A&P Chapter 10 Connect

Which of the following proteins are found within a sarcomere?

-actin -connectin

When viewed under a light microscope, the light bands, called _________, contain only ______ filaments.

I bands; thin

As a person grows older, muscle tissue has a ______ capacity to recover from disease or injury.

reduced

The cytoplasm of a skeletal muscle cell has a specific name and is known as

sarcoplasm

An individual has better proficiency in performing repeated contractions under aerobic conditions if he or she as a greater percentage of ____ fibers in specific muscles.

slow

contractility

stimulation of muscle cells generates tension within the cell

The superficial fascia is also known as the

subcutaneous layer

ACh is released into this space

synaptic cleft

A nerve signal arrives at this structure

synaptic knob

The motor end plate has folds and indentations to increase the membrane surface are adjacent to the

synaptic knob

The force generated when a skeletal muscle is stimulated to contract is muscle

tension

A cross section of a myofibril through the A band contains which myofilaments?

thick and thin

The striated appearance in skeletal muscle cells is due to size and density differences between ______ and ______ filaments.

thick and thin

In smooth muscle cells, the sarcoplasmic reticulum is sparse, and ____ tubules are absent.

transverse

tropomyosin

two intertwined strands; cover myosin binding sites

When a muscle fiber contracts, which parts of the sarcomere maintain a constant length throughout contraction?

A band

According to the sliding filament theory, the length of the _____ band remains constant, but the ____ zone disappears.

A; H

Blood vessels deliver nutrients and oxygen to the muscle fibers so that they can produce the molecule _______ which is needed for contraction.

ATP

Energy to drive the myosin movement in the sliding filament process is provided in the form of

ATP

The ACh receptors on the motor end plate are ____ ion channels.

Chemically gated

In each helical strand of F-actin, many small, spherical molecules are connected for form a long filament resembling a string of beads. Each spherical molecule is called

G-actin

Match the duration of a single muscle contraction with the source of ATP

Immediate - creatine phosphate Short term - anaerobic respiration Long term - aerobic respiration

body movement

Muscles contract and pull on the tendons that attach the muscles to the bones

The _____ discs that anchor the sarcomere on either end in skeletal muscle are absent form smooth muscle cells.

Z

fascicle

a bundle of muscle fibers

elasticity

a contracted muscle cell recoils to its resting length when the applied tension is removed

extensibility

a muscle cell is capable of extending in length in response to the contraction of opposing muscle cells

The two types of muscle contraction are: a. _____ contraction (when a muscle contracts but does not change in length) and b. _____ contraction (when a muscle contracts and does change in length.)

a. isometric b. isotonic

ACh is an acronym for

acetylcholine

After being generated, the muscle impulse continues to spread throughout the muscle fiber as long as _____ keeps the motor end plate receptors open.

acetylcholine

A tropomyosin molecule is a short, thin, twisted filament that covers small sections of the _____ strands.

actin

The filaments in smooth muscle cells contain which proteins

actin and tropomyosin

Ten minutes into a marathon, your body is relying on _______ cellular respiration for ATP.

aerobic

slow and intermediate fibers require oxygen to produce ATP, so the metabolic reaction within these fibers are termed

aerobic

For longer contractions, muscle cells obtain ATP by which process?

aerobic respiration

a tendon that forms a thin, flattened sheet is called a/an ______

aponeurosis

The endomysium is composed of what type of connective tissue?

areolar

The superficial fascia, composed of _____ and adipose connective tissue, separates muscle from skin.

areolar

Smooth muscle is found where in the respiratory system?

around the bronchioles

cardiac

autorhythmic

The sarcoplasmic reticulum stores ______ ions needed to initiate muscle contraction.

calcium

Functionally, troponin provides a binding site for

calcium ions

When a nerve signal arrives at a synaptic knob, what type of channels open in the membrane?

calcium voltage-gated

posture

contraction of specific skeletal muscles stabilizes joints

After exposure of the active sites on actin, myosin heads attach to the actin and form

cross bridges

myofibrils

cylindrical organelles specialized for contraction

a-band

dark band containing both actin and myosin

Anchoring point between intermediate filaments and the sarcoplasm

dense body

the epimysium of a muscle surrounds

entire skeletal muscle

Muscle cells are said to have what characteristic because they can respond to stimulation from the nervous system?

excitability

The synaptic knob of the neuron is a ____ of an axon.e

expanded tip

In transverse section of a muscle, you can see that each skeletal muscle is actually composed of many _____, which are bundles of muscle fibers.

fascicles

In a muscle, the perimysium surrounds ____ muscle cells

fascicles of

If used repeatedly for endurance events, _____ fibers can develop the appearance and functional capabilities of _____ fibers.

fast; intermediate

Intermediate fibers contract _____ than slow fibers and _____ than fast fibers.

faster; slower

In a normally functioning muscle, the inability to contract and produce tension is called muscle

fatigue

When the myosin head finishes pivoting, the ______ detaches and returns to its original cocked position, ready to repeat the cycle.

head

temperature regulation

heat is produced as a waste product of energy usage

if a muscle cell is stimulated to contract, allowed to partially relax, then stimulated again, its force of contraction the second time will be

higher

The diameter of a muscle fiber will predict

how much power it will produce

If you strain to push on a wall that does not move, your muscles are in a type of

isometric contraction

Eccentric contractions actively _______ a muscle.

lengthen

I-band

light band containing thin filaments only

myofibril

long, cylindrical contractile element within muscle cell

A motor unit is composed of a single _____ and all of the muscle fibers it controls.

motor neuron

muscle tissue is distributed almost everywhere in the body; it is responsible for the _____ of materials within and throughout the body.

movement

muscle

multiple bundles housing many muscle fibers

Myofibrils are made of

myofilaments

muscle fibers that rely on aerobic respiration for ATP synthesis contain a high concentration of _____ which gives them a reddish appearance.

myoglobin

Smooth muscle cells have a unique protein called _____ light-chain kinase.

myosin

Thick filaments are assembled from bundles of the protein called

myosin

ATP is generated when the enzyme creatine kinase transfers Pi from creatine ______ to ADP.

phosphate

contraction of specific skeletal muscles stabilizes joints and helps maintain the body's ______ by holding the head and trunk erect.

posture

The skeletal muscles arranged in layers along the walls of the abdominal cavity and the floor of the pelvic cavity perform what function?

protection support contraction

As we age, decreased muscle strength is compounded by a tendency toward

rapid fatigue

The plasma membrane of a skeletal muscle fiber is called the

sarcolemma

Within a myofibril, each _____ shortens as the muscle fiber contracts.

sarcomere

a contracting skeletal muscle fiber typically shortens as all of its ______ shorten in length

sarcomeres

within a myofibril, Z discs separate the functional units known as

sarcomeres

At the end of muscle contraction, calcium ions are moved back into the _______ reticulum by ATP-driven ion pumps.

sarcoplasmic

If a skeletal muscle is injured, surrounding ______ cells may be stimulated to differentiate and assist in its repair and regeneration.

satellite

a "step-wise" increase in the force of contraction of a single muscle fiber or single motor unit due to repeated stimulation without an increase in intensity or frequency of stimulation is called ______

summation

The narrow space separating the synaptic knob and the motor end plate is called the

synaptic cleft

The deep invaginations of the sarcolemma that extends into the sarcoplasm of skeletal muscle fibers as a network of narrow membranous tubules are called

transverse tubules

The two regulatory proteins associated with myofilaments are

tropomyosin and troponin

Actin

two intertwined strands; each bead has a myosin binding site

skeletal

voluntary

Individual cardiac muscle cells can be stimulated to generate a muscle impulse ________ stimulation.

without nervous

once started, a muscle impulse will travels along the sarcolemma and into the muscle fiber via the

T-tubules

TF A single myofibril runs the length of the muscle fiber.

TRUE

TF Smooth muscle retains its mitotic ability.

TRUE

TF Your biceps brachii muscle in your arm is an organ.

TRUE

TF smooth muscle cells lack transverse tubules.

TRUE

The amount of additional oxygen that must be inhaled in order to restore pre-exercise levels is called oxygen

debt

A persons tolerance for exercise _____ with age

decreases

A sarcomere is defined as the distance from one Z ______ to the next.

disc

Big muscles like the "quads" which are used for power have ____ motor units.

large

muscle fiber

metabolic activities; contraction

Cardiac muscle cells contain a large number of _____ to generate the ATP required for their unceasing work.

mitochondria

Acetylcholinesterase in the synaptic cleft is needed so that ____ will not continuously stimulate the cell to contract.

ACh

TF After diffusing across the synaptic cleft, ACh binds to receptors on the synaptic knob.

FALSE

________ distribute the muscle impulse throughout the inside of the muscle fiber.

T-tubules

TF a byproduct of anaerobic respiration is lactic acid.

TRUE

TF most muscles contain a combination of all three muscle types, slow oxidative, fast oxidative, and fast glycolytic.

TRUE

Calcium ions bind to what protein in a thin myofilament?

Troponin

storage and movement of materials

Voluntary sphincter muscles of the gastrointestinal and urinary tracts can be kept closed or opened

Contraction of a muscle fiber requires that the myosin heads in the thick filament bind to active sites on ____ molecules within the thin filaments.

actin

Which of the following proteins are found in a thin filament?

actin

After breaking your arm, you have a cast on it for three months. When the cast is removed, your arm looks much smaller than it did before. The process called _____ caused this to happen.

atrophy

The rate of rhythmic contraction of cardiac muscle is controlled by the ______ nervous system.

autonomic

troponin

bound to tropomyosin; can bind calcium ions

At an NMJ, the influx of ______ ions into the synaptic knob causes the exocytosis of ACh into the synaptic cleft.

calcium

During contraction of smooth muscle, _____ binds to calcium and activates myosin light chain kinase.

calmodulin

In addition to skeletal muscle, two other types of muscle are found in the body: _______ muscle and _______ muscle.

cardiac and smooth

The wall of the heart is composed of

cardiac muscle

The invaginations of the sarcolemma on the smooth muscle cell are called

caveolae

excitability

cell is responsive to stimuli

A muscle fiber is what level of organization in the body

cellular

The long tails of the myosin molecules in the thick filaments point toward the _____ of the filament.

center

As a result of muscle fiber contraction, thick filaments in neighboring sarcomeres move ______.

closer together

thin filament

composed of actin, troponin, and tropomyosin

thick filament

composed of myosin

There are two types of isotonic contractoins: eccentric and

concentric

h-zone

contains thick filaments only

When smooth muscle is stretched, it responds by

contracting then relaxing

anchoring between intermediate filaments and the sarcolemma

dense plaque

Myosin head attachment and pivoting do not require energy, but ATP is needed for the myosin head cross bridge to ______ from actin and re-cock.

detach

actin

double-stranded contractile protein

tropomyosin

double-stranded regulatory protein

Muscular dystrophy results from the lack of or an abnormal structure of which protein?

dystrophin

After a contraction, muscle returns to its original relaxed position due to it's natural

elasticity

muscle fiber

elongated, multinucleate, cylindrical cell

The majority of skeletal muscle fibers in the body are ____ fibers.

fast glycolytic

Overall, as aging progresses, muscle strength and endurance are impaired, and the individual has a tendency to ______ quickly.

fatigue

intermediate fibers have a high resistance to

fatigue

A skeletal muscle cell is also called a muscle

fiber

sarcomere

functional contractile unit of skeletal muscle

Smooth muscle is composed of short cells that have a ____ shape.

fusiform

With endurance training, it is possible for fast _____ fibers to take on characteristics of fast _____ fibers.

glycolytic; oxidative

in muscle contraction, as increasing numbers of motor units are recruited _____ force is exerted

greater

In a relaxed muscle fiber there are no thin filaments overlapping the thick filaments in the

h zone

Each myosin strand has a free ____ and an attached tail.

head

an increase in muscle fiber size is called

hypertrophy

In ___ tetany, a muscle cell is stimulated so frequently that it is not allowed to relax at all between stimuli

incomplete

Multiunit smooth muscle cells are stimulated

individually

Which of the following structures anchors adjacent cardiac muscle cells together?

intercalated disc

Cytoskeleton network

intermediate filaments

smooth

involuntary

smooth muscle contraction is under ___ control of the nervous system.

involuntary

smooth muscle contraction is under _____ control

involuntary

During an ____ contraction, the length of the muscle does not change.

isometric

The _____ mechanism allows smooth muscle to maintain muscle contraction without the use of additional ATP

latchbridge

In order to predict how much tension a muscle can produce when contracting, it is important to consider the ______ relationship of thick and thin filaments.

length-tension

The vascular supply to slow muscle fibers is _____ than the network of capillaries around fast muscle fibers.

more extensive

The neurons that stimulate muscle contraction are called _____ neurons.

motor

although muscle fibers obey the all-or-none principle, the force of muscle contraction can be varied depending on how many ______ units are used

motor

ACh binds to receptors on this surface

motor end plate

Upon release from the synaptic knob, acetylcholine attaches to receptors on the

motor end plate

During development, many groups of ______ fuse to form single skeletal muscle fibers.

myoblasts

hypertrophy results from an increase in the number of _____ in a muscle cell

myofibrils

As a result of exercise, each muscle fiber develops more myofibrils, and each myofibril contains a larger number of

myofilaments

Myofibrils consist of bundles of short

myofilaments

Muscle cells store oxygen bound to a _____ molecule?

myoglobin

Thick myofilaments are composed of bundles of _______ protein molecules.

myosin

After the cross bridges are formed, ATP is required to detach the _______ and complete the sequence of cyclic events.

myosin heads

The motor neuron transmits the effect of a nerve impulse to the muscle fiber at a

neuromuscular junction

The point where a motor neuron meets a skeletal muscle fiber is called the

neuromuscular junction

When a motor neuron axon terminal and a muscle cell meet is called a

neuromuscular junction

While observing skeletal muscle tissue under the microscope you note that it appears striated. You tell your lab partner this is because

of the arrangement of myofilaments in each sarcomere

An extensive network of blood vessels and nerve fibers extends through both the epimysium and the _______ of a muscle.

perimysium

As you hold a barbell and begin to flex your arm in a curl, your biceps brachii slowly lifts the weight by using more and more motor units. This phenomenon, which increases the strength of the contraction, is referred to as

recruitment

in skeletal muscle experiences markedly ______ ______, it loses both mass and tone.

reduced stimulation

sarcolemma

regulates entry and exit of materials

The endomysium contains _____ fibers to help bind together neighboring muscle fibers.

reticular

After stimulation of ACh receptors, a muscle impulse spreads quickly along the _____ and into the muscle fiber along T-tubules.

sarcolemma

myofilament

short contractile proteins of two types: thick and thin

In an isotonic contraction, the muscle fibers ______, resulting in movement.

shorten or lengthen

Cardiac muscle cells are ______ and thicker than skeletal muscle cells, and they have only _____ nuclei.

shorter; 1-2

sarcoplasm

site of metabolic processes for normal muscle fiber activities

Approximately 40-50% of your body weight is _____ muscle.

skeletal

Which is not a connective tissue component of a muscle?

skeletal muscle fibers

The length-tension relationship of ______ muscle cells is limited by the z-discs which are lacking in _____ muscle cells.

skeletal; smooth

Type I muscle fibers contract more _____ than type IIa and IIb muscle fibers.

slowly

The sodium-potassium exchange pump maintains a higher concentration of which ion outside the sarcolemma?

sodium

sarcoplasmic reticulum

stores calcium ions needed for muscle contraction

relaxation period

tension decreases

contraction period

tension increases

An action potential travels down the sarcolemma, through the t-tubules, to the

terminal cisternae

As a result of ACh stimulation, calcium ions are released from the _____ of the sarcoplasmic reticulum.

terminal cisternae

Parts of the sarcoplasmic reticulum that appear as blind sacs perpendicular to the fiber's length are called ________

terminal cisternae

latent period

there is no tension

In a sarcomere, the M-line serves as an attachment site for the ______ filaments and keeps them aligned during contraction and relaxation.

thick

Under the light microscope, the dark (A) bands observed in skeletal muscle contain ________ filaments

thick and thin

In sarcomere, Z discs serve as anchors for

thin filaments

As you sit there reading this your muscles, even your relaxed ones are not completely relaxed and soft. This is because they have some background tension called resting muscle

tone

t-tubule

transports the action potential from the sarcolemma throughout the entire muscle fiber

An action potential is carried along the sarcolemma, then down _________ tubules to the terminal cisternae of the sarcoplasmic reticulum.

transverse

spread of a muscle impulse along the sarcolemma, then down the ______,causes calcium ions to leak out of the rR into the sarcoplasm of the muscle fiber

transverse tubules

In a skeletal muscle cell, two terminal cisternae and the centrally placed T-tubule from a structure called a

triad

When a muscle fiber is in a released state, the _____ molecules cover the G-actin active sites, preventing interaction between thick filaments and thin filaments.

tropomyosin

If the sarcoplasm of a muscle cell is flooded with calcium ions, to which protein will they bind?

troponin

upon release from the terminal cisternae, some calcium ions bind to _____ causing it to change shape.

troponin

autonomic motor neurons that control smooth muscle contraction have bulbous swellings called ______ that contain synaptic vesicles.

varicosities

In a sarcomere , the __ zone (or band) is the light , central region of the A band ?

H

which are characteristics of oxidative fibers?

-high concentration of myoglobin -good for endurance -use aerobic respiration -red

Which can cause muscle fatigue?

-insufficient Ca2+ -Na+ or K+ imbalances -build up of intracellular Pi

Smooth muscle shows a different length-tension relationship than skeletal muscle because

-it lacks z discs but has dense bodies -the arrangement of the thick and thin filaments allows for contraction even when stretched

In which activities are muscles in an isometric contraction?

-pushing on a locked door -sitting up very straight -holding a yoga pose

A neuromuscular junction contains a

-synaptic cleft -motor end plate -synaptic knob

Place the following events in the correct order of occurrence once ACh diffuses across the synaptic cleft of a NMJ

1. ACh binds to receptors on the motor end plate 2. the resulting action potential moves down the sarcolemma 3. the action potential moves down the t-tubules 4. the action potential reaches the terminal cisternae of the SR 5. calcium ions are released into the sarcoplasm

Place the steps of cross-bridge cycling in order:

1. cross-bridge formation 2. power stroke 3. release of myosin head 4. reset myosin head

The sodium-potassium exchange pump moves ____ sodium ions out of the cell for every ____ potassium ions it brings in.

3;2