17 Questions
What is the primary mechanism by which smooth muscle cells contract?
By a sliding-filament mechanism
What is the effect of phosphorylation of smooth muscle myosin?
It allows myosin to bind to actin and undergo cross-bridge cycling
What is the role of the sarcoplasmic reticulum in smooth muscle contraction?
It is responsible for the release of calcium ions into the cytosol
What happens to the tension produced by smooth muscle when cytosolic calcium ions are increased?
It increases due to the increased binding of myosin to actin
What is the characteristic of smooth muscle myosin that differs from striated muscle myosin?
It has a lower rate of ATP splitting
What is the role of calmodulin in smooth muscle contraction?
It binds to Ca2+ and activates myosin light-chain-kinase
What type of channels are responsible for the influx of calcium ions during the rising phase of the smooth muscle action potential?
voltage-gated Ca2+ channels
What is the term for the spontaneous, periodic depolarizations of the membrane potential seen in some smooth muscle pacemaker cells?
Slow waves
What is the characteristic of smooth muscle cells in terms of their response to neurotransmitters?
They may be influenced by neurotransmitters from more than one neuron
What is the main difference between smooth muscle cells and cardiac muscle cells in terms of their structure?
Smooth muscle cells have a specialized end-plate region
What is the term for the type of smooth muscle that can generate action potentials in the absence of any external input?
Pacemaker smooth muscle
How do smooth muscle cells differ from skeletal muscle cells in terms of their response to neurotransmitters?
Smooth muscle cells respond to neurotransmitters, whereas skeletal muscle cells do not
What is a key difference between cardiac muscle excitation-contraction coupling and skeletal muscle excitation-contraction coupling?
L-type Ca2+ channels are involved in cardiac muscle but not skeletal muscle
What is a characteristic shared by cardiac muscle and smooth muscle?
Arrangement in layers around hollow cavities
What is a key similarity between cardiac muscle and skeletal muscle?
Striation pattern
What is a feature of cardiac muscle contractions that is not seen in skeletal muscle?
The strength and frequency of contraction are modulated by autonomic neurotransmitters and hormones
What can be said about the comparison of skeletal, smooth, and cardiac muscles?
Cardiac muscle shares characteristics with both skeletal and smooth muscles
Understand the structure and contraction mechanisms of smooth muscle cells, including their spindle shape, actin and myosin filaments, and the role of calcium and calmodulin. Learn how smooth muscle contraction is controlled and regulated.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
