CH 9

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
IntercalatedDiscs

• 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