A sustained contraction is called

Options

A. tetany
B. recovery period
C. tonus
D. contraction period

Explanation

To solve the question "A sustained contraction is called," we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Term "Sustained Contraction":**
- A sustained contraction refers to a prolonged state of muscle contraction without relaxation. This can occur due to various physiological conditions.

2. **Identifying the Causes of Sustained Contraction:**
- Sustained contractions can be caused by imbalances in electrolytes, particularly calcium. Calcium plays a crucial role in muscle contraction and relaxation.

3. **Linking Calcium Deficiency to Muscle Contraction:**
- A deficiency in calcium can lead to increased excitability of nerves and muscles. This heightened excitability can cause continuous muscle contractions.

4. **Recognizing the Condition Associated with Calcium Deficiency:**
- The condition that arises from calcium deficiency is known as "tetany." Tetany is characterized by sustained muscle contractions and spasms.

5. **Differentiating Tetany from Other Terms:**
- Other terms related to muscle activity, such as "recovery period," "muscle tone," and "contraction period," do not refer to sustained contractions.
- The recovery period is when muscles recover from stimulation, muscle tone refers to the continuous partial contraction of muscles, and the contraction period is the duration of a single contraction.

6. **Conclusion:**
- Based on the above reasoning, the correct answer to the question is "tetany," which is the term used to describe sustained muscle contractions due to calcium deficiency.

### Final Answer:
A sustained contraction is called **tetany**.