What is the general pH range of rigor mortis?

What is the general pH range of rigor mortis?

• A. 4-5
• B. 5-6
• C. 6-7
• D. 7-8

Answer: (B)

Rigor mortis happens as muscles run out of ATP after death and calcium leaks into the cells, allowing actin and myosin to form cross-bridges and lock the muscles in place. At the same time, the body switches to anaerobic metabolism, producing lactic acid and driving the pH from near neutral down to mildly acidic levels. This combination creates the stiff, early postmortem state, which sits in a mildly acidic environment roughly around pH 5 to 6. That’s why the general pH range of rigor mortis is about five to six. Ranges that are too acidic (around 4–5) would reflect a more extreme acid environment not typical for the onset of rigor, while ranges around 6–7 or 7–8 are too neutral or basic to correspond with the conditions that favor cross-bridge locking and the early stiffening seen in rigor.

Rigor mortis happens as muscles run out of ATP after death and calcium leaks into the cells, allowing actin and myosin to form cross-bridges and lock the muscles in place. At the same time, the body switches to anaerobic metabolism, producing lactic acid and driving the pH from near neutral down to mildly acidic levels. This combination creates the stiff, early postmortem state, which sits in a mildly acidic environment roughly around pH 5 to 6. That’s why the general pH range of rigor mortis is about five to six.

Ranges that are too acidic (around 4–5) would reflect a more extreme acid environment not typical for the onset of rigor, while ranges around 6–7 or 7–8 are too neutral or basic to correspond with the conditions that favor cross-bridge locking and the early stiffening seen in rigor.