Block 2 Pace Quiz Skeletal Muscle: Micro Anatomy

21 Questions | By Chachelly | Last updated: Mar 20, 2022 | Total Attempts: 467

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1.

Neuromuscular Junctions are located
- A.
  
  Midway along the length of the muscle fiber
- B.
  
  Spaced at regular intervals along each muscle fiber.
- C.
  
  Spaced at irregular intervals along each muscle fiber
- D.
  
  Near the proximal end of a muscle fiber,
- E.
  
  Near the distal end of a muscle fiber.
2.

The many nuclei of a skeletal muscle fiber are located:
- A.
  
  Midway along the length of the muscle fiber,
- B.
  
  Spaced at regular intervals along each muscle fiber
- C.
  
  Spaced at irregular intervals along each muscle fiber.
- D.
  
  Near the proximal end of a muscle fiber.
- E.
  
  Near the distal end of a muscle fiber.
3.

Z-lines represent attachment sites for:
- A.
  
  Thick filaments (myosin)
- B.
  
  Thin filaments (actin)
- C.
  
  T-tubules
- D.
  
  Sarcoplasmic reticulum
- E.
  
  Neuromuscular junctions
4.

The electrical signal of an action potential is conveyed into the interior of each muscle fiber by:
- A.
  
  Sarcomeres.
- B.
  
  Transverse tubules.
- C.
  
  Sarcoplasmic reticulum
- D.
  
  Z-lines.
- E.
  
  Thick filaments,
5.

Assuming two skeletal muscle fibers have the same myosin ATPase activity, and both are producing an equal force, but one fiber is longer than the other one, Which of the following best describes their shortening velocities?
- A.
  
  Long fiber has a higher velocity during isotonic contraction than the short one
- B.
  
  Long fiber has a higher velocity during isometric contraction than the short one
- C.
  
  Long fiber has a lower velocity during isotonic contraction than the short one
- D.
  
  Long fiber has a lower velocity during isometric contraction than the short one
- E.
  
  Both fibers have the same velocity during isotonic contraction
6.

A 13-year-old boy presents with episodes of extreme proximal muscle weakness lasting an hour or more The episodes are precipitated by rest following strenuous exercise His father and paternal grandmother have suffered similar symptoms with onset at adolescence. An electromyogram, periormed during an attack, reveals normal skeletal muscle action potentials in response to effort. It is not surprising that the disease is associated with:
- A.
  
  A mutation in the voltage sensuive K+ channel of skeletal muscle
- B.
  
  Elevated PIP2 in skeletal muscle
- C.
  
  Depressed PIP2 and elevated IP3 in gamma-motoneurons of the penpheral nerves
- D.
  
  A mutation in acetylcholine esterase
- E.
  
  A mutation in the voltage sensitive Ca2+ channel of skeletal muscle
7.

Which of the following is true for mammalian skeletal muscle?
- A.
  
  T tubules are located at the Z disk
- B.
  
  T tubules are absent
- C.
  
  Troponin is absent
- D.
  
  It possesses triads
- E.
  
  It possesses caveolae
8.

Which of the following statements concerning triads in mammalian skeletal muscle is true?
- A.
  
  They are located in the Z disk
- B.
  
  They consist of two terminal cisternae of the sarcoplasmic reticulum separated by a T tubule
- C.
  
  They can be observed with the light microscope
- D.
  
  They are characterized by a T tubule that sequesters calcium ions
- E.
  
  They consist of two T tubules separated by a central terminal cisterna
9.

Which of the following is true of skeletal muscle myosin molecules?
- A.
  
  Can be cleaved into light and heavy myoglobin by the proteolytic enzyme papain
- B.
  
  Are attached to the Z line by a-actinin
- C.
  
  Each has a head component that includes an actin-binding site
- D.
  
  Can shorten to half their resting length during contraction
- E.
  
  Have tail components that overlap In the I band
10.

Membrane depolarization occurs in skeletal muscle fibers in which order after acetylcholine crosses the synaptic cleft?
- A.
  
  T tubule, terminal cisternae, sarcoplasmic retinaculum, sarcolemma
- B.
  
  Sarcoplasmic retinaculum, T tubule, presynaptic membrane, sarcolemma
- C.
  
  Terminal cisternae, sarcolemma, sarcoplasmic retinaculum, caveolae
- D.
  
  Sarcolemma, T tubule, terminal cisternae, sarcoplasmic retinaculum
- E.
  
  Sarcolemma, sarcoplasmic retinaculum, T tubule, terminal cisternae
11.

The endomysium is a connective tissue investment that surrounds
- A.
  
  Individual muscle fibers
- B.
  
  Muscle fascicles
- C.
  
  Individual myofibrils
- D.
  
  An entire muscle
- E.
  
  Small bundles of muscle cells
12.

While you are holding a tray piled with dishes, an additional 5-pounds of dishes is placed on it. Your muscles that are holding the tray increase therr force of contraction through an increase
- A.
  
  Length of the muscle
- B.
  
  Number of motor units activated
- C.
  
  Peak intracellular calcium concentration in the muscle
- D.
  
  Strength of each cross-bridge interaction with actin
- E.
  
  Maximum shortening velocity of the muscle
13.

Which of the following is true of motor units?
- A.
  
  Are found only in cardiac muscle
- B.
  
  Are largest in muscles responsible for delicate movements
- C.
  
  Consist of a muscle fiber and all the nerves that supply it
- D.
  
  Consist of a motor neuron and all the muscles it supplies
- E.
  
  Are the same as myoneural junctions
14.

Which of the following is true of T tubules?
- A.
  
  Are evaginations of the sarcoplasmic retinaculum
- B.
  
  Sequester calcium ions during muscle relaxation
- C.
  
  Carry repolarization to the muscle fiber interior
- D.
  
  Are found overlying the A-I band junction in cardiac muscle cells
- E.
  
  Contain a rich supply of acetylcholine receptors
15.

Which of the following structures surrounds a muscle fascicle?
- A.
  
  Endomysium
- B.
  
  Epimysium
- C.
  
  Fascia
- D.
  
  Perimysium
- E.
  
  Sarcoplasmic retinaculum
16.

A 5-year-old boy sustains a tear in his gastrocnemius muscle when he is involved in a bicycle accident, Regeneration of the muscle will occur through which of the following?
- A.
  
  Differentiation of satellite cells
- B.
  
  Dedifferentiation of myocytes into myoblasts
- C.
  
  Fusion of damaged myofibers to form new myotubes
- D.
  
  Hyperplas ia of existing myofibers
- E.
  
  Differentiation of fibroblasts to form myocytes
17.

Which of the following chemicals would reduce neurotransmitter release at the neuromuscular junction synapse?
- A.
  
  Botulinum toxin
- B.
  
  Muscanne
- C.
  
  Atropine
- D.
  
  Curare
- E.
  
  Pyridostiqmine
18.

In an experiment. you want to shorten the duration of a skeletal muscle contraction There are different poss ibilities to achieve this goal. One is:
- A.
  
  To block the Ca++ ATPase activity of cell membrane
- B.
  
  To block the Ca++ ATPase activity of scarcoplasmic membrane
- C.
  
  To increase the Ca++ entry through DHP receptors
- D.
  
  To increase Ca++ release through ryanodin receptors
- E.
  
  To increase the activity of Ca++/3Na+ exchanger
19.

The sarcoplasmic reticulum of skeletal muscle functions in which of the following?
- A.
  
  Cellular Ca++ storage
- B.
  
  Cellular glycogen storage
- C.
  
  Glycogen degradation
- D.
  
  Transport of Ca++ into the terminal cisternae during muscle contraction
- E.
  
  Ca++ release from the transverse tubules during muscle relaxation
20.

Which of the following groups of terms is placed in order from smallest to largest?
- A.
  
  Myofilament, myofibril, fiber, fascicle
- B.
  
  Fiber, myofibril, myofilament, fascicle
- C.
  
  Fascicle, fiber, myofilament, myofibril
- D.
  
  Fascicle, fiber. myofibril, myofilament
- E.
  
  Fiber. myofibril. fascicle, myofilament
21.

When the neurotransmitter is released and attached to the receptors on the sarcolemma. ____ rushes into the cell causing______ . which subsequently leads to the contraction process. Choose the correct pair of terms .
- A.
  
  Na+, depotarization
- B.
  
  Na+, repolarization
- C.
  
  K+, depolarization
- D.
  
  K+, repoanzation