1
Q
Cardiac output
A
amount of blood pumped by the heart per minute (HR x SV)
2
Q
cardiac output At rest?
A
cardiac output is approx 5L/min
3
Q
what does cardiac output represent?
A
Represents blood flow of entire cardiovascular system
4
Q
- Ventricular diastole
A
5
Q
- Isovolumic ventricular relaxation (5)
A
blood flows back into cusps of semilunar valves and snaps them closed
6
Q
- Late diastole (1)
A
both sets of chambers are relaxed and ventricles fill passively
7
Q
- Atrial systole (2)
A
atrial contraction forces a small amount of additional blood into ventricles
8
Q
- Ventricular systole
A
9
Q
- Isovolumic ventricular contraction (3)
A
pushes AV valves closed but does not create enough pressure to open semilunar valves.
10
Q
- Ventricular ejection (4)
A
as pressure rises and exceeds pressure in the arteries
11
Q
A
12
Q
A
13
Q
Stroke volume: volume of blood pumped by the ventricle per beat (EDV-ESV)
A
14
Q
- Expressed in ML/beat
A
15
Q
Ejection Fraction: measure of heart’s pumping ability
A
16
Q
- Represents the % of blood that is ejected from the left ventricle during each contraction
A
17
Q
- EF= (SV/EDV) x100
A
18
Q
A
19
Q
A
20
Q
Cardiac output in aerobic exercise!
A
21
Q
- Cardiac output increases when exercise intensity increases
A
22
Q
- Can we increase our max cardiac output with training? NO
A
need a significant increase of physical activity.
23
Q
- Cardiac output goes up when heart rate and stroke volume goes up!
A
24
Q
A
25
26
Increasing HR!!!!
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1. Anticipatory response
28
- parasympathetic input decreases
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- sympathetic input increases
30
Parasympathetic control: decreases HR by releasing ACh onto muscarinic receptor
increases K permeability
31
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Sympathetic control: increases heart rate by releasing norepinephrine onto B1-adrenergic receptors
increases NA and CA permeability
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Increasing SV!
37
* EDV-ESV
38
Preload: amount of blood returned to heart during diastole
39
1. Muscle pump! Skeletal muscle contractions compress veins leading to…
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2. Respiratory pump! Decreased pressure on inferior vena cava! More blood returned from abdomen
41
3. Peripheral venoconstriction
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4. Greater preload increases SV because of the increased venous return which leads to greater lengthening of the muscle fibers. Within this physiological range there is an optimal arrangement of muscle fibers to contract!
43
5. What happens to preload during exercise in the heat? It leads to decreased venous return
due to loss of blood volume and need to divert blood to skin for cooling
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* EDV reduced
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* Stroke volume is reduced
46
* Cardiac output decreases
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* Loss of performance
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Contractility: force of myocardial contraction independent of preload or afterload
51
1. Increased sympathetic activity leads to increased norepinephrine release leads to increased strength of contraction leads to increased rate of contraction/relaxation and increased ejection fraction
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Afterload: pressure opposing the ejection of blood
55
1. Increased blood pressure leads to increased afterload
56
2. During aerobic exercise
peripheral vasodilation decreases blood pressure and therefore decreases afterload
57
If you want to increase cardiac output you must increase HR and SV at the same rate. But also stroke volume first because it is more efficient!
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60
Cardiovascular physiology! PT. 5
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The cardiac cycle
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5 phases:
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1. Heart at rest (atrial and ventricular diastole
filling with blood)
66
2. Completion of ventricular filling and atrial systole (atria contract
drive last 20% of blood volume into ventricles
67
3. Early ventricular contraction (first sound
AV close
68
4. Isovolumic ventricular contraction (the atria are filled with blood
atrial pressure is slowly increasing because the AV valves are closed.)
69
5. Ventricular Ejection (the semilunar valves open
blood is ejected into the arteries (ESV))
70
6. Ventricular relaxation (second heart sound!)
the semilunar valves shut
71
It's called ISOVOLUMIC because all the valves are closed and the ventricular volume stays the same! ISO means “same” and Volume is volume DUHHHH so it would mean SAME VOLUME. This makes sense because there is no blood coming in or out because the valves are closed!
72
* The AV valves open when the ventricular pressure drops below atrial pressure!
73
Systolic pressure: highest pressure in the ventricles and arteries
occurs during ventricular systole
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Diastolic pressure: lowest pressure in the ventricles and arteries
occurs during ventricular diastole
75
Pulse pressure: ESV-EDV
reflects the force from each heartbeat
76
Pulse rate: time between pressure waves in artery
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78
79
Pressure-volume changes:
80
1. Ventricular filling is initially passive; left ventricle increases blood volume but not yet pressure
81
2. Atrial systole drives more blood into the ventricle; further increase ventricular blood volume AND increase in ventricular pressure
82
3. Isovolumic ventricular contraction; left ventricular pressure immediately increases until aortic valve opens
left ventricular blood volume does not change
83
4. Ventricular ejection: ventricular pressure rises even further
ventricular volume decreases
84
5. Isovolumic ventricular relaxation; atrial valve closes
left ventricular blood volume stays the same
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Electrical events of heart
88
* Electrical signals coordinate heart contractions! They come from pacemakers! The following are the pacemakers that coordinate the electrical signals. The order they are in is their order. They are ranked in order from fastest to slowest.
89
* 1. Sa node
90
* 2. Av node
91
* 3. Purkinje fibers
92
Atria contract from the base downward
93
Ventricles contract from apex upward
after delay
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LETS do the electrical signals of the heart again!!!
97
1. SA nodes depolarizes first
98
2. Electrical activity goes rapidly to AV node via internodal pathways
99
3. Depolarization spreads more slowly across atria. Conduction slows through AV node
100
4. Depolarization moves rapidly through ventricular conducting system to the apex of the heart
101
5. Depolarization wave spreads upward from the apex
102
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104
SA node: the natural pacemaker
it is responsible for generating rhythmic electrical impulses
105
Internodal pathways: responsible for conduction of SA node to AV node
106
AV node: is responsible for delaying electrical impulses
this allows for the atria to contract and complete ventricular filling. This makes sense because the atria is the one that lets the last bit of blood enter to be ejected.
107
AV bundle: electrical connection between atria and ventricles
108
Purkinje fibers: fast-conducting fibers that distribute the impulse to ventricular muscle cells
triggering ventricular contractions.
109
P- wave: the SA node depolarizes which leads to atrial depolarization
110
Q-wave: bundle branches depolarization
leads to depolarization of septum
111
R-wave: purkinje fibers depolarize
leading to ventricular depolarization
kin 100
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Decks in class (5)
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