Exam 4 Flashcards
(133 cards)
1
Q
Basal metabolism of the heart consumes what percent of oxygen used by the heart?
A
25%
2
Q
What does basal metabolic activity refer to?
A
Maintain active transport mechanisms at rest
3
Q
Muscle contraction consumes what percent of the oxygen used by the heart?
A
75%
4
Q
Pressure Work
A
99% of total work
External work; works ot move blood from low pressure to high pressure
5
Q
Stroke Work
A
1% of total work of heart (up to 50% heart failure)
Work needed to accelerate blood to ejection velocity
6
Q
Workload of R side of heart vs L side
A
R side has 1/6th work load of L side
7
Q
External Work of the heart
A
Pressure Volume Work
Transferring blood to the arterial system against a resistance
8
Q
Velocity Equation
A
Velocity = Flow/ Cross Sec. A
9
Q
Minute Work Output
A
Total energy converted to work per minute
Stroke Work x HR
10
Q
Potential Energy of the heart
A
additional work heart could do if it were able to contract and empty the ventricle
11
Q
Stroke Work Output
A
Amount of energy converted to work by heart during each beat
12
Q
Total Energy of the heart
A
Potential energy + Stroke Work Output
13
Q
Equation for Efficiency of Work
A
Work Output/Total E used = Efficiency
14
Q
What is the normal efficiency of cardiac contraction?
A
20 to 25%
15
Q
Efficiency of cardiac contraction can go as low as _____to_____% with heart failure.
A
5 to 10 %
16
Q
Max systolic pressure that a normal left ventricle can generate
A
250 to 300 mmHg
17
Q
Max systolic pressure the right ventricle can generate
A
60 to 80 mmHg
18
Q
Optimal filling volume for the right/left ventricle
A
120 to 170 mls
19
Q
Normal end-systolic volume
A
50 mL
20
Q
Normal end-systolic pressure
A
2-3 mmHg
21
Q
Normal end-diastolic volume
A
120 mLs
22
Q
Normal end-diastolic pressure
A
5 to 7 mmHg
23
Q
Normal Stroke Volume
A
70mL
24
Q
Equation for Cardiac Output
A
CO = HR x SV
25
What factors change SV?
Preload (Intrinsic contractility)
Afterload
Extrinsic Contractility
26
Changing 1 mmHg preload pressure results in how many mls change?
25 mls
27
Changing 1 mmHg afterload pressure results in how many mls change?
0.5 mL
28
Why does SV increase when contractility is increased (no change in afterload or preload)?
Each muscle fiber able to generate more tension at any given resting length
29
Why does end-systolic pressure decrease when contractility is increased?
Stroke volume increased, able to expel more blood
30
How to calculate changes in contractility on the graph?
Slope of the line = Change P/Change V
31
Substrate utilization for normal energy production by the normal adult heart
70-90% oxidative metabolism of fatty acids
| 10-30% lactate and glucose
32
Substrate utilization for normal energy production of the normal fetal heart
Derive most ATP from lactate and glucose
33
Substrate utilization for energy production by the adult heart suffering from heart failure
Most ATP derived from lactate and glucose
34
Calculating Stroke Work
Volume x Pressure
35
What does ATP used for muscle contraction encompass?
ATP associate with cross-bridge action
| Sequestration of calcium; active mechanisms
36
What is the name of the protein that can bind with oxygen?
Myoglobin
37
Heart removes most of the oxygen from the blood- leaving venous sat to....
25%
38
What is the only way to increase oxygen supply to the herat?
Increase coronary blood flow
39
What percent oxygen does isovolumic contraction use?
50% off overall O2 use
40
Why is cardiac afterload a major determinant of overall oxygen use?
Related to tension development (more than pressure generation)
Law of LaPlace: Tension= P x R
41
Three Basic Principles of Circulatory Function
1. Rate of BF to each tissue is precisely controlled by tissue need (arterioles, CNS, hormones)
2. CO controlled by sum of local tissue flow (CNS)
3. Arterial Pressure independent of local BF or CO (kidneys)
42
Shear Stress Equation
SS = 4nQ/ pi*r^3
43
Reynolds' number values at which turbulence will begin to appear at a side branch
200 to 400
44
Reynold's number at which turbulence will being to appear in a straight tube
2000
45
Blood is ___x more viscous than water.
3x
46
What are the functional parts of the circulation?
Systemic
| Pulmonary
47
Which functional circulation has a constant internal environment?
Systemic Circulation
48
How much lymphatic flow circulates each day?
2.5 L/day
49
Peripheral veins
all veins outside the thorax; not affected by thoracic P
50
Central Veins
major veins within the thorax; affected by thoracic pressure; lowest pressure in vascular system. Determine ventricular filling (if no pulmonary problems)
51
Cross Sectional A of Aorta
4.5 cm^2
52
Cross Sectional A of Arteries
20 cm^2
53
Cross Sectional A of Arterioles
400 cm^2
54
Cross Sectional A of Capillaries
4500 cm^2
55
Cross Sectional A of Venules
4000 cm^2
56
Cross Sectional A of Veins
40 cm^2
57
Cross Sectional A of Vena Cava
18 cm^2
58
Blood volume in veins, venules, and venous sinuses
64%
59
Blood volume in arteries
13%
60
Blood volume in arterioles and capillaries
7%
61
Blood volume in heart
7%
62
Blood volume in lungs
9%
63
Blood volume in systemic circulation
84%
64
Flow velocity in arteries
500 mm/s
65
Flow velocity in capillaries
0.5 mm/s
66
Flow velocity in arterioles
decreasing
67
Flow velocity in venules and veins
increasing
68
Mean pressure in arteries
100 mmHg
69
Mean pressure in capillaries
25 mmHg
70
What factors affect MAP?
MAP = CO x TPR
71
Why do arterial systolic, mean, and diastolic pressure change as the patient ages?
Decreasing arterial distensibility and increased SVR; changes in pressure control mechanisms by decreasing arterial distensibility and increased SVR
72
What is MAP?
Pressure drop across the systemic system; assuming the CVP is 0 mmHg
73
As ________ goes up, MAP will be closer to systolic.
Heart rate
74
Why is MAP closer to diastolic pressure under normal circumstances?
Spend more time in diastole
75
Equation for distensibility
Distensibility =Change vol/ (change P x original volume)
76
Relative distensibilities of arteries and veins.
Veins are 8x more distensible than arteries
77
Relative distensibilities of the pulmonary and systemic arteries.
PA 6x more distensible than systemic
78
Relative distensibilities of the pulmonary and systemic veins.
PV and SV distensibilities are the same.
79
Two equations for compliance
```
Compliance= Change V/Change P
Compliance= Distensibility x Initial Volume
```
80
Normal Compliance for systemic arteries
2 ml/ mmHg
81
Normal Compliance for systemic veins
100ml/ mmHg
82
Normal pressure pulse transmission velocity in the aorta
3 to 5 m/s
83
Normal pressure pulse transmission velocity in large arteries
7 to 10 m/s
84
Normal pressure pulse transmission velocity in small arteries
15-35 m/s
85
Pulse pressure equation
PP = SV/ arterial compliance
86
Systolic pressure equation
Ps= SV x HR x SVR x (2/3)(SV/Ca)
87
Diastolic pressure equation
Pd= SV x HR x SSR x (1/3)(SV/Ca)
88
Normal pressure difference between the peripheral veins and the central veins
4 to 6 mmHg
89
How much does intra-abdominal pressure rise during pregnancy, tumors, obesity....
15-30 mmHg
90
Standing absolutely still has what venous pressure in the feet
90mmHg
91
When standing still, how much circulating blood volume can be lost
10 to 20% in 15-30 minutes (pressure in capillaries increases)
92
Normal venous pressure in the feet of a standing person
20 mmHg
93
How much does the spleen hold?
100 mls
94
How much does the liver hold?
Several hundred mls
95
How much do abdominal veins hold?
300 mls
96
How much does the venous plexus hold?
Several hundred mls
97
How much does the heart hold?
50-100 mls
98
How much do the lungs hold?
100 to 200 mls
99
ANS activated by centers in
Spinal cord
Brain stem
Hypothalamus
100
Efferent fibers originate in spinal cord from ____ to ____
T1 to L2
101
Preganglionic transmission options from sympathetic chains
1. Synapse directly with postganglionic fibers
2. Follow preganglionic pathway to one of two peripheral ganglia where they synapse with postganglionic fibers
3. Pass through sympathetic chains then through splanchnic nerves to the two adrenal medullae
102
____% of fibers in average skeletal nerve are sympathetic fibers
8%
103
Parasympathetic nervous system deals with which nerves
3, 7, 9 & 10
104
____% of the parasympathetic nerves are in the vague nerve (cranial nerve 10)
75%
105
Transmitter Vesicles store how many molecules of transmitter substance?
2,000 to 10,000 molecules
106
How big is the space between presynaptic terminal and postsynaptic membrane?
200 to 300 angstroms
107
Two types of ionophore channels
```
Cation channel (mainly sodium)
Anion channel (mainly chloride)
```
108
Alpha component can stimulate four different actions
1. Open specific ion channel through postsynaptic membrane- channel can remain open for long period of time
2. Activation of cAMP or cGMP
3. Activate enzymes
4. Gene transcription
109
Cholinergic fibers
Fibers that release acetylcholine
110
Adrenergic fibers
Fibers that release norepinephrine
111
Parasympathetic transmitter
Acetylcholine
112
Sympathetic transmitter
Norepinephrine
113
Acetylcholine Production
Acetyl-CoA + Choline -> Acetylcholine
| Requires: choline acetyltransferase
114
Acetylcholine Removal
Catalyzed by acetylcholinesterase into an acetate ion and choline
Choline transported back into terminal nerve ending to be used in production of more acetylcholine
115
Norepinephrine Production
Starts in axoplasm of terminal nerve ending
- Tyrosine --> Dopa via hydroxylation
- Dopa --> Dopamine via decarboxylation
- Dopamine into vesicles for final production
- Dopamine --> Norepinephrine via hydroxylation
116
In the medulla, ___% of the norepinephrine is converted to epinephrine via methylation process
80%
117
3 Mechanisms for Norepinephrine Removal
1. 50-80% moved back into terminal nerve ending via active transport process
2. Most of rest diffuses away from the nerve endings into surrounding tissue
3. Small amt destroyed by monoamine oxidase (nerve endings) or catechol-O-methyltransferase (all tissues)
118
Norepinephrine and epinephrine released be adrenal medullae into blood remains active for ____ to _____seconds
10-30 seconds
119
Level of activity takes __ to ___ minutes to degenerate to nothing
1 to 3 minutes
120
Norepinpherine deactivated by __________, mainly in the liver
Catechol-O-methyl transferase
121
Two main types of cholinergic receptors
Muscarinic & Nicotinic
122
What is muscarinic receptor activated by?
Muscarine (Toad-stool poison); acetylcholine
123
What is the nicotinic receptor activated by?
Nicotine, acetylcholine
124
Two types of adrenergic receptors
Alpha (1 and 2), Beta (1, 2, and 3)
125
Norepinephrine is secreted where?
Adrenal Medullae (big effect on afterload)
126
Norepinephrine has main affect on what receptors?
Alpha Receptors (smaller affect on beta receptors)
127
Epinephrine is secreted by what?
Adrenal Medullae
128
____ frequency of stimulation required for full activation of effector receptors.
Low freq.
129
How many impulses per second will maintain normal sympathetic or parasympathetic effect?
1
130
How many impulses per second will produce full activation?
10 to 20 impulses per second
131
Sympathetic tone in systemic arterioles keep almost all sympathetic arterioles contricted to _____ their normal diameter.
1/2
132
Normal release of norepinephrine
0.05 ug/kg/min
133
Normal release of epinephrine is
0.2 ug/kg/min
