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The heart is induced by what to create an action potential
Calcium and in turn releases calcium
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What are the three main phases of the slow response pacemaker action potential
- Depolarization (Ca+ influx from slow L-type channels)
- Repolarization (Close L-type Ca+, Efflux K+)
- Pacemaker potential ie. slow depolarization (K+ closure, Funny (If) Na+ influx, 2 Ca+ influx (L and T) open)
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The slow response pacemaker action potentials happen in what muscles
Cardiac and Smooth
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What are the series of events for the Fast response ventricular/atrial action potentials
- Depolarization (Fast voltage gated Na+ In)
- Early repolarization (K+ exit, Na+ inactivate)
- Plateau phase (Open L-type Ca+ In, delayed K+ Out)
- Rapid Repolarization (K+ exit faster than Ca+ enter)
- Resting membrane potential (K+ exits to maintain resting state)
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Efflux means what
Process of flowing out
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Ca+ T type is only used in what action potential
In the slow response pacemaker action potential
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What is the binding protein on the SR in Cardiac muscle holding in Ca+ that is not found in skeletal muscle
Calsequestrin
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What are the three ways that cardiac muscle removes Ca+ after an action potential
- SERCA Pump
- Ca ATPase pump on the plasma membrane
- Na-Ca+ pump on the plasma membrane
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How are the RyR and DHPR proteins different in the cardiac muscle
They are not physically bound like in skeletal
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What is SERCA
Sarcoplasmic Reticulum ATPase pump located on skeletal, cardiac, and smooth muscle
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What is EC coupling
Excitation contraction coupling
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Cardiac muscle action potentials duration compare how to skeletal muscle potentials
They are longer
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What is responsible for the automated depolarization in a pacemaker action potential
Funny Na+ channels influx
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What are the four pumps on the cardiac muscle plasma membrane and what do they do
- Ca ATPase (Pump CA out)
- Na-Ca Pump (3Na in and 1Ca out)
- NaK ATPase (3Na out 2K in)
- Na-Hx (H out Na in)
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What is required on the outside of the cell of cardiac that is not required in skeletal
Ca+
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Primary Na+/K+ pumps create an environment that is necessary for what
High Na+ on the outside of the cell that the secondary active Na+/Ca+ uses to remove Ca+ after an action potential
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The heart relies solely on what metabolism
Aerobic metabolism through oxidative phosphorylation, this is what provides the essential ATP
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In what actions is the ATP used in cardiac muscle
- To pump Ca+ out of the cell
- To pump Ca+ into the SR
- To pump Na+ out and K+ into the cell
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Because of the length of a cardiac muscle action potential, what results
There is a mandatory absolute refractory period that the heart uses to fill its ventricles, therefore there is no tetanic action in in the cardiac
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Why is it called passive tension
It doesn't require ATP to achieve it
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What makes the heart have a passive tension that increases further then in skeletal muscle
It has a lot of connective tissue
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What are the two groups that smooth muscle can be divided into
- Single unit muscle (Gap junctions)
- Multiunit muscle (No/few gap junctions)
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What are the four different states of smooth muscle contraction
- Normally contracted
- Normally partially contracted
- Phasically active
- Relaxed
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What are the different ways that a smooth muscle can be triggered
- Hormones/Autonomic nervous system
- Local changes in extracellular fluid
- Pacemaker cell
- Stretch
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What are the different mechanisms for Ca+ entry into smooth muscle
- Receptor activated channel
- Voltage dependent Ca++ channel (Act. RyR on SR)
- G-Protein coupled receptor (Act. IP3 on SR)
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What is the series of events leading to muscle contraction in smooth muscle
- Calcium binds Calmodulin
- Ca-Calmodulin binds MLCK
- MLCK uses ATP to phosphorylate myosin
- Myosin binds to actin
- Myosin is dephosphorylated by MLCP
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Where is ATP required in the smooth muscle
- Ca+ pump out of the cell
- Ca+ pump out of SR
- Na+/K+ pump out of the cell
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Why does smooth muscle stay contracted for so long
The dephosphorylation of the myosin takes much longer
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What makes the smooth muscle more efficient when it comes to the use of ATP
They can stay contracted, therefore the ATP is not needed for the release of the myosin
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Why in the smooth muscle length verse tension diagram is the passive tension started so much earlier, and the active tension so broad
The actin myosin spans the whole cell, this gives it more mysoin and actin to bind
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Beta receptors like epinephrine and norepinephrine have what affect on the cardiac muscle
Increase the conversion of ATP to cyclic AMP, the cAMP increases the Ca through L receptors into the SR for subsequent release.
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What are the primary metabolic substrates used by the heart
Lactate and fatty acids
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What does the drug digitalis do to the heart
It inhibits the Na-K ATPase pump increasing the amount of Ca+ in the cell in turn increasing contractility
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Single unit smooth muscle has what type of action potential
Pacemaker action potential
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Multi unit smooth muscle cells are often found where
lung airways, large blood vessels, eye muscles, and hair follicles.
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What are the three different ways that Ca enters smooth muscle
- Voltage activated Ca channels
- Receptor activated channel (Ligand)
- G- Protein coupled receptor (Chemical signals like hromones)
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How does a G protein receptor activate Ca+ release
It triggers the production of IP3 in the cell which stimulates Ca+ release from the SR
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