1. CH 9 Cardiac Muscle Histology J.F. Thompson, Ph.D.

2. The Myocardium Forms most of the heart wall (myocardium)

3. Cardiac Muscle Individual uninucleate cells (may occasionally be binucleate) –Not dividing Rich capillary blood supply

4. Cardiac Muscle Striated Cells may be branched

5. Cardiac Muscle Involuntary (unconscious) Autorhythmicity (contracts without external stimuli) Rapid contracting and relaxing Non-fatigable

6. Cardiac Muscle Cells Each fiber is connected to the others by intercalated discs

7. Intercalated Discs Tight Junctions Desmosomes –connect cells Gap junctions –Electrical synapses –Excitation spreads rapidly

8. Cardiac Muscle Note the striations which represent myofibrils and the sliding filament method of muscle contraction.

9. End CH 9 Cardiac Muscle Histology