Study Notes on Rigor Mortis

Rigor Mortis Overview

• Occurs after death, typically 2 to 7 hours later.

Cause of Rigor Mortis

• Skeletal muscles stiffen due to partial contraction.
• Calcium leaks out of sarcoplasmic reticulum (SR) post-mortem.

Role of ATP

• ATP is essential for cell respiration and muscle function.
• After death, ATP production ceases due to lack of oxygen.

Contraction Cycle Post-Death

• Cross-bridge formation: Yes, does not require ATP.
• Power stroke: Yes, does not require ATP.
• Release of myosin head: No, requires ATP (not available).

Resulting Effect

• Myosin heads remain attached to actin, causing muscles to stay partially contracted (rigid).

Duration of Rigor Mortis

• Lasts hours to days, depending on environmental factors (e.g., temperature).
• Eventually dissipates due to decomposition processes.