what are cardiac muscles made up of? - ✔️✔️cardiac myocytes
what are cardiac myocytes? - ✔️✔️- myocardial muscle cells
- are shorter, branched cells
- usually contain a single nucleus
what is cardiac muscle interconnected by? - ✔️✔️intercalated disks
how are desmosomes linked? - ✔️✔️mechanically
how are gap junctions linked? - ✔️✔️electrically
what do non-contracting autorhythmic cells (pacemakers) do? - ✔️✔️generate action potentials
spontaneously
where does the depolarization start? - ✔️✔️in the Sinoatrial node
what does long action potential duration prevent? - ✔️✔️summation of contraction
why is Ca entry necessary for contraction in the cardiac muscle channels? - ✔️✔️they are not
mechanically coupled to ryanodine receptors
what does an increase in Ca in excitation-contraction coupling do? - ✔️✔️triggers contraction by
removing the inhibition of cross bridge cycling
what is the SERCA pump in cardiac muscle regulated by? - ✔️✔️phospholamban
, What does phospholamban inhibit in a dephosphorylated state? - ✔️✔️SERCA
what is used for regulating force generation in skeletal muscle? - ✔️✔️frequency summation in individual
fibres and multiple-fibre recruitment
what does an increase in intracellular Ca in the cardiac myocytes enhance? - ✔️✔️contractile force
what is the length tension relationship? - ✔️✔️cardiac muscle generates a greater force when slightly
stretched
what in the heart modifies conduction/contraction? - ✔️✔️neuronal input
what is the heart innervated by? - ✔️✔️the autonomic nervous system
what does the sympathetic do? - ✔️✔️increase heart rate/conduction and contractility (autorhythmic and
contractile)
what does the parasympathetic do? - ✔️✔️decreases heart rate/conduction (autorhythmic)
what does a slightly stretched sarcomere increase? - ✔️✔️the Ca sensitivity of the myofilaments
what does a slightly stretched sarcomere put additional tension on? - ✔️✔️stress-activated Ca channels,
increasing ca entry from extracellular space and increasing Ca induced Ca release
what can autorhythmic cells be modulated by? - ✔️✔️sympathetic and parasympathetic neurons
at a resting heart rate of 70-72 BPM is sympathetic or parasympathetic dominant? -
✔️✔️parasympathetic
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