21 Questions
What structural component of smooth muscle provides structural stability?
Intermediate filaments
What is the role of myosin light chain in smooth muscle contraction?
Binds to actin when phosphorylated
Which type of smooth muscle is characterized as neurogenic?
Multiunit
What happens to the thin filaments during smooth muscle contraction?
Pass in opposite directions along thick filaments
Which molecule binds with calmodulin to initiate the cross-bridge cycle in smooth muscle contraction?
Calcium ions
What replaces Z lines in smooth muscle cells since they lack sarcomeres?
'Dense bodies'
Which type of muscle has filaments that send signals in opposite directions rather than in the middle?
Smooth muscle
What is the primary role of myosin light chain kinase in smooth muscle contraction?
Add a phosphate group to myosin light chain
What is the structural significance of the dense bodies in smooth muscle?
Structurally stabilizes and holds together the filaments in a criss-cross pattern.
Explain the role of myosin light chain phosphorylation in smooth muscle contraction.
Phosphorylation is necessary for myosin head to bind to actin and initiate the cross-bridge cycle.
What is the function of calmodulin in smooth muscle contraction?
Calmodulin binds with Ca2+ and activates myosin light chain kinase.
Describe the arrangement of thick and thin filaments in smooth muscle cells during contraction.
Thin filaments pass in opposite directions along thick filaments.
What is the role of intermediate filaments in smooth muscle cells?
Provide structural stability.
How does multiunit smooth muscle differ from single unit smooth muscle?
Multiunit smooth muscle is neurogenic and phasic.
Explain the significance of myosin light chain kinase in the cross-bridge cycle.
Myosin light chain kinase phosphorylates myosin light chain, allowing for cross-bridge formation.
How do the thick filaments in smooth muscle differ from those in skeletal muscle?
Thick filaments in smooth muscle have more heads available for binding and send filaments in opposite directions.
Smooth muscle cells have sarcomeres similar to skeletal muscles.
False
Calmodulin activates myosin light chain kinase by binding to it.
False
Multiunit smooth muscle is referred to as phasic and originates from neural stimulation.
True
The myosin light chain must be dephosphorylated for the myosin head to bind to actin in smooth muscle contraction.
False
Thin filaments in smooth muscle cells pass in the same direction along the thick filaments during contraction.
False
Learn about the structure and composition of the filaments present in smooth muscle cells found in hollow organs and tubes. Explore the arrangement of thick, thin, and intermediate filaments in these spindle-shaped cells that lack sarcomeres.
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