The term 'tetanus' refers to :

Options

A. the partial sustained contraction of major supporting muscles
B. a stronger contraction resulting from multiple motor unit summation
C. the result of wave summation, which produces a smooth and sustained contraction of a muscle
D. the state of muscle fatigue caused by depletion of ATP and accumulation of lactic acid

Explanation

**Step-by-Step Solution:**

1. **Understanding the Term 'Tetanus':** The term 'tetanus' in the context of biology primarily refers to a specific type of muscle contraction rather than the disease caused by the bacterium Clostridium tetani.

2. **Muscle Contraction:** Tetanus describes a state of prolonged and constant muscle contraction. This occurs when muscles are stimulated repeatedly without sufficient time for relaxation.

3. **Role of Motor Nerves:** The motor nerves innervate the muscles and are responsible for generating action potentials. These action potentials are electrical signals that trigger muscle contractions.

4. **High Frequency of Action Potentials:** In tetanus, the action potentials are generated at a very high rate. This high frequency is crucial for maintaining the sustained contraction of the muscle.

5. **Wave Summation:** The phenomenon of wave summation occurs when a second stimulus is applied before the muscle has completely relaxed from the previous contraction. This leads to an additive effect, resulting in a stronger and more sustained contraction.

6. **Conclusion:** Therefore, the term 'tetanus' refers to the result of wave summation that produces smooth and sustained contraction of muscles.

**Final Answer:** The term 'tetanus' refers to the result of wave summation which produces smooth and sustained contraction of the muscles.

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