Muscle System Physiology Test Mastering
Muscle tissue has the ability to shorten when adequately stimulated, a characteristic known as ____.
contractility
What is the type of chemical reaction used to rebuild ADP into ATP?
dehydration synthesis
Which layer of connective tissue surrounds each skeletal muscle fiber?
endomysium
What means of membrane transport is used to release the neurotransmitter into the synaptic cleft?
exocytosis
Which of the following processes produces molecules of ATP and has two pyruvic acid molecules as end products?
glycolysis
Which of these characteristics applies only to cardiac muscle tissue?
intercalated discs
What metabolic waste accumulates in muscle with excessive exertion?
lactic acid
Which chemical is produced during vigorous exercise when the supply of oxygen is limited or inadequate?
lactic acid
A motor neuron and all of the skeletal muscle fibers it stimulates are termed a _____.
motor unit
One neuron and all the skeletal muscles it stimulates is known as _____.
motor unit
According to the sliding filament theory, how does muscle contraction occur?
myosin heads form cross bridges and pull thin filaments, causing them to slide
What causes the power stroke?
release of ADP and Pi
What organelle wraps and surrounds the myofibril and stores calcium?
sarcoplasmic reticulum
How is acetylcholine (ACh) removed from the synaptic cleft?
simple diffusion away from the synaptic cleft and acetylcholinesterase (AChE; an enzyme)
What term does not describe smooth muscle cells?
skeletal
David's body temperature rises far above normal during his surgery. Which of the following structures plays a role in regulating body temperature?
skin and skeletal muscle
Chemical that enters a muscle cell upon excitation
sodium ions
What must rush into a muscle cell to promote its depolarization?
sodium ions
Gap between the axon terminals and the plasma membrane of a neighboring muscle cell
synaptic cleft
The gap between the axon terminal of a motor neuron and the sarcolemma of a skeletal muscle cell is called the _______.
synaptic cleft
A sarcomere is ______.
the contractile unit between two Z discs
Which one of the following is composed mostly of the protein myosin?
thick filaments
The binding of calcium to which molecule causes the myosin binding sites to be exposed?
troponin
When an action potential arrives at the axon terminal of a motor neuron, which ion channels open?
voltage-gated calcium channels
Which type of muscle fiber has a large quantity of glycogen and mainly uses glycolysis to synthesize ATP?
white fast twitch fibers
The binding of the neurotransmitter to receptors on the motor end plate causes which of the following to occur?
Binding of the neurotransmitter causes chemically gated sodium channels to open in the motor end plate and sodium enters the cell.
A neurotransmitter junction consists of one neuron and all the skeletal muscles it stimulates?
False
Depolarization of a skeletal muscle cell leads to the opening of more channels that only allow potassium entry
False
Smooth muscles stabilize joints of the skeleton.
False
What term describes the ability of a muscle to vary its degree of shortening to generate the strength needed to lift a 5 lb weight, a 7 lb weight, and finally a 10 lb weight?
Graded responses
What connective tissue bundles muscle fibers into fascicles?
Perimysium
The "rest and recovery" period, where the muscle restores depleted reserves, includes all of the following processes except ____.
Pyruvic acid is converted back to lactic acid
Muscle tissue that is multincleate
Skeletal muscle tissue
Muscle tissue that activates arrector pili muscles to stand hairs on end
Smooth muscle tissue
Muscle tissue that dilates and constricts the pupils of our eys
Smooth muscle tissue
Performs very slow, sometimes, rhythmic,contractions
Smooth muscle tissue
Which of these is NOT a problem associated with destruction of a motor neuron?
Spastic paralysis
The action potential of the muscle cell leads to contraction due to the release of calcium ions. Where are calcium ions stored in the muscle cells?
Terminal cisterns of the sarcoplasmic reticulum
The drug Dantrolene treats malignant hyperthermia by blocking calcium release into the sarcoplasm and terminating skeletal muscle contractions. Which of the following statements best describes why skeletal muscle relaxes in the absence of calcium?
The active site on actin is blocked by tropomyosin.
What structure is the functional unit of contraction in a skeletal muscle fiber?
The sarcomere
What changes occur in the sarcomere during muscle contraction?
Z discs move closer together
What is released by axon terminals into the synaptic cleft to stimulate a muscle to contract?
acetylcholine
Which neurotransmitter is released by motor neurons at the neuromuscular junction?
acetylcholine
What initiates an action potential on a muscle cell?
acetylcholine binding to receptors on the sarcolemma within the neuromuscular junction
enzyme that breaks down acetylcholine (ACh)
acetylcholinesterase
During skeletal muscle contraction, to what do myosin heads bind?
actin filaments
What is the unstoppable electrical current that travels down the length of the entire surface of a sarcolemma?
action potential
What is covered by the endomysium?
an individual muscle cell
Which method of regenerating ATP during muscle contraction can produce lactic acid?
anaerobic glycolysis
What causes the release of calcium from the terminal cisternae of the sarcoplasmic reticulum within a muscle cell?
arrival of an action potential
Neurotransmitters are released upon stimulation from a nerve impulse from the _____.
axon terminals of the motor neuron
What causes the myosin head to disconnect from actin?
binding of ATP
Which of the following is not a function of the muscular system?
blood cell formation
Why are calcium ions necessary for skeletal muscle contraction?
calcium ions trigger the binding of myosin heads to actin filaments
Striated involuntary muscle tissue is classified as ____ muscle.
cardiac
Striated involuntary muscle tissue found in the heart is _____.
cardiac muscle
What type of muscle tissue is both striated and involuntary?
cardiac muscle
The condition of skeletal muscle fatigue can be best explained by _____.
The inability of the muscle to contract even if it is being stimulated
What is acetylcholine?
The neurotransmitter that stimulates skeletal muscle to contract
When a muscle fiber contracts, the I bonds nearly disappear, the H zones disappear, and the A bands move closer together but do not change in length.
True
What enzyme breaks down acetylcholine into acetic acid and choline to prevent continued contraction of the muscle fiber?
acetylcholinesterase
A myosin head binds to which molecule to form a cross bridge?
actin
There are three types of muscle tissue. Which of the following is classified as part of the muscular system?
all skeletal muscles
The heads of the myosin myofilaments are called ________ when they link the thick and thin filaments together during skeletal muscle contraction.
cross bridges
The plasma membrane of a skeletal muscle cell is called the ____.
sarcolemma
Creating phosphate (CP) functions within the muscle cells by ______.
storing energy that will be transferred to ADP to resynthesize ATP as needed
The cross bridge cycle is a series of molecular events that occur after the excitation of the sarcolemma. What is a cross bridge?
A myosin head bound to actin
After a power stroke, the myosin head must detach from actin before another power stroke can occur. What causes cross bridge detachment?
ATP binds to the myosin head
Specific neurotransmitter that stimulates skeletal muscle cells
Acetylcholine
In a neuromuscular junction, synaptic vesicles in the motor neuron contain which neurotransmitter?
Acetylcholine (ACh)
Which of these events must occur first to trigger the skeletal muscle to generate an action potential and contract?
Acetylcholine (ACh) binds to receptors on the sarcolemma and allows passage of sodium ions into the cell.
Electrical current that travels the length of the sarcolemma that results in the contraction of the muscle fiber
Action potential
Malignant hyperthermia causes a high demand for ATP within the muscle cells. Which of the following ATP consuming events causes skeletal muscles to relax?
Active transport of Ca2+ back into the terminal cisterns
During David's hyperthermic crisis, Dr. Hodges reports that he has an elevated level of exiled carbon dioxide. Which ATP generating metabolic pathway produces carbon dioxide as a by product?
Aerobic metabolism
What causes the release of calcium ions into the sarcoplasm from the terminal cisterns?
An action potential traveling along the t tubule
What mineral is released within muscle cells to trigger contraction?
Calcium
The sarcoplasmic reticulum stores this chemical.
Calcium ions
Calcium ions couple excitation of a skeletal muscle fiber to contraction of the fiber. Where are calcium ions stored within the fiber?
Calcium ions are stored in the sarcoplasmic reticulum
What specific event triggers the uncovering of the myosin binding site on actin?
Calcium ions bind to troponin and change its shape.
Muscle tissue composed of branching cells and intercalculated discs
Cardiac muscle tissue
Muscle tissue found only in the heart
Cardiac muscle tissue
When does cross bridge cycling end?
Cross bridge cycling ends when sufficient calcium has been actively transported back into the sarcoplasmic reticulum to allow calcium to unbind from troponin.
ALS (amyotrophic lateral sclerosis) s a disease that results in progressive paralysis. While the ultimate case is unknown, _______ is the direct cause of the paralysis.
Degeneration of motor neurons
What is the function of creating phosphate?
Directly regenerates ATP from ADP within a muscle cell
Which of the following processes produces 36 ATP?
Krebs cycle and oxidative phosphorylation
What happens to a muscle when the nerve supplying that muscle is cut?
Muscle paralysis and atrophy occur.
Skeletal muscle contraction is calcium dependent. The protein ____ binds calcium and is part of the ____ myofilament.
Troponin ; thin
Cardiac and skeletal muscle both possess striations.
True
Cardiac muscle fibers are joined by special gap junctions called inter calculated discs; these discs allow heart activity to be closely coordinated.
True
The effect of the neurotransmitter of the muscle cell membrane is to temporarily modify its permeability of ions such as Na+ and K+
True
The formation of cross bridges requires both calcium ions and ATP
True
The neurotransmitter used by the nervous system to activate skeletal muscle cells is acetylcholine
True
The sarcoplasmic reticulum wraps like a sleeve around the myofibril and stores and releases calcium?
True
The striations seen in skeletal muscle are actually alternating dark A and light I bands.
True
What creates the alternating light and dark bands that provides the striations pattern on skeletal muscle tissue?
A bands and I bands
The fastest mechanism for producing ATP is aerobic respiration
False
The major cause of malignant hyperthermia is uncontrolled release of calcium into the sarcoplasmic of muscle cells. What intracellular organelle functions to store and release calcium?
Sarcoplasmic reticulum
Muscle tissue that maintains posture, body position, and stabilizes joints
Skeletal muscle tissue
voluntary muscle tissue
Skeletal muscle tissue
How does the myosin head obtain the energy require for activation?
The energy comes from the hydrolysis of ATP
