Chapter 9 - Muscles and Muscle Tissue
motor unit
A motor neuron and all the muscle fibers it supplies is called a(n) ____________.
light
Myosin is not found in the ___ band
actin, myosin, shortening
In the sliding filament model, during contraction, ___ and ____ filaments overlap to a greater degree, _____ the muscle fiber.
isometrically
Muscles that maintain upright posture are contracting _____.
first, action potential
The __ step toward generating a skeletal muscle contraction is nervous stimulation of the muscle to generate an __.
perimysium
surrounds the fascicle
sodium
when the stimulus causes a disruption in the cell membrane this ion rushes into the cell
diffusion away from the synaptic cleft, acetylcholinesterase (AChE; an enzyme), a reuptake pump on the axon terminal
How is acetylcholine (ACh) removed from the synaptic cleft?
contracted, break
If a muscle is completely depleted of ATP, the muscle would remain in a ____ state due to an inability to ___ actin-myosin cross bridges.
sarcomeres
Smooth muscle is not in appearance, because it lacks ______.
sarcomere
A _____ is a muscle segment and is the smallest contractile unit of a muscle fiber.
muscle twitch
A ______ is a brief, maximum contraction of a muscle in response to a stimulus.
excitation, contraction
Action potentials propagating down the T-tubule cause a voltage-sensitive protein to change shape. This shape change opens calcium release channels in the sarcoplasmic reticulum, allowing calcium ions to flood the sarcoplasm. This flood of calcium ions is directly responsible for the coupling of ____ to _____ in skeletal muscle fibers.
Short-term intense movements
Activities best-suited for fast-glycolytic fibers
removes, cross bridge
Binding of calcium ions to troponin, which ____ the blocking action of tropomyosin, is a key event in excitation-contraction coupling. This "triggers" ____ cycling, thus contraction, by allowing actin and myosin to interact.
H band
area of sarcomere containing only thick filaments
tropomyosin
covers thin filament-binding sites
myoglobin
hemoglobin is to blood, as this is to muscle tissue
fibromyositis
inflammation of a muscle, its connective tissue coverings and tendons, and capsules of nearby joints
blood vessels, hollow organs
Smooth muscle sheets are present in all but the smallest _____ and in the walls of _______ of the respiratory, digestive, reproductive, and urinary systems.
pathway
T tubules penetrate a skeletal muscle fiber and provide a _____ for excitation into the interior.
action potential
Yes, calcium is stored in the terminal cisternae of the sarcoplasmic reticulum until it is released by an _____.
potassium
Yes, sodium enters the cell and causes depolarization. A small amount of ___ also leaves the motor end plate.
voltage, axon terminal
Yes, the action potential opens ___-gated calcium channels and calcium rushes into the _____, leading to the release of the neurotransmitter.
ATP, actin
Yes, the binding of ___ causes the myosin head to disconnect from ___.
power, myosin
Yes, the hydrolysis of ATP provides the energy for the ___ stroke. Energy is transferred from ATP to the ____ head.
cross bridge
Yes, the myosin head binds to actin, the major component of thin filaments to form a
exocytosis
Yes, the synaptic vesicles (where the neurotransmitter is stored) merge with the membrane and release the neurotransmitter by means of ____.
tropomyosin, myosin
Yes, when calcium binds to troponin, troponin releases ____, exposing the ____ binding sites.
ATP, contracted
__ is needed to break actin-myosin cross bridges. If these bridges are not broken, the muscle remains in a ____ state.
Isometric, isotonic
___ contraction does not lead to load movement. In contrast, ___ contractions will result in load movement.
cardiac
___ muscle is striated and branched
Calcium , myosin
____ binds to ____ heads during the increase of hemoglobin concentration in muscle fibers.
Skeletal
____ muscle is striated, cylindrical and multinucleated.
skeletal
_____ muscles normally respond to stimulation in a controlled and smooth manner.
Perimysium, endomysium, epimysium
_____ surrounds bundles of fibers (fasciculi), and _____ surrounds each fiber. The entire muscle is surrounded by _____.
Fast glycolytic
______ fibers are best suited for short-term powerful or intense movements.
Fast oxidative
______ fibers are best suited for sprinting.
Endomysium, Perimysium
______ surrounds each muscle fiber. ______ surrounds each fascicle.
Slow oxidative
_________ muscle fibers are best suited for endurance activities.
sub, no
__threshold stimuli produce __ muscle response.
unfused or incomplete tetanus
a muscle stimulated at high-frequency with some short relaxation time between, such that sustained but quivering contractions occurs
fused or complete tetanus
a muscle that is stimulated so frequently that the relaxation phase is completely eliminated and smooth, sustained contraction results
synaptic vesicles, sacs
acetylcholine
M line
actin slides toward the ___ during a contraction
T tubule
action potential in the ___ causes the release of calcium from the terminal cisternae of the sarcoplasmic reticulum.
endurance-type activities
activities best suited for slow-oxidative fibers
sprinting, walking
activities best-suited for fast-oxidative fibers
maintain homeostasis
an action potential is a serious of biochemical events that occurs on the nerve cell membrance with one goal in mind:
calsequestrin
an intracellular protein found in the SR cisternae
A band
are of sarcomere containing overlapping thick and thin filaments
extensibility
characteristic which allows muscles to extend and shorten
isotonic contraction
contraction of muscle during which the muscle changes in length and the tension remains constant through most of the contractile period
eccentric contraction
contraction of muscle in which the muscle contracts as it lengthens
sarcoplasm
cytoplasm for muscle cells
calmodulin
cytoplasmic, calcium-binding protein
Na+, K+, K+ , outside
during repolarization, there is a change in the sarcolemma after the wave of depolarization; __ channels close and __ channels open, allowing __ to create a positive charge ____ the membrane
tranverse tubules
found at the junction of the A and I bands
neuron
has the best developed ER of all body cells
creatine phosphate
high-energy compound in muscle
fibrils, filaments
myo___ are the structures in which the myo___ are found
contraction
myosin changes shape during the ___ cycle
muscles
sarcomeres are the functional units of
synapse
space between nerve cells
totally
tetanus is an example of a ___ contracted state
depolarization, action potential
the production of an end plate potential at the motor end plate and consequent depolarization of adjacent areas is considered _____ and generation of _____
calcium and potassium
what are the two major ions involved in generating an action potential?
de
what do we call the change in Na+ and K+ caused by a stimulus? _polarization
myofibrils
what muscles are composed of
varicosities
where neurotransmitters are released in smooth muscle
a reuptake pump on the axon terminal, diffusion away from the synaptic cleft, acetylcholinesterase (AChE; an enzyme)
How is acetylcholine (ACh) removed from the synaptic cleft?
not change
If a muscle is applied to a load that exceeds the muscle's maximum tension, the muscle length will ___ during contraction
isometric, shorten
In _____ contractions, tension may build to the muscle's peak tension-producing capacity, but the muscle does not lengthen or shorten. In isotonic contractions, the muscle will ____.
unbalanced
In the initial stages of repolarization, the electrical conditions are restored and Ions are left ___
No
Is the sarcolemma part of the triad?
twitches
Muscle _____ are single jerking contractions
tetanic, Tetanic
Muscle tone is a state of partial, sustained contraction in a muscle that results from ____ contraction of about 10% of the muscle fibers on a rotating basis. ____ contraction is sustained and forceful contraction that results from high-frequency stimulation from the nervous system.
sarcomeres
Myofibrils are composed of repeating contractile units called _____.
MYOSIN, actin
Myofilaments are made of ___ filaments and ___ filaments.
graded muscle response
Properly controlled skeletal muscle contractions produced by changing the frequency of stimulation or the strength of stimulation are accomplished by __________.
positive
Re: the electrical conditions of a resting sarcolemma, the outside is ____ relative to the inside
chemically gated
Receptors that open ion channels in response to binding a neurotransmitter are
myofilaments
Sarcomeres are made of _____.
muscle fibers
Skeletal and smooth muscle cells (but not cardiac muscle cells) are elongated, and for this reason, are called ____
sliding filament, calcium, ATP
Skeletal muscle and smooth muscle both employ a ______ mechanism for contraction, they both depend upon a rise in intracellular ____ to trigger contraction, and they both depend on __ to fuel contraction.
calcium, calmodulin, calcium, troponin
Smooth muscle depends on the ____-_____ system to regulate contraction while skeletal muscle relies on the _____-_____ system to regulate contraction.
myalgia
muscle pain resulting from any muscle disorder
sheets
smooth muscle tends to be organized in ____.
intra
A short-lived rise in ___cellular calcium ion levels (Ca2+) is the final trigger for contraction of skeletal muscle.
decrease
ATP, CP, glucose, and oxygen all ___ during muscle contraction.
one
As a rule, each muscle fiber has ___ neuromuscular junction(s).
sarcolemma, sarcoplasmic reticulum
As depolarization occurs, the action potential is propagated through the ___ toward T tubules. The _____ then releases Ca2+ ions into the intracellular environment, and the Ca2+ ions bind to troponin in order to facilitate the formation of actin-myosin cross bridges.
detachment, contractile
Decreased Ca2+ concentrations in the sarcoplasm leads to ___ of cross bridges and, consequently, decreased ____ force.
sarcoplasmic reticulum
During muscle contraction calcium is released from
de, sodium
During the _polarization of the sarcolemma ____ enters the muscle fiber
contraction phase
During which phase of a muscle contraction is cross bridge formation occurring?
latent phase
During which phase of muscle contraction is depolarization occurring?
neuromuscular junction
Each skeletal muscle fiber is controlled by a neuron at a single ___________.
synaptic vesicles
Neurotransmitter is released from
the arrangement of thick and thin filaments
Striations in skeletal muscle tissue are a result of what?
autonomic
The alternating contraction and relaxation of layers of smooth muscle is regulated by the ___ nervous system.
neuromuscular junction, fiber
The axon of each motor neuron divides as it enters the muscle, and each of these axonal endings forms a branching ______ with a single muscle ____.
synaptic cleft, glycoprotein
The axonal ending and the muscle fiber do not actually touch and remain separated by a space called the ______, which is filled with a gel-like substance rich in ____.
sarcomere
The contractile unit of a muscle is the
myosin
The dark band is composed primarily of
twitch
The response of a motor unit to a single action potential of its motor neuron is called a muscle _____
wave summation
The term ______ describes how a muscle response changes with respect to changes in stimulus frequency.
multiple motor unit summation
The term ________ describes how a muscle response changes with respect to changes in stimulus strength.
three, transverse tubule, terminal cisternae
The triad refers to a set of ____ membranous channels and is formed by a single _____ and two ______, or elements of the sarcoplasmic reticulum.
graded
The variation needed in skeletal muscle contraction in order to have controlled movement is called a ___ muscle response.
many more, one to ten, one to thousand
There are ___ skeletal muscle fibers than there are motor neurons. The ratio of neurons to fibers varies from approximately ____ to approximately _____.
-55 mV
Threshold is
regenerative
Unlike cardiac and skeletal muscle, smooth muscle is ______
calmodulin, calcium
Unlike skeletal muscle, smooth muscle depends on the calcium-_____ system to regulate contraction. Skeletal muscle utilizes a ____-troponin regulation mechanism.
sodium-potassium pumps
What is responsible for reclaiming potassium ions after depolarization?
T-tubules, changes shape, terminal cisternae
When action potentials propagate along ___, a voltage-sensitive protein _____ and triggers a different protein to open it's channels, resulting in the release of calcium from the ______.
acetylcholine, depolarization
When an action potential arrives at the neuromuscular junction, _____ is released, then binds to receptors on the sarcolemma of the muscle fiber. This binding event leads to _____ of the sarcolemma.
depolarization
When the membrane potential changes from -70 mV to +30 mV, what has occurred?
presence of acetylcholine
Which of the following would not result in relaxation?
Sarcoplasmic reticulum, skeletal, ions
Yes! ____ is the specific name given to the smooth endoplasmic reticulum in muscle cells. It is especially abundant and convoluted in _____ muscle cells. It functions in the storage, release, and reuptake of calcium __.
calcium, action
Yes, ____ is stored in the terminal cisternae of the sarcoplasmic reticulum until it is released by an ___ potential.
neuromuscular
Yes, acetylcholine is the neurotransmitter found in ____ junctions.
cardiac muscle cell
branching chains of cells; uni- or binucleate striations; intercalated discs. What muscle cell type?
end plate potential
depolarization occurring only at neuromuscular junction
fascicle
muscle bundle is AKA
myoglobin
oxygen storage molecules in skeletal muscle
tropomyosin, active
protects the ___ site on myosin
calmodulin
provides a metabolic signal in smooth muscle
endoplasmic reticulum
responsible for producing cellular proteins and lipids
repolarization
restoration of membrane potential to resting potential
endomysium
reticular fibers that surround individual muscle fibers
smooth muscle cell
single, fusiform, uninucleate; no striations. What muscle cell type?
sarcolemma
the cell membrane for muscle cells
acetylcholine
the most abundant neurotransmitter in the body
dendrite
the part of the nerve cell that receives the impulse
latent period
the time between the stimulus or the electrical event and the mechanical event of contraction
relaxation period
the time during which the muscle is returning to its original length
contraction period
the time during which the muscle is shortening
chemical and electrical
the two types of synapses
refractory period
the very brief time after one stimulus during which the muscle is unresponsive to a second stimulus
contractility
this trait sets muscles apart from all other tissue
-55
threshold is __mV
fast-glycolytic
type of fibers that have few mitochondria
slow-oxidative fibers
type of muscle fibers that are most resistant to fatigue