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18 Cards in this Set
- Front
- Back
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What are cardiac cells electrically connected by?
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gap junctions
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do nerves regulate or drive?
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regulate
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Cardiac cells can initiate their own AP --> ...
... influx during AP is what makes the difference between cardiac and skeletal muscle cells |
automaticity
Calcium |
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... : extrinsic control of the amount of response to preload and afterload.
-regulated by ANS and hormones |
Contractility
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True or false?
Recruitment occurs in cardiac muscle |
false. it occurs in skeletal muscle. In cardiac muscle, every muscle cell is active with every beat.
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What is the best measure of left ventricular preload?
What is the best measure of ventricular preload clinically? |
muscle fiber length
left ventricular volume @ the end of diastole |
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Measures of left ventricular preload in descending order of reliability:
-muscle fiber length -left ventricular volume -left ventricular diameter -left ventricular end diastolic pressure -left atrial pressure -pulmonary capillary wedge pressure -pulmonary artery pressure -... (better measure of R. ventricle preload and overall effectiveness of heart pumping) |
central venous pressure
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What is a regulatory mechanism that governs the response to changes of afterload?
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contractility
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Cardiac muscle cannot get ... contraction. You can get ..., but it is much more modest due to refractory periods extending well into the period of force production.
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tetanic
summation |
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Active force is controlled by ... length and ... Ca++ concentration during the active state.
When you increase the preload, actin and myosin attachments get closer together. Troponin increases its affinity for calcium when muscle is ... |
preload
intracellular stretched |
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...: heart rate
...: rate of relaxation |
Chronotropy
Lusitropy |
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Cardiac muscle: ...% of energy from oxidation of fatty acids (higher % than skeletal)
Metabolism of ... provides intermediates necessary for oxidative metabolism Cardiac force highly dependent on ... supply ... relationship between cardiac work, cardiac oxygen consumption and coronary blood flow Loss of active force within 30 seconds of occlusion |
90
glucose oxygen Direct |
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decreased ATP/ADP reduces energy of hydrolysis of ATP required for force.
inability to resequester or pump Ca++ out poisons mitochondrial energy production. Excess myoplasmic Ca++ increases risk of ... |
free radical damage
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Autonomic control:
Sympathetic neurons and circulating catecholamines (mainly epinepherine) -Primarily ... receptors on cardiac cells -Alter ion conductance mainly via ... -Increase Ca++ influx and release of Ca++ by SR -Increase rate of transport and resequestration -Stronger, faster, shorter duration Parasympathetic -... receptors for acetylcholine -Decreases ... -Weaker, slower, longer duration -Also some ion channel effects |
β1-adrenergic
cAMP Muscarinic M2 cAMP |
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What are dilation and hypertrophy examples of?
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remodeling
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Cardiac force production has similarities and differences with skeletal muscle
... mechanisms, preload and afterload behave similarly but have different cellular basis Cardiac cells are electrically connected, thus are ... by autonomic nerves, not ... by somatic nerves ... influx controls the SR ... mechanisms regulate inotropy, heart rate, conduction and relaxation The heart structurally and functionally changes when exposed to increased demand for work |
Intrinsic
regulated driven Calcium Extrinsic |
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What is the effect of a drug that blocks L-type channels in ventricular muscle?
1. Decreased preload 2. Faster heart rate 3. Increased Ca++ release from SR 4. Reduce active force 5. Slower rate of relaxation |
4. Reduce active force
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Which is the best measure of preload on the right ventricle?
1. Central venous pressure 2. End diastolic volume of the right ventricle 3. Pulmonary capillary wedge pressure 4. Right atrial pressure |
2. End diastolic volume of the right ventricle
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