Question

Rigor mortis in meat tissues occurs due to -

• A. Aerobic respiration
• B. Anaerobic respiration
• C. wasting of muscles
• D. softening of muscles

Hint:

ATP is essential for both muscle contraction and relaxation.
In living tissue, ATP binds to the myosin head, allowing it to detach from actin.
The post-mortem depletion of ATP is the direct biochemical trigger that locks the muscle in a contracted state.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Rigor mortis is a post-mortem physiological state characterized by the stiffening and loss of extensibility of muscle fibers following slaughter.

Step 2: Detailed Explanation:
Upon animal slaughter, blood circulation ceases, depriving the muscles of oxygen and stopping aerobic respiration.
To maintain ATP levels, muscles switch to anaerobic respiration (glycolysis), fermenting stored glycogen into lactic acid.
This anaerobic pathway produces lactic acid, causing the muscle pH to drop from around \(7.2\) to about \(5.5\).
As glycogen reserves are depleted, the synthesis of ATP stops.
Without ATP, the actin and myosin filaments remain permanently bound as actomyosin cross-bridges, preventing muscle relaxation and causing the muscle tissue to enter rigor mortis.

Step 3: Final Answer:
Therefore, rigor mortis is driven by the post-mortem metabolic shift to anaerobic respiration, corresponding to option (B).