Question

Smooth muscles are held together by (a) Connective tissue (b) Cell junctions (c) Epithelial tissue (d) None of these

Short answer

(b) Cell junctions

Step-by-step solution

Understanding question

The question is asking what structure holds the smooth muscle cells together. There are different types of structures that make up different types of muscles, such as skeletal or cardiac, but in this case, we are interested in smooth muscles.

Identifying structures of smooth muscles

Smooth muscle cells are individual spindle-shaped cells with a single central nucleus. Unlike skeletal muscles, these do not have any connective tissue coverings. These muscle cells are held together by cell junctions, structures that provide contact between neighbouring cells or between a cell and the extracellular matrix.

Confirming the answer

According to the information in step 2, we can confirm that the correct answer to the provided alternatives is cell junctions, as these are structures that hold together smooth muscle cells.

Key concepts

Cell Junctions

Cell junctions play a crucial role in holding smooth muscle cells together. These are specialized structures that allow cells to attach to each other or connect with their surrounding matrix. They serve several important functions, such as providing structural stability and facilitating communication between cells. Cell junctions can be found not only in smooth muscles but also in other muscle types and different tissues.

• They ensure that cells adhere tightly to maintain the integrity of the tissue.
• They enable the transmission of signals, allowing coordinated contraction of the smooth muscle tissue.
• These junctions prevent the separation of cells under stress, which is especially crucial in smooth muscles that work continuously.

New lines create compartments where ions and molecules can pass, ensuring smooth muscle behaves as a single unit during contraction. Understanding how cell junctions function is essential for grasping how smooth muscles operate seamlessly in organs such as the digestive tract and blood vessels.

Connective Tissue

Unlike other muscle types, smooth muscles generally lack the extensive connective tissue framework found in skeletal muscles. Connective tissue is typically associated with providing support and facilitating movement by connecting different body parts.

• In skeletal muscles, it provides the external sheath and structure.
• However, in smooth muscles, it plays a minimal role compared to the importance of cell junctions.

Some connective tissue presence is crucial for anchoring smooth muscles to various body structures and helping distribute the force generated by these muscles. Despite its limited presence, the connective tissue still contributes to the elasticity and the overall function of smooth muscle tissues.

Muscle Structures

Understanding the overall structure of muscles helps in identifying how smooth muscles function uniquely. Muscle structures vary significantly across the major types: skeletal, cardiac, and smooth.

• Skeletal muscles feature long, striated fibers and are voluntary, enabling movement, posture, and heat production.
• Cardiac muscles, found only in the heart, have striated fibers like skeletal but are structured to work involuntarily, constantly pumping blood.
• Smooth muscles have spindle-shaped cells that lack striations and work involuntarily to control activities like digestion and blood flow.

Smooth muscles' unique structure, unlike the others, allows them to sustain long-term, consistent contractions without fatigue. This property is pivotal for organs requiring sustained muscular tension, reflecting their structural design optimized for continuous function.