PPT301: Chapter 12

What is name given to the regularly spaced infoldings of the sarcolemma? terminal cisternae motor endplates sarcoplasmic reticulum transverse or T tubules

transverse or T tubules

Harriet is studying for a history test by verbally repeating important dates about the French Revolution. Which type of memory is she trying to develop? View Available Hint(s) procedural memory nonassociative memory associative memory declarative memory

declarative memory

Most commonly, the infection occurs after __________ become contaminated by soil and/or feces containing the microbe. superficial puncture wounds superficial skin abrasions surgical incisions deep puncture wounds

deep puncture wounds

When larger stimulatory forces are needed, the nervous system can activate extra fibers, increasing the number of active motor units. This is known as ____________. recruitment summation isometric twitch latent period

recruitment

What is the minimum voltage needed to generate active force in the skeletal muscle? stimulus voltage contraction voltage recruitment voltage threshold voltage

threshold voltage

In which of the following phenomena is calcium allowed to reach pre-contraction levels in the cytosol between stimuli? View Available Hint(s) summation complete tetanus incomplete tetanus treppe

treppe

The binding of calcium to which molecule causes the myosin binding sites to be exposed? troponin actin myosin tropomyosin

troponin

Which of the following proteins binds Ca++ to initiate skeletal muscle crossbridge cycling? tropomyosin actin troponin myosin

troponin

If an action potential is generated on a skeletal muscle cell, the cell will contract. View Available Hint(s) True False

true

If you re-engineered myosin filaments to have four heads instead of two, do you think you could get stronger contractions for the same amount of stimulation? True False

true

The triad of a skeletal muscle cell is formed by what three structures? two transverse tubules and one terminal cisternae two terminal cisternae and one transverse tubule three terminal cisternae three transverse tubules

two terminal cisternae and one transverse tubule

When an action potential arrives at the axon terminal of a motor neuron, which ion channels open? View Available Hint(s) voltage-gated sodium channels chemically gated calcium channels voltage-gated calcium channels voltage-gated potassium channels

voltage-gated calcium channels

When the frequency of stimulation of a muscle is great enough, _______. full relaxation of the muscle occurs wave summation results and muscle twitches overlap. full relaxation of the muscle occurs and wave summation results wave summation results muscle twitches overlap

wave summation results and muscle twitches overlap

In the lab, a researcher finds that the threshold stimulus to induce an action potential in a muscle fiber's sarcolemma was 3.0 volts. Which of the following would result in muscle tension? 3.0 volts 3.0 volts and 4.0 volts 2.0 volts 4.0 volts 1.0 volt

3.0 volts and 4.0 volts

The most common incubation period (time to onset of symptoms) for this disease is __________. 1 day 5-10 days 3 hours 20-30 days

5-10 days

The cross bridge cycle is a series of molecular events that occur after excitation of the sarcolemma. What is a cross bridge? Troponin bound to tropomyosin ATP bound to a myosin head A myosin head bound to actin Calcium bound to troponin

A myosin head bound to actin

A triad is composed of a T-tubule and two adjacent terminal cisternae of the sarcoplasmic reticulum. How are these components connected? Myosin cross-bridge binding sites. A series of proteins that control calcium release. Voltage-gated sodium channels. Potassium leak channels.

A series of proteins that control calcium release.

After a power stroke, the myosin head must detach from actin before another power stroke can occur. What causes cross bridge detachment? Calcium ions bind to troponin. ATP binds to the myosin head. ADP and inorganic phosphate are bound to the myosin head. Acetylcholine binds to receptors in the junctional folds of the sarcolemma.

ATP binds to the myosin head.

Action potential propagation in a skeletal muscle fiber ceases when acetylcholine is removed from the synaptic cleft. Which of the following mechanisms ensures a rapid and efficient removal of acetylcholine? Acetylcholine is transported into the postsynaptic neuron by receptor-mediated endocytosis. Acetylcholine is transported back into the axon terminal by a reuptake mechanism. Acetylcholine is degraded by acetylcholinesterase. Acetylcholine diffuses away from the cleft.

Acetylcholine is degraded by acetylcholinesterase.

The neuromuscular junction is a well-studied example of a chemical synapse. Which of the following statements describes a critical event that occurs at the neuromuscular junction? Acetylcholine is released and moves across the synaptic cleft bound to a transport protein. When the action potential reaches the end of the axon terminal, voltage-gated sodium channels open and sodium ions diffuse into the terminal. Acetylcholine is released by axon terminals of the motor neuron. Acetylcholine binds to its receptor in the junctional folds of the sarcolemma. Its receptor is linked to a G protein.

Acetylcholine is released by axon terminals of the motor neuron

Which of the following statements is NOT the case with smooth muscle? View Available Hint(s) Troponin is not present in smooth muscle. Actin and myosin are not present. Most of the calcium used to initiate contraction enters the cell via the sarcolemma. Smooth muscle contracts more slowly than skeletal muscle.

Actin and myosin are not present.

Which of the following does NOT describe treppe? An increase in stimulus intensity is required to see the effect. It is also referred to as the "staircase" effect. A period of relaxation can be seen on the muscle twitch tracing. An incremental increase in force occurs

An increase in stimulus intensity is required to see the effect.

The binding of the neurotransmitter to receptors on the motor end plate causes which of the following to occur? View Available Hint(s) Binding causes voltage-gated sodium channels to open in the motor end plate (junctional folds of the sarcolemma) and sodium enters the cell. Binding causes chemically gated potassium channels to open in the motor end plate (junctional folds of the sarcolemma) and potassium enters the cell. Binding causes potassium voltage-gated channels to open in the motor end plate (junctional folds of the sarcolemma) and potassium enters the cell. Binding of the neurotransmitter causes chemically gated sodium channels to open in the motor end plate (junctional folds of the sarcolemma) and sodium enters the cell.

Binding of the neurotransmitter causes chemically gated sodium channels to open in the motor end plate (junctional folds of the sarcolemma) and sodium enters the cell.

The main cranial nerve involved in jaw movement is __________. CN V (trigeminal) CN VII (facial) CN X (vagus) CN I (olfactory)

CN V (trigeminal)

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. Calcium ions are stored in the transverse tubules. Calcium ions are stored in the nuclei. Calcium ions are stored in the mitochondria.

Calcium ions are stored in the sarcoplasmic reticulum.

What specific event triggers the uncovering of the myosin binding site on actin? Calcium release channels open in the sarcoplasmic reticulum, and calcium levels rise in the sarcoplasm. Calcium ions bind to tropomyosin and change its shape. Sodium ions bind to troponin and change its shape. Calcium ions bind to troponin and change its shape.

Calcium ions bind to troponin and change its shape.

Which of the following is most directly responsible for the coupling of excitation to contraction of skeletal muscle fibers? Action potentials. Sodium ions. Calcium ions. Acetylcholine.

Calcium ions.

Which of the following occurs during the latent period of muscle contraction? An action potential is generated. Acetylcholine is released at the axon terminal. Acetylcholine is released at the axon terminal and an action potential is generated. Calcium is released from the sarcoplasmic reticulum.

Calcium is released from the sarcoplasmic reticulum.

Excitation of the sarcolemma is coupled or linked to the contraction of a skeletal muscle fiber. What specific event initiates the contraction? Voltage-sensitive proteins change shape. Calcium release from the sarcoplasmic reticulum initiates the contraction. Action potentials propagate into the interior of the skeletal muscle fiber. Sodium release from the sarcoplasmic reticulum initiates the contraction.

Calcium release from the sarcoplasmic reticulum initiates the contraction.

All EXCEPT which of the following are characteristics of cardiac muscle tissue? Cardiac muscle has neurogenic contractile ability. Cardiac action potentials are relatively long lasting. Gap junctions are present. Cardiac muscle has myogenic contractile ability.

Cardiac muscle has neurogenic contractile ability.

Tetanus is a neuromuscular disease caused by the toxin of __________ and leads to __________ muscle tone. Clostridium tetani; increased Clostridium botulinum; increased Clostridium tetani; no change in Clostridium tetani; decreased

Clostridium tetani; increased

When does cross bridge cycling end? Cross bridge cycling ends when calcium ions are passively transported back into the sarcoplasmic reticulum. Cross bridge cycling ends when calcium release channels in the sarcoplasmic reticulum open. Cross bridge cycling ends when sufficient calcium has been actively transported back into the sarcoplasmic reticulum to allow calcium to unbind from troponin. Cross bridge cycling ends when ATP binds to the myosin head.

Cross bridge cycling ends when sufficient calcium has been actively transported back into the sarcoplasmic reticulum to allow calcium to unbind from troponin.

Which of the following occurs during the contraction phase? Ca2+ release from the sarcoplasmic reticulum is blocked. The sarcomeres are increasing in length. Cross-bridge cycling is taking place. Acetylcholine binds to the sarcolemma.

Cross-bridge cycling is taking place.

DNA is double stranded. It is arranged in nitrogenous base pairs, where a certain purine on one strand is hydrogen bonded to a pyrimidine on the other DNA strand. Along each DNA strand, the DNA is arranged in triplet codes. The triplet codes are comprised of 3 nucleotides in succession, arranged in a specific direction on the DNA molecule. Each triplet code codes for a particular amino acid. If one or two base pairs are deleted from DNA, it will disturb the order of the three nucleotides in succession after that point; it changes the triplet nucleotide set in each reading frame after the mutated point. This is type of deletion mutation is termed a "frame-shift" mutation; it is the type of mutation in __________. Since so many amino acids will be affected in this condition, it is more deleterious than some of the other forms of muscular dystrophy. Duchenne MD Becker MD myasthenia gravis tetanus

Duchenne MD

Excitation-contraction coupling is a series of events that occur after the events of the neuromuscular junction have transpired. The term excitation refers to which step in the process? Excitation refers to the shape change that occurs in voltage-sensitive proteins in the sarcolemma. Excitation refers to the propagation of action potentials along the axon of a motor neuron. Excitation, in this case, refers to the propagation of action potentials along the sarcolemma. Excitation refers to the release of calcium ions from the sarcoplasmic reticulum.

Excitation, in this case, refers to the propagation of action potentials along the sarcolemma.

Which of the following statements is true of motor unit recruitment? View Available Hint(s) Larger motor units are recruited only when smaller motor units become exhausted. The neurons of larger motor units are easier to depolarize and are therefore easier to recruit. Motor units are recruited based on size, with smaller motor units being recruited first and progressively larger motor units being recruited thereafter. Motor units are not recruited based on size.

Motor units are recruited based on size, with smaller motor units being recruited first and progressively larger motor units being recruited thereafter.

Why does wave summation occur? A large amount of time elapses between stimulations. Muscle twitches are not yet overlapping. Muscle fibers are partially contracted when the next stimulus arrives. Muscle fibers have been allowed to fully relax.

Muscle fibers are partially contracted when the next stimulus arrives.

All EXCEPT which of the following are properties of smooth muscle? Muscle cells are under involuntary control. Striations are structured as a sarcomere. The cells are connected by gap junctions. Neural connections occur through varicosities.

Striations are structured as a sarcomere.

Calcium entry into the axon terminal triggers which of the following events? Acetylcholine binds to its receptor. Synaptic vesicles fuse to the plasma membrane of the axon terminal and release acetylcholine. Cation channels open and sodium ions enter the axon terminal while potassium ions exit the axon terminal. Acetylcholine is released into the cleft by active transporters in the plasma membrane of the axon terminal.

Synaptic vesicles fuse to the plasma membrane of the axon terminal and release acetylcholine.

How does the myosin head obtain the energy required for activation? The energy comes from the direct phosphorylation of ADP by creatine phosphate. The energy comes from the hydrolysis of ATP. The energy comes from oxidative phophorylation. The energy comes from the hydrolysis of GTP.

The energy comes from the hydrolysis of ATP.

__________ will determine whether only local muscles close to the wound are affected or distant muscles are affected as well. The extent of toxin spread The sex of the person The mood of the person How often a person uses a muscle

The extent of toxin spread

Sodium and potassium ions do not diffuse in equal numbers through ligand-gated cation channels. Why? The inside surface of the sarcolemma is negatively charged compared to the outside surface. Sodium ions diffuse inward along favorable chemical and electrical gradients. The outside surface of the sarcolemma is negatively charged compared to the inside surface. Sodium ions diffuse outward along favorable chemical and electrical gradients. The inside surface of the sarcolemma is negatively charged compared to the outside surface. Potassium ions diffuse inward along favorable chemical and electrical gradients. The outside surface of the sarcolemma is negatively charged compared to the inside surface. Potassium ions diffuse outward along favorable chemical and electrical gradients.

The inside surface of the sarcolemma is negatively charged compared to the outside surface. Sodium ions diffuse inward along favorable chemical and electrical gradients.

Which of the following is true regarding the latent period of an isotonic contraction? View Available Hint(s) A lighter load will result in a longer latent period than a larger load. The latent period will be the same length regardless of load. A heavier load will result in a longer latent period than a smaller load. The latent period is typically the longest phase of a muscle twitch.

The latent period will be the same length regardless of load.

As the stimulus voltage was increased in this activity, which of the following occurred? The muscle force generated increased. The latent period increased in length. The muscle force generated decreased. The latent period decreased in length.

The muscle force generated increased.

What structure is the functional unit of contraction in a skeletal muscle fiber? The cross bridge The sarcomere The junctional folds of the sarcolemma The triad

The sarcomere

Which of the following describes the relaxation phase? The sarcomeres are increasing in length, and the force generated increases. The sarcomeres are decreasing in length, and the force generated decreases. The sarcomeres are increasing in length, and the force generated decreases. The sarcomeres are decreasing in length, and the force generated increases.

The sarcomeres are increasing in length, and the force generated decreases.

What is the relationship between the number of motor neurons recruited and the number of skeletal muscle fibers innervated? Motor neurons always innervate thousands of skeletal muscle fibers. A motor neuron typically innervates only one skeletal muscle fiber. Typically, hundreds of skeletal muscle fibers are innervated by a single motor neuron. A skeletal muscle fiber is innervated by multiple motor neurons.

Typically, hundreds of skeletal muscle fibers are innervated by a single motor neuron.

The two most common forms of muscular dystrophy, Duchenne and Becker, are sex-linked recessive genetic problems involving the __________ chromosome. Y X 21st 22nd

X

Since Duchenne and Becker muscular dystrophy are __________ linked and recessive, it mainly affects __________. X-linked; males X-linked; females X-linked; both sexes equally Y-linked; females

X-linked; males

Treppe is the phenomenon that results in _______. motor unit recruitment a progressive increase in the force generated with repetitive stimulation an increase in the stimulation frequency maximal force production by a skeletal muscle

a progressive increase in the force generated with repetitive stimulation

Which structure of a skeletal muscle transmits forces from muscles to bones? View Available Hint(s) enlargements of the sarcoplasmic reticulum a structure made of cords of elastic connective tissue the structures that impart a striated appearance to muscle tissue the sarcolemma

a structure made of cords of elastic connective tissue

In a neuromuscular junction, synaptic vesicles in the motor neuron contain which neurotransmitter? View Available Hint(s) norepinephrine serotonin acetylcholine (ACh) dopamine

acetylcholine (ACh)

A myosin head binds to which molecule to form a cross bridge? tropomyosin actin troponin

actin

Golgi tendon organs __________. View Available Hint(s) are found within the contractile component of muscle cause contraction of the muscle in which the GTO was activated are found within the series elastic component of muscle protect the muscle from being stretched too quickly

are found within the series elastic component of muscle

Part A Part complete What causes the release of calcium from the terminal cisternae of the sarcoplasmic reticulum within a muscle cell? arrival of an action potential ATP calcium ion pump troponin

arrival of an action potential

Which part of the brain enhances the transition from sleep to awakening? View Available Hint(s) descending reticular activating system pons ascending reticular activating system forebrain

ascending reticular activating system

What causes the myosin head to disconnect from actin? binding of troponin binding of calcium binding of ATP hydrolysis of ATP

binding of ATP

Which of the following is the first step in the crossbridge cycle? unbinding of myosin and actin rigor power stroke binding of myosin and actin

binding of myosin and actin

From the outside to the inside, what is the order of the coverings of the spinal cord? View Available Hint(s) bone, dura mater, arachnoid, cerebrospinal fluid, and pia mater cerebrospinal fluid, pia mater, arachnoid, dura mater, and bone arachnoid, bone, cerebrospinal fluid, dura mater, and pia mater bone, dura mater, arachnoid, pia mater, and cerebrospinal fluid

bone, dura mater, arachnoid, pia mater, and cerebrospinal fluid

Death generally results from inability to __________. talk breathe move the arms and legs swallow

breathe

In muscular dystrophy (MD), a sarcomeric protein does NOT function properly. What types of muscle tissue are affected by MD? View Available Hint(s) smooth muscle and cardiac muscle cardiac and skeletal smooth muscle and skeletal muscle skeletal muscle only

cardiac and skeletal

Which of the following produced an increase in stimulus frequency? increasing the voltage applied clicking the mouse in rapid succession and allowing the muscle to completely relax in between contractions allowing the muscle to completely relax between contractions clicking the mouse in rapid succession

clicking the mouse in rapid succession

DNA is double stranded. It is arranged in nitrogenous base pairs, where a certain purine on one strand is hydrogen bonded to a pyrimidine on the other DNA strand. Along each DNA strand, the DNA is arranged in triplet codes. The triplet codes are comprised of three nucleotides in succession, arranged in a specific direction on the DNA molecule. Each triplet code codes for a particular amino acid. If a mutation in DNA involves the loss of, at least, one base pair, it is termed a deletion. The type of mutation in both Becker MD and Duchenne MD is a __________. insertion deletion duplication inversion

deletion

What is the name of the receptors found in T-tubule membranes that function as voltage sensors? NMDA receptors acetylcholine receptors dihydropyridine receptors (DHP receptors) histamine 1 (H1)

dihydropyridine receptors (DHP receptors)

Duchenne and Becker muscular dystrophy involves problems with the proper formation of a protein known as __________, which is important in attaching certain cytoskeletal proteins to the cell membrane (sarcolemma) of muscle, particularly skeletal muscle. titin actin myosin dystrophin

dystrophin

Which cells make up the blood-brain barrier? View Available Hint(s) astrocytes epithelial cells Schwann cells endothelial

endothelial

The sequence of events that links an end plate potential to the activation of crossbridge cycling is referred to as __________. View Available Hint(s) the neuromuscular junction excitation-contraction coupling the sliding filament mechanism muscle fatigue

excitation-contraction coupling

What means of membrane transport is used to release the neurotransmitter into the synaptic cleft? View Available Hint(s) exocytosis a protein carrier a channel

exocytosis

Action potentials travel the length of the axons of motor neurons to the axon terminals. These motor neurons __________. extend from the brain to the sarcolemma of a skeletal muscle fiber extend from the spinal cord to the sarcolemma of a skeletal muscle fiber extend from the brain or spinal cord to the sarcolemma of a skeletal muscle fiber arise in the epimysium of a skeletal muscle and extend to individual skeletal muscle fibers

extend from the brain or spinal cord to the sarcolemma of a skeletal muscle fiber

Muscular dystrophy is a(n) __________ disorder. genetic (inherited) tumor inflammatory autoimmune

genetic (inherited)

If the microbe causing tetanus is subjected to a __________ oxygen environment, it will __________. high-; die no-; die normal atmospheric; multiple profusely very, very low-; die

high-; die

Currently, __________ is (are) the best protection against tetanus. antibiotics viral medications fungal medication immunization

immunization

As the stimulus voltage increased, the resulting muscle tension _______. remained the same increased proportionally increased to a point until it reached a plateau decreased proportionally

increased to a point until it reached a plateau

Which of the following produced an increase in stimulus intensity? increasing the voltage applied clicking the mouse in rapid succession allowing the muscle to completely relax in between contractions clicking the mouse in rapid succession and allowing the muscle to completely relax in between contractions

increasing the voltage applied

In its energized form, myosin __________. View Available Hint(s) is in an "un-cocked" position has a decreased affinity for actin is bound to ADP and Pi is in a state of rigor

is bound to ADP and Pi

In which phase of a muscle twitch are voltage-gated calcium channels first activated in order to release calcium from the SR? View Available Hint(s) Voltage-gated Ca++ channels are not involved in any aspect of a muscle twitch. relaxation phase latent period contraction phase

latent period

Which of the following terms are NOT used interchangeably? muscle cell - muscle fiber muscle tension - muscle force in vivo - in the body/ the living motor unit - motor neuron

motor unit - motor neuron

Increasing the applied voltage in the simulation corresponds to which in vivo event? motor neuron recruitment muscle fiber recruitment motor unit recruitment muscle twitch recruitment

motor unit recruitment

Where does the acetylcholine that stimulates muscle contraction bind? receptors in troponin receptors in the sarcoplasmic reticulum receptors in the motor end plate receptors in the axon terminal

receptors in the motor end plate

Muscular dystrophy is a medical condition that is somewhat opposite to tetanus, in terms of cause and presentation; muscular dystrophy involves problems with the __________ and gives muscle __________. nerve; hyperexcitability muscle itself; flaccidity (decrease in muscle tonus) muscle itself; spasticity (increase in muscle tonus) nerve; hypoexcitability

muscle itself; flaccidity (decrease in muscle tonus)

There is __________ for muscular dystrophy. Physical therapy helps to delay the progression of __________ and anti-inflammatory drugs may decrease the progression. no cure; hypertrophy no cure; contractures a cure; hyperplasia a cure; contractures

no cure; contractures

A reading frame is one triplet code on a strand of DNA that is being read by messenger RNA; it codes for one particular amino acid. Thus, the triplet code determines which amino acid will be inserted into the protein or polypeptide. If one complete triplet code (all three nucleotides in succession) is removed, it is termed a deletion type mutation. Because a complete reading frame was removed __________ will not be present in the protein or polypeptide. one monosaccharide one amino acid two amino acids one fatty acid

one amino acid

Duchenne and Becker muscular dystrophy mainly involve problems with __________ muscles; when muscles __________ and start to form __________. eye; atrophy; contractures jaw; hypertrophy; contractures postural; atrophy; contractures postural; hypertrophy; smooth muscle

postural; atrophy; contractures

What is the neural pathway for an automatic, patterned response to a sensory stimulus called? reflex arc autonomic reflex cranial reflex spinal reflex

reflex arc

What causes the power stroke? binding of ATP hydrolysis of ATP release of ADP and Pi calcium

release of ADP and Pi

Which of the following can trigger a muscle twitch? electrical stimulation release of calcium from the sarcolemma release of acetylcholine or release of calcium from the sarcolemma release of acetylcholine or electrical stimulation release of acetylcholine

release of acetylcholine or electrical stimulation

In an isometric contraction, __________. sarcomeres lengthen sarcomeres do not change length myosin and actin shorten sarcomeres shorten

sarcomeres shorten

Which of the following is NOT a phase of a muscle twitch? latent period relaxation phase shortening phase contraction phase

shortening phase

How is acetylcholine (ACh) removed from the synaptic cleft? View Available Hint(s) simple diffusion away from the synaptic cleft and acetylcholinesterase (AChE; an enzyme) acetylcholinesterase (AChE; an enzyme) only acetylcholinesterase (AChE; an enzyme) and endocytosis into the muscle fiber simple diffusion away from the synaptic cleft and endocytosis into the muscle fiber

simple diffusion away from the synaptic cleft and acetylcholinesterase (AChE; an enzyme)

Because of the correlation between the size of a motor unit and the type of fiber it contains, recruitment of fibers happens in a specific order. Which of the following fibers are recruited first? fast glycolytic fibers slow glycolytic fibers fast oxidative fibers slow oxidative fibers

slow oxidative fibers

Part E Part complete The neuronal circuitry to skeletal muscles involves neurons that stimulate contractions and those that inhibit contractions. The muscle spindles and Golgi tendon organs are involved in maintaining the proper muscle tonus (resting muscle tension); they work by signaling the CNS. Since tetanus involves __________, the neurons involved in muscle contraction __________ are affected. somatic motor neuron hypoexcitability; excitation somatic motor neuron hyperexcitability; inhibition autonomic motor neuron hyperexcitability; inhibition somatic sensory hyperexcitability; inhibition

somatic motor neuron hyperexcitability; inhibition

The most frequent early systemic symptom of tetanus is __________. stiffness of the jaw laxity of the jaw stiffness of the legs stiffness of the arms

stiffness of the jaw

The action potential on the muscle cell leads to contraction due to the release of calcium ions. Where are calcium ions stored in the muscle cell? View Available Hint(s) T tubule terminal cisterns (cisternae) of the sarcoplasmic reticulum sarcolemma cytosol

terminal cisterns (cisternae) of the sarcoplasmic reticulum

Summation happens whenever muscle twitches occur at such high frequencies that calcium cannot be removed from the cytosol as rapidly as it is released. If sustained at a high enough frequency, summation could lead to a condition known as __________ (also a term that refers to a condition in which bacterial toxins cause inappropriate motor neuron stimulation). tetanus isotonic twitch treppe botulism

tetanus

A motor unit is defined as _______. the axon terminals of a single motor neuron and all of the muscle fibers that it stimulates a single muscle fiber and all its axon terminals a nerve and a muscle a single neuron and a single muscle fiber

the axon terminals of a single motor neuron and all of the muscle fibers that it stimulates

When acetylcholine binds to its receptors, it results in __________. a change in ion permeability the end plate potential the end plate potential, a graded depolarization, and a change in ion permeability a graded depolarization

the end plate potential, a graded depolarization, and a change in ion permeability

NO force is generated during which of the following? the contraction phase the relaxation phase a muscle twitch the latent period

the latent period

When wave summation occurs, _______. the muscle force generated increases the muscle fiber has received a single stimulus event individual muscle twitches are separated the muscle force generated decreases

the muscle force generated increases

Which of the following is proportional to the amount of tension produced by a skeletal muscle? the length of the latent period the number of motor units activated the threshold voltage the length of the relaxation phase

the number of motor units activated

Acetylcholine binds to its receptor in the sarcolemma and triggers __________. View Available Hint(s) the opening of ligand-gated anion channels the opening of ligand-gated cation channels the opening of voltage-gated calcium channels the opening of calcium-release channels

the opening of ligand-gated cation channels