G Book 8. Smooth Muscle Contraction Mechanisms Quiz

<p>The unique structure and regulatory mechanisms of smooth muscle enable greater force generation, despite the fewer myosin filaments. (D)</p> Signup and view all the answers

<p>4 to 6 kg/cm² (C)</p> Signup and view all the answers

<p>The myosin cross-bridge heads have a lower ATPase activity in smooth muscle. (A)</p> Signup and view all the answers

<p>The prolonged attachment of myosin cross-bridges to actin, even with reduced excitation. (A)</p> Signup and view all the answers

<p>It ensures the efficient use of ATP during prolonged contractions. (A)</p> Signup and view all the answers

<p>Smooth muscle cells have slower cycling of myosin cross-bridges due to lower ATPase activity. (C)</p> Signup and view all the answers

<p>It is much slower in smooth muscle. (B)</p> Signup and view all the answers

<p>The duration of the myosin cross-bridge attachment to actin. (B)</p> Signup and view all the answers

<p>Smooth muscle gradually relaxes when stretched and held at a constant length. (B)</p> Signup and view all the answers

<p>It is much longer in smooth muscle. (C)</p> Signup and view all the answers

<p>Decrease in calcium ion concentration (D)</p> Signup and view all the answers

<p>It splits phosphate from the regulatory light chain. (D)</p> Signup and view all the answers

<p>The number of myosin heads attached to actin remains high. (D)</p> Signup and view all the answers

<p>The amount of active myosin phosphatase (D)</p> Signup and view all the answers

<p>Latch phenomenon. (B)</p> Signup and view all the answers

<p>Nervous signals and hormonal stimulation. (A)</p> Signup and view all the answers

<p>ATP is not degraded to ADP during this phase. (C)</p> Signup and view all the answers

<p>Electrical stimulation from heart contractions (A)</p> Signup and view all the answers

<p>It facilitates the attachment of myosin to actin during contraction. (D)</p> Signup and view all the answers

<p>They conduct action potentials like transverse tubules in skeletal muscle. (C)</p> Signup and view all the answers

<p>Extracellular calcium concentration changes have little to no effect on contraction force. (B)</p> Signup and view all the answers

<p>Skeletal muscle uses action potentials to trigger calcium release directly from the sarcoplasmic reticulum. (C)</p> Signup and view all the answers

<p>It suggests a rudimentary system similar to that of skeletal muscle. (B)</p> Signup and view all the answers

<p>It allows for more rapid contractions. (D)</p> Signup and view all the answers

<p>Smooth muscle does not require ATP for contraction. (A)</p> Signup and view all the answers

<p>Action potentials traveling through caveolae excite calcium release. (C)</p> Signup and view all the answers

<p>Either excite or inhibit smooth muscle contraction (B)</p> Signup and view all the answers

<p>They form diffuse junctions that are a few micrometers away (A)</p> Signup and view all the answers

<p>The type of receptor for the neurotransmitter (A)</p> Signup and view all the answers

<p>−50 to −60 millivolts (A)</p> Signup and view all the answers

<p>Only the outer layer of muscle cells (A)</p> Signup and view all the answers

<p>Through diffusion and action potential conduction (C)</p> Signup and view all the answers

<p>They decide the muscle's reaction to the neurotransmitter (C)</p> Signup and view all the answers

<p>Smooth muscle has no neuromuscular junctions (A)</p> Signup and view all the answers

<p>Hyperpolarization (B)</p> Signup and view all the answers

<p>Epinephrine (D)</p> Signup and view all the answers

<p>They serve as second messengers that affect muscle function. (A)</p> Signup and view all the answers

<p>To generate cAMP or cGMP. (B)</p> Signup and view all the answers

<p>To inhibit contraction. (C)</p> Signup and view all the answers

<p>By triggering the release of calcium from the sarcoplasmic reticulum. (A)</p> Signup and view all the answers

<p>Hyperpolarization of the muscle cell. (C)</p> Signup and view all the answers

<p>The inhibition of smooth muscle contraction. (A)</p> Signup and view all the answers

The process of myosin attaching to, releasing from, and reattaching to actin filaments during muscle contraction.

A mechanism in smooth muscle that allows prolonged contraction with minimal energy use.

Smooth muscle requires significantly less energy (1/10 to 1/300) than skeletal muscle for contraction maintenance.

Smooth muscle cross-bridges cycle 1/10 to 1/300 slower than in skeletal muscle, impacting contraction speed.

In smooth muscle, cross-bridges remain attached to actin longer, contributing to sustained force.

Smooth muscle has lower ATPase activity in myosin heads compared to skeletal muscle, affecting energy usage.

Smooth muscle can maintain constant contraction for long periods with reduced energy expenditure.

A phenomenon where smooth muscle maintains tension while adapting to new stimuli over time.

Contraction of smooth muscle is slower and prolonged due to slow cross-bridge cycling.

Calcium ions increase intracellular levels, triggering smooth muscle contraction.

Smooth muscle can exert a maximum force greater than skeletal muscle despite fewer myosin filaments.

Smooth muscle does not contain troponin, which regulates contraction in skeletal muscle.

Smooth muscle contraction can be initiated by nerve stimulation, hormones, or stretch.

One of the light chains of myosin that is phosphorylated to regulate contraction in smooth muscle.

The addition of a phosphate group to a molecule, often activating proteins like the regulatory chain in myosin.

Small invaginations of the cell membrane in smooth muscle that interact with sarcoplasmic tubules.

Structures in smooth muscle that store calcium ions and aid contraction when excited by action potentials.

The process by which an action potential leads to muscle contraction through calcium ion release.

Essential ions that trigger contraction in smooth muscle by interacting with proteins.

The level of calcium outside the cell, which significantly influences smooth muscle contraction strength.

The organelle that stores calcium in muscle cells, more extensive in smooth muscle for rapid contractions.

Proteins on smooth muscle membrane that respond to neurotransmitters.

A neurotransmitter that can excite or inhibit smooth muscle.

A neurotransmitter that affects smooth muscle contraction differently than acetylcholine.

Spaces where neurotransmitters diffuse to reach smooth muscle cells.

The resting intracellular voltage is typically -50 to -60 mV.

Electrical impulses that allow excitation to spread through muscle layers.

Nerves that branch and release neurotransmitters to control smooth muscle.

Smooth muscle response depends on receptor type for neurotransmitter binding.

Calcium channels close, reducing calcium entry into smooth muscle cells.

Transports calcium ions out of cytosol, aiding muscle relaxation.

Enzyme that dephosphorylates myosin, allowing muscle relaxation.

Myosin heads remain attached to actin during relaxation due to enzyme activity.

Mechanism in smooth muscle that sustains tension with low energy use.

The amount of active myosin phosphatase affects muscle relaxation speed.

Smooth muscle is influenced by nervous signals, hormones, and stretch.

How often myosin heads attach and detach during contraction affects speed.

A state of increased negativity inside a muscle cell that inhibits contraction.

Hormones can initiate muscle contraction without changing membrane potential directly.

Calcium ions are released from the sarcoplasmic reticulum to induce muscle contraction.

An enzyme activated by certain receptors that increases cAMP levels, inhibiting contraction.

Cyclic adenosine monophosphate, a second messenger affecting muscle contraction.

Cyclic guanosine monophosphate, another second messenger involved in muscle relaxation.

The organelle that stores and releases calcium for muscle contraction.

Molecules like cAMP and cGMP that relay signals for various effects in smooth muscles.