Question 1

Which of the following observations confirms the sliding filament mechanism for muscle contraction?

Accepted Answer

A)  As the sarcomere shortens, the H zone becomes smaller. 
B)  As the sarcomere shortens, the width of the A band remains the same. 
C)  As the sarcomere shortens, the I band becomes smaller. 
D)  Two of these. 
E)  All of these. 
A)  As the sarcomere shortens, the H zone becomes smaller. 
B)  As the sarcomere shortens, the width of the A band remains the same. 
C)  As the sarcomere shortens, the I band becomes smaller. 
D)  Two of these. 
E)  All of these.

Question 2

In skeletal muscle depolarization of the T tubule membrane causes

Accepted Answer

A)  activation of Ca2+ ATPase pumps which triggers a rise in intracellular calcium levels 
B)  dihydropyridine to bind calcium channel receptors which triggers a rise in intracellular calcium levels. 
C)  activation of stretch-activated Ca2+ channels which triggers a rise in intracellular calcium levels. 
D)  activation of dihydroxypyridine receptors in membrane of the T tubule which triggers a rise in intracellular calcium levels. 
E)  ryanodine to bind calcium channel receptors which triggers a rise in intracellular calcium levels. 
A)  activation of Ca2+ ATPase pumps which triggers a rise in intracellular calcium levels 
B)  dihydropyridine to bind calcium channel receptors which triggers a rise in intracellular calcium levels. 
C)  activation of stretch-activated Ca2+ channels which triggers a rise in intracellular calcium levels. 
D)  activation of dihydroxypyridine receptors in membrane of the T tubule which triggers a rise in intracellular calcium levels. 
E)  ryanodine to bind calcium channel receptors which triggers a rise in intracellular calcium levels.

Question 3

Which of the following features distinguishes skeletal muscle from smooth muscle?

Accepted Answer

A)  Only smooth muscle contraction is modified by hormones. 
B)  Only smooth muscle takes up Ca2+ from the extracellular fluid. 
C)  Only skeletal muscle is neurogenic. 
D)  Only skeletal muscle has a moderately developed sacroplasmic reticulum. 
E)  Two of these. 
A)  Only smooth muscle contraction is modified by hormones. 
B)  Only smooth muscle takes up Ca2+ from the extracellular fluid. 
C)  Only skeletal muscle is neurogenic. 
D)  Only skeletal muscle has a moderately developed sacroplasmic reticulum. 
E)  Two of these.

Question 4

How much of the energy available in ATP is lost as heat energy during an isotonic contraction by skeletal muscle?

Accepted Answer

A)  15% 
B)  25% 
C)  50% 
D)  60% 
E)  75% 
A)  15% 
B)  25% 
C)  50% 
D)  60% 
E)  75%

Question 5

Match each sentence with the most appropriate choice:
-H-zone

Accepted Answer

A)  T tubule 
B)  Lateral sacs 
C)  Motor endplate 
D)  Heart 
E)  Type I
F) Type IIa
G) Type IIx
H) ATP depletion
I) Myosin heads
J) Myosin tails 
A)  T tubule 
B)  Lateral sacs 
C)  Motor endplate 
D)  Heart 
E)  Type I
F) Type IIa
G) Type IIx
H) ATP depletion
I) Myosin heads
J) Myosin tails

Question 6

Fast muscle fibers differ from slow muscle fibers in that fast muscle fibers

Accepted Answer

A)  are able to take up oxygen more quickly from the blood. 
B)  are equipped with a myosin-ATPase with more rapid kinetics. 
C)  are able to generate ATP more rapidly. 
D)  conduction action potentials more rapidly. 
E)  are recruited by the nervous system more rapidly. 
A)  are able to take up oxygen more quickly from the blood. 
B)  are equipped with a myosin-ATPase with more rapid kinetics. 
C)  are able to generate ATP more rapidly. 
D)  conduction action potentials more rapidly. 
E)  are recruited by the nervous system more rapidly.

Question 7

An isometric contraction is a contraction in which

Accepted Answer

A)  tension (or force) increases, but length stays the same. 
B)  tension (or force) stays the same, but length increases. 
C)  tension (or force) stays the same, and length stays the same. 
D)  tension (or force) stays the same, but length decreases. 
E)  tension (or force) decreases, and length decreases. 
A)  tension (or force) increases, but length stays the same. 
B)  tension (or force) stays the same, but length increases. 
C)  tension (or force) stays the same, and length stays the same. 
D)  tension (or force) stays the same, but length decreases. 
E)  tension (or force) decreases, and length decreases.

Question 8

Which of the following statements is NOT true?

Accepted Answer

A)  Smooth muscle can be classified according to the timing and means of increasing cytosolic Ca2+. 
B)  In smooth muscle, C-type Ca2+ channels regulate the influx of extracellular Ca2+. 
C)  Smooth muscle tone exists because the muscle has a relatively low resting potential. 
D)  In smooth muscle, Ca2+ binds directly to myosin light chain kinase as opposed to troponin as it does in skeletal muscle. 
E)  Skeletal, cardiac, and smooth muscle differ in the energy source used for contraction. 
A)  Smooth muscle can be classified according to the timing and means of increasing cytosolic Ca2+. 
B)  In smooth muscle, C-type Ca2+ channels regulate the influx of extracellular Ca2+. 
C)  Smooth muscle tone exists because the muscle has a relatively low resting potential. 
D)  In smooth muscle, Ca2+ binds directly to myosin light chain kinase as opposed to troponin as it does in skeletal muscle. 
E)  Skeletal, cardiac, and smooth muscle differ in the energy source used for contraction.

Question 9

Match each sentence with the most appropriate choice:
-Cross bridges

Accepted Answer

A)  T tubule 
B)  Lateral sacs 
C)  Motor endplate 
D)  Heart 
E)  Type I
F) Type IIa
G) Type IIx
H) ATP depletion
I) Myosin heads
J) Myosin tails 
A)  T tubule 
B)  Lateral sacs 
C)  Motor endplate 
D)  Heart 
E)  Type I
F) Type IIa
G) Type IIx
H) ATP depletion
I) Myosin heads
J) Myosin tails

Question 10

The myosin filaments of a sarcomere are attached to the Z line by an elastic protein.

Accepted Answer

A) True 
 B)False

Question 11

Creatine is an important metabolite in muscle physiology. Based on your understanding of its role in muscle energetics, which of the following statements is true?

Accepted Answer

A)  The concentration of creatine rises as the concentration of ATP rises. 
B)  The concentration of creatine falls as the concentration of ATP rises. 
C)  The concentration of creatine is independent of the concentration of ATP. 
D)  The concentration of creatine rises as the concentration of ADP rises. 
A)  The concentration of creatine rises as the concentration of ATP rises. 
B)  The concentration of creatine falls as the concentration of ATP rises. 
C)  The concentration of creatine is independent of the concentration of ATP. 
D)  The concentration of creatine rises as the concentration of ADP rises.

Question 12

Which of the following muscle types has tone in the absence of an external stimulus?

Accepted Answer

A)  skeletal 
B)  multiunit smooth muscle 
C)  single-unit smooth muscle 
D)  cardiac muscle 
E)  all of these 
A)  skeletal 
B)  multiunit smooth muscle 
C)  single-unit smooth muscle 
D)  cardiac muscle 
E)  all of these

Question 13

Which of the following ATP-dependent steps of the contraction-relaxation cycle could be accomplished with a non-hydrolyzable form of ATP such as ATP-$\gamma$-S for example?

Accepted Answer

A)  cocking of the cross-bridge in anticipation of the power-stroke 
B)  release of actin by myosin 
C)  sequestration of calcium into the sarcoplasmic reticulum 
D)  All of these could be accomplished with ATP-$\gamma$-S. 
E)  None of these could be accomplished with ATP-$\gamma$-S. 
A)  cocking of the cross-bridge in anticipation of the power-stroke 
B)  release of actin by myosin 
C)  sequestration of calcium into the sarcoplasmic reticulum 
D)  All of these could be accomplished with ATP-$\gamma$-S. 
E)  None of these could be accomplished with ATP-$\gamma$-S.

Question 14

In spinal reflex pathways, motor neurons receive inputs from

Accepted Answer

A)  sensory afferents and/or internurons. 
B)  cortical neurons whose cell bodies reside in the primary motor cortex. 
C)  cortical neurons whose cell bodies reside in the somatosensory cortex. 
D)  cerebellar neurons. 
E)  brain stem neurons. 
A)  sensory afferents and/or internurons. 
B)  cortical neurons whose cell bodies reside in the primary motor cortex. 
C)  cortical neurons whose cell bodies reside in the somatosensory cortex. 
D)  cerebellar neurons. 
E)  brain stem neurons.

Question 15

Match each sentence with the most appropriate choice:
-Rigor

Accepted Answer

A)  T tubule 
B)  Lateral sacs 
C)  Motor endplate 
D)  Heart 
E)  Type I
F) Type IIa
G) Type IIx
H) ATP depletion
I) Myosin heads
J) Myosin tails 
A)  T tubule 
B)  Lateral sacs 
C)  Motor endplate 
D)  Heart 
E)  Type I
F) Type IIa
G) Type IIx
H) ATP depletion
I) Myosin heads
J) Myosin tails

Question 16

The sarcomere lies within the boundaries of which of these structures?

Accepted Answer

A)  A bands 
B)  H bands 
C)  I bands 
D)  sarcoplasmic reticulum 
E)  Z lines 
A)  A bands 
B)  H bands 
C)  I bands 
D)  sarcoplasmic reticulum 
E)  Z lines

Question 17

In vivo, muscles are usually positioned at a relaxed length that is approximately 80% of
 their optimal length which maximizes contraction strength.

Accepted Answer

A) True 
 B)False

Question 18

Match each sentence with the most appropriate choice:
-Slow-oxidative

Accepted Answer

A)  T tubule 
B)  Lateral sacs 
C)  Motor endplate 
D)  Heart 
E)  Type I
F) Type IIa
G) Type IIx
H) ATP depletion
I) Myosin heads
J) Myosin tails 
A)  T tubule 
B)  Lateral sacs 
C)  Motor endplate 
D)  Heart 
E)  Type I
F) Type IIa
G) Type IIx
H) ATP depletion
I) Myosin heads
J) Myosin tails

Question 19

In the length-tension curve shown, why does force decrease at sarcomere lengths less than lo?

Accepted Answer

A)  Not as much Ca2+ is released in a sarcomere with a length less than lo.. 
B)  Interference between actin filaments originating from opposite ends of the sarcomere prevents maximal or optimal cross-bridge formation. 
C)  The muscle fiber runs out of ATP. 
D)  In this situation, Ca2+ availability and the position of the actin filaments are responsible for the decrease in muscle shortening because ATP will still be available. 
E)  All of these contribute to reduced muscle shortening in a sarcomere with a length less than lo. 
A)  Not as much Ca2+ is released in a sarcomere with a length less than lo.. 
B)  Interference between actin filaments originating from opposite ends of the sarcomere prevents maximal or optimal cross-bridge formation. 
C)  The muscle fiber runs out of ATP. 
D)  In this situation, Ca2+ availability and the position of the actin filaments are responsible for the decrease in muscle shortening because ATP will still be available. 
E)  All of these contribute to reduced muscle shortening in a sarcomere with a length less than lo.

Question 20

Arthropod muscles attach to internal ridges of the exoskeleton called apodemes.

Accepted Answer

A) True 
 B)False

Which of the following observations confirms the sliding filament mechanism for muscle contraction?

In skeletal muscle depolarization of the T tubule membrane causes

Which of the following features distinguishes skeletal muscle from smooth muscle?

How much of the energy available in ATP is lost as heat energy during an isotonic contraction by skeletal muscle?

Match each sentence with the most appropriate choice: -H-zone

Fast muscle fibers differ from slow muscle fibers in that fast muscle fibers

An isometric contraction is a contraction in which

Which of the following statements is NOT true?

Match each sentence with the most appropriate choice: -Cross bridges

The myosin filaments of a sarcomere are attached to the Z line by an elastic protein.

Creatine is an important metabolite in muscle physiology. Based on your understanding of its role in muscle energetics, which of the following statements is true?

Which of the following muscle types has tone in the absence of an external stimulus?

Which of the following ATP-dependent steps of the contraction-relaxation cycle could be accomplished with a non-hydrolyzable form of ATP such as ATP- $\gamma$ -S for example?

In spinal reflex pathways, motor neurons receive inputs from

Match each sentence with the most appropriate choice: -Rigor

The sarcomere lies within the boundaries of which of these structures?

In vivo, muscles are usually positioned at a relaxed length that is approximately 80% of their optimal length which maximizes contraction strength.

Match each sentence with the most appropriate choice: -Slow-oxidative

In the length-tension curve shown, why does force decrease at sarcomere lengths less than l_o?

Arthropod muscles attach to internal ridges of the exoskeleton called apodemes.

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Exam 8: Muscle Physiology

Which of the following observations confirms the sliding filament mechanism for muscle contraction?

In skeletal muscle depolarization of the T tubule membrane causes

Which of the following features distinguishes skeletal muscle from smooth muscle?

How much of the energy available in ATP is lost as heat energy during an isotonic contraction by skeletal muscle?

Match each sentence with the most appropriate choice: -H-zone

Fast muscle fibers differ from slow muscle fibers in that fast muscle fibers

An isometric contraction is a contraction in which

Which of the following statements is NOT true?

Match each sentence with the most appropriate choice: -Cross bridges

The myosin filaments of a sarcomere are attached to the Z line by an elastic protein.

Creatine is an important metabolite in muscle physiology. Based on your understanding of its role in muscle energetics, which of the following statements is true?

Which of the following muscle types has tone in the absence of an external stimulus?

Which of the following ATP-dependent steps of the contraction-relaxation cycle could be accomplished with a non-hydrolyzable form of ATP such as ATP- γ\gammaγ -S for example?

In spinal reflex pathways, motor neurons receive inputs from

Match each sentence with the most appropriate choice: -Rigor

The sarcomere lies within the boundaries of which of these structures?

In vivo, muscles are usually positioned at a relaxed length that is approximately 80% of their optimal length which maximizes contraction strength.

Match each sentence with the most appropriate choice: -Slow-oxidative

In the length-tension curve shown, why does force decrease at sarcomere lengths less than lo?

Arthropod muscles attach to internal ridges of the exoskeleton called apodemes.

Homeostasis and Integration: The Foundations of Physiology

Cellular and Molecular Physiology

Membrane Physiology

Neuronal Physiology

Nervous Systems

Sensory Physiology

Endocrine Systems

Circulatory Systems

Defense Systems

Respiratory Systems

Excretory Systems

Fluid and Acid-Base Balance

Digestive Systems

Energy Balance and Thermal Physiology

Reproductive Systems

Filters

Which of the following ATP-dependent steps of the contraction-relaxation cycle could be accomplished with a non-hydrolyzable form of ATP such as ATP- $\gamma$ -S for example?

In the length-tension curve shown, why does force decrease at sarcomere lengths less than l_o?