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The stimulus above which no stronger contraction can be elicited, because all motor units are firing in the muscle

maximal stimulus

The phenomenon in which the contraction of a muscle increases, due to increased Ca2+ availability and enzyme efficiency during the warm-up

Treppe

Continued sustained smooth contraction due to rapic stimulation

Tetanus

The situation in which contractions become stronger due to stimulation before complete relaxation occurs

Wave summation

How a smooth increase in muscle force is produced

multiple motor unit summation

A sarcomere is the distance between two _______.

Z discs

The _______ contains only the actin filaments.

I band

The thicker filaments are the _______ filaments

Myosin

Both actin and myosin are located in the ________.

A band

Serves as the actual "trigger" for muscle contraction by removing the inhibition of the troponin molecules.

Calcium Ions

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

Acetylcholine

Diffusion across the cell membrane results in depolarization

Sodium-potassium ions

Activate synaptic vesicles in axon terminals

Calcium Ions

Used to convert ADP to ATP by transfer of a high-energy phosphate group. A reserve high-energy compound

Creatine phosphate

Destroys ACh

Acetylcholinesterase

(True/False)Once a motor neuron has fired all of the muscle fibers in a muscle contract

False

(True/False)The thin filaments(actin) contain a polypeptide subunit G actin that bearts active sites for myosin attachment

True

(True/False) the force of muscle contraction is controlled by multiple motor unit summation or recruitment

True

(True/False) Eccentric contractions are more forceful than concentric contractions.

True

(True/False) A Motor neuron and all the muscle cells that it stimulates are referred to as a motor end plan.

False

(True/False) Peristalsis is characteristic of smooth muscle

True

(True/False) A contraction in which the muscle does not shorten but its tension increases is called isometric

True

(True/False) During isotonic contraction, the heavier the load, the faster the velocity of contraction

False

(True/False) During isometric contraction, the energy used appears as movement

False

(True/False) One of the important functions of skeletal muscle contractions is production of heat

True

(True/False) An increase in the calcium ion level in the sarcoplasm starts the sliding of the thin filaments. When the level of calcium ions declines, sliding stops

True

(True/False) Muscle contraction will always promote movement of body parts regardless of how they are attached

False

(True/False) Although there are no sarcomeres, smooth muscle still possesses thick and thin filaments.

True

(True/False) Muscle tone is the smallest amount of tautness or tension in the muslce due to weak, involuntary contractions of its motor units.

True

(True/False) Single-unit smooth muscle is found in the intestines.

True

(True/False) A resting potential is caused by a difference in the concentration of certain ions inside and outside the cell

True

(True/False) The effect of a neurotransmitter on the muscle cell membrane is to modify its ion permeability properties temporarily

True

(True/False) When a muscle fiber contracts, the I bands diminish in size, the H zones disappear, and the A bands move closer together but do not diminish in length

True

(true/false) Contractures are a result of a total lack of ATP

True

(true/false) Smooth muscles relax when intracellular Ca2+ levels drop but may not cease contractions

True

What is the role of tropomyosin in skeletal muscle?
A) Tropomyosin is the name of the contracting unit.
B) Tropomyosin serves as a contraction inhibitor by blocking the actin binding sites on the myosin molecules.
C) Tropomyosin serves as a contraction inhibitor by blocking the myosin binding sites on the actin molecules.
D) Tropomyonsin is the receptor for the motor neuron neurotransmitter.

C) Tropomyosin serves as a contraction inhibitor by blocking the myosin binding sites on the actin molecules

Which muscle cells have the greatest ability to regenerate?
A) smooth
B) cardiac
c) skeletal
d) no muscle can regenerate

A) smooth

Most skeletal muscles contain:
A) a predominance of slow oxidative fibers
B) muscle fibers of the same type
c) a mixture of fiber types
D) a predominance of fast oxidative fibers

c) a mixture of fiber types

Fatigued muscle cells that recover rapidly are the products of ___________.
a) slow exercise of short duration
b) intense exercise of long duration
c) intense exercise of short duration
d) slow exercise of long duration

c) intense exercise of long duration

The strongest muscle contractions are normally achieved by ___________.
A) increasing the stimulation up to the maximal stimulus.
B) recruiting small and medium muscle fibers
c) increasing stimulus above the threshhold
d) incrasing stimulus above the treppe threshhold

a) increasing the stimulation up to the maximum stimulus

Which of the following would be recruited later in muscle stimulation when contractile strength increases?
A) many small motor units with the ability to stimulate other motor units.
B) motor units with the longest muscle fibers
c) motor units with larger, less excitable neurons
d) large motor units with small, highly excitable neurons

c) motor units with larger, less excitable neurons

Which of the following is NOT a usual result of resistance excercise?
A) increase in the efficience of the circulatory system
B) increase in the number of muscle cells
c) increase in the number of myofibrils within the muscle cells
d) increase in the efficiency of the respiratory system.

b) increase in the number of muscle cells

Excitation-contraction coupling requires which of the following substances?
A)ATP and glucose
B) ATP only
C) Ca2+ only
d) Ca2+ and ATP

D) Ca2+ATP

Which of the following is a factor that affects the velocity and duration of muscle contraction?
A) muscle length
B) number of muscle fibers stimulated
c) load on the fiber
D) size of the muscle fibers stimulated

c) load of the fiber

Myoglobin ________.
a) stores oxygen in muscle cells
b) produces the end plate potential.
c) breaks down glycogen
d) is a protein involved in the direct phosyphorylation of ADP

A) stores oxygen in muscle cells

What structure in skeletal muscle cells functions in calcium storage?
A) sarcoplasmic reticulum
B) mitochondria
c) myofibrillar network
d) intermediate filament network

a) sarcoplasmic reticulum

What does oxygen deficit represent?
A) the amount of oxygen taken into the body immediately after the exertion
B) the amount of oxygen taken into the body prior to the exertion
c) the difference between the amount of oxygen needed for totally aerobic muscle activity and the amount actually needed
d) amount of energy needed for exertion

c) the difference between the amount of oxygen needed for totally aerobic muscle activity and the amount actually needed

Immediately following the arrival of the stimulus at a skeletal muscle cell there is a short period called the _______ period during which the events are excitation-contraction coupling to occur.
a) refractory
b) contraction
c) relaxion
d) latent

d) latent

Creatine phosphate functions in the muscle cell by ________.
a) inducing a conformational change in the myofilaments
b) forming a termporary chemical compound with myosin
c) storing energy that will be transferred to ADP to resynthesize ATP
D) forming a chemical compound with actin.

c) storing energy that will be transferred to ADP to resynthesize ATP

What controls the force of muscle contraction?
a) concentric contractions
b)treppe
c) multimotor unit summation
d) wave summation

c) multimotor unit summation

The major function of the sarcoplasmic reticulum in muscle contraction is to __________.
a) regulate intracellular calcium concentration.
b) make and store phospheocreatine
c) synthesize actin and myosin myofilaments
d) provide a source of myosin for the contraction process

a) regulate intracellular calcium concentration

What produces the striations of a skeletal muscle cell?
a) a sarcoplasmic reticulum
b) the arrangement of myofilaments
c) a difference in the thickness of the sarcolemma
d) the t tubules

b) the arrangment of myofilaments

which of the following are composed of myosin?
a) thick filaments
b) z discs
c) thin filaments
d) all myofilaments

a) thick filaments

During muscle contraction, myosin cross bridges attach to which active sites?
A) thick filaments
b) actin filaments
c) z discs
d) myosin filaments

b) actin filaments

which of the following surrounds the individual muscle cell?
a) perimysium
b) epimysium
c)endomysium
d) fascicle

c) endomysium

Smooth muscles that act like skeletal muscles but are controlled by autonomic nerves and hormones are _______.
a)white muscles
b) multiunit muscles
c) red muscles
d) single-unit muscles

b) multi-unit muscles

Rigor mortis occurs because_______.
a) sodium ions leak out of the muscle
b) the cells are dead
c) proteins are beginning to break down, thus preventing a flow calcium ions
d) no ATP is available to release attached actin and myosin molecules

d) no ATP is available to release attached actin and myosin

Which of the choices below does NOT describe how recovery oxygen uptake (oxygen deficit) restores metabolic conditions?
A) increases the level of lactic acid in the muscle
b) converts lactic acid back into glycogen stores in the liver
c) resynthesizes creatine phosphate and ATP in muscle fibers
d) replaces the oxygen removed from myoglobin

a) incrases the level of lactic acid in the muscle

The term aponeurosis refers to __________.
A) the bands of myofibrils
b) the sheetlike indirect attachement to a skeletal element
c) the tropomyosin-troponin complex
d) the rough endoplasmic reticulum

b) the sheetlike indirect attachment to a skeletal element

The oxygen-binding protein found in muscle cells is _________.
a) ATP
b) hemoglobin
c) immunoglobin
d) myoglobin

d) myoglobin

the contractile units of of skeletal muscles are __________.
a) myofibrils
b) t tubules
c) mitochondria
d) microtubules

myofibrils

which of the following is NOT a way muscle contractions can be graded?
a) changing the type of neurotransmitter released by the motor neuron
b) changing the frequency of stimulation
c) changing the type of muscle fibers involved in the contraction
d) changing the strength of the stimulus

c) changing the type of muscle fibers involved in the contraction

what is the functional unit of a skeletal muscle called?
A) the sarcoplasmic reticulum
b) a sarcomere
c) a myofilament
d) a myofibril

B) a sarcomere

What is the functinal role of the T tubules?
A) enhance cellular communication during muscle contraction
B) synthesize ATP to provide energy for muscle contraction
c) hold cross bridges in place in a resting muscle
D) stabilize the G and F actin

A) enhance cellular communication during muscle contraction

what is the role of calcium ions in muscle contraction?
A) increase levels of myoglobin
B) reestablish glycogen stores
c) bind to regulatory sites on troponin to remove contraction inhibition
D) form dydroxyapatite crystals

C) bind to regulatory sites on troponin to remove contraction inhibition

The warm-up period required of athletes in order to bring their muscles to peak performance is called __________.
A) incomlete tetanus
B) twitch
c) treppe
D) wave summation

C) Treppe

The main effect of the warm up period of athletes, as the muscle contractions increase in strength, is to ________.
A) convert glycogen to glucose
B) enhance the availability of calcium and efficiency of enzyme system
c) tone the muscles and stabilize the joints for workout.
D) increase the myoglobin content

B) enhance the availability of calcium and the efficiency of enzyme systems

During rigorous exercise there may be insufficient oxygen available to completely break down pyruvic acid for energy. As a result, the pyruvic acid is converted to __________.
A) stearic acid
B) hydorchlorid acid
C) a strong base
D) lactic acid

D) lactic acid

When a muscle is unable to respond to stimuli temporily, it is in which of the following periods?
A) fatigue period
B) refractory period
C) laten period
D) relaxation period

B) refractory period

In an isotonic contraction, the muscle ________.
A) changes in length and moves the "load"
B) never converts pyruvate to lactate
c) rapidly resynthsizes creatine phosphate and ATP
D) does not change in length but increases tensions

A) changes in length and moves the "load"

The muscle cell membrane is called the________.
A) epimysium
B) endomysium
C) perimysium
D) sarcolemma

D) sarcolemma

Which of the following is the correct sequence of events for muscle contractions?
A) motor neuron action potential, neurotransmitter release, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke, sliding of myofilaments
B) neurotransmitter release, motor neuron action potential, muscle cell action potential, release of calcium ions from SR, ATP driven power stroke.
C) neurtotransmitter release, muscle cell action potential, release of calcium ions from SR, sliding of myofilaments, ATP-driven power stroke
D) muscle cell action potential, neurotransmitter release, ATP-driven power stroke, calcium ion release from SR, slid
C

A) motor neuron action potential, neurotransmitter release, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke, sliding of myofilaments.

The mechanism of contraction in smooth muscle is different from skeletal muscle in that _________.
A)the site of calcium regulation differs
B) the trigger for contraction is a rise in intracellular calcium
C) ATP energizes the sliding process
D) actin and myosin interact by the sliding filament mechanism.

A)the site of calcium regulation differs

Which of the following describes the cells of single-unit visceral muscle?
A) they exhibit spontaneous action potential
B) they are chemically coupled to one another by gap junctions.
C) the contract all at once
D) they consist of muscle fibers that are structurally independent of each other

A) they exhibit spontaneous action potential

Which of the following is not a role of ionic calcium in muscle in muscle in muscle contraction?
A)promotes breakdown of glycogen and ATP synthesis
B) triggers neurotransmitter secretion
c) removes contraction inhibitor
D) activates epinepherine released from adrenal gland

D) activates epinepherine released from adrenal gland

Which of the following is try about smooth muscle contraction?
A) Smooth muscle cannot stretch as much as skeletal muscle
B) Certain smooth muscle cells can actually divide to increase their numbers
C) Smooth muscle has well developed T tubules at the site of invagination
d) Smooth muscle, in contrast to skeletal muscle, cannot synthesize or recrete any connective tissue elements

B) certain smooth muscle cells can actually divide to increase their numbers

Smooth muscle is characterized by all of the following except ___________.
A) thre are more thick filaments than thin filaments.
B) there are no sarcomeres
c) there are noncontractile intermediate filaments that attach to dense bodies within the cell
D) it appears to lack troponin

A) there are more thick filaments than thin filaments.

Muscle tissue has all of the following properties except__________.
A) secretion
B) extensibility
C)excitability
D)contractility

A)secretion

The giant protein titin maintains the organization of the _________ assisting in muscle stretching.
A) Z disc
B) M line
C) I band
D) A band

D) A band

Which of the following statements is true?
A) Cardiac muscle cells are found in the heart and large blood vessels
B) Smooth muscle cells have T tubules
C) Striated muscle cells are long and cylindrical with many nuclei
D) Cardiac muscle cells have many nuclei

C) Striated muscle cells are long and cylindrical with many nuclei

An anaerobic metabolic pathway that results in the production of two net ATPs per glucose plus two pyruvic acid molecules is _________.
A) hydrolysis
B) the electron transport chain
C) the citric acid cycle
D)glycolysis

D) glycolysis

Muscle tone is _________.
A) the condition of athletes after intensive training
B) the feeling of well being following exercise
C) a state of sustained muscle contraction
D) the ability of a muscle to efficiently cause skeletal contractions.

C) a state of sustained muscle contraction

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

D) actin and myosin sliding past each other and partially overlapping

After nervous stimulation stops, what prevents ACh in the synaptic cleft from continuing to stimulate contraction?
A) acetylcholinersterase destroying the ACh
B) calcium ions returning to the terminal cisternae
C) the tropomyosin blocking the myosin once full contraction is achieved
D) the action potential stops going down the overloaded T tubules

A) acetylcholinersterase destroying the ACh

Which of the following statements is most accurate?
A) Muscle tension remains relatively constant during isotonic contraction
B)the I band lengthens during isotonic contraction
C) T tubules may be sliding during isotonic contraction
D) myofilaments slide during isometric contractions

A) Muscle tension remains relatively constand during isotonic contraction

What is the most distinguishing characteristic of muscle tissue?
A) the sarcoplasmic reticulum
B) the ability to transform chemical energy into mechanical energy
C) the diversity of activity of muscle tissue
D) the design of the fibers

B) the ability to transform chemical energy into mechanical energy

Three discrete types of muscle fibers are identified on the basis fo their size, speed, and endurance. Which of the following athletic endeavors best represents the use of red fibers?
A) a sprint by and Olympic runner
B) a long relaxing swim
C) mountain climbing
D) playing baseball or basketball

B) a long relaxing swim

Of the following muscle types, which has only ONE nucleus, NO sarcomeres, and rare gap junctions?
A) skeletal muscle
B) multiunit smooth muscle
C) cardiac muscle
D) visceral smooth muscle

B) multiunit smooth muscle

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

C) no muscle tension would be generated

What part of the sarcolemma contains acetylcholine receptors?
A)part adjacent to another muscle cell
B) motor end plate
C) any part of the sarcolemma
D) end of the muscle fiber

B) motor end plate

Which of the following statements is false of incorrect?
A) Cardiac muscle fibers can use lactic acid to make ATP
B) Cardiac muscle fibers depend mostly on anaerobic cellular respiration to generate ATP
C) Under normal resting conditions, cardiac muscle tissue contracts and relaxes about 75 times per minute.
D) Cardiac muscle contracts when stimulated by its own autorythmic muscle cells

B) Cardiac muscle fibers depend mostly on anaerobic cellular respiration to generate ATP

Only _______ muscle cells are always multinucleated.

Skeletal

Claudication might more simply be called _______.

Limping

The end of the muscle that typically moves when a muscle contracts is called the _________.

insertion

In the synaptic cleft of a neuromuscular junction, an enzyme called __________ is always present.

Acetylcholinesterase

The time is which cross bridges are active is called the period of _________.

Contraction

________(color) fibers are slow (oxidative) fibers.

Red

Only ______ muscle cells commonly branch.

cardiac

A smooth, sustained contraction is called _______.

Tetanus

Define physiological fatigue

fatigue occurs when ATP production fails to keep pace with ATP use even though the muscle still recieves stimulus

Compare red and white muscles relative to their speed of action and endurance.

Red muscles tend to have a slow(oxidative) rate and fatigue resistance, whereas white muscle cells have a fast(oxidative) rate and fatigue early

Briefly, what causes rigor mortis?

follwing the death of an individual, ATP is rapidly consumed and cannot be replaced. Because cross bridge detachment and calcium active transport is ATP driven, calcium leakage from the sarcoplasmic reticulum cause attachment of cross bridges, and lack of ATP prevents detachments.

What ulitmately stops muscle stimulation when the motor neuron ceases firing?

The ultimate switch is the enzymes acetycholinesterase. When the neuron stops releasing ACh, the muscle would not stop contracting if the acetylcholinesterase did not split the ACh into its two components, acetyl and choline, making them release their binding sites.

A long-distance runner is about to enter a 5 mile race. Beforehand, he spends several minutes warming up. During the warm-up period, the phenomenon of treppe is occurring in the body muscles being used. What is treppe and why does it occur?

Treppe is the staircase phenomenon in which muslces increase their strength of contraction due to increased availability of calcium. Additionally, the increased warmth due to activity causes an increase in the efficience of muscle enzyme systems.

Skeletal muscles have two special inclusions that help them perform their function of movement. What are the two special inclusions of skeletal muscle cells and how would the be useful to the cell?

Skeletal muscle cells require a lot of rapidly available fuel to burn in order to function properly they also require a lot of oxygen to burn this fuel efficiently. Glycosomes store glycogen that can be quickly converted to glucose, which in turn can be burned to produce ATP. Myoglobin is a chemical much like hemoglobin in blood cells that can store large quanities of oxygen.

What are the parts of the skeletal muscle triad and what are their functions?

The sarcoplasmic reticulum is a reservoir for calcium ions in the cells normal resting state. The T tubule is a fold in the cell membrane between the sarcoplasmic reticuli. When an impulse is activated by a motor neuron, the voltage regulated change causes SR foot proteins to open Ca2+ channels. The calcium ions are flushed out where they interact with the troponin complex to initiate a contraction. Once the axon stops firing, the membrane polarity is quickly restored and the calcium ions are pulled off the troponin and attracted back into the sarcoplasmic reticulum

Briefly explain the sources of energy for a one-minute sustained muscle contraction

1. The first 4-6 seconds of energy comes from stored ATP in the muscle cell.
2. 6-15 seconds of energy come from the transfer of creatine phosphate and ADP(which comes from the first few seconds of burn) to form additional ATP
3. 15-60 seconds of energy come from glycolysis, which by now has begun full production of ATP from glucose

What are caveolae?

Folds on the surface of smooth muscle cells that correspond to T tubules in skeletal muscle cells

How is it that norepinepherine(NE) can inhibit smooth muscle action in airways, yet stimulate contraction in smooth muscle everywhere else in the body?

Airway passages have smooth muscle cells that are unique in that they have two receptor sites on their outer membrane. One receptor site accepts ACh as the neurotransmitter. When exicted it causes the smooth muscle to contract. The second site accepts NE and the inhibitory effect is that the ACh dilates the airway

How do the three muscle types respond to being stretched?

All three muscle types initially respond by contracting more forcefully. However, in smooth muscle cells the increased tension persists only briefly, and the muscle adapts to its new length and relaxes

What is agrin?

Agrin is a growth factor of developing muscles. Agrin stimulates ACh receptors to cluster around a newly forming motor end plate.

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

Absolute refractory period

The interior of the cell becomes LESS negative due to an influx of sodium ions.

Depolarization

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

Repolarization

Also called a nerve impulse transmitted by axons

Action potential

An exceptionally strong stimulus can trigger a response

Relatively refractory period

Numerous nerve impulses arriving at a synapse at closely timed intervals exert a cumulative effect

Temporal summation

Stimulation of a postsynaptic neuron by many terminals at the same time.

Spatial summation

An insufficient stimulus

Subthreshhold stimulus

Any stimulus below this intensity will result in no reponse in a neuron

Threshold stimulus

Area where nerve impuse is generated

Trigger zone

Recieves stimuli

Receptive region

Plasma membraned exhibits voltage gated Na+ and K+ channels

conducting region

Plasma membrane exhibits voltage gated Ca+ channels

secretory region

Axon terminals release neurotransmitters

Secretory zone

Plasma membrane exhibits chmically gated ion channels

receptive region

One incoming fiber triggers reponses in ever-increasing numbers farther and father along the circuit

Diverging circuit

May be involved in complex, exacting types of mental processing

parallel after discharge circuit

Involved in control of rhythmic activities such as breathing

reverberating circuit

Involved in activating fibers of a skeletal muscle such as the biceps muscle

Diverging circuit

Different types of sensory input can have the same ultimate effect

converging circuit

increases acid secretion in the stomach; blocked by cimetidine

histamine

"feel good" neurotransmitter

norepinepherine

Mediates pain

Substance P

Principle inhibitory neurotransmitter of the spinal cord

Glycine

Natural opiates that inhibit pain, effect mimicked by morphine

endorphines

(t/f) 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

Reflexes are rapid, automatic responses to stimuli (T/F)

True

Efferent nerve fibers may be described as motor nerve fibers (T/F)

True

Cell bodies of sensory neurons may be located in ganglia lying outside the central nervous system. (T/F)

True

Myelination of the nerve fibers in the central nervous system is the job of the oligodendrocyte(T/F)

True

During depolarization the inside of the neurons membrane becomes less negative(t/f)

True

Neurons in the CNS are organized into functional groups(t/f)

True

Strong stimuli case the amplitude of action potenals generated to increase(t/f)

False

The oligodendrocytes can myelinate several axons(t/f)

True

Enkephalins and endorphines are peptides that act like morphine(t/f)

True

In myelinated axons the voltage regulated sodium channels are concentrated at the nodes of Ranvier(t/f)

True

A postsynaptic potential is a graded potential that is the result of neurotransmitter released into the synapse between two neurons(t/f)

True

Large diameter nerve fibers conduct impulses much faster than small diameter fibers (t/f)

True

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