Anatomy + Physiology I Exam 3

a sarcomere is the distance between two ___________.

Z discs

most skeletal muscles contain ________.

a mixture of fiber types

which of the following is true of axons?

a neuron can have only one axon, but the axon may have occasional branches along its length

muscle tone is ________.

a state of sustained partial contraction

which type of lever is exemplified by the flexing of the forearm by the biceps brachii muscle?

a third-class lever

what type of event is required for an action potential to be generated?

a threshold level depolarization

the neuron cannot respond to a second stimulus, no matter how strong

absolute refractory period

the period after an initial stimulus when a neuron is not sensitive to another stimulus is the _______.

absolute refractory period

a neurotransmitter released at motor end plates by the axon terminals.

acetylcholine

breaks down ACh into its building blocks, rendering it inactive

acetylcholinesterase

after nervous stimulation stops, what prevents ACh in the synaptic cleft from continuing to stimulate contraction?

acetylcholinesterase breaks apart the ACh

which protein is indicated by the letter A?

actin

also called a nerve impulse transmitted by axons

action potential

which of the following mechanisms is most significant in returning the ion concentrations to the resting state (from point D to point E)?

active transport by the Na+-K+ pump

which of the following muscles is named for its action?

adductor longus

marathons

aerobic pathway

muscle that is primarily responsible for bringing about a particular movement

agonist

which of the following describes a bipennate pattern of fascicles?

an arrangement in which the fascicles insert into the tendon from opposite sides

25 meter swim

anaerobic pathway

which of the following describes the nervous system integrative function?

analyzes sensory information, stores information, makes decisions

muscle that opposes and reverses the action of another muscle

antagonist

which functional group has the major responsibility for countering a specific movement?

antagonists

the concentration of ions in the chemical environment surrounding the neurons must be tightly regulated for neurons to function properly. which of the following cells is most responsible for this?

astrocytes

which statement accurately describes the event indicated by B?

binding of acetylcholine to a receptor triggers the opening of an ion channel

the term central nervous system refers to the ________.

brain and spinal cord

activates synaptic vesicles in axon terminals to fuse with plasma membrane of axon terminal

calcium ions

the final chemical messenger and "trigger" for muscle contraction. it binds to troponin.

calcium ions

in an isotonic contraction, the muscle _________.

changes in length and moves the "load"

the ability of muscle to shorten forcibly when adequately stimulated is known as ________, and sets muscle apart from other tissue types.

contractibility

which of the following are correctly matched?

convergent arrangement of fascicles; fan-shaped muscle

curare is a poisonous plant extract. curare molecules have a chemical structure like the neurotransmitter ACh. curare can bind to the ACh receptor site on the chemically gated ion channels in the motor end plate. even though curare will bind to the receptor site it will not open the channel and no ions will pass through. what do you think the symptoms of curare poisoning would look like?

curare will only affect muscles with ACh receptors, paralyzing them

which of the following is a factor that determines the rate of impulse propagation, or conduction velocity, along an axon?

degree of myelination of the axon

what is the structure at A?

dendrite

the interior of the cell becomes less negative due to an influx of sodium ions

depolarization

what event directly triggers the release of neurotransmitter shown in A?

diffusion of Ca2+ into the axon terminal

weight lifting

direct phosphorylation

the energy reserves for which of the ATP regenerating pathways will be depleted first during an extended period of light to moderate exercise?

direct phosphorylation of ADP by creatine phosphate

the sliding filament model of contraction states that ___________.

during contraction, the thin myofilaments slide past the thick myofilaments so that the actin and myosin myofilaments overlap to a greater degree

which of the following surrounds an individual muscle cell?

endomysium

what cell organelle plays a role in the process of regulating intracellular calcium ions for muscle contraction?

endoplasmic reticulum

by which method does the structure at B release neurotransmitter?

exocytosis

what cellular event is indicated by A?

exocytosis

a motor neuron and all the muscle cells that it stimulates are referred to as a motor end plate.

false

although all skeletal muscles have different shapes, the fascicle arrangement of each muscle is exactly the same

false

both first- and second-class levers operate at a mechanical disadvantage

false

during isometric contraction, the energy used appears as movement.

false

muscle contraction will always promote movement of body parts regardless of how they are attached.

false

once a motor neuron has fired, all the muscle fibers in a muscle contract.

false

strong stimuli cause the amplitude of action potentials generated to increase

false

the all-or-none phenomenon as applied to nerve conduction states that the whole nerve cell must be stimulated for conduction to take place

false

ATP is required to cause the power stroke in the myosin head.

false; ATP is required to re-cock the myosin head so that it can generate a second power stroke

addition of more myoglobin to a muscle fiber would have the largest effect on ________.

fast oxidative and slow oxidative fibers

muscle that stabilizes the origin of another muscle

fixator

which description of a muscle action is NOT correct?

fixators hold joints in place, so movement does not occur

what does the central nervous system use to determine the strength of a stimulus?

frequency of action potentials

which of the following is NOT a function of dendrites?

generate nerve impulses and transmit them away from the cell body

when a sensory neuron is excited by some form of energy, the resulting graded potential is called a ___________.

generator potential

which of the following muscles is named for its size?

gluteus maximus

loss of function in the enzyme acetylcholine esterase would result in which of the following?

inability to destroy and remove acetylcholine from the synaptic cleft

which of the following is NOT a function of the autonomic nervous system?

innervation of skeletal muscle

a neuron that has its primary function the job of connecting other neurons is called a(n) ___________.

interneuron

during vigorous exercise, there may be insufficient oxygen available to completely break down pyruvic acid for energy. as a result, the pyruvic acid is converted to __________.

lactic acid

immediately following the arrival of the stimulus at a skeletal muscle cell there is a short period called the ________ period during which the neurotransmitter is released by exocytosis, diffuses across the synaptic cleft, and binds to its receptors.

latent

the sternocleidomastoid muscle inserts on the __________.

mastoid process of the temporal bone

meningitis can be caused by infection of the central nervous system by bacteria. which cells would be most responsible for removing the infection

microglia

which of the following types of glial cells monitors the health of neurons, and can transform into a special type of macrophage to protect endangered neurons?

microglia

what part of the sarcolemma contains acetylcholine receptors?

motor end plate

which of the choices below describes the ANS?

motor fibers that conduct nerve impulses from the CNS to smooth muscle, cardiac muscle, and glands

each neuron in this figure innervates a group of muscle fibers. what is the term for a group of muscle fibers and the single neuron that innervates them?

motor unit

during development embryonic cells will fuse to form muscle fibers. this will result in ________.

multinucleated muscle fibers that can extend as long as 30 centimeters

what structural classification describes this neuron?

multipolar

which of the following pairings does NOT fit?

multipolar neurons: peripheral nervous system sensory neurons; unipolar neurons function as sensory neurons in the peripheral nervous system

which term best identifies a muscle cell?

muscle fiber

the thicker filaments are the __________ filaments.

myosin

which protein is indicated by the letter E?

myosin

the interior surface of a neuron's plasma membrane at resting membrane potential will have a ________.

negative charge and contains less sodium than outside of the cell

where the axon of a motor neuron connects with the muscle fibers

neuromuscular junction

if both motor neurons shown in this figure were to develop action potentials and stimulate muscle fibers, would all the muscle cells shown here contract?

no, because neurons in this figure do not innervate every muscle cell shown

schwann cells are functionally similar to _________.

oligodendrocytes

troponin, a major protein in thin filaments, is a globular protein with three polypeptide subunits. which of the following is NOT a function of the troponin?

one subunit binds to potassium ions

nerve impulses are sent to slow the heart's rate of contraction. the nerve fibers sending these signals will most likely belong to which division of the nervous system?

parasympathetic division

which of the following movements demonstrates a first-class lever?

raising your head up off your chest

which of the following are correctly matched?

rectus; straight

when a muscle is unable to respond to stimuli temporarily, it is in which of the following periods?

refractory period

an exceptionally strong stimulus can trigger a response

relative refractory period

which of the following is NOT one of the basic functions of the nervous system?

release hormones into the bloodstream that travel around the systemic blood circulation to communicate with cells in multiple location within the body

which of the following events triggers the subsequent steps of excitation-contraction coupling?

release of acetylcholine from axon terminals at the neuromuscular junction

the specific period during which potassium ions diffuse out of the neuron due to a change in membrane permeability

repolarization

the _________ shorten(s) during muscle contraction

sarcomere

which of the following peripheral nervous system (PNS) neuroglia form the myelin sheaths around larger nerve fibers in the PNS?

schwann cells

which of the following is NOT a normal function of muscle tissue?

secreting hormones

cranial nerve II, the optic nerve, sends nerve impulses to the brain carrying information about the things we see. these nerve fibers most likely belong to which division of the nervous system?

sensory (afferent) division

nerve impulses leading to the brain carry information about cool temperatures on the skin. the nerve fibers sending these signals will most likely belong to which division of the nervous system?

sensory (afferent) division

which type of muscle tissue is the only one that can correspond to voluntary nervous stimulation in most people?

skeletal

of the following muscle types, which has the longest muscle cells and has obvious stripes called striations?

skeletal muscle

which of the following statements is FALSE?

skeletal muscle cells use creatine phosphate instead of ATP to do work; muscle cells, just like other cells, use ATP to do work. creatine phosphate is used by muscle cells to directly phosphorylate (donate a high-energy phosphate group to) ADP to resynthesize ATP

which of the following is true?

skeletal muscle fibers contain sarcomeres; smooth muscle fibers do not

of the following items listed below, which is the best description for why skeletal muscle stores glycogen?

skeletal muscle is a heavy consumer of energy

which of the following are correctly paired?

skeletal muscle; voluntary control

which muscle fiber type is best suited for endurance activities, such as long-distance jogging?

slow oxidative fibers

the smallest contractile unit within skeletal muscle would correspond to the distance between which two points in the figure?

1 and 7

identify the sequence of events that occurs at a synapse

1. an action potential arrives at the synaptic terminal 2. calcium channels open, and calcium ions enter the synaptic terminal 3. vesicles containing neurotransmitter fuse with the plasma membrane of the sending neuron 4. neurotransmitter molecules diffuse across the synaptic cleft 5. the neurotransmitter molecules bind to receptors in the plasma membrane of the receiving neuron, causing ion channels there to open

the region between which two points corresponds to the entire A (dark) band?

2 and 6

both actin and myosin are found in the __________.

A band

the myosin filaments are located in the _________.

A band

at which point of the illustrated action potential would voltage-gated Na+ channels be mostly open but voltage-gated K+ channels be mostly closed?

B

in which phase of the muscle twitch shown in the figure would the maximum amount of ATP be consumed by myosin head groups?

B

which of the following corresponds to a single fascicle?

B

which of the structures is surrounded by the connective tissue sheath known as the perimysium?

B

in which phase in the figure would the net movement of Ca2+ INTO the sarcoplasmic reticulum (SR) be greatest?

C

which structure in the figure corresponds to a single skeletal muscle cell?

C

which of the following is most directly required to initiate the coupling of myosin to actin?

Ca++

what ion is entering the axon terminal at A, and what effect does it have?

Ca+2, which then causes release of neurotransmitter from the axon terminal

the _________ contains actin filaments, but not myosin filaments.

I band

which of the following correctly states the direction followed by the specified ions when their voltage-gated channels open

Na+ ions move into the axon; K+ ions move out.

the connective tissue that covers structure A is continuous with which of the following?

tendon

when a sarcomere contracts and thin filaments move over thick filaments you would expect to see _________.

the I bands to appear smaller

the force of a muscle contraction is NOT affected by _________.

the amount of ATP stored in the muscle cells

what is the major factor controlling how levers work?

the difference int he positioning of the effort, load, and fulcrum

which criterion is used to functionally classify neurons?

the direction in which the nerve impulses travels relative to the central nervous system

one brief stimulus of a skeletal muscle may result in a single isolated contractile event, which is called a twitch. in a living organism, one twitch can generate max tension in a whole muscle. are these statements true or false?

the first statement is true; the second statement is false.

a toxin released by certain bacteria can block the release of neurotransmitters into a neuromuscular synapse. what would result from such a block?

the loss of ability to contract the muscle

which of the following statements most accurately described the effect caused by binding of the neurotransmitter (green dots) to the structure labeled C?

the membrane potential of the postsynaptic membrane changes

when the term biceps, triceps, or quadriceps forms part of a muscle's name, what does it tell you about the muscle?

the muscle has two, three, or four origins, respectively

what result would be expected if an additional stimulus, equal in intensity to the first, were to be applied to the muscle at the 60 millisecond (ms) time point?

the muscle would increase in tension to a level greater than that measured at the beginning of phase C

saltatory conduction is made possible by __________.

the myelin sheath

which of the following is NOT used as a criterion for naming muscles?

the nervous system's control of the muscle

you discover that a new chemical compound interacts with K+ voltage-dependent channels. what would be the effect on a neuron if the chemical came into contact with the axonal membrane?

the neuron would be unable to repolarize

the contractile, or functional, unit of a muscle fiber is __________.

the sarcomere

the mechanism of contraction in smooth muscle is different from skeletal muscle in that ________.

the site of calcium binding site differs

as you start working out, you notice that your heart rate and breathing rate start to increase. which division of your nervous system is generating this response? be as specific as possible.

the sympathetic division of the autonomic nervous system

a contraction in which the muscle does not shorten but its tension increases is called isometric contraction.

true

a postsynaptic potential is a graded potential that is the result of a neurotransmitter released into the synapse between two neurons

true

a wheelbarrow is a good example of a second-class lever

true

during depolarization, the inside of the neuron's membrane becomes less negative.

true

excitability is the ability of a cell to receive and respond to stimulus by changing its membrane potential.

true

if the neuron membrane becomes more permeable to Na+, Na+ will transport across the membrane, causing the cell to depolarize.

true

muscles are only able to pull, they never push

true

one of the functions of skeletal muscle contraction is production of heat.

true

regardless of type, all levers follow the same basic principle: effort farther than load from fulcrum= mechanical advantage; effort nearer than load to fulcrum= mechanical disadvantage

true

the action potential is caused by permeability changes in the plasma membrane

true

the alternating contraction and relaxation of the longitudinal and circular layers mixing substances in the lumen and squeezing them through an organ's internal pathway is characteristic of smooth muscle.

true

the arrangement of a muscle's fascicles determines its range of motion and power.

true

the effect of a neurotransmitter on the muscle cell membrane is to modify its ion permeability properties temporarily

true

the peripheral nervous system is divided into afferent and efferent divisions

true

which of these materials or structures would be found in greatest amounts or numbers at E?

vesicles containing neurotransmitter

immediately after an action potential has peaked, which of the following channels will open?

voltage-gated potassium channels

myasthenia gravis is a disease that is believed to be caused by autoimmune disorder, resulting in the loss of ACh receptors at the motor end plate of muscle fibers. which of the following is likely to be a symptom of myasthenia gravis?

weakness of muscle

it diffuses across the cell membrane resulting in depolarization

sodium ions

nerve impulses leading to the skeletal muscle carry information to direct movement. the nerve fibers sending these signals will most likely belong to which division of the nervous system?

somatic nervous system

what division of the nervous system is most specifically responsible for voluntary motor control?

somatic nervous system

myoglobin _________.

stores oxygen in muscle cells

creatine phosphate functions in the muscle cell by _________.

storing energy that will be transferred to ADP to resynthesize ATP

muscle that aids another by promoting the same movement

synergist

what is the main factor that determines the power of a muscle?

the total number of muscle fibers (cells) available for contraction

which of these is NOT a way of classifying muscles?

the type of muscle fibers

smooth muscle is characterized by all of the following except ________.

there are more thick filaments than thin filaments

which of the following is NOT a characteristic of neurons?

they are mitotic

which of the following is NOT true of graded potentials?

they increase amplitude as they move away from the stimulus point

if L= load, F= fulcrum, and E= effort, what type of lever system is described as LEF?

third-class lever

an enzyme known as acetylcholinesterase is present in the synaptic cleft. what is its role?

to break down acetylcholine

what is the role of tropomyosin in skeletal muscles?

tropomyosin serves as a contraction inhibitor by blocking the myosin binding sites on the actin molecules

the interaction between which protein and ion initiates muscle coupling?

troponin; calcium ions