Anatomy Chapters 10, 12, 13

skeletal

Which type of muscle tissue has the greatest effect on the body’s heat production? skeletal cardiac smooth All of these muscle types have about the same effect on the body’s heat production.

contraction

Muscle tissue, one of the four basic tissue groups, consists chiefly of cells that are highly specialized for peristalsis. contraction. conduction. secretion cushioning.

all of the answers are correct.

Which of the following is a recognized function of skeletal muscle? guard body entrances and exits produce movement maintain body temperature maintain posture All of the answers are correct.

endomysium

The capillaries that wrap around each muscle fiber are located within the __________. sarcolemma perimysium endomysium epimysium

aponeurosis

Muscles are attached to bones by tendons or __________. perimysium aponeuroses ligaments superficial fascia

perimysium

A thin layer of connective tissue that surrounds a muscle fascicle is called the __________. tendon perimysium epimysium endomysium

tendon

At each end of the muscle, the collagen fibers of the epimysium, and each perimysium and endomysium, come together to form a sheath. tendon. tenosynovium. satellite cell. ligament.

epimysium

The dense layer of connective tissue that surrounds an entire skeletal muscle is the fascicle. endomysium. epimysium. tendon. perimysium.

tendon

The bundle of collagen fibers at the end of a skeletal muscle that attaches the muscle to bone is called a(n) myofibril. ligament. epimysium. tendon. fascicle.

storage of calcium

What is the function of the muscle cell feature indicated by the arrow? (sarcoplasmic reticulum) making of ATP – the "power house" of the cell part of coupling the action potential to contraction storage of calcium houses the genetic material of the cell

houses the genetic material of the cell

What is the function of the muscle cell feature indicated by the arrow? (nucleus) part of coupling the action potential to contraction storage of calcium making of ATP – the "power house" of the cell houses the genetic material of the cell

part of coupling the action potential to contraction

What is the function of the muscle cell feature indicated by the arrows? (t-tubules) storage of calcium houses the genetic material of the cell part of coupling the action potential to contraction making of ATP – the "power house" of the cell

making of ATP- the "power house" of the cell

What is the function of the muscle cell feature indicated by the arrow? (mitochondria) houses the genetic material of the cell part of coupling the action potential to contraction making of ATP – the "power house" of the cell storage of calcium

the region of the resting sarcomere that only contains thick filaments

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

the boundary between adjacent sarcomeres

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

is the point of connection for adjacent thick filaments

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 boundary between adjacent sarcomeres is the point of connection for adjacent thick filaments the region of the resting sarcomere that only contains thick filaments

the region of the sarcomere that contains only thin filaments

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

myosin

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

sarcolemma

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

elastic protein

Titin is a(n) __________. calcium-binding protein elastic protein thin filament protein tropomyosin-binding protein

muscle contraction

Interactions between actin and myosin filaments of the sarcomere are responsible for the striped appearance of skeletal muscle. muscle relaxation. muscle fatigue. muscle contraction. the conduction of neural stimulation to the muscle fiber.

myoblasts

Skeletal muscle fibers are formed from embryonic cells called myofibrils. sarcomeres. myoblasts. myomeres. fascicles.

sarcomere

The repeating unit of a skeletal muscle fiber is the sarcomere. myofibril. myofilament. sarcolemma. sarcoplasmic reticulum.

sarcolemma

The plasma membrane of a skeletal muscle fiber is called the sarcoplasm. sarcomere. sarcosome. sarcolemma. sarcoplasmic reticulum.

repeating unit of striated myofibrils

Which of the following best describes the term sarcomere? repeating unit of striated myofibrils protein that accounts for elasticity of resting muscle largely made of myosin molecules thin filaments are anchored here storage site for calcium ions

have many nuclei

Muscle fibers differ from "typical cells" in that muscle fibers are very small. have large gaps in the cell membrane. have many nuclei. lack a plasma membrane. lack mitochondria.

storage and release site for calcium ions

Which of the following best describes the term sarcoplasmic reticulum? repeating unit of striated myofibrils storage and release site for calcium ions protein that accounts for elasticity of resting muscle thin filaments are anchored here largely made of myosin molecules

a traverse tubule and two terminal cisternae

The skeletal muscle complex known as the triad consists of actin, myosin, and filaments. a transverse tubule and two terminal cisternae. actin, myosin, and sarcomeres. A bands, H bands, and I bands. filaments, myofibrils, and sarcomeres.

I band

The region of the sarcomere that always contains thin filaments is the I band. A band. M line. H band. Z line.

all of the answers are correct

Which statement about the microscopic anatomy of skeletal muscle fibers is true? Each fiber has many nuclei. Muscle fibers are continuous from tendon to tendon. Cross striations result from the lateral alignment of thick and thin filaments. Tubular extensions of the sarcolemma penetrate the fiber transversely. All of the answers are correct.

All of the answers are correct

When a skeletal muscle fiber contracts, the H bands and I bands get smaller. the Z lines get closer together. the width of the A band remains constant. the zones of overlap get larger. All of the answers are correct.

Acetylcholine is degraded by acetylcholinesterase

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 diffuses away from the cleft. Acetylcholine is transported back into the axon terminal by a reuptake mechanism. Acetylcholine is degraded by acetylcholinesterase. Acetylcholine is transported into the postsynaptic neuron by receptor-mediated endocytosis.

Acetylcholine is released by axon terminals of the motor neuron

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 by axon terminals of the motor neuron. When the action potential reaches the end of the axon terminal, voltage-gated sodium channels open and sodium ions diffuse into the terminal. Acetylcholine binds to its receptor in the junctional folds of the sarcolemma. Its receptor is linked to a G protein. Acetylcholine is released and moves across the synaptic cleft bound to a transport protein.

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

Action potentials travel the length of the axons of motor neurons to the axon terminals. These motor neurons __________. extend from the spinal cord to the sarcolemma of a skeletal muscle fiber extend from the brain 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

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

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

the opening of ligand-gated cation channels

Acetylcholine binds to its receptor in the sarcolemma and triggers __________. the opening of ligand-gated anion channels the opening of voltage-gated calcium channels the opening of calcium-release channels the opening of ligand-gated cation channels

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

Sodium and potassium ions do not diffuse in equal numbers through ligand-gated cation channels. Why? 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. Sodium 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. Potassium ions diffuse inward along favorable chemical and electrical gradients.

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

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.

Calcium release from the sarcoplasmic reticulum initiates the contraction.

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

a series of proteins that control calcium release

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

transverse or T tubules

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

Calcium ions

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

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

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

a myosin head bound to actin

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

the sarcomere

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

calcium ions are stored in the sarcoplasmic reticulum

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

ATP binds to the myosin head

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.

the energy comes from the hydrolysis of ATP

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 GTP. The energy comes from oxidative phophorylation. The energy comes from the hydrolysis of ATP.

Calcium ions bind to troponin and change its shape

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

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

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 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. Cross bridge cycling ends when calcium release channels in the sarcoplasmic reticulum open.

acetylcholine (ACh)

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

voltage-gated calcium channels

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

exocytosis

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

binding of the neurotransmitter causes chemically gated sodium channels to open in the motor end plate

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. Binding causes potassium voltage-gated channels to open in the motor endplate. Binding causes voltage-gated sodium channels to open in the motor endplate. Binding causes chemically gated potassium channels to open in the motor end plate.

acetylcholinesterase (AChE; n enzyme)

How is acetylcholine (ACh) removed from the synaptic cleft? a reuptake pump on the axon terminal diffusion away from the synaptic cleft acetylcholinesterase (AChE; an enzyme)

terminal cisternae of the sarcoplasmic reticulum

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 cisternae of the sarcoplasmic reticulum cytosol sarcolemma T tubule

muscle fiber

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

synaptic terminal

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

the space between the synaptic terminal and the motor end plate

What is the synaptic cleft? the step where acetylcholinesterase (AChE) breaks down, or cleaves, acetylcholine the space between the synaptic terminal and the motor end plate the border between the motor end plate and the sarcolemma the region of the neuron containing synaptic vesicles

vesicles

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

an action potential in the neuron

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

on the motor end plate

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

the muscle fiber to contract

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

remove acetylcholine from the synaptic cleft

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

fascicles

Inside a muscle, bundles of single muscle fibers form __________. sarcomeres fascicles thick filaments T tubules

T-tubules

The muscle action potentials that initiate contraction are transmitted from the sarcolemma into the interior of the muscle fiber by __________. T tubules myofilaments the sarcoplasmic reticulum myofibrils

triads

T tubules and the terminal cisternae are clustered into structures called __________. fascicles sarcomeres myofibrils triads

calcium

The sarcoplasmic reticulum contains __________. T tubules myofilaments troponin calcium

sarcoplasmic reticulum

Which organelle completely surrounds each myofibril inside a muscle fiber? sarcoplasmic reticulum nucleus calcium fascicle

troponin

To what regulatory protein does calcium bind during the initiation of the contraction cycle in skeletal muscle fibers? actin troponin myosin tropomyosin

tropomyosin shifting position

Which of the following causes the active site on actin to be exposed or uncovered? cross-bridge formation calcium entering the sarcoplasmic reticulum tropomyosin shifting position troponin releasing calcium

the generation of the action potential in the sarcolemma

Which of the following most correctly describes excitation in the context of excitation-contraction coupling in skeletal muscle? the formation of cross-bridges the generation of an action potential in the sarcolemma the binding of calcium to troponin the release of calcium by the sarcoplasmic reticulum

through calcium release from the sarcoplasmic reticulum

Which of the following phrases best describes how excitation is coupled to contraction in skeletal muscle fibers? through cross-bridge formation through T tubules through electrical impulses travelling along the sarcolemma through calcium release from the sarcoplasmic reticulum

the muscles would contract because of the calcium binding to troponin

Malignant hyperthermia (MH) is a rare genetic disease in which the sarcoplasmic reticulum leaks calcium when the patient is put under general anesthesia. Which of the following best describes how anesthesia would affect the skeletal muscles of a patient with MH? The muscles would contract because of increased action potential generation in the sarcolemma. The muscles would relax because of calcium being pumped back into the sarcoplasmic reticulum. The muscles would contract because of calcium binding to troponin. The muscles would contract because of increased nerve stimulation.

made of a series of sarcomeres

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

sarcomeres

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

thick filament

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

myosin

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

actin

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

tropomyosin

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

troponin

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

actin

Myosin molecules form cross-bridges when they attach to __________. actin troponin tropomyosin calcium

the myosin head pivots, moving the actin strand

What happens immediately after the myosin head binds to the active site on actin? ATP binds to the myosin head. The myosin head pivots, moving the actin strand. Tropomyosin moves away from the active site on actin. The myosin head detaches from the active site on actin.

detaching and resetting cross-bridges

ATP binding leads to which of the following actions? exposure of active sites on actin cross-bridge formation detaching and resetting cross-bridges pivoting of the myosin head

troponin

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

acetylcholinesterase

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

transverse tubules

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

repeated cycling of cross-bridges causes all of these effects

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

sarcoplasmic reticulum

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

calcium ions

In response to action potentials arriving along the transverse tubules, the sarcoplasmic reticulum releases hydrogen ions. potassium ions. sodium ions. acetylcholine. calcium ions.

neuromuscular junction

Each skeletal muscle fiber is controlled by a motor neuron at a single synaptic cleft. neuromuscular junction. sarcomere. synaptic knob. transverse tubule.

synaptic cleft

The narrow space between the synaptic terminal and the muscle fiber is the synaptic knob. synaptic cleft. motor unit. motor end plate. M line.

rigor mortis

After death, muscle fibers run out of ATP and calcium begins to leak from the sarcoplasmic reticulum into the sarcoplasm. This results in a condition known as treppe. depolarization. rigor mortis. tetany. oxygen debt.

all of the answers are correct

In rigor mortis ATP is depleted. muscles are inextensible. the myosin heads are attached to actin. cross-bridge cycling is absent. All of the answers are correct.

the head portion of the myosin molecule

Which of the following acts as an ATPase during the contraction cycle of muscle? tropomyosin molecules troponin molecules the head portion of the myosin molecule actin molecules the tail portion of the myosin molecule

tropomyosin moves into the groove between the helical actin strands

When calcium ion binds to troponin, tropomyosin moves into the groove between the helical actin strands. actin heads will bind to myosin. muscle relaxation occurs. myosin shortens. active sites on the myosin are exposed.

acetylcholine

The cytoplasm of the neuromuscular terminal contains vesicles filled with molecules of the neurotransmitter epinephrine. acetylcholine. antidiuretic hormone. adrenaline. norepinephrine.

all of the answers are correct

When contraction occurs, the H bands get smaller. the Z lines move closer together. the I bands get smaller. the width of the A band remains constant. All of the answers are correct.

loss of acetylcholine receptors in the end-plate membrane

The muscle weakness of myasthenia gravis results from insufficient acetylcholine release from presynaptic vesicles. inability of the muscle fiber to produce ATP. loss of acetylcholine receptors in the end-plate membrane. the motor neuron action potential being too small to shock the muscle fibers. excessive acetylcholinesterase that destroys the neurotransmitter

exocytosis

Synaptic vesicles contain neurotransmitters that are released by ________ when the action potential arrives. apoptosis endocytosis exocytosis hydrolysis sodium

reduces the muscle’s ability for contraction

A patient takes a medication that blocks ACh receptors of skeletal muscle fibers. What is this drug’s effect on skeletal muscle contraction? produces a strong, continuous state of contraction causes a strong contraction similar to a "charlie horse" cramp reduces the muscle’s ability for contraction increases the muscle’s excitability increases tone in the muscle

arrival of an action potential

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

troponin

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

actin

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

binding of ATP

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

hydrolysis of ATP

What energizes the power stroke? hydrolysis of ATP binding of ATP calcium

a single pulse of calcium ion release

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

complete tetanus

A muscle producing its maximum tension is in __________. rigor mortis incomplete tetanus complete tetanus treppe

all of these can increase muscle tension

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

muscles that control the eyes

In which of the following would the motor units have the fewest muscle fibers? muscles of the neck postural muscles of the back thigh muscles calf muscles muscles that control the eyes

isometric

The type of contraction in which the muscle fibers do not shorten is called tetany. isometric. concentric. treppe. isotonic.

muscle tension exceeds the load and the muscle lifts the load

In an isotonic contraction, postural muscles stabilize the vertebrae. many twitches always fuse into one. muscle tension exceeds the load and the muscle lifts the load. the peak tension is less than the load. tension rises and falls but the muscle length is constant.

dehydration synthesis

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

glycolysis

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

Krebs cycle and oxidative phosphorylation

Which of the following processes produces 36 ATP? glycolysis Krebs cycle and oxidative phosphorylation hydrolysis of creatine phosphate

pyruvic acid is converted back to lactic acid

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.

white fast twitch fibers

Which type of muscle fiber has a large quantity of glycogen and mainly uses glycolysis to synthesize ATP? red slow twitch fibers white fast twitch fibers

lactic acid; decrease

Muscle fatigue occurs due to a buildup of __________ and __________ in pH. lactic acid; decrease lactic acid; increase creatine phosphate; decrease creatine phosphate; increase

glucose is produced from lactic acid

During the Cori cycle, in the liver glucose is produced from lactic acid. lactic acid is produced from pyruvic acid. lactic acid is shuffled to muscle cells. glucose is released from glycogen. lactic acid is produced from glucose.

additional oxygen is required o restore energy reserves consumed during exercise

During the recovery period the body’s need for oxygen is increased because additional oxygen is required to restore energy reserves consumed during exercise. the muscles are not producing ATP. muscle cells are producing energy anaerobically. the individual is panting. the liver requires more oxygen to produce lactic acid.

aerobic metabolism of fatty acids

A resting muscle generates most of its ATP by the tricarboxylic acid cycle. aerobic metabolism of fatty acids. glycogenolysis. hydrolysis of creatine phosphate. anaerobic respiration.

acts as an energy reserve in muscle tissue

Creatine phosphate is produced by the process of anaerobic respiration. is only formed during strenuous exercise. can replace ATP in binding to myosin molecules during contraction. cannot transfer its phosphate group to ADP. acts as an energy reserve in muscle tissue.

all of the answers are correct

During anaerobic glycolysis ATP is produced. oxygen is not consumed. carbohydrate is metabolized. pyruvic acid is produced. All of the answers are correct.

95

Aerobic metabolism normally provides ________ percent of the ATP demands of a resting muscle cell. 25 95 100 70 50

fast

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

they are large in diameter

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

slow

The type of muscle fiber that is most resistant to fatigue is the ________ fiber. intermediate fast slow anaerobic high-density

most of the muscle’s energy i produced in mitochondria

During activities requiring aerobic endurance fatigue occurs in a few minutes. glycogen and glycolysis are the primary sources of reserve energy. most of the muscle’s energy is produced in mitochondria. oxygen is not required. oxygen debts are common.

all of the answers are correct

Which of the following statements is (are) true regarding human muscles? Most have both slow and fast fibers. Slow fibers are abundant in the back muscles. Slow fibers are abundant in the calf muscles. Eye muscles are composed entirely of fast fibers. All of the answers are correct.

all of the answers are correct

When comparing slow muscle fibers to fast muscle fibers, slow fibers are rich in the red protein myoglobin. have much smaller fiber diameters. generate much less tension. take about three times as long to reach peak tension. All of the answers are correct.

fast fibers

Large-diameter, densely packed myofibrils, large glycogen reserves, and few mitochondria are characteristics of fatty muscles. red muscles. fast fibers. intermediate fibers. slow fibers.

all of these are true of cardiac fibers

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

intercalated disks

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

cardiac muscle stimulation is neural

Which of the following statements is false? Cardiac muscle stimulation is neural. Cardiocytes are interconnected through intercalated discs. Skeletal muscle stimulation is neural. Cardiac muscle contractions cannot be summated. Skeletal muscle contractions may be summated.

plasticity

Resting smooth muscle can be stretched without developing much tension because of its __________. elasticity extensibility contractility plasticity

centrioles

Which of these components is usually absent from a neuron? axons dendrites centrioles cell body

carries sensory information

The afferent division of the PNS _____________. carries motor commands carries sensory information controls skeletal muscle controls smooth muscle

direct long-term functions, such as growth

Which of the following is not a function of the nervous system? control peripheral effectors coordinate voluntary and involuntary activities sense the internal and external environments direct long-term functions, such as growth integrate sensory information

central

The ________ nervous system is composed of the brain and spinal cord. autonomic peripheral central afferent efferent

somatic

The ________ nervous system controls the skeletal muscles. parasympathetic afferent somatic sympathetic autonomic

afferent

The part of the peripheral nervous system that carries sensory information to the CNS is designated afferent. motor. somatic. efferent. autonomic.

all of the answers are correct

The efferent division of the peripheral nervous system innervates: smooth muscle cells skeletal muscle cells heart muscle cells glandular cells All of the answers are correct.

psuedopolar

Which of these is not a neuron structural category? multipolar bipolar unipolar pseudopolar

multipolar

Most CNS neurons fall into which structural category? anaxonic bipolar multipolar unipolar

cell body (soma)

The axon hillock connects the axon with the __________. synapse telodendria cell body (soma) collaterals

all of the answers are correct

The axoplasm of the axon contains which of the following? mitochondria vesicles neurotubules neurofibrils All of the answers are correct.

pseudopolar

Which of the following is not a recognized structural classification for neurons? bipolar multipolar anaxonic unipolar pseudopolar

multipolar

The most abundant class of neuron in the central nervous system is bipolar. multipolar. pseudopolar. anaxonic. unipolar.

retrograde axoplasmic transport

The rabies virus travels to the CNS via retrograde axoplasmic transport. subcutaneous connective tissue. anterograde axoplasmic transport. cerebrospinal fluid. blood vessels.

synapse

The site of intercellular communication between a neuron and another cell is the telodendria. hillock. synapse. synaptic terminals. collateral.

anaxonic

Neurons that are rare, small, and lack features that distinguish dendrites from axons are called anaxonic. unipolar. multipolar. tripolar. bipolar.

unipolar

Neurons in which dendritic and axonal processes are continuous and the soma lies off to one side are called anaxonic. tripolar. unipolar. multipolar. bipolar.

bipolar

Neurons that have one axon and one dendrite, with the soma in between, are called bipolar. multipolar. anaxonic. tripolar. unipolar.

multipolar

Neurons that have several dendrites and a single axon are called tripolar. anaxonic. bipolar. unipolar. multipolar.

multipolar

________ neurons are the most common class in the CNS. Bipolar Anaxonic Multipolar Sensory Unipolar

sensory

________ neurons form the afferent division of the PNS. Somatic sensory Neural sensory Motor Sensory Visceral sensory

neuron

The basic functional unit of the nervous system is the ________.

astrocytes

Which is the largest and most abundant type of neuroglia? satellite cells ependymal cells astrocytes oligodendrocytes

satellite cells

Which of these types of neuroglia are abundant in peripheral ganglia? satellite cells microglia astrocytes oligodendrocytes

astrocytes

The largest and most numerous of the glial cells in the central nervous system are the ependymal cells. satellite cells. oligodendrocytes. microglia. astrocytes

conducting action potentials

Functions of astrocytes include all of the following, except guiding neuron development. maintaining the blood-brain barrier. responding to neural tissue damage. conducting action potentials. forming a three-dimensional framework for the CNS

satellite cells

Which of the following is a type of glial cell found in the peripheral nervous system? microglia oligodendrocytes astrocytes ependymal cells satellite cells

neuroglia

________ account for roughly half of the volume of the nervous system. Axons Dendrites Synapses Neuroglia Efferent fibers

astrocytes

The neuroglial cells that participate in maintaining the blood-brain barrier are the microglia. ependymal cells. oligodendrocytes. Schwann cells. astrocytes.

all of the answers are correct

The function of the astrocytes in the CNS includes which of the following? maintaining the blood-brain barrier guiding neuron development adjusting the composition of the interstitial fluid repairing damaged neural tissue All of the answers are correct.

oligodendrocytes

The myelin sheath that covers many CNS axons is formed by oligodendrocytes. astrocytes. ependymal cells. satellite cells. microglia.

ependymal cells

________ line the brain ventricles and spinal canal. Satellite cells Astrocytes Oligodendrocytes Microglia Ependymal cells

microglia

Small, wandering cells that engulf cell debris and pathogens in the CNS are called ependymal cells. microglia. oligodendrocytes. astrocytes. satellite cells.

Schwann cells

The neurilemma of axons in the peripheral nervous system is formed by microglia. satellite cells. Schwann cells. oligodendrocytes. astrocytes.

satellite cells

Glial cells that surround the neurons in ganglia are oligodendrocytes. microglia. satellite cells. astrocytes. ependymal cells.

white

Regions of the CNS with an abundance of myelinated axons constitute the ________ matter.

resting membrane potential (RMP)

Ions are unequally distributed across the plasma membrane of all cells. This ion distribution creates an electrical potential difference across the membrane. What is the name given to this potential difference? Resting membrane potential (RMP) Threshold potential Action potential Positive membrane potential

leak channels

Sodium and potassium ions can diffuse across the plasma membranes of all cells because of the presence of what type of channel? Sodium-potassium ATPases Leak channels Ligand-gated channels Voltage-gated channels

the inside surface of the plasma membrane is much more negatively charged than the outside surface

On average, the resting membrane potential is -70 mV. What does the sign and magnitude of this value tell you? The outside surface of the plasma membrane is much more negatively charged than the inside surface. The inside surface of the plasma membrane is much more positively charged than the inside surface. The inside surface of the plasma membrane is much more negatively charged than the outside surface. There is no electrical potential difference between the inside and the outside surfaces of the plasma membrane.

there are many more K+ leak channels than Na+ leak channels in the plasma membrane

The plasma membrane is much more permeable to K+ than to Na+. Why? The Na+-K+ pumps transport more K+ into cells than Na+ out of cells. Ligand-gated cation channels favor a greater influx of Na+ than K+. There are many more voltage-gated K+ channels than voltage-gated Na+ channels. There are many more K+ leak channels than Na+ leak channels in the plasma membrane.

the presence of concentration gradients and leak channels

The resting membrane potential depends on two factors that influence the magnitude and direction of Na+ and K+ diffusion across the plasma membrane. Identify these two factors. The presence of a resting membrane potential and leak channels The presence of concentration gradients and Na+-K+ pumps The presence of concentration gradients and leak channels The presence of concentration gradients and voltage-gated channels

Na+-K+ ATPase

What prevents the Na+ and K+ gradients from dissipating? Na+ cotransporter Na+ and K+ leaks Na+-K+ ATPase H+-K+ ATPase

K+; Na+

The membranes of neurons at rest are very permeable to _____ but only slightly permeable to _____. Na+; Cl- K+; Na+ Na+; K+ K+; Cl-

both the electrical and chemical gradients

During depolarization, which gradient(s) move(s) Na+ into the cell? Na+ does not move into the cell. Na+ moves out of the cell. only the electrical gradient both the electrical and chemical gradients only the chemical gradient

-70mV

What is the value for the resting membrane potential for most neurons? -90 mV +30 mV -70 mV

Na+ is pumped out of the cell and K+ is pumped into the cell

The Na+-K+ pump actively transports both sodium and potassium ions across the membrane to compensate for their constant leakage. In which direction is each ion pumped? Both Na+ and K+ are pumped out of the cell. Na+ is pumped out of the cell and K+ is pumped into the cell. Both Na+ and K+ are pumped into the cell. K+ is pumped out of the cell and Na+ is pumped into the cell.

Na+ and Cl-

The concentrations of which two ions are highest outside the cell. Na+ and A- (negatively charged proteins) K+ and A- (negatively charged proteins) Na+ and Cl- K+ and Cl-

the sodium concentration is higher outside the cell than inside the cell and the potassium concentration is higher inside the cell than outside the cell

In a neuron, sodium and potassium concentrations are maintained by the sodium-potassium exchange pump such that __________. the sodium concentration is higher inside the cell than outside the cell and the potassium concentration is higher outside the cell than inside the cell. both sodium and potassium concentrations are higher outside the cell compared to inside. the sodium concentration is higher outside the cell than inside the cell and the potassium concentration is higher inside the cell than outside the cell. the concentration of sodium outside the cell is equal to the concentration of potassium inside the cell.

sodium ions are transported out of the cell. potassium ions are transported into the cell

The sodium-potassium exchange pump transports potassium and sodium ions in which direction(s)? Sodium and potassium ions are both transported out of the cell. Sodium ions are transported into the cell. Potassium ions are transported out of the cell. Sodium and potassium ions are both transported into the cell. Sodium ions are transported out of the cell. Potassium ions are transported into the cell.

channel-mediated diffusion

Leak channels allow the movement of potassium and sodium ions by what type of membrane transport? channel-mediated diffusion facilitated diffusion simple diffusion active transport

a chemical gradient going out of the cell and an electrical gradient going into the cell

The electrochemical gradient for potassium ions when the transmembrane potential is at the resting potential (-70 mV) is caused by what? chemical and electrical gradients both going out of the cell chemical and electrical gradients both going into the cell a chemical gradient going out of the cell and an electrical gradient going into the cell a chemical gradient going into the cell and an electrical gradient going out of the cell

the sum of the electrical and chemical gradients for that ion

What is the electrochemical gradient of an ion? the transmembrane potential at which the electrical and chemical gradients are equal in magnitude, but opposite in direction the difference between the concentrations of an ion inside and outside the cell The electrochemical gradient is the direction an ion would diffuse (either outward or inward) when the neuron is at rest, regardless of the transmembrane potential. the sum of the electrical and chemical gradients for that ion

-90mV

In a typical neuron, what is the equilibrium potential for potassium? +66 mV -90 mV -70 mV 0 mV

chemical and electrical gradients both going into the cell

Part G The electrochemical gradient for sodium ions in a neuron when the transmembrane potential is at the resting potential is caused by what? a chemical gradient going out of the cell and an electrical gradient going into the cell a chemical gradient going into the cell and an electrical gradient going out of the cell chemical and electrical gradients both going into the cell chemical and electrical gradients both going out of the cell

in the same direction and of the same magnitude

Compared to the electrical gradient for sodium at rest, the electrical gradient for potassium at rest is __________. in the opposite direction but of the same magnitude. in the same direction and of the same magnitude. in the same direction but of greater magnitude. in the same direction but of lesser magnitude.

+66mV

In a typical neuron, what is the equilibrium potential for sodium? -90 mV +66 mV +30 mV -70 mV

the membrane is much more permeable to potassium ions than to sodium ions

At rest, why is the transmembrane potential of a neuron (-70 mV) closer to the potassium equilibrium potential (-90 mV) than it is to the sodium equilibrium potential (+66 mV)? For each ATP hydrolyzed, the sodium-potassium exchange pump transports more sodium ions out of the cell (three) than it transports potassium ions into the cell (two). The concentration of potassium ions inside the cell is greater than the concentration of sodium ions outside the cell. There are more negatively charged proteins inside the cell than outside the cell. The membrane is much more permeable to potassium ions than to sodium ions.

synaptic delay

The events that occur at a functioning cholinergic synapse cause _____________ . strengthening of the synapse a flow of acetylcholine (ACh) into the synaptic cleft that is removed only by simple diffusion synaptic delay loss of transmission of the action potential

potassium; chloride

The most abundant intracellular cation is __________ while the most abundant extracellular anion is __________. sodium; chloride potassium; protein anions sodium; protein anions potassium; chloride

passive

Which type of ion channel is always open? mechanically gated passive voltage-gated chemically gated

-70mV

The sodium-potassium exchange pump stabilizes resting potential at about __________. -90 mV -10 mV -70 mV +66 mV

chemically-gated channels

________ open or close in response to binding specific molecules. Voltage-gated and chemically-gated channels Chemically-gated channels Voltage-gated channels Leak channels Activated channels

mechanically-gated

________ channels open or close in response to physical distortion of the membrane surface. Mechanically-gated Active Leak Voltage-gated Chemically-gated

all of the answers are correct

Any stimulus that opens ________ ion channel will produce a graded potential. ANSWER: a voltage-gated a mechanically-gated a sodium a chemically-gated All of the answers are correct.

all of the answers are correct

Ions can move across the plasma membrane in which of the following ways? through passive or leak channels through chemically-gated channels as in neuromuscular transmission through voltage-gated channels as in the action potential by ATP-dependent ion pumps like the sodium-potassium exchange pump All of the answers are correct.

inactivation

Voltage-gated sodium channels have both an activation gate and a(n) ________ gate. repolarization ion swinging inactivation threshold

initial segment

Where do most action potentials originate? Nodes of Ranvier Initial segment Cell body Axon terminal

voltage-gated Na+ channels

What opens first in response to a threshold stimulus? Voltage-gated K+ channels Ligand-gated Cl- channels Voltage-gated Na+ channels Ligand-gated cation channels

the membrane potential changes from a negative value to a positive value

What characterizes depolarization, the first phase of the action potential? The membrane potential changes from a negative value to a positive value. The membrane potential changes to a much more negative value. The membrane potential changes to a less negative (but not a positive) value. The membrane potential reaches a threshold value and returns to the resting state.

once the membrane depolarizes to a peak value of +30mV, it repolarizes to its negative resting value of -70 mV

What characterizes repolarization, the second phase of the action potential? As the membrane repolarizes to a negative value, it goes beyond the resting state to a value of -80 mV. Once the membrane depolarizes to a threshold value of approximately -55 mV, it repolarizes to its resting value of -70 mV. Before the membrane has a chance to reach a positive voltage, it repolarizes to its negative resting value of approximately -70 mV. Once the membrane depolarizes to a peak value of +30 mV, it repolarizes to its negative resting value of -70 mV.

the membrane potential must depolarize from the resting voltage of -70mV to threshold value of -55 mV

What event triggers the generation of an action potential? The membrane potential must depolarize from the resting voltage of -70 mV to a threshold value of -55 mV. The membrane potential must hyperpolarize from the resting voltage of -70 mV to the more negative value of -80 mV. The membrane potential must return to its resting value of -70 mV from the hyperpolarized value of -80 mV. The membrane potential must depolarize from the resting voltage of -70 mV to its peak value of +30 mV.

voltage-gated Na+ channels change shape and their activation gates open

What is the first change to occur in response to a threshold stimulus? Voltage-gated Na+ channels change shape, and their inactivation gates close. Voltage-gated Na+ channels change shape, and their activation gates open. Voltage-gated K+ channels change shape, and their activation gates open. Voltage-gated Ca2+ channels change shape, and their activation gates open.

continuous conduction

What type of conduction takes place in unmyelinated axons? Continuous conduction Electrical conduction Saltatory conduction Synaptic transmission

depolarizing currents established by the influx of Na+ flow down the axon and trigger an action potential at the next segment

An action potential is self-regenerating because __________. depolarizing currents established by the influx of K+ flow down the axon and trigger an action potential at the next segment depolarizing currents established by the influx of Na+ flow down the axon and trigger an action potential at the next segment repolarizing currents established by the efflux of Na+ flow down the axon and trigger an action potential at the next segment repolarizing currents established by the efflux of K+ flow down the axon and trigger an action potential at the next segment

the inactivation gates of voltage-gated Na+ channels close in the node, or segment, that has just fired an action potential

Why does regeneration of the action potential occur in one direction, rather than in two directions? The activation gates of voltage-gated K+ channels open in the node, or segment, that has just depolarized. The activation gates of voltage-gated Na+ channels close in the node, or segment, that has just depolarized. The inactivation gates of voltage-gated Na+ channels close in the node, or segment, that has just fired an action potential. The inactivation gates of voltage-gated K+ channels close in the node, or segment, that has just fired an action potential.

the myelin sheath increases the speed of action potential conduction from the initial segment to the axon terminals

What is the function of the myelin sheath? The myelin sheath increases the insulation along the entire length of the axon. The myelin sheath decreases the speed of action potential conduction from the initial segment to the axon terminals. The myelin sheath decreases the resistance of the axonal membrane to the flow of charge. The myelin sheath increases the speed of action potential conduction from the initial segment to the axon terminals.

inactivation gates of voltage-gated Na+ channels close, while activation gates of voltage-gated K+ channels open

What changes occur to voltage-gated Na+ and K+ channels at the peak of depolarization? Activation gates of voltage-gated Na+ channels close, while activation gates of voltage-gated K+ channels open. Inactivation gates of voltage-gated Na+ channels close, while inactivation gates of voltage-gated K+ channels open. Activation gates of voltage-gated Na+ channels close, while inactivation gates of voltage-gated K+ channels open. Inactivation gates of voltage-gated Na+ channels close, while activation gates of voltage-gated K+ channels open.

myelinated axons with the largest diameter

In which type of axon will velocity of action potential conduction be the fastest? Myelinated axons with the smallest diameters Unmyelinated axons with the largest diameter Unmyelinated axons of the shortest length Myelinated axons with the largest diameter

axon hillock

Where in the neuron is an action potential initially generated? soma and dendrites axon hillock anywhere on the axon

voltage-gated Na+ channels

The depolarization phase of an action potential results from the opening of which channels? chemically gated Na+ channels voltage-gated Na+ channels voltage-gated K+ channels chemically gated K+ channels

the opening of voltage-gated K+ channels

The repolarization phase of an action potential results from __________. the opening of voltage-gated K+ channels the opening of voltage-gated Na+ channels the closing of voltage-gated K+ channels the closing of voltage-gated Na+ channels

slow closing of voltage-gated K+ channels

Hyperpolarization results from __________. slow closing of voltage-gated Na+ channels fast closing of voltage-gated K+ channels slow closing of voltage-gated K+ channels

100mV

What is the magnitude (amplitude) of an action potential? 30 mV 100 mV 70 mV

an influx of sodium ions from the current action potential depolarizes the adjacent area

How is an action potential propagated along an axon? Stimuli from the graded (local) potentials from the soma and dendrites depolarize the entire axon. An influx of sodium ions from the current action potential depolarizes the adjacent area. An efflux of potassium from the current action potential depolarizes the adjacent area.

the areas that have had the action potential are refractory to a new action potential

Why does the action potential only move away from the cell body? The flow of the sodium ions only goes in one direction—away from the cell body The areas that have had the action potential are refractory to a new action potential.

a small myelinated axon

The velocity of the action potential is fastest in which of the following axons? a large unmyelinated axon a small unmyelinated axon a small myelinated axon

initial segment of the axon

In what part of the neuron does the action potential typically initiate? dendrites soma (cell body) initial segment of the axon axon terminals

the transmembrane potential (voltage)

During an action potential of a neuron, what directly causes the different channels to open and close? Sodium and potassium ions neurotransmitter binding to chemically gated channels the transmembrane potential (voltage) calcium ions

2 ms

What is the typical duration of a nerve action potential? 200 ms 2 ms 20 ms 0.2 ms

-60mV

Around what transmembrane potential does threshold commonly occur? -60 mV -70 mV -60 V +60 mV

Na+ (sodium)

What ion is responsible for the depolarization of the neuron during an action potential? Na+ (sodium) Cl- (chloride) Ca2+ (calcium) K+ (potassium)

diffusion

What type of membrane transport causes the depolarization phase of the action potential in neurons? filtration active transport diffusion facilitated diffusion

voltage-gated sodium channels begin to inactivate (close) and voltage-gated potassium channels begin to open

During an action potential, after the membrane potential reaches +30 mV, which event(s) primarily affect(s) the membrane potential? Voltage-gated potassium channels begin to open and the sodium-potassium exchange pump begins removing the excess Na+ ions from the inside of the cell. Voltage-gated sodium channels begin to inactivate (close) and voltage-gated potassium channels begin to open. Voltage-gated sodium channels begin to inactivate (close). Voltage-gated sodium channels begin to inactivate (close) and the sodium-potassium exchange pump begins removing the excess sodium ions from the inside of the cell.

K+ (potassium)

What ion causes repolarization of the neuron during an action potential? Na+ (sodium) Ca2+ (calcium) K+ (potassium) Mg2+ (magnesium)

potassium efflux (leaving cell)

What causes repolarization of the membrane potential during the action potential of a neuron? sodium influx (entering the cell) potassium efflux (leaving the cell) potassium influx (entering the cell) sodium efflux (leaving the cell)

voltage-gated potassium channels taking some time to close in response to the negative membrane potential

What is primarily responsible for the brief hyperpolarization near the end of the action potential? the sodium/potassium exchange pump taking some time to restore the normal ion concentrations voltage-gated potassium channels taking some time to close in response to the negative membrane potential voltage-gated sodium channels taking some time to recover from inactivation voltage-gated potassium channels opening as the membrane potential becomes more negative (repolarized)

initial segment

Action potential propagation begins (is first generated at) what region of a neuron? dendrite myelin node initial segment

at every segment of the axon

Where are action potentials regenerated as they propagate along an unmyelinated axon? at the nodes at the internodes at myelin at every segment of the axon

sodium (Na+)

The movement of what ion is responsible for the local currents that depolarize other regions of the axon to threshold? calcium (Ca2+) voltage-gated sodium (Na+) channels sodium (Na+) Potassium (K+)

the previous axonal segment is refractory

In an unmyelinated axon, why doesn’t the action potential suddenly "double back" and start propagating in the opposite direction? Positive charges only move in one direction. New action potential generation near the soma repels previously generated action potentials. The previous axonal segment is refractory. The extracellular sodium concentration is too low around the previous axonal segment for an action potential to be (re)generated.

1 meter per second

Approximately how fast do action potentials propagate in unmyelinated axons in humans? 120 meters per second 1 meter per second 0.1 meters per second 12 meters per second

have lower membrane resistance to ion movement

In contrast to the internodes of a myelinated axon, the nodes __________. have higher membrane resistance to ion movement only occur at the beginning and end of the axon have lower membrane resistance to ion movement are wrapped in myelin

at the nodes

Where are action potentials regenerated as they propagate along a myelinated axon? at the internodes at myelin at the nodes at every segment of the axon

saltatory propagation

The node-to-node "jumping" regeneration of an action potential along a myelinated axon is called __________. local propagation continuous propagation myelinated propagation saltatory propagation

propagation is faster in myelinated axons

How do action potential propagation speeds in myelinated and unmyelinated axons compare? Propagation in myelinated axons is faster over short distances, but slower over long distances. Propagation speeds are similar in both axon types. Propagation is faster in unmyelinated axons. Propagation is faster in myelinated axons.

without myelin, the internode membrane resistance decreases, preventing local currents from reaching adjacent nodes

Multiple sclerosis (MS) is a disease that stops action potential propagation by destroying the myelin around (normally) myelinated axons. Which of the following best describes how MS stops action potential propagation? Without myelin, the node membrane more easily becomes refractory. Without myelin, the internode membrane resistance decreases, preventing local currents from reaching adjacent nodes. Without myelin, the internode membrane resistance increases, preventing local currents from reaching adjacent nodes. Without myelin, the internode membrane is depolarized more easily.

all of these events occur during propagation of the action potential

During propagation of the action potential, __________. the axon hillock depolarizes the initial segment local currents depolarize a spot adjacent to the active zone after threshold is reached, sodium channels open rapidly All of these events occur during propagation of the action potential.

sodium channels open

Which of these is the earliest step in the generation of an action potential? Sodium channels open. Potassium channels open. Potassium channels inactivate. Sodium channels inactivate.

all stimuli great enough to bring the membrane to threshold will produce identical action potentials

The all-or-none principle states that all stimuli will produce identical action potentials. only motor stimuli can activate action potentials. the greater the magnitude of the stimuli, the greater the magnitude of the action potential. only sensory stimuli can activate action potentials. all stimuli great enough to bring the membrane to threshold will produce identical action potentials.

depolarization necessary to cause an action potential

A threshold stimulus is the resting potential. hyperpolarization of an axon. electrical current that crosses the synaptic cleft. depolarization necessary to cause an action potential. peak of an action potential.

it is more positive than the resting potential

Which of the following is true about threshold for an action potential? The membrane begins to hyperpolarize. Voltage-gated potassium channels begin to open. Threshold for a typical neuron is approximately -30 mV. It is more positive than the resting potential. Voltage-gated potassium channels begin to close.

type C axons have all of these characteristics

Compared to type A axons, type C axons are __________. unmyelinated slower propagating smaller diameter Type C axons have all of these characteristics.

type A fiber

Which of these axons will conduct an action potential most quickly? Type C fiber Type B fiber Type A fiber All fibers have the same propagation speed.

whether or not the impulse begins in the CNS

Which of the following does not influence the time necessary for a nerve impulse to be transmitted? diameter of the axon length of the axon presence or absence of a myelin sheath whether or not the impulse begins in the CNS presence or absence of nodes

synaptic cleft

The small space between the sending neuron and the receiving neuron is the vesicle. synaptic terminal. synaptic cleft. neurotransmitter. calcium channel.

neurotransmitter

A molecule that carries information across a synaptic cleft is a receiving neuron. neurotransmitter. sending neuron. synaptic cleft. synapse.

they cause vesicles containing neurotransmitter molecules to fuse to the plasma membrane of the sending neuron

When calcium ions enter the synaptic terminal, they cause an action potential in the sending neuron. the inside of the receiving neuron becomes more positive. neurotransmitter molecules are quickly removed from the synaptic cleft. the inside of the receiving neuron becomes more negative. they cause vesicles containing neurotransmitter molecules to fuse to the plasma membrane of the sending neuron.

ion channels in the plasma membrane of the receiving neuron open

When neurotransmitter molecules bind to receptors in the plasma membrane of the receiving neuron, vesicles in the synaptic terminal fuse to the plasma membrane of the sending neuron. the receiving neuron becomes more negative inside. the receiving neuron becomes more positive inside. ion channels in the plasma membrane of the receiving neuron open. ion channels in the plasma membrane of the sending neuron open.

the receiving neuron is less likely to generate an action potential

If a signal from a sending neuron makes the receiving neuron more negative inside, the receiving neuron is more likely to generate an action potential. the sending neuron becomes more positive inside. the sending neuron becomes more negative inside. the receiving neuron immediately generates an action potential. the receiving neuron is less likely to generate an action potential.

presynaptic neuron

In a synapse, neurotransmitters are stored in vesicles located in the __________. presynaptic neuron postsynaptic neuron synaptic cleft

voltage-gated Ca2+ channels

An action potential releases neurotransmitter from a neuron by opening which of the following channels? voltage-gated Na+ channels chemically gated Ca2+ channels voltage-gated K+ channels voltage-gated Ca2+ channels

chemically gated; postsynaptic

Binding of a neurotransmitter to its receptors opens __________ channels on the __________ membrane. chemically gated; postsynaptic voltage-gated; postsynaptic chemically gated; presynaptic voltage-gated; presynaptic

either depolarize or hyperpolarize

Binding of the neurotransmitter to its receptor causes the membrane to __________. either depolarize or hyperpolarize hyperpolarize depolarize

acetylcholine

The mechanism by which the neurotransmitter is returned to a presynaptic neuron’s axon terminal is specific for each neurotransmitter. Which of the following neurotransmitters is broken down by an enzyme before being returned? acetylcholine glutamate

a neuron

Which of the following is an example of a presynaptic cell? a secretory cell a muscle cell a neuron a Schwann cell

synaptic cleft

What separates the presynaptic and postsynaptic cells at a chemical synapse? synaptic cleft chemically gated ion channels vesicles filled with neurotransmitter calcium channels

calcium influx into the synaptic terminal causes vesicle fusion with the plasma membrane and the release of neurotransmitter

Which of the following best describes the role of calcium in synaptic activity? Calcium diffuses across the synaptic cleft and binds to chemically gated channels on the postsynaptic cell. Calcium breaks down acetylcholine. Calcium influx into the axon causes an action potential to propagate into the synaptic terminal. Calcium influx into the synaptic terminal causes vesicle fusion with the plasma membrane and the release of neurotransmitter.

neurotransmitter binds to receptors on the postsynaptic cell membrane

What is the role of neurotransmitter at a chemical synapse? Neurotransmitter causes vesicles to fuse with the presynaptic membrane. Neurotransmitter binds to receptors on the postsynaptic cell membrane. Neurotransmitter causes an action potential in the presynaptic cell. Neurotransmitter causes calcium to enter the presynaptic cell.

exocytosis

What mechanism releases neurotransmitter from presynaptic neurons? exocytosis endocytosis phagocytosis pinocytosis

a chemically gated channel

What type of channel in the postsynaptic membrane binds neurotransmitter? a chemically gated channel a voltage-gated channel a leakage channel a mechanically gated channel

degrades acetylcholine in the synaptic cleft

What is the primary role of the enzyme acetylcholinesterase (AChE) at a cholinergic synapse? AChE binds to ACh receptors, causing them to open. AChE degrades acetylcholine in the synaptic cleft. AChE depolarizes the postsynaptic cell. AChE releases acetylcholine into the synaptic cleft.

b-a-d-c

Events that occur at a cholinergic synapse are listed here, but they are arranged in an incorrect order. Choose the correct order of these events below. (a) Calcium influx triggers exocytosis of ACh. (b) An action potential depolarizes the synaptic terminal. (c) ACh is removed by AChE. (d) ACh binds to receptors on the postsynaptic membrane. b→ a→ d→ c c→ d→ b→ a a→ b→ d→ c b→ a→ c→ d

all of these factors affect what happens at the postsynaptic neuron

The effect of a nerve impulse on a postsynaptic neuron depends on the __________. characteristics of the receptor on the postsynaptic neuron quantity of neurotransmitter released kind of neurotransmitter released by the presynaptic neuron All of these factors affect what happens at the postsynaptic neuron.

the postsynaptic neuron

A neuron that receives neurotransmitter from another neuron is called an oligodendrocyte. an interneuron. the postsynaptic neuron. the presynaptic neuron. the motor neuron.

chemical

Which type of synapse is most common in the nervous system? chemical electrical mechanical radiative processing

calcium

The ion that triggers the release of acetylcholine into the synaptic cleft is potassium. sodium. calcium. chloride. magnesium.

acetylcholine

Cholinergic synapses release the neurotransmitter adrenalin. serotonin. GABA. norepinephrine. acetylcholine.

nitric oxide

Which of these neurotransmitters does not bind to a plasma membrane receptor? GABA norepinephrine nitric oxide serotonin

norepinephrine

Which of these neurotransmitters is released at CNS adrenergic synapses? adrenaline serotonin GABA norepinephrine

norepinephrine

Which of these neurotransmitters do adrenergic synapses use? GABA nitric oxide norepinephrine acetylcholine

change the type of receptor found in the postsynaptic membrane

Which of the following is not a possible drug effect on synaptic function? interfere with neurotransmitter synthesis prevent neurotransmitter inactivation interfere with neurotransmitter reuptake block neurotransmitter binding to receptors change the type of receptor found in the postsynaptic membrane

all of the answers are correct

Which of the following is a recognized class of opioid neuromodulators? dynorphins endomorphins endorphins enkephalins All of the answers are correct.

EPSPs

The neurotransmitter glutamate opens channels that are permeable to sodium ions. What effect does glutamate produce on a postsynaptic neuron? both IPSPs and EPSPs EPSPs neither IPSPs nor EPSPs IPSPs

presynaptic inhibition

The neurotransmitter GABA blocks presynaptic voltage-gated calcium channels. Consequently, GABA produces __________. presynaptic inhibition EPSPs presynaptic facilitation IPSPs

spinal cord; spinal nerve

The __________ is part of the CNS and the __________ is part of the PNS. cranial nerve; spinal nerve spinal cord; spinal nerve spinal nerve; spinal cord brain; spinal cord

4

The spinal cord stops elongating at about __________ years of age. 15 4 2 10

31

The spinal cord consists of __________ segments, each associated with two pairs of nerve roots. 5 12 31 29 to 31

subarachnoid space

The cerebrospinal fluid (CSF) circulates within the __________. dura mater subarachnoid space subdural space pia mater

filum terminale

The ________ is a strand of fibrous tissue that provides longitudinal support as a component of the coccygeal ligament. ventral root cauda equina filum terminale conus medullaris dorsal root

both sensory and motor

Spinal nerves are involuntary. purely sensory. purely motor. both sensory and motor. interneuronal.

cell bodies of sensory neurons

The dorsal root ganglia mainly contain cell bodies of sensory neurons. cell bodies of motor neurons. axons of sensory neurons. synapses. axons of motor neurons.

dura mater

The tough, fibrous, outermost covering of the spinal cord is the dura mater. epidural block. pia mater. periosteum. arachnoid.

the dura mater and the arachnoid mater

The subdural space lies between the arachnoid mater and the pia mater. the dura mater and the arachnoid mater. the pia mater and the dura mater. the endosteum and the periosteum. the pia mater and the subarachnoid space.

pia mater

The layer of the meninges in direct contact with the spinal cord is the subarachnoid space. arachnoid. dura mater. pia mater. choroid plexus.

spinal nerve

A dorsal and ventral root of each spinal segment unite to form a spinal meninx. lumbar enlargement. spinal nerve. cervical enlargement. spinal ganglion.

all of the answers are correct

In meningitis, bacteria can be the cause. CSF flow can be disrupted. viruses can be the cause. inflammation of the meninges occurs. All of the answers are correct.

all of the answers are correct

Which of the following is true regarding an epidural block? It can provide mainly sensory anesthesia, depending on the anesthetic selected. It can provide sensory and motor anesthesia, depending on the anesthetic selected. It is commonly used as a method of pain control during labor and delivery. It affects only the spinal nerves in the immediate area of the injection. All of the answers are correct.

subarachnoid space

Cerebrospinal fluid flows within the pia mater. arachnoid mater. dura mater. subarachnoid space. filum terminale.

subarachnoid space

Samples of CSF for diagnostic purposes are normally obtained by placing the tip of a needle in the epidural space. arachnoid mater. dura mater. cerebral ventricles. subarachnoid space.

myelinated and unmyelinated axons

The white matter of the spinal cord is mainly Schwann cells. nodes of Ranvier. unmyelinated axons. neuroglia. myelinated and unmyelinated axons.

brachial plexus

Which nerve plexus innervates the pectoral girdle and upper limbs? brachial plexus lumbar plexus cervical plexus sacral plexus

phrenic nerve

Which of these cervical plexus nerves innervates the diaphragm? lesser occipital nerve phrenic nerve great auricular nerve transverse cervical nerve

obturator nerve

Which nerve does NOT belong to the sacral plexus? obturator nerve sciatic nerve fibular nerve tibial nerve

skin over the medial surface of the leg

What area of the body does the obturator nerve serve? skin over the medial surface of the leg muscles of the posterior thigh abdominal muscles skin over the posterior surface of the leg

endoneurium

The connective tissue layer that covers Schwann cells is the __________. endomysium epineurium perineurium endoneurium

dermatome

The region of the body surface monitored by a pair of spinal nerves is known as a(n) __________. input domain dermatome segment dermal band

phrenic

The brachial plexus gives rise to all of the following nerves, except the musculocutaneous. radial. median. ulnar. phrenic.

a reflex arc always includes all of these structures

A reflex arc always includes a(n) __________. sensory receptor afferent axon efferent axon A reflex arc always includes all of these structures.

all of these processes are part of every reflex arc

Which processes are always part of a reflex arc? receptor activation afferent action potential efferent action potential All of these processes are part of every reflex arc.

tendon

The reflex that limits muscle tension is the __________ reflex. tendon reciprocal flexor stretch

crossed extensor

The __________ reflex involves activating muscles contralateral to the receptor. flexor crossed extensor tendon stretch

moves a limb away

A distinction about the flexor reflex is that it __________. moves a limb away from a painful stimulus is an example of a monosynaptic reflex prevents a muscle from generating excessive tension prevents a muscle from overstretching

are arranged according to dermatomes

All of the following are true of polysynaptic reflexes, except that they have reverberating circuits that prolong the reflexive motor response. are arranged according to dermatomes. involve reciprocal innervation. are intersegmental in distribution. involve pools of interneurons.

a polysynaptic reflex

In which of the following would the delay between stimulus and response be greater? a polysynaptic reflex a monosynaptic reflex