exam 3 bio 220

A fascicle consists of A. a bundle of muscle fibers within a muscle. B. a row of sarcomeres aligned end to end. C. a tendon and the connective tissues of the muscle that merge with the tendon. D. a group of muscles that function as synergists to produce a given movement. E. a bundle of myofibrils within a muscle fiber.

A. a bundle of muscle fibers within a muscle.

The following are events associated with excitation-contraction coupling. Which one would happen THIRD in the sequence? A. activation of voltage-sensitive receptors in the T tubule B. exposure of binding sites on actin C. propagation of action potentials along the sarcolemma D. opening of calcium-release channels E. propagation of action potentials along the T tubule

A. activation of voltage-sensitive receptors in the T tubule

Opening of sodium gates typically leads to A. depolarization of the plasma membrane. B. repolarization of the plasma membrane. C. plasma membrane voltage returning to the resting membrane potential. D. hyperpolarization of the plasma membrane. E. drifting of plasma membrane voltage toward a more negative value.

A. depolarization of the plasma membrane.

The function of myoglobin in muscle fibers is to _____. A. hold a reserve supply of oxygen B. convert ADP to ATP C. release calcium ions into the sarcoplasm D. break down glycogen E. form crossbridges with actin

A. hold a reserve supply of oxygen

Which of the following structures is most responsible for producing the absolute refractory period? A. inactivation gates on voltage gated sodium channels B. activation gates on voltage gated sodium channels C. slow opening/closing voltage gated potassium channels D. sodium leak channels E. sodium potassium pumps

A. inactivation gates on voltage gated sodium channels

Release of ACh A. increases permeability of the motor end plate to sodium ions. B. decreases the release of Ca2+ from the sarcoplasmic reticulum. C. reduces the exposure of actin binding sites. D. lowers the threshold of the muscle fiber. E. decreases the positive charge on the sarcolemma.

A. increases permeability of the motor end plate to sodium ions.

Membrane potential is functionally important because A. it is a form of stored energy that can be used to do work B. it keeps ion levels within normal ranges C. cells wouldn't be able to carry out membrane transport without it D. it is the only way that cells can transmit information to other cells

A. it is a form of stored energy that can be used to do work

Conduction speed of a nerve fiber (axon) would be the fastest in a A. large unmyelinated fiber. B. large myelinated fiber. C. small unmyelinated fiber. D. small fiber with multiple collaterals. E. small myelinated fiber.

A. large myelinated fiber.

In what way does the interior surface of a cell membrane of a resting neuron differ from the external environment? The interior is: A. negatively charged and contains less sodium. B. positively charged and contains more sodium. C. negatively charged and contains no sodium. D. negatively charged and contains more sodium. E. positively charged and contains less sodium.

A. negatively charged and contains less sodium.

The sarcolemma of a resting muscle fiber is most permeable to calcium. A. potassium. B. sodium. C. lithium. D. magnesium.

A. potassium

Hyperpolarization occurs during an action potential because A. potassium channels close slowly during repolarization B. some potassium channels begin to open as the membrane reaches its resting state C. the inactivation gates of the sodium channels remain closed until the membrane potential reaches -90mV D. chloride channels open and allow chloride ions to enter the cell E. the sodium/potassium pump hasn't started working yet

A. potassium channels close slowly during repolarization

As you are lifting a box someone places extra weight on top of it. For your muscle to continue contracting and lifting the box, the muscle must A. recruit more muscle fibers. B. lower its threshold. D. reduce its wave summation. E. shift from isometric to isotonic contraction. E. shift from slow-twitch to fast-twitch mode.

A. recruit more muscle fibers.

The wall of a T tubule is a continuation of the ____. A. sarcolemma B. sarcoplasm C. sarcoplasmic reticulum D. endomysium E. epimysium

A. sarcolemma

The point at which an impulse from one nerve cell is communicated to another nerve cell is the: axon hillock A. synapse. B. effector. C. receptor. D. cell body.

A. synapse.

To stimulate muscle contraction, acetylcholine is released from the ___________ into the synaptic cleft. A. synaptic knob B. junctional folds C. sarcoplasmic reticulum D. sarcolemma E. terminal cisterna

A. synaptic knob

The minimum stimulus needed to cause muscle contraction is called A. the threshold. B. the latent period. C. twitch. D. recruitment. E. innervation.

A. the threshold.

A single high-voltage stimulation of a muscle will result in A. wave summation. B. recruitment. C. treppe. D. incomplete tetanus. E. complete tetanus.

B. recruitment

The striations of a skeletal muscle fiber arise from the _____. A. organization of the sarcoplasmic reticulum around the myofibirls B. regular arrangement of thick and thin myofilaments within the myofibrils C. differences in the thickness of the sarcolemma along the length of the fiber D. alignment of the terminal cisternae and T tubules

B. regular arrangement of thick and thin myofilaments within the myofibrils

Which of the following would not occur on a particular neuron if a drug was administered that blocked the opening of its voltage-gated calcium channels? A. an action potential at the initial segment B. release of neurotransmitter at the synaptic knobs C. propagation of action potentials along the axon D. the production of a local potential on the cell body E. anterograde transport of neurotransmitters

B. release of neurotransmitter at the synaptic knobs

The functional contractile units of skeletal muscles are _____. A. microtubules B. sarcomeres C. mitochondria D. T tubules E. myomeres

B. sarcomeres

Most metabolic and regulatory functions in a neuron happen at the A. axon. B. soma. C. dendrites. D. axon hillock. E. Schwann cell.

B. soma

A neuron can receive thousands of EPSPs from different neurons, and responds by triggering or not triggering an action potential. This addition and response to the net effect of postsynaptic potentials is called A. neuronal coding. B. spatial summation. C. recruitment. D. temporal summation. E. neural summation.

B. spatial summation.

The absence or inhibition of AChE at a synapse would lead to which of the following? A. flaccid paralysis B. tetanus C. atrophy D. numbness E.muscle wasting

B. tetanus

Which of the following are composed of myosin? A. thin myofilaments B. thick myofilaments C. all myofilaments D. M line E. Z discs

B. thick myofilaments

Which of the following statements best describes the membrane situation in the resting state in the neuron? A. Only the voltage-gated Na+ channels are opened. B. Only the voltage-gated K+ channels are opened. C. All the voltage-gated Na+ and K+ channels are closed. D. Only the voltage-gated Na+ channels are closed. E. Only the voltage-gated K+ channels are closed.

C. All the voltage-gated Na+ and K+ channels are closed.

Which of the following would NOT be found in the zone of overlap of a sarcomere? A. Myosin heads B. Thick filament C. I Band D. Actin E.Thin filament

C. I Band

When myosin heads bind to actin and pivot towards the __________, the sarcomere shortens. A. sarcolemma B. thick filament C. M line D. Z disc E. thin filament

C. M lineA. a bundle of muscle fibers within a muscle.

During the depolarization phase of an action potential in a neuron A. K+ ions move from inside to outside the membrane thru gated channels. B. K+ and Na+ ions trade places across the membrane. C. Na+ ions move from outside to inside the membrane thru gated channels. D. the Na/K ATPase pumps Na+ into the cell. E. both K+ and Na+ move from outside to inside the membrane thru gated channels.

C. Na+ ions move from outside to inside the membrane thru gated channels.

_____________ allows multiple subthreshold graded potentials to lead to the production of an action potential. A. Amplification B. Activation of second messengers C. Summation D. Recruitment E. Consolidation

C. Summation

Which of the following allows recoil of the muscle fiber when contraction ends? A. Tropomyosin B. Actin C. Titin D. Myosin E. Troponin

C. Titin (elastic filaments)

The sliding filament model of contraction involves _____. A. the shortening of thick filaments so that thin filaments slide past B. actin and myosin shortening but not sliding past each other C. actin and myosin sliding past each other but not shortening D. the Z discs sliding over the myofilaments

C. actin and myosin sliding past each other but not shortening

The following are events associated with excitation-contraction coupling. Which one would happen THIRD in the sequence? A. propagation of action potentials along the sarcolemma B. exposure of binding sites on actin C. activation of voltage-sensitive receptors in the T tubule D. propagation of action potentials along the T tubule E. opening of calcium-release channels

C. activation of voltage-sensitive receptors in the T tubule

An excitatory local potential A. neutralizes the plasma membrane. B. repolarizes the plasma membrane. C. depolarizes the plasma membrane. D. drifts the membrane potential towards the resting membrane potential E. hyperpolarizes the plasma membrane.

C. depolarizes the plasma membrane.

Local potentials are ___, whereas action potential are ___. A. self-propagating; local B. irreversible; reversible C. graded; all or none D. produced by voltage-gated channels; produced by E. mechanically-gated channels F. nondecremental; decremental

C. graded; all or none

Which of the following will cause the plasma membrane to hyperpolarize when at its RMP? A. inflow of potassium B. inflow of sodium C. inflow of chloride D. inflow of calcium

C. inflow of chloride

Immediately following the arrival of the stimulus at a skeletal muscle cell there is a short period called the ________ period during which the events of excitation-contraction coupling occur. A. contraction B. relaxation C. latent D. refractory

C. latent

All of the following are functions of skeletal muscle, except A. supporting the organs of the abdominal cavity. B. opening an closing the eyelids. C. maintaining appropriate levels of blood calcium. D. stabilizing joints to maintain an erect posture. E. generating heat to maintain an adequate body temperature.

C. maintaining appropriate levels of blood calcium.

Each skeletal muscle fiber is controlled by a neuron at a single ____________________. A. sarcomere B. synaptic cleft C. neuromuscular junction D. synaptic knob E.Transverse tubule

C. neuromuscular junction

A subthreshold excitatory postsynaptic potential that reaches the axon hillock will cause A. a weak action potential to be produced B. a single action potential to be produced C. no action potential to be produced D. continuous propagation to occur on the axon E. saltatory propagation to occur on the axon

C. no action potential to be produced

During hyperpolarization A. potassium ions are entering the cell. B. sodium ions are entering the cells. C. potassium ions are leaving the cell. D. sodium ions are leaving the cell. E. both sodium and potassium ions are leaving the cell.

C. potassium ions are leaving the cell.

Where are neurotransmitters synthesized? A. dendrites B. the synaptic cleft C. the cell body D. synaptic knobs E. axon hillock

C. the cell body

In a relaxed muscle fiber, the myosin binding sites of actin are blocked by __________. A. dystrophin B. G actin. C. tropomyosin D. troponin E. ATP

C. tropomyosin

Calcium ions bind to ___________ on the thin filament, which leads to the exposure of myosin binding sites on actin. A. tropomyosin B. dystrophin C. troponin D. titin E. actin

C. troponin

Differences in signal strength are produced during action potential propagation by A. varying the peak that each action potential reaches during depolarization. B. varying the threshold value. C. varying the rate at which action potentials are propagated. D. varying the length of time it requires to produce an action potential.

C. varying the rate at which action potentials are propagated.

When the voltage of a plasma membrane shifts from +30mV towards 0 mV, we say the cell is A. reaching the threshold. B. exiting the threshold. C. hyperpolarizing. D. repolarizing. E. depolarizing.

D. repolarizing.

In skeletal muscle, alternating light and dark bands are termed A. treppe. B. myofibrils. C. strabismus. D. striations. E. myoblasts.

D. striations.

When a neuron is at rest A. there are no open channels in the membrane B. sodium leaks out of the cell and potassium leaks into the cell C. the inactivation gates on voltage-gated sodium channels are closed D. the sodium-potassium pump moves sodium ions out of the cell and potassium ions into the cell E. some sodium enters the cell, but no potassium leaves the cell

D. the sodium-potassium pump moves sodium ions out of the cell and potassium ions into the cell

In the sliding filament model of muscle contraction, the myofilaments move toward each other, resulting in an overlapping of _________. A. myofibrils B. Z discs C. sarcomeres D. thick and thin myofilaments E. troponin and tropomyosin

D. thick and thin myofilaments

The optimal length of a resting sarcomere would be A. There is no known optimal resting length for a sarcomere. B. short as possible with overlap between the entire thick and thin filaments. C. stretched to the point of no overlap between the thick and thin filaments. D. stretched to the point where there is a slight amount of overlap between the thick and thin filaments. E. intermediate with overlap between the section of the thick filament with myosin heads and the thin filaments.

E. intermediate with overlap between the section of the thick filament with myosin heads and the thin filaments.

A neuron that has as its primary function the job of connecting other neurons is called a(n): A. astrocyte. B. commissural neuron. C. efferent neuron. D. afferent neuron. E. interneuron.

E. interneuron

The term for shortening of a muscle while maintaining constant tension is A. treppe. B. tetanus. C. isokinetic contraction. D. isometric contraction. E. isotonic contraction.

E. isotonic contraction.

Most of the myelin sheath is composed of A. carbohydrates. B. glycoproteins. C. proteins. D. polysaccharides. E. lipids.

E. lipids.

All of the following are functions of skeletal muscle, except A. generating heat to maintain an adequate body temperature. B. supporting the organs of the abdominal cavity. C. opening an closing the eyelids. D. stabilizing joints to maintain an erect posture. E. maintaining appropriate levels of blood calcium.

E. maintaining appropriate levels of blood calcium.

Stronger skeletal muscle contractions may be brought about by ____. A. increasing resting sarcomere length to allow only slight overlap between thick and thin filaments. B. stimulating the smallest muscle fibers D. decreasing the frequency of stimulation so the fibers can recover between cycles and produce more ATP. E. recruiting more motor units

E. recruiting more motor units

Most of the calcium ions that are used during muscle contraction in skeletal muscles come from A. the terminal cisternae B. myoglobin C. a motor neuron D. the extracellular fluid E. the T tubules

E. the terminal cisternae

What happens to the I band when a muscle fiber relaxes? A. It increases in width. B. It remains unchanged. C. It decreases in width.

A. It increases in width.

In which region of the neuron would you find ligand-gated channels? A. Receiving zone B. Trigger zone C. Conducting zone D. Output zone

A. Receiving zone

Which of the following moves Ca++ back into the tubules of A. the SR after a contraction? B. The ATP-dependent calcium pump C. The ATP-dependent myosin pump D. The ATP-dependent H+ pump E. Simple diffusion F. The ATP-dependent Na+/K+ pump

A. The ATP-dependent calcium pump

Most neurons have multiple dendrites. A. True B. False

A. True

Unipolar neurons have only a single process leading away from the soma. A. True B. False

A. True

Which of the following can be accomplished by both temporal and spatial summation? A.Altered frequency of action potentials produced B. Altered speed of action potential propagation C. Altered type of signal from excitatory to inhibitory or vice versa D. Altered threshold potential E. All of the above can be accomplished by both types of summation

A. Altered frequency of action potentials produced

A reason that muscle twitches become progressively stronger in treppe is A. Ca2+ accumulates in the sarcoplasm faster than the sarcoplasmic reticulum can reabsorb it. B. ATP is regenerated faster than it is consumed. C. myosin heads show faster and faster power strokes. D. more and more ACh is released with each stimulus. E. as the muscle warms up, aerobic respiration is accelerated.

A. Ca2+ accumulates in the sarcoplasm faster than the sarcoplasmic reticulum can reabsorb it.

In a skeletal muscle fiber, which of the following best describes the composition of the triad, the structures responsible for linking electrical stimulation of the muscle fiber with the contraction cycle? A. A transverse tubule flanked by terminal cisternae on each side B. The sarcolemma, T Tubule, and sarcoplasmic reticulum C. An A band, I Band, and H Zone D. ATP, myoglobin, and glycogen E. Actin, troponin, and tropomyosin

A. A transverse tubule flanked by terminal cisternae on each side

Rigor mortis occurs because A. ATP is unavailable to break cross bridges. B. sodium ions leak out of the muscle fiber. C. neurons can no longer stimulate the muscle to contract. D. proteins are beginning to break down, thus preventing the flow of calcium ions out of the sarcoplasmic reticulum through leak channels. E. acetylcholinesterase is no longer able to remove acetylcholine from the neuromuscular junction.

A. ATP is unavailable to break cross bridges.

Which of the following is true concerning isotonic eccentric contraction? A. The muscle lengthens and tension declines. B. The muscle lengthens but tension remains constant. C. The muscle tenses but length remains unchanged. D. The muscle shortens but tension remains constant. E. The muscle tenses and shortens.

B. The muscle lengthens but tension remains constant.

Which of these is an example of an EPSP in a typical neuron? A. a voltage change from +35 mV to 0 mV B. a voltage change from -70 mV to -69.5 mV C. a voltage change from -69.5 mV to -70 mV D. a voltage change from 0 mV to +0.35 mV E. a voltage change from -70 mV to -70.5 mV

B. a voltage change from -70 mV to -69.5 mV

The myelin sheath is formed by A. fibers. B. cells. C. macromolecules. D. polymers. E. organelles.

B. cells

Opening of __ gates produces an ___. A. sodium; IPSP B. calcium; IPSP C. chloride; IPSP D. potassium; EPSP E. sodium and chloride; EPSP

B. chloride; IPSP

Local potentials are _____, meaning they weaken with distance from the point of stimulation. A. decremental B. reversible C. graded D. inhibitory E. excitatory

B. decremental

The opening of a ligand-gated potassium channel will lead to action potential production along a neuron A. release of neurotransmitter by a neuron B. hyperpolarization of a neuron and a reduced likelihood of action potential production C. depolarization of a neuron and an increased likelihood of action potential production D. the production and propagation of weaker action potentials

B. hyperpolarization of a neuron and a reduced likelihood of action potential production

The training regimen of a competitive weight lifter is designed partly to A. convert certain parallel muscles into stronger pennate muscles. B. increase the average number of myofibrils per muscle fiber. C. convert white muscle tissue to red muscle. D. increase the size of his motor units. E. lower the threshold for muscle excitation.

B. increase the average number of myofibrils per muscle fiber.

During the relative refractory period A. no stimulus of any strength will trigger a new action potential. B. it is possible to trigger a new action potential, but only with an unusually strong stimulus. C. the neuron is in a slightly depolarized state. D. the signal grows weaker with distance. E. the neuron is at RMP.

B. it is possible to trigger a new action potential, but only with an unusually strong stimulus.

What is the significance of the initial segment of the axon? A. it is the point of contact between a sending and receiving neuron. B. it is the first place on the neuron where action potentials are produced. C. it contains both ligand-gated and voltage-gated channels D. it is the first neuron in a neural pathway that transmits information to the brain.

B. it is the first place on the neuron where action potentials are produced.

Muscles that control very fine movements, such as the muscles that control movement of the eyeballs, have A. slow twitches B. many, small motor units C. a few, large motor units D. a higher density of myosin heads in the sarcomeres E. Faster acting calcium pumps

B. many, small motor unitsC.

The overall purpose of cellular signaling is to ____________________. A. change membrane potential B. modify the activity of the receiving cell C. restore homeostasis D. stimulate protein synthesis E. turn off a process

B. modify the activity of the receiving cell

If a muscle were stretched to the point where thick and thin filaments no longer overlapped, theoretically, _____. A. ATP consumption would increase since the sarcomere is "trying" to contract B. no active muscle tension could be generated C. maximum force production would result since the muscle has a maximum range of travel D. cross bridge attachment would be optimum because of all the free binding sites on actin

B. no active muscle tension could be generated

A skeletal muscle generates the greatest tension when it is A. greatly stretched before being stimulated. B. partially stretched before being stimulated. C. fully relaxed before being stimulated. D. well-rested and low in creatine phosphate. E. in a state of treppe.

B. partially stretched before being stimulated.

Which of the following statements concerning inhibitory synapses (IPSPs) is correct? A. The postsynaptic membrane becomes less permeable to sodium. B. Channels allow both sodium and potassium ions to diffuse simultaneously through the membrane. C. The permeability of the postsynaptic membrane to sodium, potassium, and chloride is not changed. D. Postsynaptic membrane becomes more permeable to potassium or chloride. E. The postsynaptic membrane becomes less permeable to potassium.

D. Postsynaptic membrane becomes more permeable to potassium or chloride.

___ has the greatest influence on the resting membrane potential. Sodium A. Chloride B. Calcium C. Phosphate D. Potassium

D. Potassium

Which of the follow is not a feature of graded potentials? A. The can be depolarizing or hyperpolarizing. B. They are established via ligand-gated channels. C. They lose strength as they spread. D. The amount of depolarization or hyperpolarization depends on the intensity of the stimulus. E. They exhibit refractory periods in which the membrane cannot be stimulated.

D. They exhibit refractory periods in which the membrane cannot be stimulated.

The part of the neuron that normally receives stimuli from other neurons is called: A. neurilemma. B. an axon hillock. C. a synaptic knob. D. a dendrite. E. an axon.

D. a dendrite.

The period after an initial stimulus when a neuron is not able to respond to another stimulus is the: A. resting period. B. hyperpolarization phase. C. relative refractory period. D. absolute refractory period. E. total refractory period.

D. absolute refractory period.

The following are events associated with excitation-contraction coupling. Which one would happen THIRD in the sequence? A. opening of calcium-release channels B. propagation of action potentials along the T tubule C. propagation of action potentials along the sarcolemma D. activation of voltage-sensitive receptors in the T tubule E. exposure of binding sites on actin

D. activation of voltage-sensitive receptors in the T tubule

Action potentials occur A. along the sarcolemma and T tubules of a muscle fiber. B. at the motor end plate of the sarcolemma. C. along the terminal cisternae of the sarcoplasmic reticulum. D. along the myofibrils of a muscle fiber. E. at all of the above locations.

D. along the sarcolemma and T tubules of a muscle fiber.

Loss of muscle mass from lack of activity is termed A. myopathy. B. dystrophy. C. apathy. D. atrophy. E. treppe.

D. atrophy.

Which of the following is NOT a phase of the contraction cycle? A. power stroke B. cross bridge formation C. detachment of myosin from actin D. blocking of the actin binding sites E. recovery stroke

D. blocking of the actin binding sites

Which fibers are primarily responsible for producing lactic acid? A. intermediate fibers B.fast-twitch oxidative fibers C. all fiber types D. fast-twitch glycolytic fibers E. slow-twitch oxidative fibers

D. fast-twitch glycolytic fibers

The substance released at axonal endings to propagate a nervous impulse in another cell is called a A. neurohormone. B. neurofacilitator. C. neuromodulator. D. neurotransmitter. E. neuroregulator.

D. neurotransmitter

Immediately after an action potential has peaked, which gates are open? A. calcium B. chloride C. sodium D. potassium

D. potassium

Nodes of Ranvier are gaps between adjacent A. neurons. B. synaptic knobs and dendrites. C. dendrites. D. regions of myelin sheath.

D. regions of myelin sheath.

Which of the following is NOT directly dependent upon ATP? A. re-energizing myosin heads B. return of calcium ions to the sarcoplasmic reticulum. C. cross-bridge detachment D. release of calcium ions from the terminal cisternae

D. release of calcium ions from the terminal cisternae

Rigor mortis occurs because A. neurons can no longer stimulate the muscle to contract. B. acetylcholinesterase is no longer able to remove acetylcholine from the neuromuscular junction. C. proteins are beginning to break down, thus preventing the flow of calcium ions out of the sarcoplasmic reticulum through leak channels. D. sodium ions leak out of the muscle fiber. E. ATP is unavailable to break cross bridges. 1 points

E. ATP is unavailable to break cross bridges.

Changes to membrane potential can be caused by A. adding more ion leak channels to the membrane of a cell B. opening or closing gated ion channels C. changing the concentration of ions inside or outside the cell D. increasing or decreasing sodium potassium pump activity E. Any of the above will lead to changes in membrane potential

E. Any of the above will lead to changes in membrane potential

____ are the primary site for receiving signals from other neurons. A. Synaptic knobs B. Axons C. Axon collaterals D. Somas E. Dendrites

E. Dendrites

Which of the following events is not involved in the transfer of information across a chemical synapse? A. Neurotransmitters bind to the postsynaptic receptors B. Calcium channels open in the presynaptic region C. Ion channels open in the postsynaptic membrane D. A neurotransmitter is released by exocytosis E. Ions flow through gap junctions

E. Ions flow through gap junctions

The strength of local potentials will vary depending on A. how much neurotransmitter is released into the synaptic cleft B. how long the neurotransmitter remains bound to receptors in the postsynaptic membrane C. how many ligand-gated channels are opened D. how long the ligand-gated channels remain open E. all of the above factors

E. all of the above factors

If subsequent stimuli arrive at a muscle fiber before it has the chance to completely relax between them, the most likely result will be A. treppe. B. fatigue. C. recruitment. D. complete tetanus. E. incomplete tetanus.

E. incomplete tetanus.