Question 1

Which of the following is a characteristic of slow-twitch oxidative skeletal muscle fibers?

Accepted Answer

A)  long contraction duration only 
B)  few mitochondria only 
C)  high capillary density only 
D)  long contraction duration and high capillary density 
E)  long contraction duration, few mitochondria, and high capillary density 
A)  long contraction duration only 
B)  few mitochondria only 
C)  high capillary density only 
D)  long contraction duration and high capillary density 
E)  long contraction duration, few mitochondria, and high capillary density

Question 2

When a skeletal muscle cell contracts and the muscle shortens,

Accepted Answer

A)  myosin heads generate a single power stroke. 
B)  the position of an actin molecule relative to a myosin molecule does not change. 
C)  some myosin heads are forming crossbridges as others are releasing them. 
D)  the actin ATPase allows the actin molecule to swivel. 
E)  the actin molecule swivels during the power stroke. 
A)  myosin heads generate a single power stroke. 
B)  the position of an actin molecule relative to a myosin molecule does not change. 
C)  some myosin heads are forming crossbridges as others are releasing them. 
D)  the actin ATPase allows the actin molecule to swivel. 
E)  the actin molecule swivels during the power stroke.

Question 3

The contraction cycle is triggered by the rise in ________ released from the sarcoplasmic reticulum (SR).

Accepted Answer

A)  Na+ 
B)  K+ 
C)  Ca2+ 
A)  Na+ 
B)  K+ 
C)  Ca2+

Question 4

List and explain the functions of the regulatory molecules in a sarcomere,specifying how the on and off positions are controlled and its impact on the crossbridges formed.

Accepted Answer

Troponin and tropomyosin and the primary

Question 5

The I band contains

Accepted Answer

A)  thick filaments only. 
B)  thin filaments only. 
C)  myosin only. 
D)  thick and thin filaments. 
A)  thick filaments only. 
B)  thin filaments only. 
C)  myosin only. 
D)  thick and thin filaments.

Question 6

The function of the titin protein is to

Accepted Answer

A)  stabilize the position of the contractile filaments. 
B)  pull Z lines together during contraction. 
C)  interact with actin during contraction. 
D)  release calcium during contraction. 
E)  cover the myosin binding site on the actin molecule. 
A)  stabilize the position of the contractile filaments. 
B)  pull Z lines together during contraction. 
C)  interact with actin during contraction. 
D)  release calcium during contraction. 
E)  cover the myosin binding site on the actin molecule.

Question 7

Smooth muscle cells lack which protein(s)?

Accepted Answer

A)  actin only 
B)  myosin only 
C)  troponin only 
D)  tropomyosin only 
E)  troponin and tropomyosin 
A)  actin only 
B)  myosin only 
C)  troponin only 
D)  tropomyosin only 
E)  troponin and tropomyosin

Question 8

Relative to skeletal muscle,smooth muscle

Accepted Answer

A)  only uses less energy to generate a given amount of force. 
B)  only can sustain contractile force without fatigue. 
C)  only uses calcium from the sarcoplasmic reticulum and extracellular space. 
D)  uses less energy to generate a given amount of force and can sustain contractile force without fatigue. 
E)  uses less energy to generate a given amount of force, can sustain contractile force without fatigue and uses calcium from the sarcoplasmic reticulum and extracellular space. 
A)  only uses less energy to generate a given amount of force. 
B)  only can sustain contractile force without fatigue. 
C)  only uses calcium from the sarcoplasmic reticulum and extracellular space. 
D)  uses less energy to generate a given amount of force and can sustain contractile force without fatigue. 
E)  uses less energy to generate a given amount of force, can sustain contractile force without fatigue and uses calcium from the sarcoplasmic reticulum and extracellular space.

Question 9

In order to contract and relax,muscle cells require energy in the form of ________.The immediate backup energy source is ________ that requires the enzyme ________.

Accepted Answer

ATP,phosph

Question 10

Striated muscles are so-called because of a repeating pattern of light and dark bands.One repeating unit of the banding pattern is called a

Accepted Answer

A)  myofilament. 
B)  myomere. 
C)  sarcofibril. 
D)  sarcomere. 
E)  crossbridge. 
A)  myofilament. 
B)  myomere. 
C)  sarcofibril. 
D)  sarcomere. 
E)  crossbridge.

Question 11

Match the structures with the accurate description.
-a bundle of adjacent muscle cells

Accepted Answer

A) muscle fiber 
B) fascicle 
C) sarcolemma 
D) myofibril 
E) t-tubules 
A) muscle fiber 
B) fascicle 
C) sarcolemma 
D) myofibril 
E) t-tubules

Question 12

Define and explain the difference between isotonic,isometric and eccentric contractions and give an example of a specific movement for each.What is the role of series elastic elements in muscle contraction?

Accepted Answer

Isotonic means same tension,that is,a ty

Question 13

Muscle fatigue arises primarily from failure in

Accepted Answer

A)  neuromuscular transmission. 
B)  initiation of contraction by the motor cortex. 
C)  excitation-contraction coupling. 
D)  signal relay from brain to spinal cord. 
E)  calcium pumps in the skeletal muscles. 
A)  neuromuscular transmission. 
B)  initiation of contraction by the motor cortex. 
C)  excitation-contraction coupling. 
D)  signal relay from brain to spinal cord. 
E)  calcium pumps in the skeletal muscles.

Question 14

A change in smooth muscle cell tension in the absence of a change in electrical potential of the cells is described as a

Accepted Answer

A)  pacemaker potential. 
B)  slow wave potential. 
C)  pharmacomechanical coupling. 
D)  electromechanical coupling. 
A)  pacemaker potential. 
B)  slow wave potential. 
C)  pharmacomechanical coupling. 
D)  electromechanical coupling.

Question 15

Within a single fiber,the tension developed during a twitch depends upon the

Accepted Answer

A)  amplitude of the action potential. 
B)  length of the sarcomeres prior to contraction. 
C)  length of the thick filament. 
D)  duration of the stimulus. 
A)  amplitude of the action potential. 
B)  length of the sarcomeres prior to contraction. 
C)  length of the thick filament. 
D)  duration of the stimulus.

Question 16

You and your lab partner use a living nerve and muscle preparation to study muscle contraction.When you stimulate the nerve electrically,the muscle contracts; why? When you turn off the stimulator but add a high concentration of caffeine to the fluid surrounding the tissues,the muscle contracts; why (speculate on possible sites/mechanisms of action)? When curare (which blocks neuromuscular transmission)is added with caffeine,contraction occurs; why (speculate,and how does this alter your previous answer)? Can you identify a single site of action from this information? If not,what additional experiment would narrow your choices?

Accepted Answer

The applied electrical current opens vol

Question 17

A certain drug is known to block monovalent cation channels.This drug is used as a "muscle relaxer." Would it affect both smooth and skeletal muscles or only skeletal muscles? Defend your answer.

Accepted Answer

Skeletal muscle relies on monovalent cat

Question 18

Match the structures with the accurate description.
-the muscle cell membrane

Accepted Answer

A) muscle fiber 
B) fascicle 
C) sarcolemma 
D) myofibril 
E) t-tubules 
A) muscle fiber 
B) fascicle 
C) sarcolemma 
D) myofibril 
E) t-tubules

Question 19

Match the structures with the accurate description.
-highly organized bundles of contractile proteins within a skeletal muscle cell

Accepted Answer

A) muscle fiber 
B) fascicle 
C) sarcolemma 
D) myofibril 
E) t-tubules 
A) muscle fiber 
B) fascicle 
C) sarcolemma 
D) myofibril 
E) t-tubules

Question 20

Describe the process of relaxation of a skeletal muscle fiber.

Accepted Answer

Relaxation is an active process,resultin

Exam 12: Muscles

Which of the following is a characteristic of slow-twitch oxidative skeletal muscle fibers?

When a skeletal muscle cell contracts and the muscle shortens,

The contraction cycle is triggered by the rise in ________ released from the sarcoplasmic reticulum (SR).

List and explain the functions of the regulatory molecules in a sarcomere,specifying how the on and off positions are controlled and its impact on the crossbridges formed.

The I band contains

The function of the titin protein is to

Smooth muscle cells lack which protein(s)?

Relative to skeletal muscle,smooth muscle

In order to contract and relax,muscle cells require energy in the form of ________.The immediate backup energy source is ________ that requires the enzyme ________.

Striated muscles are so-called because of a repeating pattern of light and dark bands.One repeating unit of the banding pattern is called a

Match the structures with the accurate description. -a bundle of adjacent muscle cells

Define and explain the difference between isotonic,isometric and eccentric contractions and give an example of a specific movement for each.What is the role of series elastic elements in muscle contraction?

Muscle fatigue arises primarily from failure in

A change in smooth muscle cell tension in the absence of a change in electrical potential of the cells is described as a

Within a single fiber,the tension developed during a twitch depends upon the

A certain drug is known to block monovalent cation channels.This drug is used as a "muscle relaxer." Would it affect both smooth and skeletal muscles or only skeletal muscles? Defend your answer.

Match the structures with the accurate description. -the muscle cell membrane

Match the structures with the accurate description. -highly organized bundles of contractile proteins within a skeletal muscle cell

Describe the process of relaxation of a skeletal muscle fiber.

Introduction to Physiology

Molecular Interactions

Compartmentation: Cells and Tissues

Energy and Cellular Metabolism

Membrane Dynamics

Communication, Integration, and Homeostasis

Introduction to the Endocrine System

Neurons: Cellular and Network Properties

The Central Nervous System

Sensory Physiology

Efferent Division: Autonomic and Somatic Motor Control

Integrative Physiology I: Control of Body Movement

Cardiovascular Physiology

Blood Flow and the Control of Blood Pressure

Blood

Mechanics of Breathing

Gas Exchange and Transport

The Kidneys

Integrative Physiology II: Fluid and Electrolyte Balance

The Digestive System

Metabolism and Energy Balance

Endocrine Control of Growth and Metabolism

The Immune System

Integrative Physiology III: Exercise

Reproduction and Development

Filters

In order to contract and relax,muscle cells require energy in the form of .The immediate backup energy source is that requires the enzyme .