Term
What are the 4 factors that increase cardiac output?
Which are cardiac factors and coupling factors? |
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Definition
heart rate, myocardial contractility (strictly cardiac factors)
preload and after load (coupling- cardiac and vascular) |
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Term
What ion must rise sufficiently for contraction to occur?
What must be removed for relaxation? |
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Definition
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Term
What gives the muscle the potential to develop force and or shorten
What is it influenced by? |
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Definition
Cross bridge interaction (sarcomere shortening)
This is influenced by external constraints during the cardiac cycle |
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Term
| What type of contraction occurs when there is a constant pressure or tension but there is a change in volume or length (influenced by the initial length of the muscle) |
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Definition
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Term
True or false
Isometric contractile force is influenced by the initial length of the muscle |
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Definition
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Term
True or false
Force is required to stretch the muscle |
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Definition
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Term
| What is the sum of active and resting tension? |
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Definition
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Term
| if you stretch out muscle fiber, you will impact the amount of _________ that can be developed. |
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Definition
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Term
True or false
if you stretch a muscle past Lmax, you will increase the tension. |
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Definition
False
you will actually reduce the amount of active tension that can be develope |
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Term
| What is a fixed load contraction (the same pressure or tension and you change volume or length) |
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Definition
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Term
| Isotonic: The load on the muscle at rest is the ________, and the load on the muscle during contraction is the _______ |
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Definition
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Term
Isotonic: ________ added increases the tension that must be overcome to allow contraction.
Final length with afterload is (more or less) than non-afterloaded condition with same preload |
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Definition
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Term
| *The factors that affect cardiac muscle shortening during preloaded vs afterloaded contraction is important because this affects ___________ |
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Definition
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Term
| What type of length-tension relationship is held at a defined length and tension measured? |
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Definition
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Term
| What type of length-tension relation involves stimulating muscle at each defined length (isometric conditions) and measure tension from its resting or passive value |
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Definition
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Term
The basis for ______________ is the degree of overlap of thick and thin filaments and the number of possible sites for cross-bridge formation.
This depends on an increase in _____ |
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Definition
length-tension relationships
Ca2+ |
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Term
The passive tension of cardiac muscle begins to increase at much (shorter or longer) sarcomere lengths than for skeletal muscle
Cardiac muscle developed tension rises more or less steeply that skeletal muscle
Why is this? |
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Definition
shorter
more
The reason for this difference is that the noncontractile, elastic, components of cardiac muscle are less distensible. As a result, cardiac muscle will break if the sarcomere length exceeds 2.6 um. Much greater stretch can be applied to skeletal muscle. |
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Term
| What is the relationship between the initial length of individual fibers and the amount of blood that could be pumped per cycle |
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Definition
| The Frank-Starling Relationship |
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Term
| A greater fiber length (i.e. greater ventricular volume) causes the heart to deliver (more or less) mechanical energy. |
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Definition
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Term
True or false
the initial length of myocardial fibers determines the work done during the cardiac cycle. |
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Definition
true
The heart is able to generate more pressure when more blood is ‘presented’ to it. |
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Term
| The ability of the heart to change its force of contraction and therefore stroke volume in response to changes in venous return (preload) is called the ___________ |
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Definition
| Frank-Starling mechanism (or Starling's Law of the heart) |
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Term
True or false
The degree of tension developed by cardiac muscle depends upon both ‘preload’ and ‘afterload’ |
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Definition
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Term
_________ is the amount of force produced during a contraction at a given preload.
What is this altered by? (2) |
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Definition
Contractility
Altered by autonomic activity and/or circulating hormones. |
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Term
Preload or after load:
Volume of blood in the ventricles at end of diastole (end diastolic pressure) |
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Definition
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Term
preload or after load
resistance left ventricle must overcome to circulate blood |
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Definition
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Term
What will NOT increase preload?
hypervolemia
regurgitation of cardiac valves
hypertension
heart failure |
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Definition
| hypertension (increases afterload) |
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Term
True or false
increasing after load, decreases cardiac workload |
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Definition
false
increase after load increases cardiac workload |
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Term
What will NOT increase after load?
hypertension
heart failure
vasoconstriction |
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Definition
| heart failure (increases preload) |
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Term
Any intervention (sympathetic stimulation) that increases the amount of tension developed for a given beginning length is said to be a positive ______ (increase in contractility)
Rise of tension is a positive _________ |
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Definition
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Term
| What molecule is the most important physiologic regulator of contractility? |
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Definition
| norepinephrine (positive inotrope and chronotrope) |
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Term
True or false
Stroke work is equivalent to Starlings Systolic Pressure |
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Definition
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Term
| (Left or right) atrial pressure corresponds to Starling’s end diastolic volume (or muscle length) |
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Definition
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Term
| the greater the afterload, the (faster or slower) the velocity of shortening |
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Definition
slower
(inverse relationship between velocity and after load) |
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Term
| (Increased or decreased) preload enables muscle to contract faster at given afterload |
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Definition
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Term
| With increased inotropy, there is a parallel shift up and to the (right or left) – thus an increase in Vmax as well as force |
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Definition
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Term
| HR x stroke volume (SV=blood ejected/time) = ? |
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Definition
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Term
Ventricular end diastolic volume (EDV) – Ventricular end systolic volume (ESV) = ?
(this is the difference between the maximal and minimal ventricular volumes) |
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Definition
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Term
SV/EDV= ?
What does this indicate? |
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Definition
ejection fraction (EF)
contractility |
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Term
What is normal cardiac output?
normal stroke volume?
normal ejection fraction in healthy adult? |
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Definition
5000 ml/min
70 ml
>0.55 or 55% |
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Term
What will NOT increase stroke volume?
increased contractility
increased preload
increased afterload |
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Definition
| increased after load (have to work harder to pump blood out) |
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Term
| Increasing after load decreases stroke volume. What can you increase to return SV to normal? |
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Definition
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Term
| _________ output is a major determinant of cardiac output because it is the filling pressure of the heart |
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Definition
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Term
| The (lower or higher) the pressure in the right atrium the greater the pressure gradient between the right atrium and veins and hence the greater the venous return |
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Definition
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Term
| If the heart were stopped, the right atrial pressure (or central venous pressure) = ___mmHg also known as the mean systemic filling pressure |
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Definition
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Term
| What are the 2 major factors that affect mean systemic filling pressure? |
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Definition
blood volume
vascular tone |
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Term
| If you increase blood volume, will you increase or decrease mean systemic filling pressure? |
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Definition
increase (more blood contained within vessels)
(decrease volume=reduction in venous return) |
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Term
| Changing the _________ has similar effects to changing blood volume that affect mean systemic filling pressure |
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Definition
| venomotor tone (squeezes blood out of veins) |
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Term
| If you vasodilate arteries, will that increase or decrease volume of blood brought back to the heart? |
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Definition
increase
(vasoconstrict-less blood) |
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Term
Positive or negative inotropic effect?
more blood ejected leading to a decrease in RAP but increase in CO |
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Definition
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Term
Positive or negative inotropic effect?
Less blood ejected leading to a increase in RAP, but a decrease in CO |
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Definition
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Term
Increased or decreased blood volume?
Vascular function curve shifted to right, increase CO |
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Definition
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Term
increased or decreased blood volume?
Vascular function curve shifted to left, decrease CO |
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Definition
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Term
increased or decreased total peripheral resistance?
Increase afterload, decrease CO, less blood returned |
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Definition
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Term
increased or decreased total peripheral resistance?
Decrease afterload, increase CO, more blood returned |
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Definition
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Term
| What does O2 supply to myocardium depend on (2)? |
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Definition
| O2 carrying capacity of blood and rate of coronary blood flow |
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Term
| Coronary vessels have maximal flow during (diastole or systole)? |
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Definition
| diastole (very important!) |
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Term
The heart derives its energy almost entirely from _______ metabolism.
The heart relies exclusively on the oxidation of ________ and _______ for immediate source of energy |
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Definition
aerobic
fatty acids (preferred) and glucose (limited 02 supply) |
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Term
| Myocardial O2 consumption is directly related to _____ use |
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Definition
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Term
| In many pathological situations such as severe coronary athereosclerosis, insufficient O2 is delivered. The result is ___________ |
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Definition
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Term
True or false
In a healthy heart ATP hydrolysis is matched to ATP resynthesis |
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Definition
True
mainly from mitochondria
no change in [ATP]i with exercise |
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Term
An increase in ATP demand requires an increase in ______ delivery
Myocardial tissue extracts ~50% (periperal or arterial) O2 vs (peripheral or arterial) tissues ~30% |
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Definition
O2
Myocardial tissue extracts ~50% arterial O2 vs peripheral tissues ~30% |
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Term
True or false
there is a parallel relationship between cardiac output and oxygen consumption |
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Definition
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Term
True or false
Fick Principle states there is conservation of mass and assumes that LV CO > RV CO |
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Definition
False
Fick Principle states there is conservation of mass and assumes that LV CO = RV CO |
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Term
| how would you calculate O2 consumption? |
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Definition
| cardiac output x [O2]pulmonary vein - cardiac output x [O2] pulmonary artery |
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Term
| if SvO2 is decreasing, the O2 consumption is (increasing or decreasing) |
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Definition
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