Which of the following statements is consistent with smooth muscle architecture?

Options

A. The presence of deep, invaginating. T-tubules
B. Actin and myosin orgainzed into visible striations
C. Multicellular units of muscle tissue that function voluntarily
D. Multiunit muscle cells that are active during Gl peristalsis

Answer

To determine which statement is consistent with smooth muscle architecture, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Understanding Smooth Muscle Characteristics**:
- Smooth muscles are also known as visceral muscles and are found in the walls of hollow organs such as the gastrointestinal (GI) tract and blood vessels.
- They are involuntary muscles, meaning their activity cannot be consciously controlled.
- Smooth muscle cells are typically uninucleated (having one nucleus).

2. **Analyzing Each Option**:
- **Option 1: Presence of deep invaginating T-tubules**:
- T-tubules are characteristic of skeletal muscle, not smooth muscle. Smooth muscles do not have deep invaginations like T-tubules.
- **Conclusion**: This statement is **not consistent** with smooth muscle architecture.

- **Option 2: Actin and myosin organized into visible striations**:
- In skeletal muscles, actin and myosin are organized into striations, giving them a striped appearance. Smooth muscles do not have visible striations; instead, they have a more uniform appearance.
- **Conclusion**: This statement is **not consistent** with smooth muscle architecture.

- **Option 3: Multicellular units of muscle tissue that functions voluntarily**:
- Smooth muscles are involuntary, meaning they cannot be controlled consciously. This statement incorrectly describes smooth muscle as voluntary.
- **Conclusion**: This statement is **not consistent** with smooth muscle architecture.

- **Option 4: Multi-unit muscles that are active during GI peristalsis**:
- Smooth muscles are indeed involved in GI peristalsis, which is the rhythmic contraction and relaxation of the gastrointestinal tract that helps move food along.
- Multi-unit smooth muscles can be found in certain areas of the GI tract and are responsible for involuntary movements.
- **Conclusion**: This statement is **consistent** with smooth muscle architecture.

3. **Final Answer**:
- The correct answer is **Option 4: Multi-unit muscles that are active during GI peristalsis**.