Cardiac Muscle Flashcards
Does cardiac muscle contain T-tubules and sarcoplasmic reticuli?
Yes, the basic principles of contraction are the same as skeletal muscle.
What is the difference in T-tubule and sarcoplasmic reticulum structure in cardia myocytes compared to skeletal muscle?
In skeletal muscle these are arrange in a TRIAD organisation
In cardiac muscle these are arranged as a DYAD (X1 of each structure)
What is the shape of cardiac muscle cells?
‘Brick’ shape
Are cardiac myocytes branched or unbranched?
Branched
Are cardiac myocytes uni or multinucleate?
Uninucleate
What is the Vm (resting membrane potential) for skeletal and cardiac muscle cells?
-90mV
What is the threshold potential for myocardiocytes?
-70mV
What is excitation-contraction coupling?
The process which links excitation (the muscle action potential propagating along the sarcolemma and into the t-tubules) with contraction (the sliding of the filaments)
What is the ion responsible for excitation-contraction coupling?
What is the short oscillation of this ion called?
Calcium
A calcium transient
Where does the calcium come from for muscle contraction?
X2 locations:
1) intercellularly from sarcoplasmic reticulum stores
2) extracellularly from the interstitial fluid
What is the name of the relationship which links the heart rate and the force of cardiac contraction?
What does it state?
What is this effect also called?
The force-frequency relationship.
It states that an increase in chronotropy causes an increase in inotropy in a ‘staircase effect’.
It is also called the TREPPE or BOWDITCH effect.
