volume:

A

Hemorrhage
Burn trauma
Vomiting
Diarrhea

70
Q

Ways to increase venous compliance:

A

Inhibit sympathetic
Alpha block
Venodilator
Standing upright

71
Q

What vascular event would increase filling of the ventricles?

Decrease filling of ventricles?

A

Increase mean systemic filling pressure

Decreasing would decrease filling of ventricles

72
Q

Equilibrium shifts to a higher CO and a correspondingly lower R atrial pressure.

R atrial pressure decreases b/c there’s increased SV

A

Positive inotropic effect

73
Q

Equilibrium shifts to a lower CO and a correspondingly higher R atrial pressure

A

Negative inotropic effect

74
Q

Large blood flow during skeletal muscle activity is d/t mainly chemicals that act directly on muscle arterioles to dilate them

A

Local controls

75
Q

Ex of local controls

A 
Reduction in oxygen 
Adenosine 
K+ ion
ATP lactic acid
CO2
76
Q

Controls that affect blood flow through skeletal muscles:

A

Local controls

Nervous controls

77
Q

Nervous controls in blood flow regulation:

A

Sympathetic

Adrenal medullae

78
Q

Secrete norepinephrine

Can decrease blood flow through resting muscles to as little as 1/2 to 1/3 normal

A

Sympathetic vasoconstrictor nerves

79
Q

Secretes norepinephrine and epinephrine

Epinephrine also has slight vasodilator effect

A

Adrenal medulla

80
Q

3 effects of mass discharge of sympathetic nervous system:

A
  • HR increases
  • most peripheral arteries are strongly contracted except: those in active muscles, coronary arteries and cerebral arteries
  • muscle walls of veins are contracted: increases mean systemic filling pressure
81
Q

How does sympathetic stimulation increase arterial pressure

A

Vasoconstriction of arterioles and small arteries in most tissues

Increased pumping activity in heart

Increase in mean filing pressure caused mainly by venous contraction

82
Q

Effects of muscle exercise on blood flow in the calf:

A

C=blood flow increases and decreases between contractions

83
Q

Exercise has what effect on CO and venous return?

A

Increases

84
Q

coronary arteries:

A

RCA, LAD, Left circumflex

85
Q

Coronary blood flow in the left ventricle falls to a low value during:

A

Systole

86
Q

Coronary blood flow is _______ to flow in vascular beds elsewhere in body

A

Opposite

87
Q

The cardiac muscle relaxes and no longer obstructs blood flow the rough the left ventricular capillaries during:

A

Diastole

88
Q

Coronary arteries are perfused during which cardiac cycle?

A

Diastole

89
Q

Coronary arteries show

A

Inverse phasic changes

90
Q

What is primary controller of coronary flow?

A

Local muscle metabolism

91
Q

Coroconary flow increases in direct proportion to:

A

additional metabolic consumption of O2 by heart

92
Q

Direct ANS stimulation acts on:

Indirect acts on:

A

blood vessels themselves

Cardiac muscle stissue and indirectly on the coronary vessels via local control mechanisms

93
Q

Causes of death after acute coronary occlusion:

A
  • Decreased CO
  • Damming of blood in pulmonary blood vessels and death resulting from pulmonary edema
  • fibrillation of heart
  • rupture of heart
94
Q

Areas of ischemic myocardium are at risk of

A

Systolic stretch

Physiology (10 decks)

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