Question 1

In smooth muscle,actin and myosin filaments:

Accepted Answer

A) Are organized into sarcomeres and aligned in a striated pattern. 
B) Overlap,with the actin filaments anchored at dense bodies. 
C) Overlap and contain a tropomyosin-troponin complex on the actin filament. 
D) Require phosphorylation of the myosin heavy chain to initiate muscle contraction. 
E) Typically generate contractile force in the absence of cytosolic Ca++. 
A) Are organized into sarcomeres and aligned in a striated pattern. 
B) Overlap,with the actin filaments anchored at dense bodies. 
C) Overlap and contain a tropomyosin-troponin complex on the actin filament. 
D) Require phosphorylation of the myosin heavy chain to initiate muscle contraction. 
E) Typically generate contractile force in the absence of cytosolic Ca++. B

Question 2

Smooth muscle can contract without a change in membrane potential after:

Accepted Answer

A) Stimulation of $\beta$-adrenergic receptors in the smooth muscle. 
B) Inhibition of Rho kinase in the smooth muscle. 
C) Stimulation of InsP3 production in the smooth muscle. 
D) Stimulation of nitric oxide release from endothelial cells. 
E) Stimulation of K+ channels in the smooth muscle. 
A) Stimulation of $\beta$-adrenergic receptors in the smooth muscle. 
B) Inhibition of Rho kinase in the smooth muscle. 
C) Stimulation of InsP3 production in the smooth muscle. 
D) Stimulation of nitric oxide release from endothelial cells. 
E) Stimulation of K+ channels in the smooth muscle. C

Question 3

An increase in smooth muscle tension can occur at a given intracellular [Ca++] in response to:

Accepted Answer

A) Opening of K+ channels in the smooth muscle membrane. 
B) Inhibition of myosin phosphatase by Rho kinase in the smooth muscle. 
C) Cyclic adenosine monophosphate (cAMP)-dependent phosphorylation of myosin light-chain kinase in the smooth muscle. 
D) Release of nitric oxide from adjacent endothelial cells. 
E) Hyperpolarization of the smooth muscle membrane. 
A) Opening of K+ channels in the smooth muscle membrane. 
B) Inhibition of myosin phosphatase by Rho kinase in the smooth muscle. 
C) Cyclic adenosine monophosphate (cAMP)-dependent phosphorylation of myosin light-chain kinase in the smooth muscle. 
D) Release of nitric oxide from adjacent endothelial cells. 
E) Hyperpolarization of the smooth muscle membrane. B

Question 4

A variety of stimuli can elevate cyclic guanosine monophosphate (cGMP)concentration in smooth muscle,which results in activation of cGMP-dependent signaling pathways in the smooth muscle.This activation typically:

Accepted Answer

A) Promotes relaxation,partly because of inhibition of myosin phosphatase. 
B) Promotes contraction,partly because of decreased endothelin production. 
C) Promotes relaxation,partly because of activation of potassium channels . 
D) Promotes contraction,partly because of inhibition of InsP3 production. 
E) Promotes relaxation,partly because of activation of voltage-gated Ca channels. 
A) Promotes relaxation,partly because of inhibition of myosin phosphatase. 
B) Promotes contraction,partly because of decreased endothelin production. 
C) Promotes relaxation,partly because of activation of potassium channels . 
D) Promotes contraction,partly because of inhibition of InsP3 production. 
E) Promotes relaxation,partly because of activation of voltage-gated Ca channels.

Question 5

Endogenous agonists such as adenosine and prostacyclin,as well as $\beta$2-adrenergic receptor agonists,can elevate cAMP concentration in smooth muscle.The elevation of cAMP in the smooth muscle results in activation of cAMP-dependent signaling pathways in the smooth muscle.This activation typically:

Accepted Answer

A) Promotes relaxation,partly because of activation of myosin phosphatase. 
B) Promotes contraction,partly because of activation of potassium channels. 
C) Promotes relaxation,partly because of activation of Rho kinase. 
D) Promotes contraction,partly because of inhibition of InsP3 production. 
E) Promotes relaxation,partly because of inhibition potassium channels. 
A) Promotes relaxation,partly because of activation of myosin phosphatase. 
B) Promotes contraction,partly because of activation of potassium channels. 
C) Promotes relaxation,partly because of activation of Rho kinase. 
D) Promotes contraction,partly because of inhibition of InsP3 production. 
E) Promotes relaxation,partly because of inhibition potassium channels.

Question 6

A variety of smooth muscle relaxants can promote the occurrence of Ca++ sparks beneath sarcolemma of smooth muscle.The Ca++ sparks are thought to originate from a local activation of the ryanodine receptor,just beneath the sarcolemma.These Ca++ sparks promote relaxation by:

Accepted Answer

A) Activating the Na+-Ca++ antiporter in the smooth muscle. 
B) Activating the Ca++-dependent phosphatase calcineurin in the smooth muscle. 
C) Activating Ca++-dependent K+ channels in the smooth muscle. 
D) Promoting myosin light-chain phosphorylation in the smooth muscle. 
E) Activating Rho kinase in the smooth muscle. 
A) Activating the Na+-Ca++ antiporter in the smooth muscle. 
B) Activating the Ca++-dependent phosphatase calcineurin in the smooth muscle. 
C) Activating Ca++-dependent K+ channels in the smooth muscle. 
D) Promoting myosin light-chain phosphorylation in the smooth muscle. 
E) Activating Rho kinase in the smooth muscle.

Question 7

Decreased cytosolic Ca++ in smooth muscle typically promotes relaxation by:

Accepted Answer

A) Closing Ca++-activated K+ channels in the smooth muscle. 
B) Reducing myosin light-chain kinase activity in the smooth muscle. 
C) Reducing nitric oxide release from endothelial cells. 
D) Reducing Ca++ influx through transient receptor potential vanilloid (TRPV)channels in the smooth muscle. 
E) Reducing production of inositol 1,4,5-triphosphate (InsP3)in the smooth muscle. 
A) Closing Ca++-activated K+ channels in the smooth muscle. 
B) Reducing myosin light-chain kinase activity in the smooth muscle. 
C) Reducing nitric oxide release from endothelial cells. 
D) Reducing Ca++ influx through transient receptor potential vanilloid (TRPV)channels in the smooth muscle. 
E) Reducing production of inositol 1,4,5-triphosphate (InsP3)in the smooth muscle.

Question 8

During exercise,skeletal muscle can release local factors,such as adenosine,which can relax neighboring vascular smooth muscle and thus promote vasodilation in the exercising muscle.The mechanism by which adenosine promotes relaxation of smooth muscle typically involves:

Accepted Answer

A) Inhibition of K+ channels in the vascular smooth muscle. 
B) Stimulation of InsP3 production in the vascular smooth muscle. 
C) Stimulation of release of endothelin from adjacent endothelial cells. 
D) Stimulation of cAMP production in the vascular smooth muscle. 
E) Activation of voltage-gated Ca++ channels in the vascular smooth muscle. 
A) Inhibition of K+ channels in the vascular smooth muscle. 
B) Stimulation of InsP3 production in the vascular smooth muscle. 
C) Stimulation of release of endothelin from adjacent endothelial cells. 
D) Stimulation of cAMP production in the vascular smooth muscle. 
E) Activation of voltage-gated Ca++ channels in the vascular smooth muscle.

Question 9

The latch property of smooth muscle concerns the ability of the smooth muscle to maintain:

Accepted Answer

A) A relaxed state independent of cytosolic Ca++ level. 
B) Force while decreasing the rate of energy utilization. 
C) The rate of InsP3 production after agonist removal. 
D) Force in the absence of myosin light-chain phosphorylation. 
E) Membrane potential independent of contractile state. 
A) A relaxed state independent of cytosolic Ca++ level. 
B) Force while decreasing the rate of energy utilization. 
C) The rate of InsP3 production after agonist removal. 
D) Force in the absence of myosin light-chain phosphorylation. 
E) Membrane potential independent of contractile state.

Exam 14: Smooth Muscle

In smooth muscle,actin and myosin filaments:

Smooth muscle can contract without a change in membrane potential after:

An increase in smooth muscle tension can occur at a given intracellular [Ca++] in response to:

A variety of stimuli can elevate cyclic guanosine monophosphate (cGMP)concentration in smooth muscle,which results in activation of cGMP-dependent signaling pathways in the smooth muscle.This activation typically:

A variety of smooth muscle relaxants can promote the occurrence of Ca++ sparks beneath sarcolemma of smooth muscle.The Ca++ sparks are thought to originate from a local activation of the ryanodine receptor,just beneath the sarcolemma.These Ca++ sparks promote relaxation by:

Decreased cytosolic Ca++ in smooth muscle typically promotes relaxation by:

During exercise,skeletal muscle can release local factors,such as adenosine,which can relax neighboring vascular smooth muscle and thus promote vasodilation in the exercising muscle.The mechanism by which adenosine promotes relaxation of smooth muscle typically involves:

The latch property of smooth muscle concerns the ability of the smooth muscle to maintain:

Principles of Cell Function

Homeostasis of Body Fluids

Signal Transduction, membrane Receptors, second Messengers, and Regulation of Gene Expression

The Nervous System: Introduction to Cells and Systems

Generation and Conduction of Action Potentials

Synaptic Transmission

The Somatosensory System

The Special Senses

Organization of Motor Function

Higher Functions of the Nervous System

The Autonomic Nervous System and Its Central Control

Skeletal Muscle Physiology

Cardiac Muscle

Overview of Circulation

Elements of Cardiac Function

Properties of the Vasculature

Regulation of the Heart and Vasculature

Integrated Control of the Cardiovascular System

Structure and Function of the Respiratory System

Static Lung and Chest Wall Mechanics

Dynamic Lung and Chest Wall Mechanics

Ventilation

Oxygen and Carbon Dioxide Transport

Control of Respiration

Non-Physiologic Functions of the Lung: Host Defense and Metabolism

Functional Anatomy and General Principles of Regulation in the Gastrointestinal Tract

The Cephalic, oral, and Esophageal Phases of the Integrated Response to a Meal

The Gastric Phase of the Integrated Response to a Meal

The Small Intestinal Phase of the Integrated Response to a Meal

The Colonic Phase of the Integrated Response to a Meal

Transport and Metabolic Functions of the Liver

Elements of Renal Function

Solute and Water Transport Along the Nephron: Tubular Function

Control of Body Fluid Osmolality and Volume

Potassium, calcium, and Phosphate Homeostasis

Role of the Kidneys in the Regulation of Acid-Base Balance

Introduction to the Endocrine System

Hormonal Regulation of Energy Metabolism

Hormonal Regulation of Calcium and Phosphate Metabolism

The Hypothalamus and Pituitary Gland

The Thyroid Gland

The Adrenal Glands

The Male and Female Reproductive Systems

Filters

An increase in smooth muscle tension can occur at a given intracellular [Ca⁺⁺] in response to:

A variety of smooth muscle relaxants can promote the occurrence of Ca⁺⁺ sparks beneath sarcolemma of smooth muscle.The Ca⁺⁺ sparks are thought to originate from a local activation of the ryanodine receptor,just beneath the sarcolemma.These Ca⁺⁺ sparks promote relaxation by:

Decreased cytosolic Ca⁺⁺ in smooth muscle typically promotes relaxation by: