Question

art-labeling activity: structure of a smooth muscle fiber
1 part | 0 of 1 point

drag the labels onto the diagram to identify the parts of a smooth muscle fiber.

show instructions

relaxed (sectional view)
actin
myosin
dense body

relaxed (superficial view)

Explanation:

🆕 New Concept Discovered: Smooth Muscle Microanatomy
Understanding how non-striated muscle cells organize contractile proteins.

Step 1: Identify the visible labels

The image shows a diagram of a smooth muscle fiber in a relaxed state (sectional view and superficial view).
Three labels are already placed on the sectional view:

• Actin: Points to the thin filaments (red lines).
• Myosin: Points to the thick filaments (darker, thicker bars).
• Dense body: Points to the dark circular structures anchoring the thin filaments (analogous to Z-discs in striated muscle).

Step 2: Determine the missing labels

In standard anatomy art-labeling activities for the "Structure of a Smooth Muscle Fiber" (typically from Pearson/Marieb Human Anatomy & Physiology), the labels to be dragged onto the diagram generally include:

1. Sarcolemma (the plasma membrane of the muscle cell)
2. Nucleus (the central, single oval structure in the middle of the cell)
3. Intermediate filaments (the non-contractile cytoskeletal elements connecting the dense bodies)
4. Caveolae (pouch-like infoldings of the sarcolemma that sequester calcium)
5. Dense plaques (or attachment plaques, anchoring dense bodies to the sarcolemma)

Looking at the sectional view:

• The large, central, textured oval structure in the middle of the cell is the Nucleus.
• The outer boundary membrane of the cell is the Sarcolemma.
• The network of structural lines running between dense bodies represents Intermediate filaments.

Answer:

Based on standard anatomical diagrams of a smooth muscle fiber, the remaining labels to place on the diagram are:

1. Nucleus (points to the central blue/green textured organelle)
2. Sarcolemma (points to the outer cell membrane)
3. Intermediate filaments (points to the cytoskeletal lattice lines connecting the dense bodies)
4. Caveolae (points to the tiny indentations along the sarcolemma membrane)