Cardiac Muscle - Electrical Properties
Dr. Mariano J. Rey
Goals
- To understand the ionic basis for the resting potentials and action potentials of cardiac cells.
- To be able to distinguish the differences between the action potentials of cardiac cells and those of nerve cells, and skeletal and smooth muscle cells.
- To understand the initiation and propagation of electrical activity throughout the heart.
Outline
- Historical background
- Myogenic vs. Neurogenic hypotheses
- Galen - "origin in the heart" (1600's)
- Harvey - "origin in the cardiac auricle" (1651)
- C. J. Muller - sinus venosus ganglion (1842)
- Stannius - a hierarchy of pacemakers (1852)
- Special Electrical Features of Cardiac Muscle
- Automaticity
- Rhythmicity
- Syncytial Conduction
- Cardiac Action Potential - compared to that of:
- Nerve
- Skeletal Muscle
- Smooth Muscle
- Cardiac Action Potential - Generation
- Fast Action Potential
- Myocardial cells
- Purkinje's Fibers
- Slow Action Potential
- Sino-Atrial Node
- Atrio-Ventricular Node
- Cardiac Action Potential - Conduction
- Sino-Atrial Node
- Atriae
- Atrio-Ventricular Node
- His Bundle and branches
- Purkinje's Fibers
- Myocardium
- Cardiac Action Potential - Regulation
- Refractory Periods
- Cycle Length
- Overdrive Suppression
For Review
- fast and slow Na channels
- m and h gates
- L type and T type Ca channels
- Types of K channels
- Delayed vs. Inward Rectification
- syncytium
- intercalated disks
- gap junctions
- connexons
- desmosomes
- chronotropy
- dromotropy
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