lecture 8; cardiac muscle and smooth muscle

histological features of cardiac muscle

• Striated

• Sarcomeres - similar to skeletal muscle  with A (dark) and I (light) bands and Z lines

• Branched cells

• 1 or 2 nuclei, centrally located

• Joined end to end by intercalated disks

• Adherens-type junctions

• Desmosone junctions

• Gap junctions

• Abundant mitochondria; indicative of high aerobic metabolism

• Numerous capillaries coursing through the branched cardiac muscle cells

cardiac; intercolated disks (blue)

cardiac muscle image

• nucleus in green

• dark grey circles = mitochondria

histological features of smooth muscle

• No striations

  • But still rely on actin/myosin interactions for contraction

  • Plaques in cytoplasm with contractile filaments attached

  • Under neural, humoral and mechanical control

• Fusiform shape

• Centrally located mono-nuclei

• Interconnected through many gap junctions for communication

• Adjust their contraction/relaxation status by reorganising the actin cytoskeleton/intermediate filament network

• weak, slow, involuntary contractions

smooth muscle cells images

• endomysium= white