Ch. 10: Muscle Tissue

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

I band

light band containing thin filaments only

Z disc

made of dark proteins that create a zig-zag line

Because muscle cells require a huge amount of ATP in order to contract, they have a large number of which organelle?

mitochondria

Slow fibers have a relatively large number of ______. This permits slow muscle fibers to produce a greater amount of ______ than fast muscle fibers while contractions are underway.

mitochondria; ATP

Athletes have more defined muscles than non-athletes even while at rest because they have ______ motor units contracting all the time.

more

Neurons that stimulate muscle contraction are called ______ neurons.

motor

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

motor neuron

In a motor unit, a single _____ neuron typically controls numerous muscle fibers in a muscle.

motor or somatic

muscle fiber

muscle cell

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

Excitability

True or false: Smooth muscle cells lack transverse tubules.

True

Storage and movement of materials

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

sarcomere

functional contractile unit of skeletal muscle

Smooth muscle cells are ______ in shape.

fusiform

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

fusiform

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

head

What part of a myosin molecule does ATP bind to?

head

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

In which activities are muscles in an isometric contraction?

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

The diameter of a muscle fiber will predict ______.

how much power it will produce

An increase in the number of mitochondria can be observed in ______.

hypertrophy

thin filament

composed of actin, troponin, and tropomyosin bind to thick filaments and cause contraction

thick filament

composed of myosin bind to thin filaments and cause contraction

H zone

contains thick filaments only lighter region in the middle of an A band

When smooth muscle is stretched, it responds by ______.

contracting then relaxing

You make a New Year's resolution to work out more and by March notice your muscles are getting bigger. This is a result of muscle ______.

hypertrophy

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

isometric or Isometric

myofibrils

cylindrical organelles specialized for contraction contain myofilaments that are responsible for muscle contraction

Sarcoplasm is another term for skeletal muscle ______.

cytoplasm

sarcoplasm

cytoplasm of a muscle cell (fiber)

A band

dark band containing both actin and myosin

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

debt or deficit

In an isometric contraction, the muscle ______ body movement.

does not produce

In an isometric contraction, the muscle ______ body movement. Multiple choice question.

does not produce

actin

double-stranded contractile protein binding site for myosin to shorten a sarcomere matches two intertwined strands; each bead has a myosin-binding site

tropomyosin

double-stranded regulatory protein covers the active sites on actin when muscle cell is at rest two intertwined strands; cover myosin-binding sites

Muscle tissue demonstrates the property of _____ when it is done contracting and returns to its resting length.

elasticity

In a muscle there are concentric layers of connective tissues. From deep to superficial these connective tissue layers are the

endomysium perimysium epimysium

The connective tissue layer that surrounds an entire muscle is called ______.

epimysium

The three connective tissue layers surrounding the individual components of a muscle are the

epimysium perimysium endomysium

A skeletal muscle cell is also called a muscle

fiber

What is the force generated when a skeletal muscle is stimulated to contract called?

muscle tension

After the age of 30, the number of ______ in existing muscle fibers decreases.

myofibrils

The sarcoplasm of a skeletal muscle fiber contains hundreds to thousands of long, cylindrical structures called

myofibrils

Muscle fibers contain cylindrical structures called myofibrils, which are composed of ______.

myofilaments

Myofibrils are made of ______.

myofilaments

Myofibrils consist of bundles of short ______.

myofilaments

Termination of the nerve impulse at an NMJ results in the passive sliding of ______ back to their original state.

myofilaments

Thick filaments are assembled from bundles of the protein called

myosin

Thick myofilaments are composed of bundles of _____ protein molecules.

myosin

T-tubule

narrow, tubular extensions of the sarcolemma into the sarcoplasm

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

As you struggle to twist open a jar, more motor units are called into action until you finally generate enough force to open it. This is an example of ______.

recruitment

An internal membrane complex in skeletal muscle cells that is similar to the smooth endoplasmic reticulum of other cells is called the sarcoplasmic

reticulum

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

shorter; 1-2

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

skeletal

Somatic motor neurons innervate ______ muscle.

skeletal

The _____ filament theory explains how muscle fibers shorten during contraction.

sliding

sarcoplasmic reticulum

smooth endoplasmic reticulum in a muscle fiber

A "step-wise" increase in the force of contraction of a single muscle fiber or single motor unit due to repeated stimulation is called

summation

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

tension

relaxation period

tension decreases

contraction period

tension increases

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

terminal cisternae

The epimysium of a muscle surrounds ______.

the entire skeletal muscle

Slow-twitch and fast-twitch muscle fibers differ primarily in ______. Multiple choice question.

their ATPase which splits ATP

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

The H band (or H zone) is more lightly shaded because only _____ filaments are present.

thick or myosin

Single unit muscle cells contract ______.

together

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

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

transverse tubules

As the troponin changes shape (due to binding calcium), it moves the ______ molecule to which it is attached, thus exposing the active sites on the G-actin molecules.

tropomyosin

Calcium ions bind to what protein in a thin myofilament?

troponin

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

troponin

A single contraction and relaxation of a muscle fiber is referred to as a muscle

twitch

Each myosin protein molecule in a thick filament consists of ______ strands.

two

Thick filaments are about ______ the diameter of thin filaments.

two times

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

actin

M line

appears as a dark protein disc in center of H zone

Smooth muscle is found where in the respiratory system?

around the bronchioles

The connective tissue layers in muscle provide protection, distribution sites for blood vessels and nerves, and a means of ______ to the skeleton.

attachment

troponin

bound to tropomyosin; can bind calcium ions

Which can cause muscle fatigue?

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

fascicles

bundles of muscle fibers

Functionally, troponin provides a binding site for ______ ions.

calcium

The sarcolemma of smooth muscle cells has small invaginations called ______.

caveolae

A muscle fiber is what level of organization in the body?

cellular

During the development of skeletal muscle cells, some myoblasts do not fuse and instead become ______ cells.

satellite

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

satellite or stem

the events that occur at a neuromuscular junction in order.

1st - nerve signal arrives at synaptic knob 2nd - calcium enters and binds synaptic vesicle 3rd - ACh is released via exocytosis into the synaptic cleft 4th - ACh binds receptors on the motor end plate

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

A band

Glycolysis and aerobic respiration are used to generate ______ in muscle fibers.

ATP

Posture

Contraction of specific skeletal muscles stabilizes joints.

True or false: A muscle fiber that is partially shortened can produce a contraction stronger than the contraction it can produce when at its resting length.

False

At maximal contraction of a muscle fiber, the thin filaments are pulled into the ______ zone which disappears.

H

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

H

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

H

Temperature regulation

Heat is produced as a waste product of energy usage

The act of shivering is an example of skeletal muscle performing what function?

Heat production

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

I; thin

The ______ line is a thin, transverse, protein meshwork structure in the center of the H zone of a sarcomere.

M

Body movement

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

Muscle cells store oxygen bound to a _____ molecule?

Myoglobin or myoglobin

True or false: Skeletal muscle is usually attached to the skeleton, but it is also found at the openings between the digestive tract and the external environment and the urinary tract and the opening to the external environment.

TRUE

Deep invaginations of sarcolemma are called ______.

T-tubules

When calcium ions bind to troponin, which of the following then occurs?

The myosin-binding sites on actin are exposed.

Smooth muscle cells retains their mitotic ability.

True

True or false: A single myofibril runs the length of the muscle fiber.

True

True or false: In the absence of calcium, troponin attaches to tropomyosin to hold it in place on the surface of the F actin strand.

True

True or false: Most muscles contain a combination of all three muscle types, slow oxidative, fast oxidative, and fast glycolytic.

True

Slow and intermediate fibers require oxygen to produce ATP, so the metabolic reactions within these fibers are termed ______. Multiple choice question.

aerobic

In a muscle cell, the short-term energy is supplied by ______ respiration, whereas long-term energy is supplied by ______.

anaerobic; aerobic

In a transverse section of a muscle, you can see that each skeletal muscle is actually composed of many

fascicles

A piano player uses her hands for brief quick movements. Which muscle fiber type would you therefore predict to be predominant in these muscles?

fast glycolytic

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

fatigue

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

fatigue or tire

Smooth muscle is found in which of the following locations?

in the wall of the small intestine around blood vessels in wall of the uterus

Multiunit smooth muscle cells are stimulated ______.

individually

Cardiac muscle cells form Y-shaped branches and join to adjacent muscle cells at junctions called

intercalated

When a nerve impulse reaches the end of an axon of a neuromuscular junction, calcium flows ______ the synaptic knob.

into

Smooth muscle contraction is under ______ control.

involuntary

After you stop running, you notice that you keep breathing heavily for some time. This is because your body is in ______.

oxygen debt

sarcolemma

plasma membrane of a muscle fiber

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

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

sarcolemma

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 contractile units known as

sarcomeres or sarcomere

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

sarcoplasm

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

sarcoplasmic