[2] Lecture 13: CO And Blood Flow In Muscle Tissues Flashcards
(94 cards)
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
2
Q
Cardiac output per sq. Meter of body surface
A
Cardiac index
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
4
Q
Through life, cardiac index increases til about age _____ and decreases from there on
A
- Indicative of declining muscle mass and/ or activity w/ age
5
Q
Increasing levels of execise:
A
Increase oxygen consumption and CO and CI
6
Q
Used to calc blood flow through an organ
A
Flick principle of blood flow
7
Q
Flick principle formula:
A
CO= O2 consumption / [O2] pul.vein - [O2] pul.artery
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
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
10
Q
CV system:
A
2 pumps and 2 circuits
11
Q
What are the 2 CV pumps?
A
L and r side of heart
12
Q
What’re the 2 circuits of CV system?
A
Pulmonary and systemic circuits
13
Q
The CV circuits are connected in :
A
Series
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
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
16
Q
Factors affecting CO (4):
A
Basic level of metabolism
Whether person is exercising
Age
Size of body
17
Q
WNL CO values:
A
Young healthy men: 5.6 L/min
Women: 4.9L/min
Resting adult: 5L/min
18
Q
Heart automatically pumps whatever amt. of blood that flows into R atrium
A
Frank-starling law
19
Q
What initiates bainbridge reflex?
A
Stretched R atrium
20
Q
Strecthing heart causes:
A
Heart to pump faster
21
Q
Most important factors in controlling heart:
A
Peripheral system factors primarily control CO
22
Q
Anytime a long-term level of TPR changes CO changes quantitatively in exactly the oppo direction
A
Ohm’s law
23
Q
MOst important controller of CO:
A
Peripheral factors
24
Q
2 reflexes that control heart rate
A
Bainbridge and baroreceptor reflexes
25
Responds to changes in blood volume as detected by stretch receptors in R atrium
Bainbridge reflex
26
Respond to changes in arterial pressure
Baroreceptors
27
After birth, what happens to mother who recently delivered baby:
Tachycardia, b/c of blood return form uteroplacental return that activates bainbridge reflex
28
Is bainbridge considered detrimental to humans?
No, its not significant in humans
29
Formula for CO:
CO = Art. Pressure / TPR
30
Factors casing hypereffective heart:
Nervous stimulation
Hypertrophy
Exercise via the NS
31
Hyper effective heart:
Too effective
32
Exercise effect on CV:
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
33
Factors to hypoeffective heart:
```
Increased arterial pressure;
Inhibition of NS excitation;
Pathological factors causing abnormal HR;
CAD blockage;
Valvular heart Dz;
Congenital heart Dz;
Cardiac hypoxia
```
34
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?
Ex of frank-starling mechanism
35
Factors decreasing CO
```
Severe vessel blockage- MI
Severe valvular Dz
Myocarditis
Cardiac tamponade
Cardiac metabolic arrangements
```
36
Non-cardiac factors leading to decreased CO
```
Decreased blood volume
Acute venous dilation
Obstruction of large veins
Decreased tissue mass (muscle mass)
Decreased metabolic rate of tissues
```
37
what is req'd to maintain CO?
Nervous control/maintenance
38
Factors that affect venous return to heart from systemic circulation:
Right atrial pressure
Degree of filing of systemic circulation
Resistance to blood flow
39
When venous return is 0 (mean systemic filling pressure)
This is when right atrial pressure =+7 mm Hg
40
Pressures everywhere in the body become equal
Mean circulatory filling pressure
41
The greater the difference btw the mean systemic filling pressure and right atrial pressure:
The greater the venous return
42
The difference between the mean systemic filling pressure and the right atrial pressure
Pressure gradient for venous return
43
Mean systemic filing pressure - R atrial pressure
/
Resistance to venous return
=
Venous return
44
2/3 of resistance to venous return is determined by venous resistance b/c of
Vein distensibility. There is little rise in venous return
45
About 1/3 of the resistance to venous return is determined by arteriolar and small artery resistance d/t
Accumulation of blood overcomes Munich of the resistance
46
Impedes flow of blood from veins into r atrium
R atrial pressure
47
Forces systemic blood toward heart
Pressure when atrial and venous pressure come to equilibrium and systemic circulation flow comes to a stop (=7mm Hg)
Mean systemic filling pressure
48
Thiamine deficiency. Reduced peripheral resistance
This causes heart failure by means of high cardiac output
Beriberi
49
fusion of artery and vein leads to a lowering in peripheral resistance....causes increased CO
Atriovenous fistula
50
Elevated levels of hormone induces vasodilation of circulatory beds supplying muscle and skin.
Reduced peripheral resistance
This leads to an increase in CO
Hyperthyroidism
51
This decrease causes a lowered afterload effect
Reduced peripheral resistance
This increases CO
Anemia
52
The loss of this tissue req's less circulation b/c there is less tissue
This decreases CO
Decreased skeletal muscle mass
53
This condition req's less nutrient transportation to tissues leading to decrease in CO
Decreased metabolic rate
54
Where R atrial pressure = mean systemic filling pressure, venous return =
0
55
What does the plateau of venous return graph signify?
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
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?
Strong sympathetic stimulation
This is a shift to the left?
57
What relaxes all the systemic and pulmonary blood vessels and the chambers of the heart and leads to decreased mean circulatory filling pressures.
Complete sympathetic INHIBITION
This causes a shift to the Right
58
What happens to venous return when R arterial pressure increases?
Venous return decreases
59
What happens w/ blood flow (venous return) when resistance decreases?
More venous return
60
What is the highest level to which the R atrial pressure can rise is
Equal to the mean systemic filling pressure
61
As resistance decreases= venous return __________
Increases
62
What function is shown as the cardiac output curve?
Ventricular function
63
What does the point at which venous return curve and CO curve insect signify?
The amount of blood pumped is = the amt. of blood returned.
64
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
Mean systemic filling pressure
65
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?
Increases
Shifts to the right
Increases CO and R atrial pressure
66
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?
Decreases mean systemic pressure
Shifts the vascular function curve to the left
Decreases CO and R atrial pressure
67
How to increase vascular volume:
Infusion
Activation of renin-aldosterone system
68
Ways to decrease venous compliance (3):
Sympathetic stimulation
Muscle pump exercise
Lying down
69
What could cause decrease in vascular volume:
Hemorrhage
Burn trauma
Vomiting
Diarrhea
70
Ways to increase venous compliance:
Inhibit sympathetic
Alpha block
Venodilator
Standing upright
71
What vascular event would increase filling of the ventricles?
Decrease filling of ventricles?
Increase mean systemic filling pressure
Decreasing would decrease filling of ventricles
72
Equilibrium shifts to a higher CO and a correspondingly lower R atrial pressure.
R atrial pressure decreases b/c there's increased SV
Positive inotropic effect
73
Equilibrium shifts to a lower CO and a correspondingly higher R atrial pressure
Negative inotropic effect
74
Large blood flow during skeletal muscle activity is d/t mainly chemicals that act directly on muscle arterioles to dilate them
Local controls
75
Ex of local controls
```
Reduction in oxygen
Adenosine
K+ ion
ATP lactic acid
CO2
```
76
Controls that affect blood flow through skeletal muscles:
Local controls
Nervous controls
77
Nervous controls in blood flow regulation:
Sympathetic
Adrenal medullae
78
Secrete norepinephrine
Can decrease blood flow through resting muscles to as little as 1/2 to 1/3 normal
Sympathetic vasoconstrictor nerves
79
Secretes norepinephrine and epinephrine
Epinephrine also has slight vasodilator effect
Adrenal medulla
80
3 effects of mass discharge of sympathetic nervous system:
- 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
How does sympathetic stimulation increase arterial pressure
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
Effects of muscle exercise on blood flow in the calf:
C=blood flow increases and decreases between contractions
83
Exercise has what effect on CO and venous return?
Increases
84
coronary arteries:
RCA, LAD, Left circumflex
85
Coronary blood flow in the left ventricle falls to a low value during:
Systole
86
Coronary blood flow is _______ to flow in vascular beds elsewhere in body
Opposite
87
The cardiac muscle relaxes and no longer obstructs blood flow the rough the left ventricular capillaries during:
Diastole
88
Coronary arteries are perfused during which cardiac cycle?
Diastole
89
Coronary arteries show
Inverse phasic changes
90
What is primary controller of coronary flow?
Local muscle metabolism
91
Coroconary flow increases in direct proportion to:
additional metabolic consumption of O2 by heart
92
Direct ANS stimulation acts on:
Indirect acts on:
blood vessels themselves
Cardiac muscle stissue and indirectly on the coronary vessels via local control mechanisms
93
Causes of death after acute coronary occlusion:
- Decreased CO
- Damming of blood in pulmonary blood vessels and death resulting from pulmonary edema
- fibrillation of heart
- rupture of heart
94
Areas of ischemic myocardium are at risk of
Systolic stretch
