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Zak, Physiology > Exam 3: Lecture 12 > Flashcards

Exam 3: Lecture 12 Flashcards

0
Q

Define cardiac index

A

Cardiac output/square meter of body surface

*CI for normal human = 3L/min/m^2

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1
Q

Define cardiac output

A

1) Quantity of blood pumped into the aorta each minute
2) Quantity of blood that flows through circulation
3) Sum of all the blood flows to all tissues of the body

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2
Q

What are factors that control cardiac output?

A

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

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3
Q

What is the normal cardiac output value for young, healthy men?

A

5.6L/min

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4
Q

What is the normal cardiac output value for women?

A

4.9L/min

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5
Q

What is the normal cardiac output value for resting adults?

A

5.0L/min

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6
Q

What is the Frank-Starling law?

A

Heart will automatically pump whatever amount of blood flows into the right atrium

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7
Q

T/F: Peripheral factors are the most important controllers of cardiac output.

A

True, due to the Frank-Starling law

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8
Q

What is Ohm’s law?

A

Long-term changes in peripheral resistance levels cause cardiac output changes quantitatively in exactly the opposite direction

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9
Q

What is the Bainbridge reflex?

A

Controls HR along with baroreceptor reflex
a.k.a. Arterial Stretch Reflex
Responds to changes in blood volume as detected by stretch receptors in the right atrium

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10
Q

T/F: The Bainbridge reflex is only significant in humans immediately after birth.

A

True, because that is when a large volume of uteroplacental blood returns to the mother’s circulation and results in tachycardia

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11
Q

What is a hypereffective heart?

A

A heart functioning better than normal (athletic heart)

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12
Q

What are 3 factors that cause a hypereffective heart?

A

Nervous Stimulation
Hypertrophy of heart
Exercise via the nervous system

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13
Q

What is a hypoeffective heart?

A

A heart that is not functioning as well as it could

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14
Q

What are 7 conditions that lead to a hypoeffective heart?

A

1) Increased arterial pressure
2) Inhibition of nervous excitation of the heart
3) Coronary artery blockage
4) Congenital heart disease
5) Cardiac hypoxia
6) Valvular heart disease
7) Pathological factors

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15
Q

What are 4 conditions that cause increased cardiac output?

A

1) Beriberi
2) Atriovenous Fistula
3) Hyperthyroidism
4) Anemia

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16
Q

How does Beriberi increase cardiac output?

A

Caused by Vitamin B deficiency
Causes diminished ability of tissues to use some nutrients
Vessels vasodilate causing long-term venous return and cardiac output to rise

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17
Q

How does Atriovenous Fistula increase cardiac output?

A

Occurs when AV shunt placed between major artery and vein
Causes tremendous blood flow from artery into vein
Causes decreased peripheral resistance and increases venous return/cardiac output

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18
Q

How does Hyperthyroidism increase cardiac output?

A

Caused by increased metabolism of most tissues of body which increases vasodilator products
Causes total peripheral resistance to decrease and venous return/cardiac output to rise to 40-80% above normal

19
Q

How does Anemia increase cardiac output?

A

Causes decreased viscosity of blood due to decreased [RBC] and deliver of O2 to tissues
Causes local vasodilation and cardiac output increases

20
Q

What 2 conditions cause decreased cardiac output?

A

1) Decreased skeletal muscle mass

2) Decreased metabolic rate (hypothyroidism)

21
Q

How does decreased skeletal muscle mass decrease cardiac output?

A

Causes decreased O2 consumption and blood flow needs to the muscles
Results in decreased skeletal muscle blood flow and cardiac output

22
Q

How does decreased metabolic rate decrease cardiac output?

A

Means reduction of O2 consumption and nutrient needs to tissues
Therefore, blood flow decreases resulting in reduced cardiac output

23
Q

When right atrial pressure is _____, venous return is _____.

A

+7 mmHg

0 mmHg

24
Q

If right atrial pressure goes to -2 mmHg…

A

Venous return reaches a plateau due to collapse of veins entering chest

25
Q

Mean systemic filling pressure - Right atrial pressure = ?

A

Pressure gradient for venous return

26
Q

How much resistance of venous return is due to venous resistance?

A

~2/3

27
Q

How much resistance to venous return is due to arteriolar/small arteries?

A

~1/3

28
Q

Venous Return = ???

A

Pressure gradient for venous return / Resistance to venous return

29
Q

What are the normal values for venous return, mean systemic filling pressure, & resistance to venous return?

A 
VR = 5L
SfP = 7 mmHg
RVR = 1.4 mmHg/L/min
30
Q

What are the local control factors that regulate blood flow to skeletal muscle?

A 
Reduction in O2
Adenosine
K+ ion
ATP
Lactic acid
CO2
31
Q

What are the nervous control factors that regulate blood flow to skeletal muscle?

A

Sympathetic vasoconstrictor nerves

Adrenal Medullae

32
Q

What affect do sympathetic vasoconstrictor nerves have on nervous control?

A

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

33
Q

What affect do adrenal medullae have on nervous control?

A

Secrete norepinephrine/epinephrine

***Epinephrine also has a slight dilator effect

34
Q

What 3 things happen during mass discharge of SNS?

A

1) HR increases
2) Most peripheral arteries are strongly contracted
3) Muscle walls of veins are contracted

35
Q

T/F: All peripheral arteries are strongly contracted during a mass action SNS response.

A

False, all except…
Those in active muscles
Coronary arteries
Cerebral arteries

36
Q

Increased arterial pressure caused by sympathetic stimulation causes…

A

Vasoconstriction of arterioles and small arteries in most tissues
Increased pumping activity of the heart
Increase in mean filling pressure caused mainly by venous contraction
Increase in cardiac output

37
Q

What are the names of the 4 coronary arteries?

A

1) Right coronary artery
2) Left coronary artery
3) Left circumflex branch
4) Left anterior descending branch

38
Q

Where is the right coronary artery located?

A

Extends from ascending aorta (between pulmonary trunk and vena cava) and runs along right, anterior atrium, then wraps around posteriorly

39
Q

Where is the left coronary artery located?

A

Extends from ascending aorta (left of pulmonary trunk) and runs down left atrium, then splits into left circumflex & left anterior descending branches

40
Q

Where is the left circumflex branch located?

A

Runs posteriorly along left atrial/ventricular border

41
Q

Where is the left anterior descending branch located?

A

Runs anteriorly along septum dividing right/left ventricles and extends out to both ventricle
*Most critical branch

42
Q

What is the phasic change of coronary blood during systole?

A

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

43
Q

What is the phasic change of coronary blood during diastole?

A

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

44
Q

What is the primary controller of coronary blood flow?

A

Local muscle metabolism

45
Q

What are the 4 causes of death after acute coronary occlusion?

A

1) Decreased cardiac output
2) Fibrillation of heart
3) Rupture of heart
4) Damming of blood in pulmonary blood vessels and death resulting from pulmonary edema

Zak, Physiology (20 decks)

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