Mastering Bio Muscular system

In a neuromuscular junction, synaptic vesicles in the motor neuron contain which neurotransmitter?

Acetlycholine

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

Which thick filament binds to actin once its active binding sites are exposed? tropomyosin troponin myosin actin

Myosin Myosin is a thick filament that contains a hinge, allowing its interaction with actin when binding sites are exposed.

In response to an action potential along the transverse tubules, the __________ release(s) calcium ions into the sarcoplasm. sarcoplasmic reticulum troponin molecules thin filaments calcitonin

SR

The muscle action potential penetrates into a fiber along the __________. Z discs transverse tubules neuromuscular junction sarcoplasmic reticulum

T tubules

Sarcomere is best defined as ___________.

a repeating unit of striated muscle

A single muscle action potential will normally be followed by __________. a single pulse of calcium ion release treppe two pulses of calcium ion release incomplete tetanus

a single pulse of calcium ion release

During neuromuscular transmission, the axon terminals release __________. acetylcholine calcium ions acetylcholinesterase sodium ions

acetlycholine

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

actin

Which of the following proteins contains the active site involved in cross-bridge formation? myosin actin troponin tropomyosin

actin

The biochemical reaction that consumes the majority of a muscle's ATP is the __________. neuromuscular transmission sodium-potassium pump muscle action potential actin myosin cross-bridge cycle

actin myosin cross-bridge cycle

To increase muscle tension, the nervous system can __________. recruit larger motor units increase the number of active motor units increase the stimulation frequency All of these can increase muscle tension.

all

Cycling of myosin cross-bridges results in ___________. muscle shortening ATP hydrolysis force production Repeated cycling of cross-bridges causes all of these effects.

all of these

Which of these is true of cardiac muscle fibers? Cardiac fibers have a single nucleus. Cardiac fibers have a long twitch duration compared to skeletal fibers. Cardiac fibers branch. All of these are true of cardiac fibers.

alll

What causes the vesicles inside a neuron to fuse with the plasma membrane? an action potential in the neuron acetylcholine binding to acetylcholine receptors acetylcholine being broken down by acetylcholinesterase an action potential in the muscle fiber

an action potential in the neuron

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

arrival of action potential

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

binding of ATP

Triads in skeletal muscle fibers function in __________. calcium ion uptake neuromuscular transmission calcium ion release sarcomere shortening

calcium ion release

Smooth muscle contracts when calcium binds to __________ and activates __________. troponin; tropomyosin calmodulin; troponin calmodulin; myosin light chain kinase troponin; myosin light chain kinase

calmodulin; myosin light chain kinase

What is the type of chemical reaction used to rebuild ADP into ATP? dehydration synthesis rehydration synthesis hydrolysisv

dehydration sythesis

Titin is an:

elastic protein

What means of membrane transport is used to release the neurotransmitter into the synaptic cleft? exocytosis a channel a protein carrier

exocytosis

The __________ type of muscle fiber has relatively few mitochondria. intermediate cardiac fast slow

fast

Which of the following processes produces molecules of ATP and has two pyruvic acid molecules as end products? Krebs cycle and oxidative phosphorylation glycolysis hydrolysis of creatine phosphate

glyolysis

All of the following are found in both skeletal and cardiac muscle fibers except __________. All of the following are found in both skeletal and cardiac muscle fibers except __________. sarcomeres mitochondria striations intercalated disks

intercalculated discs

Which arrangement of the sarcomere gives rise to the structure (band or line) indicated by the arrow? (M line) the region of the sarcomere that contains only thin filaments the region of the resting sarcomere that only contains thick filaments is the point of connection for adjacent thick filaments the boundary between adjacent sarcomeres

is the point of connection for adjacent thick filaments The M line is the central portion of the sarcomere (M stands for middle).

When a muscle contraction develops tension but doesn't shorten the muscle, the contraction is called __________. isometric unfused tetanus incomplete twitch isotonic

isometric

Muscle fatigue occurs due to a buildup of __________ and __________ in pH.

lactic acid; decrease in pH

Myofibrils are __________. made of a series of sarcomeres connections between actin and myosin bundles of muscle cells inside a whole muscle proteins that cover active sites on actin

made of a series of sarcomeres

The neuromuscular junction is a connection between a neuron and a __________. muscle fiber vesicle synaptic terminal myofibril

muscle fiber

Which of the following is involved in the power stroke? -Z lines -myofibrils -tropomyosin -myosin

myosin

The intercalated disk is a not site of __________. force transmission myofibril attachment action potential propagation neuromuscular transmission

neuromuscular transmissio

Acetylcholine receptors are primarily located __________. = on the synaptic terminal inside the muscle fiber on the motor end plate inside vesicles

on the motor end plate

Anaerobic glycolysis provides energy for muscle contraction when the supply of __________ is limited.

oxygen

Which of these is not a function of smooth muscle? pushing blood into the arteries elevating skin hairs churning the stomach contents adjusting airway diameter

pushing blood into arteries

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. Oxygen rebinds to myoglobin. ATP is used to rephosphorylate creatine into creatine phosphate. Glycogen is synthesized from glucose molecules.

pyruvic is not converted back to lactic

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

release of ADP and Pi

The role of acetylcholinesterase in the neuromuscular junction is to __________. generate a muscle action potential release acetylcholine from the synaptic terminal increase the sodium permeability of the motor end plate remove acetylcholine from the synaptic cleft

remove ACh from the synaptic cleft

The action potential in skeletal muscle fibers is generated by the __________. sarcolemma sarcophagus sarcoplasmic reticulum sarcoplasm

sarcolemma

Z lines define the edges of which of the following? sarcomeres myosin myofibrils cross-bridges

sarcomeres

The end of a neuron, where acetylcholine-filled vesicles are located, is called the _________. synaptic terminal synaptic cleft motor end plate acetylcholine receptor

synaptic terminal

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? terminal cisterns (cisternae) of the sarcoplasmic reticulum T tubule sarcolemma cytosol

terminal cisterns (cisternae) of the SR

Which arrangement of the sarcomere gives rise to the structure (band or line) indicated by the arrow? the boundary between adjacent sarcomeres the region of the resting sarcomere that only contains thick filaments is the point of connection for adjacent thick filaments the region of the sarcomere that contains only thin filaments

the boundary between adjacent sarcomeres The Z line marks the boundary between neighboring sarcomeres.

An action potential in the muscle fiber causes __________. the release of acetylcholine into the synaptic cleft acetylcholine to bind to receptors on the motor end plate acetylcholinesterase to break down acetylcholine the muscle fiber to contract

the muscle fiber to contract

Which arrangement of the sarcomere gives rise to the structure (I band) indicated by the arrow? is the point of connection for adjacent thick filaments the boundary between adjacent sarcomeres the region of the resting sarcomere that only contains thick filaments the region of the sarcomere that contains only thin filaments

the region of the sarcomere that contains only thin filaments The I band extends from the A band of one sarcomere to the A band of the neighboring sarcomere and is the region where only thin filaments are found.

Which of these is not a property of slow muscle fibers? They contract slowly. They are large in diameter. They resist fatigue. They are rich in myoglobin.

they are NOT large in diameter

Myosin molecules form what part of the sarcomere? thin filament thick filament actin tropomyosin

thick filaments

When the sarcomere is at rest, what is covering the active sites on actin? cross-bridges myosin troponin tropomyosin

tropomoysin

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

troponin

When calcium is released inside a muscle cell, what does it bind to? troponin actin tropomyosin myosin

troponin

Which component of a thin filament binds to calcium once the calcium ion is released from the sarcoplasmic reticulum? actin troponin tropomyosin myosin

troponin

Inside a neuron, acetylcholine is contained within __________. vesicles the synaptic cleft the motor end plate acetylcholine receptors

vesicles

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

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 red slow twitch fibers

white fast twich