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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

(59 cards)

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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?

Study These Flashcards
A

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

25
If right atrial pressure is -2 mmHg, venous return reaches a ______ and is caused by ______
plateau, collapsed of veins entering chest
26
When the heart pumping stops what happens?
all blood flow ceases, pressures everywhere in body become equal
27
What is mean circulatory filing pressure
when pressures everywhere in body become equal, = 0 when blood volume =4 L =7 mmHg when blood volume = 5L
28
The greater the difference between men systemic filing pressure and the right atrial pressure, the ________ the venous return
greater
29
The difference between the man systemic filling pressure and right atrial pressure = _______
pressure gradient for venous return
30
What are the factors that affect venous return to the heart from the systemic circulation?
resistance to blood flow | venous return
31
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
2/3 | 1/3
32
What is the equation for venous return?
(mean systemic filling pressure - right atrial pressure) / resistance to venous return
33
What are factors that affect venous return?
right atrial pressure mean systemic filling pressure blood flow resistance between peripheral vessels and right atrium
34
How does right atrial pressure affect venous return?
impedes flow of blood from veins into right atrium
35
How does mean systemic filling pressure affect venous return?
forces systemic blood toward heart | pressure when arterial and venous pressures come to equilibrium and systemic circulation flow comes to a stop
36
Decreases in resistance allows _______ while an increase in resistance ______
more blood to flow; has the opposite affect
37
The highest level to which right atrial pressure can rise is equal to the
mean systemic filling pressure
38
What can increase systemic filling pressure?
increase vascular volume | decrease venous compliance
39
How can you increase vascular volume?
infusion or activation of renal-angiotensin-aldosterone system
40
How do you decrease venous compliance?
sympathetic stimulation muscle pump exercise, lying down
41
What does increasing systemic filling pressure result in?
shift in the vascular return curve to the right, enhances filling of the ventricles
42
How do you decrease systemic filling pressure?
decrease vascular volume | increase venous compliance
43
How do you decrease vascular volume?
hemorrhage burn trauma vomiting diarrhea
44
How do you increase venous compliance?
inhibit sympathetics alpha block venodilators standing upright
45
What happens when you decrease systemic filling pressure?
shift in vascular return curve to left | reduces filling of ventricles
46
What is the positive inotropic effect?
equilibrium shifts to a higher cardiac output and a correspondingly lower right atrial pressure
47
What is the negative inotropic effect?
equilibrium shifts to a lower cardiac output and a correspondingly higher right atrial pressure
48
What are local controls that regulate blood flow to skeletal muscles?
``` 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
What are nervous controls that regulate blood flow to skeletal muscles?
sympathetic vasoconstrictor nerves | adrenal medulla
50
What does sympathetic vasoconstrictor nerves do?
secrete norepinephrine | decrease blood flow through resting muscles to as little as one half to one third normal
51
What does the adrenal medulla do?
secrete norepinephrine and epinephrine
52
What does exercise do to blood flow to skeletal muscles?
mass discharge of sympathetic nervous system heart rate increases most perisperhal arteries are strongly contracted muscles walls of veins are contracted
53
during systole, coronary blood flow in the left ventricle ______
falls to a low value
54
During diastole, cardiac muscles realize and no longer _______ through the left ventricular capillary
obstructs blood flow
55
What is the primary controller of coronary flow?
local muscle metabolism
56
Coronary flow increases in ______ proportion to additional metabolic consumption of oxygen by heart
direct
57
Direct ANS stimulation acts on ______
blood vessels
58
Indirect ANS stimulation is on the ______ tissue and indirectly on the ______ via local control mechanisms
cardiac muscle; coronary vessels
59
What causes death after acute coronary occlusion?
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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