VPB 121: Veterinary Physiology - II (2+1)

RIGOR MORTIS

Muscle exhibits

• In-excitable
• Shortens in length
• Increases in thickness
• Become viscous and losses translucency
• Acidic pH 5.8
• Stiff
• Glycogen disappears
• Gives off H₂CO₃
• Rigor mortis starts in the 2^nd hour and is completed in 3 hrs after death. Rigor mortis disappears 24 – 36 hrs after death due to autolysis.
• Deficiency of ATP causing establishment of permanent link between actin and myosin. When ATP falls to 85% and creatine PO₄ to 30% of its initial value, symptoms of rigor mortis begin to appear.
  • Ca⁺⁺ pumps run out of ATP
  • Ca⁺⁺ cannot be removed
  • Continuous contraction
  • Eventually tissues break down
• This is major physiological different between cardiac and skeletal muscles. Skeletal muscles ordinarily contracts only when stimulated by nerve impulse.
• In contrast cardiac muscles tissue can contract with out our nerve stimulation. Its source of stimulation is conducting tissue of specialized muscle with in the heart.
• Nerve stimulation causes the conducting tissue to increase or decrease its rate or discharge. Cardiac muscle tissue has got an extra long refractory period.