Electrical Activity of the Heart Flashcards
What acts as a large calcium store?
Sarcoplasmic reticulum
What does calcium bind to?
Troponin
What does cardiac muscle act as?
A massive functional syncytium
How are cells linked together?
- Desmosomes
- Intercalated discs
- Gap junctions
What kind of connection to desmosomes provide?
Physical connection
What kind of connection do gap junctions provide?
Electrical connection
How is the strength of contraction regulated?
Control of the amount of calcium entering the cell
What kind of refractory period do cardiac muscle cells experience?
Very long
Why do you not want tetanic muscle contraction in your heart?
It would mean that your heart would beat once and there would not be another bet causing asystole
What form the intercalated discs?
Gap junctions and desmosomes
How does the action potential in cardiac muscle compare to that in skeletal?
It is much longer
What does the long refractory period of cardiac muscle mean?
It cannot exhibit tetanic contraction
Why can regulation of Ca release be used to vary strength of contraction?
Ca release does not saturate troponin
What do cells which have unstable resting membrane potentials act as?
Pacemaker cells
What is responsible for the resting membrane potential of non-pacemaker action potentials?
High resting PK
What is responsible for the initial depolarisation in non-pacemaker action potentials?
Increase in PNa
