Autonomic Nervous System and Smooth Muscle Quiz

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What characterizes the latch bridge mechanism in smooth muscle contraction?

Enhances ATP binding affinity to myosin head

Phosphorylation of myosin light chain kinase

Rapid removal of myosin heads from actin

Leaves myosin head bound to actin without Pi (correct)

In the smooth muscle contraction cycle, what causes muscle relaxation?

Binding of myosin heads to actin

Phosphorylation of actin filaments

Activation of myosin ATPase

Removal of calcium and phosphate by phosphatase (correct)

What is the function of the latch bridge cycle in smooth muscle contraction?

Increases ATP consumption

Reduces energy consumption by maintaining tension (correct)

Shortens the period of tension

Enhances speed of muscle relaxation

How does the latch bridge mechanism contribute to tonic contraction in smooth muscle?

Maintains myosin head binding to actin without phosphate Signup and view all the answers

What is the primary role of phosphatase in the smooth muscle contraction cycle?

Remove phosphate from myosin Signup and view all the answers

What is the term for the swelling of a neuron where neurotransmitter is stored?

Varicosity Signup and view all the answers

Which neurotransmitters are released by autonomic nerves?

Norepinephrine and acetylcholine Signup and view all the answers

In smooth muscles, which type of system is associated with norepinephrine?

Sympathetic Signup and view all the answers

Which type of smooth muscle can contract in response to stretch?

Multi-unit smooth muscle Signup and view all the answers

What is the purpose of having gap junctions in single-unit smooth muscles?

To enable coordinated contraction as a unit Signup and view all the answers

What is the role of dense bodies in smooth muscles?

Anchor actin and connect to the extracellular matrix Signup and view all the answers

How are neurons connected to smooth muscles?

Not directly connected Signup and view all the answers

What is a key characteristic of autonomic neurons at the junction of smooth muscles?

Connection to smooth muscles without neuromuscular junctions Signup and view all the answers

Where are smooth muscles mainly located in vessels?

Tunica media Signup and view all the answers

How do contractions of smooth muscles compare to skeletal muscles?

Skeletal muscles contract more slowly but sustain tension better than smooth muscles Signup and view all the answers

What are the two types of cholinergic receptors?

Muscarinic and adrenergic Signup and view all the answers

Where are alpha 2 receptors primarily found?

Presynaptic side Signup and view all the answers

What is the primary action of alpha 1 receptors?

Vasoconstriction Signup and view all the answers

Which neurotransmitters do beta 2 receptors respond to mainly?

Epinephrine and norepinephrine Signup and view all the answers

What is the mechanism of action for removing acetylcholine from a synaptic cleft?

Degraded by acetylcholinesterase Signup and view all the answers