Question

In addition to their contractile properties, smooth muscle cells demonstrate the characteristic features of secretory cells. For example, endomysium, a thin layer of connective tissue, and the basal lamina that surrounds smooth muscle fibers are produced and deposited by smooth muscle cells. Reticular fibers in the endomysium form an intricate network that supports the parenchymal cells and binds them together. In large blood vessels, smooth muscle cells secrete type I collagen and elastic tissue components. What are the characteristic features of smooth muscle cells in addition to their contractile properties?

1) They produce and deposit endomysium and basal lamina
2) They form an intricate network of reticular fibers
3) They secrete type I collagen and elastic tissue components
4) They support parenchymal cells and bind them together
5) All of the above

Answer 1

Smooth muscle cells have multiple non-contractile characteristics, including producing and depositing endomysium and basal lamina, forming reticular fibers, secreting type I collagen and elastic tissue components, and supporting parenchymal cells. They can also undergo hyperplasia and exhibit sustained contractions and a stress-relaxation response.

Step-by-step explanation:

Smooth muscle cells demonstrate several characteristic features in addition to their contractile properties. They are responsible for producing and depositing endomysium and basal lamina that surround the muscle fibers. In this process, they secrete type I collagen and components of elastic tissue, which are crucial for the structure and function of large blood vessels. Additionally, smooth muscle cells form an intricate network of reticular fibers that support the parenchymal cells and ensure they are bound together.

These cells are spindle-shaped with a single nucleus and demonstrate a remarkable ability to undergo hyperplasia, which allows for the growth and repair of smooth muscle tissue. Their contraction is triggered by calcium ions released from the sarcoplasmic reticulum (SR) as well as from the extracellular fluid. This process is facilitated by their sarcoplasm, which is filled with actin and myosin, and dense bodies that serve as anchors for the thin filaments. Unlike striated muscle, smooth muscle can sustain long-term contractions, exhibit a stress-relaxation response, and maintain function when stretched.