physiology & anatomy chapter 9 practice exam

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tetanus of muscles is described as

action potential frequency is high enough that no relaxation of muscle fibers occurs

a lack of mitochondria within skeletal muscle fibers would impair which ATP-yielding chemical process

aerobic respiration

when skeletal muscle is producing CO, and water while making ATP, which chemical processes could be active at this time

aerobic respiration

smooth muscle and cardiac muscle are similar in that they both

are under involuntary control

how many ATP (i.e., the net gain) are generated in the reactions converting glucose to lactic acid?

2

at the neuromuscular junction, chemical transmitters diffuse across a microscopic gap called the:

synapse

these invaginations of the plasma membrane in smooth muscle are thought to function similar to both the SR and T tubule of skeletal muscle:

terminal cisternae

a sustained muscle contraction is known as

tetanus

which of the following events occurs during the lag phase of a muscle twitch

the action potential is propagated from presynaptic to postsynaptic membrane

this component of the actin myofilament consists of two strands that spiral about the actin core and help to stiffen the molecule. In addition it serves to block the myosin binding sites on the actin molecule:

tropomyosin

which of these terms might best indicate the size of a muscle:

vastus

during resting conditions,_ is synthesized to store energy

creatine phosphate

during resting conditions,___is synthesized to store energy.

creatine phosphate

sarcoplasm is the

cytoplasm of a muscle fiber

which of the following conditions in muscle fibers would contribute to muscle fatigue

depletion of ATP reserves

the specialized junctions/contacts that are responsible for electrical synapses are called

gap junctions

which of the following is part of a thin myofilament

globular (G) actin

troponin

has a calcium-binding site.

the role of ionic calcium in cross bridge attachment is:

none of the above

a sarcomere extends from

one Z disk to an adjacent Z disk

the end of the muscle attached to the less moveable bone is the

origin

when repolarization of the plasma membrane is complete, the

original polarity of the cell is restored

a skeletal muscle generates the greatest tension when it is

partially stretched before being stimulated

muscles exhibit the property of excitability. this means that the muscle

responds to stimulation by the nervous system

the signal for release of calcium from the terminal cisternae

results from depolaization of the T tubule

in the structure called a triad, the T tubule is sandwiched between:

sacs of sarcoplasmic reticulum

T tubules are invaginations of the

sarcolemma

in order for excitation-contraction coupling to occur, the production of an action potential must occur within the__of a muscle fiber.

sarcolemma

the plasma membrane of a muscle fiber is called

sarcolemma

these muscle fibers have slow acting myosin ATPases and are best suited for endurance activities

slow oxidative fibers

in the case of the sodium-potassium pump:

- ATP is required - both ions are moved against their respective concentration gradient

during a muscle fiber contraction, which of the following decreases in size? check all that apply.

- H zone - I band - entire sarcomere

which of the following describes titin's roles in muscle contraction? (Check all that apply.)

- accounts for muscle's excitability - accounts for muscle's extensibility and elasticity

which type of muscle is autorhythmic

- cardiac - smooth

electrical synapses may be found in

- cardiac muscle - smooth muscle

spontaneous depolarization would most likely be seen in:

- cardiac muscle - visceral smooth muscle

ionic calcium

- promokes neurotransmitter release from the axonal terminal - binds with TC of the troponin complexto trigger the sliding of myofilaments and ATPase activity

in order to stop the stimulation of the post-synaptic membrane, neurotransmitter must be removed from the synapse. this is accomplished by:

- reuptake of the neurotransmitter by the presynaptic terminal - degradation by enzymes such as acetylcholinesterase

during muscle contraction

- the I band shorten - the thick and thin filaments actually slide over each other - the distance between the Z discs (lines) decreases

arrange the following list of biochemical events in the correct sequence: (1) an action potential is conducted deep into the muscle fiber by the T tubule. (2) calcium ions bind to troponin. (3) the membranes of the sarcoplasmic reticulum become more permeable to calcium ions. (4) calcium ions diffuse into the sarcoplasm around the myofibril. (5) the troponin-tropomyosin complex moves exposing active sites.

1, 3, 4, 2, 5

the region of the sarcomere that contains both actin and myosin myofilaments is called the

A band

as demonstrated by rigor mortis, this molecule is essential for the myosin cross bridge tc detach:

ATP

during the contraction phase of a muscle twitch,

actin-myosin cross-bridges form

what is a triad

a T tubule and two adjacent terminal cisternae

a isometric contraction is described as

a muscle produces an increasing tension as the length remains constant

an eccentric contraction is described as

a muscle produces tension, but the length of the muscle is increasing

what is tropomyosin

a protein found along the groove of the F-actin double helix

in the presence of oxygen, the pyruvic acid is generated in glycolysis:

accepts hydrogen from NADH and is thereby reduced to lactic acid

synaptic vesicles in the neuromuscular junction contain

acetylcholine

the active sites to which cross-bridges attach are found on the

actin myofilaments

visceral smooth muscle

all of the choices are correct

treppe

all of these choices are correct

neostigmine

an acetylcholinesterase inhibitor

a stimulus either causes an action potential or it doesn't. this is called

an all-or-none response

which metabolic pathway do skeletal muscles rely on when someone is lifting weights

anaerobic respiration

which type of respiration rapidly produces ATP for short time periods

anaerobic respiration

a fascicle

is surrounded by perimysium

which of the following statements regarding the sliding filament model is false

both actin and myosin myofilaments shorten during contraction

which type of muscle tissue is autorhythmic

both cardiac and smooth muscle

acetylcholinesterase (AChE)

breaks down acetylcholine in the synaptic space

when an action potential reaches the presynaptic terminal

calcium ions diffuse into the presynaptic terminal through voltage-gated ion channels

which type of muscle tissue has cells that branch

cardiac muscle

diffusion of acetylcholine across the neuromuscular junction

causes depolarization of the sarcolemma

the chief extracellular anion in the cell's environment is:

chloride

muscle myofibrils

contain myosin and actin myofilaments

actin myofilaments

contain strands of fibrous actin

lack of acetylcholinesterase in the synaptic cleft would result in

continuous stimulation of the postsynaptic membrane

the capacity of a muscle cell to shorten forcefully is known as

contractility

in this portion of the myogram associated with the twitch response, excitation-contraction coupling is occurring

contraction

if Na+ cannot enter a muscle fiber in response to a stimulus,

contraction cannot occur

in terms of the layers of smooth muscle lining the digestive tract, contraction of the longitudinal layer:

dilates the organ and shortens it

individual skeletal muscle fibers are covered by delicate connective tissue membrane called the

endomysium

which of the following connective tissue layers is outside all the others

epimysium

which of the following is true about skeletal muscle

every muscle fiber receives a branch of an axon from the nerve

acetylcholine is released from the presynaptic terminal by the process of

exocytosis

muscle fibers are grouped into bundles which are called

fascicles

assume an individual has hyperkalemia. what does this do the resting membrane potential

hyperpolarizes the cell making it less irritable

curare blocks acetylcholine receptors at the motor end plate. this would result in

inability of the muscle fiber to respond to nervous stimulation

in muscle, the so-called "H zone"

is visible only in relaxed fibers

a sarcomere will generate a more forceful contraction if:

it is slightly stretched

a by-product of anaerobic respiration in muscle fibers is

lactate

the time between application of the stimulus to a motor neuron and the beginning of contraction is called the _____ phase

latent or lag

skeletal muscle develops from cells called

myoblasts

bundles fine fibers that extend lengthwise along muscle fibers are called

myofibrils

muscle cells have the ability to store their own oxygen by combining this gas with

myoglobin

this molecule is most likely to exhibit ATP binding sites and ATPase

myosin

ATPhase is found in

myosin heads

at rest, the inside of the sarcolemma is relative to the outside

negatively charged

the sites where a chemical substance is transmitted from the presynaptic terminal of an axon to the postsynaptic membrane of a muscle fiber are called

neuromuscular junctions

the sites where a chemical substance is transmitted from the presynaptic terminal of an axon to the postsynaptic membrane of a muscle fiber are called

neuromuscular junctions

which of the following is true during the resting membrane potential

potassium is concentrated primarily inside the cell

when the myosin head flexes into a bend, pulling the actin filament along with it, this is called the

power stroke

in terms of the two layers of muscle lining the digestive tract, contraction of the longitudinal layer:

shortens and dilates the organs

which type of muscle tissue is multinucleated

skeletal muscle

which type of muscle tissue is multinucleated?

skeletal muscle

which type of muscle tissue would cause flexion and extension of the arm

skeletal muscle

the model that describes the contraction of the muscle is called the

sliding filament model

force of contraction produced by a muscle can be increased by

summation

muscles involved in precise movements would be more likely to have

small motor units

which type of muscle tissue causes vasoconstriction

smooth muscle

which type of muscle tissue has spindle-shaped cells

smooth muscle

which of the following would be characterized as multiunit smooth muscle:

smooth muscle of the iris and the arrector pili muscles

the chief extracellular cation in a typical cell's environment is

sodium

depolarization of the plasma membrane occurs when there is a rapid influx (inflow) of rev:

sodium ions

the sarcoplasmic reticulum

stores calcium

a sarcomere is the

structural and functional unit of the skeletal muscle fiber

oxygen deficit represents

the amount of O2 that cells need to replenish ATP supplies after exercise

the type of muscle fatigue known as "psychological fatigue" is the result of

the emotional state of an individual

skeletal muscles contract with varying degrees of strength at different times. this is referred to as:

the graded strength principle

concentric contractions occur when

the muscle produces increasing tension as it shortens

when comparing smooth and skeletal muscle cells, which of the following statements is true

the myofilaments in smooth muscle do not form sarcomeres

whole muscles can respond in a graded fashion to stimuli by varying

the number of motor units recruited

the "external oblique" muscle is most likely named on the basis of

the orientation of the muscle's fibers

the active transport mechanism is responsible for maintaining resting membrane potential in cells:

the sodium potassium pump

this active transport mechanism is responsible for maintaining resting membrane potential in cells

the sodium potassium pump

the refractory period

the time during which the tissue cannot respond again

the plasma membrane of an excitable cell is more permeable to K+ because

there are more leak ion channels for K+ than Na+.

what is the role of pacemaker cells

they rapidly develop action potentials

which of the following statements concerning fast-twitch muscle fibers is true

they split ATP rapidly

which of the following is composed of myosin molecules

thick myofilaments

channels that open or close in response to changes in the electrical charge or voltage across the plasma membrane are called

voltage-gated ion channels

aerobic respiration

yields as many as 36 ATP per glucose molecule metabolized


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