Electrical Activities of the Heart Flashcards
Are cardiac muscles able to exhibit tetanus (Y/N)
No
Why are cardiac muscles not able to exhibit tetanus
Long refractory period and a long action potential which allows a period of relaxation and contraction
What do cardiac muscles form
A functional syncytium
What is a synctium
Cells are electrically connected via gap junctions
Physically connected by desmosomes to form intercalated discs
What is used to regulate contraction
Ca2+
Why is Ca2+ able to regulate contraction
Does not saturate troponin
Non pacemaker resting membrane potential
High resting K+
Non pacemaker initial depolarisation
Increase in Na+
Non pacemaker plateau
Increase in Ca2+
Decrease in K+
Non pacemaker repolarisation
Decrease in Ca2+ and increase in K+
Pacemaker action potential
Increase in Ca2+ (L-type)
Pacemaker pre-potential (3)
Gradual decrease in Pk+
- Early increase in PNa+= PF
- Late increase in PCa2+
What does the pacemaker function explain
autorythmicity
Modulators for electrical activity
Sympathetic & parasympathetic systems Drugs Temperature Calcium Potassium
How does drugs modulate electrical activity
Ca2+ blockers- reduces force of contraction
Cardiac glycocides- increase force of contraction
