Cardiac Muscle and Smooth Muscle

Dr. Mariano J. Rey

Goals

1. To learn the physiologic aspects of cardiac muscle mechanics that result in the generation of the cardiac input.
2. To understand the role of smooth muscle mechanics in the regulation of the cardiovascular system and other organ systems.
3. To better appreciate the physiologic differences of skeletal muscle, cardiac muscle, and smooth muscle.

Outline

1. Historical Background
• Otto Frank - frog heart model (1895)
• Ernest starling - canine heart-lung model (1914)
2. Cardiac Muscle
• Excitation-contraction coupling
• THe Proteins
• The Membranes
• Calcium
• Contraction
  • Frank-Starling relationship
  • Preload and afterload
  • Isometric vs. isotonic
  • Concept of contractility
3. Smooth Muscle
• Functional types
• Phasic
• Tonic
• Fibrillar contractile apparatus
• Cytoskeletal
• Myofilaments
• Regulation
• Neuromuscular relationship
• Force length relations
• Velocity-stress relations
• Calcium and cross-bridge regulations

For Review

Define or Explain

• motor unit
• series elastic component
• tetanic contraction
• twitch contraction
• slow and fast twitch fibers
• "red" and "white" fibers

Briefly Answer

• What is the basis for the staircase phenomenon is muscle tension with increased stimulus frequency?
• Explain why a muscle fiber achieves greater tension through tetanic activation than through a singe twitch.
• Compare the physiologic and structural differences between the leg muscles of a long-distance runner and the arm muscles of a weight-lifter.

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