Previous page 3.2.3.10.1.1.2. Types of skeletal muscle   461 / 795  Next page 3.2.3.10.1.3. Smooth muscles Return 3.2.3.10.1. Muscle structure
Notes
      3. Old stuff
          3.2. Old physio stuff (around 2005)
              3.2.3. Physiology
                  3.2.3.10. Muscle
                      3.2.3.10.1. Muscle structure
 3.2.3.10.1.2. Cardiac muscles 

Cardiac muscles

[Ref: WG21:Chp3]

See Fast-response cardiac action potential for cardiac action potential

 

Some differences

  • Very rich in mitochondria
  • Transverse-tubular system is at Z lines

Intercalated disks

  • Located at Z lines
  • Gap junctions present
  • Allow myocytes to act as a syncytium
  • Provide strong cell-to-cell cohesion

 

Contraction

  • Contractile response begins just after the start of the depolarisation
  • Last about 1.5 times as long as the AP

 

Excitation-contraction coupling

Voltage change in membrane

--> Activation of dihydropyridine channels in the T-tubules

--> Influx of Ca2+ from ECF

--> Release of stored Ca2+ from SR via calcium release channels (ryanodine receptors)

--> Contraction initiated

Ca2+ from ECF alone is insufficient to induce contraction.

Previous page 3.2.3.10.1.1.2. Types of skeletal muscle Next page 3.2.3.10.1.3. Smooth muscles Return 3.2.3.10.1. Muscle structure
Table of contents  | Bibliography  | Index
Revised at