Week 3, Muscle Flashcards
(50 cards)
Identify the incorrect statement about a single motor unit.
Answers:
The more neurons involved, the more powerful the contraction.
The smaller the number of muscle fibers, the more precise the movement.
Fine motor skills depend on the development of small motor units.
Some motor units include as many as 2000 muscle fibers.
Muscle fibers of one motor unit intermingle with the fibers of another motor unit.
The more neurons involved, the more powerful the contraction.
The increase in muscle tension that is produced by increasing the number of active motor units is called
recruitment.
Each skeletal muscle fiber contains ________ myofibrils.
hundreds to thousands
In a sarcomere, the central portion of thick filaments are linked laterally by proteins of the
M line.
Deep inward extensions of the sarcolemma form a tunnel-like network inside the muscle cell known as;
transverse tubules (T-tubules).
When a skeletal muscle fiber contracts, the
zones of overlap get larger.
Nerves and blood vessels that service a muscle fiber are located in the connective tissues of its
endomysium.
The skeletal muscle complex known as the triad consists of
a transverse tubule and two terminal cisternae.
A single motor neuron together with all the muscle fibers it innervates is called a(n)
motor unit.
The action potential is conducted into a skeletal muscle fiber by
transverse tubules.
The type of contraction in which the muscle fibers do not shorten is called
isometric.
At each end of the muscle, the collagen fibers of the epimysium, perimysium, and endomysium, come together to form a
tendon.
Active sites on the actin become available for binding after
calcium binds to troponin.
Which of the following best describes the term sarcomere?
Answers:
protein that accounts for elasticity of resting muscle
repeating unit of striated myofibrils
storage site for calcium ions
thin filaments are anchored here
largely made of myosin molecules
repeating unit of striated myofibrils
The region of the sarcomere that always contains thin filaments is the
I band.
Which of the following best describes the series of membranous channels that surround each myofibril called the sarcoplasmic reticulum?
Answers:
protein that accounts for elasticity of resting muscle
repeating unit of striated myofibrils
storage and release site for calcium ions
thin filaments are anchored here
largely made of myosin molecules
storage and release site for calcium ions
The following is a list of the events that occur during a muscle contraction. What is the correct sequence of these events?
- Myosin cross-bridges bind to the actin.
- The free myosin head splits ATP.
- Calcium ion is released from the sarcoplasmic reticulum.
- The myosin head pivots toward the center of the sarcomere.
- Calcium ion binds to troponin.
- The myosin head binds an ATP molecule and detaches from the actin.
Answers:
1, 3, 5, 4, 6, 2
5, 1, 4, 6, 2, 3
3, 5, 1, 2, 4, 6
3, 5, 1, 4, 6, 2
1, 4, 6, 2, 3, 5
3, 5, 1, 4, 6, 2
Skeletal muscle fibers are formed from embryonic cells called
myoblasts
The most important factor in decreasing the intracellular concentration of calcium ion after contraction is
active transport of calcium into the sarcoplasmic reticulum.
How would the loss of acetylcholinesterase from the motor end plate affect skeletal muscle?
It would cause muscles to stay contracted.
What is required for excitation-contraction coupling in skeletal muscle?
calcium ions and ATP.
The neurotransmitter which binds to the receptors on the motor end plate is;
acetylcholine.
The type of muscle fiber that is most resistant to fatigue is the ________ fiber.
slow
Which of the following best describes the term titin?
protein that accounts for elasticity of resting muscle
