Identify the FALSE statement.
A) There are only three types of muscle tissue in the human body.
B) Skeletal muscle is always striated.
C) Smooth muscle is often present in the walls of hollow organs.
D) Skeletal muscle contraction is always under consciou
skeletal muscle contraction is always under conscious control
Which statement about cardiac muscle is FALSE?
A) It is found only in the heart.
B) It is classified as a striated muscle.
C) It is controlled involuntarily.
D) It can contract spontaneously.
E) It is easily fatigued.
it is easily fatigued
the origin of a particular skeletal muscle is defined as
the attachment site to the less movable bone
In the arm, the biceps brachii is a flexor whereas triceps brachii is an extensor. Which of the
following statements is TRUE?
A) The biceps brachii is the primary muscle responsible for movement of the hand and forearm
towards the shoulder.
B) The triceps
the biceps brachii is the primary muscle responsible for movement of the hand and forearm towards the shoulder
these muscles are an example of antagonistic muscles
the purpose of transverse tubules is to
rapidly conduct action potentials to the interior of the muscle fiber
made up of multiple globular molecules polymerized to form long chains or filaments
actin
most of the time, the parallel thick and thin filaments of the myofibrils are connected by... that span the space between the parallel thick and thin filaments
nebulin molecules
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
sarcomere
the I band contains
thin filaments
the H zone contains
thick filaments
Which of the following statements is TRUE?
A) Titin returns stretched muscles to their resting length.
B) Titin stabilizes the position of the contractile filaments.
C) Titin is helped by actin.
D) A and B
E) all of the above
titin returns stretched muscles to their resting length
titin stabilizes the position of the contractile filaments
Which statement is TRUE?
A) As the sarcomere shortens, the two Z disks at each end move closer together, and the I band
and H zone virtually disappear.
B) The thin actin filaments slide along the thick myosin filaments as they move toward the M
line in th
As the sarcomere shortens, the two Z disks at each end move closer together, and the I band
and H zone virtually disappear.
the thin actin filaments slide along the thick myosin as they move toward the M line in the center of the sarcomere
the tension generated in a muscle fiber is directly proportional to the
number of crossbridges formed
when a muscle cell contracts
some myosin heads form crossbridges as others release them
Which statement is TRUE?
A) Myosin is a motor protein that converts the chemical bond energy of ATP into the mechanical
energy of motion.
B) Each myosin molecule acts as an enzyme that both binds ATP and releases its energy.
C) The energy released by ATP
myosin is a motor protein that converts the chemical bond energy of ATP into the mechanical energy of motion
each myosin molecule acts as an enzyme that both binds ATP and releases its energy
the energy released by ATP produces the power stroke by swiveli
each myosin head has
a binding site for an ATP molecule, a binding site for an actin molecule, and the ability to swivel when powered by ATP
as ATP binds to the myosin head at the beginning of a muscle contraction cycle,
the myosin head detaches from actin
the power stroke begins when
the inorganic phosphate and ADP are released from the myosin
at the conclusion of the power stroke
inorganic phosphate has been released from the myosin, actin has been moved toward the M line, ADP is released from the myosin head, and the myosin head is tightly bound to actin
regulation of cross-bridge formation is accomplished by
tropomyosin, troponin, and calcium ions
excitation-contraction coupling refers to
the chemical and electrical events that trigger the mechanical events in a muscle fiber
when acetylcholine is released into the neuromuscular junction
it binds to receptors that allow Na+ and K+ ions to cross the sarcolemma, the muscle membrane depolarizes creating an end-plate potential (EPP), and action potentials are triggered, which lead to activation of the contraction cycle
the contraction cycle is triggered by the rise in.... released from the SR
Ca 2+
the brief period of time between the end of the action potential in the muscle and the beginning of contraction is referred to as
latent period
the period of time during which the sarcomeres return to their resting length is referred to as
relaxation phase
metabolism of ... is the fastest way for cells to increase their supply of ATP in order to meet the ATP demands of heavy exercise
glucose
muscle fatigue is classified into these types
central and peripheral
muscle fatigue arises primarily from failure in
excitation-contraction cycle
the onset of fatigue in a muscle cell is influenced by
the intensity and duration of the contractile activity, the use of aerobic or anaerobic metabolism, and the fitness level of the individual
muscle fatigue is known to be associated mainly with
depletion of glycogen stores
central fatigue
includes feeling tired and may precede physiological muscle fatigue
within a single fiber, the tension developed during a twitch depends on
the length of the sarcomeres prior to contraction
When comparing complete tetanus with unfused tetanus, which is true?
A) In complete tetanus, no relaxation occurs between stimuli.
B) In complete tetanus, maximum tension is developed.
C) In complete tetanus, the muscle fiber is stimulated at a higher fre
in complete tetanus, no relaxation occurs between stimuli
in complete tetanus, maximum tension is developed
in complete tetanus, the muscle fiber is stimulated at a higher frequency
a motor unit consists of
one neuron and the muscle fibers it controls
in muscles used for fine actions. such as controlling eye movement or use of the hand, a motor unit will have... muscle fibers when compared to a motor unit in muscles used for power and strength
very few
Each of these statements is true, except one. Identify the exception.
A) A power muscle, such as in the calf of the leg, may have 2000 muscle fibers in one motor
unit.
B) All muscle fibers in a single motor unit are of the same fiber type.
C) With enduran
the entire skeletal muscle contracts in an all-or-none manner
Which fibers generate more force?
A) fast-twitch fibers
B) slow-twitch fibers
fast-twitch fibers
Which fibers fatigue faster?
A) fast-twitch fibers
B) slow-twitch fibers
fast-twitch fibers
asychronous recruitment
helps avoid fatigue during sustained muscle contractions.
refers to different motor units taking turns maintaining muscle tension
makes an entire muscle seem to contract smoothly
A contraction that generates force and moves a load is known as __________, whereas one
that generates force without movement is known as __________.
isotonic; isometric
the components of muscle that allow force generation without a change in length are the
series elastic elements
In the body, the bones act as __________ whereas the joints form the __________, so that
the muscles attached to the bones can create force when they contract.
levers; fulcrums
compared to skeletal muscle, smooth muscle
is slower to contract in response to a stimulus and sustains contractions longer without fatigue
smooth muscle cells lack which protein?
troponin
caveolae are important because they contain
voltage-regulated Ca 2+ gates and chemically regulated Ca 2+ gates
in smooth muscle, what is the small protein chain the regulates contraction and relaxtion?
myosin light chain
the primary calcium release channel in smooth muscle sarcoplasmic reticulum is
an IP3 receptor channel
inward extensions of the muscle cell membrane
t-tubules
an intracellular structure that generates the force of muscle contraction
myofibril
a single muscle cell
muscle fiber
the muscle cell membrane
sarcolemma
a bundle of adjacent muscle cells
fascicle
the structures that serve as the attachment site for the thin filaments and mark the boundaries for one sarcomere
Z disk
the letter assigned to this structure stands for the German word for middle; it is the attachment site for the thick filaments
M line
the lightest color bands of the sarcomere, occupied only by thin filaments
I band
the darkest band with the most overlapping filaments; its abbreviation derives from its property of scattering light unevenly
A band