Chapter 10 Muscular Tissue

List the general functions of muscular tissue.

1.Producing motions. 2.Stabilizing body positions. 3.Storing and moving substances within the body. 4.Generating heat (thermogenesis).

What happens to the I band and H zone as muscle contracts? Do the lengths of the thick and thin filaments change?

Actin and titin anchor into the Z disc. A bands contain myosin, actin, troponin, tropomyosin, and titin; I bands contain actin, troponin, tropomyosin, and titin.

Which of the following are commonly used to produce ATP during skeletal muscle contraction? Aerobic cellular metabolism Anaerobic cellular metabolism Meiosis Creatine phosphate Kreb's cycle

Aerobic cellular metabolism Anaerobic cellular metabolism Creatine phosphate Kreb's cycle

The different types of muscle tissue differ from each other by: -Microscopic Anatomy -type of control (voluntary vs involuntary) -Location -Both microscopic anatomy and location -All of the above

All of the above

After prolonged strenuous exercise has stopped, heavy breathing will often continue for several minutes in order to provide the oxygen needed to... - convert the lactic acid produced during exercise back into glycogen - replace oxygen displaced from muscle myoglobin - resynthesize creatine phosphate - All of these choices - None of these choices

All of these choices -convert the lactic acid produced during exercise back into glycogen - replace oxygen displaced from muscle myoglobin - resynthesize creatine phosphate

Which event occurs during the latent period?

An action potential moves ...

Asynchronous recruitment allows for

An increase in ATP levels Possible relaxation of one or more motor units Sustained contraction in a muscle.

Cross bridges are formed during muscle contraction when _____ on the thick filaments binds to ______ on the thin filaments.

Myosin; actin

A structural protein that is associated with thin filaments and serves to anchor the thin filaments to the Z-discs is called

Nebulin

___________ provides enough energy for approximately 15 seconds of contractions.

Creatine phosphate

Polio is a disease caused by a virus that can attack the somatic motor neurons in the central nervous system. Individuals who suffer from polio can develop muscle weakness and atrophy. In a certain percentage of cases, the individuals may die due to respiratory paralysis. Relate your knowledge of how muscle fibers function to the symptoms exhibited by infected individuals.

Destruction of the somatic motor neurons to skeletal muscle fibers will result in a loss of stimulation to the skeletal muscles. When not stimulated on a regular basis, a muscle begins to lose its muscle tone. Through lack of use, the muscle fibers will weaken, begin to decrease in size, and can be replaced by fibrous connective tissue, resulting in a type of denervation atrophy. A lack of stimulation of the breathing muscles (especially the diaphragm) from motor neurons can result in inability of the breathing muscles to contract, thus causing respiratory paralysis and possibly death of the individual from respiratory failure.

What events occur during the latent period?

During the latent period, the muscle action potential sweeps over the sarcolemma and calcium ions are released from the sarcoplasmic reticulum.

muscle tissue has several important properties, such as electrical excitability. Another property of muscular tissue is that it is able to stretch, and return to its original size and shape. Which property of muscular tissue is this?

Elasticity

Describe the four properties of muscular tissue.

Electrical excitability Contractility Extensibility Elasticity

True/False: Tension on a muscle increases with increasing sarcomere length.

False

_______________ can do work for a moderate length of time such as a 200 meter dash.

Fast oxidative-glycolitive fibers

Where inside a skeletal muscle fiber are Glycolysis and oxidation of pyruvic acid, amino acids, and fatty acids (aerobic respiration) occurs in?

Glycolysis, exchange of phosphate between creatine phosphate and ADP, and glycogen breakdown occur in the cytosol. Oxidation of pyruvic acid, amino acids, and fatty acids (aerobic respiration) occurs in mitochondria.

The contraction cycle will end due to all of the following except

High Calcium levels.

What type of contraction occurs in your neck muscles while you are walking?

Holding your head upright without movement involves mainly isometric contractions.

What causes rigor mortis?

If ATP were not available, the cross‐bridges would not be able to detach from actin. The muscles would remain in a state of rigidity, as occurs in rigor mortis.

Would the peak force of the second contraction in part (b) be larger or smaller if the second stimulus were applied a few milliseconds later?

If the second stimulus were applied a little later, the second contraction would be smaller than the one illustrated in part (b).

which of the following microscopic structures is only found in the cardiac muscle tissue? Sarcomeres Myosin Tropomyosin Striations Intercalated Discs

Intercalated Discs

Transverse tubules are filled with

Interstitial fluid

Holding your phone in front of you (without any motion) involves what type of muscular contraction?

Isometric

Which type of channels are ACh receptors?

Ligand-gated ion channels

During muscle contraction by the sliding filament mechanism, thin filaments are pulled towards the

M-line

What is the effect of the size of a motor unit on its strength of contraction? (Assume that each muscle fiber can generate about the same amount of tension.)

Motor units having many muscle fibers are capable of more forceful contractions than those having only a few fibers.

Weightlifter Jamal has been practicing many hours a day, and his muscles have gotten noticeably bigger. He tells you that his muscle cells are "multiplying like crazy and making him get stronger and stronger." Do you believe his explanation? Why or why not?

Muscle cells lose their ability to undergo cell division after birth. Therefore, the increase in size is not due to an increase in the number of muscle cells but rather is due to enlargement of the existing muscle fibers (hypertrophy). This enlargement can occur from forceful, repetitive muscular activity. It will cause the muscle fibers to increase their production of internal structure

What disorder is characterized by the wasting away of muscles due to the progressive loss of myofibrils? Myasthenia gravis Tremors Fibromyalgia Muscular hypertrophy Muscular atrophy

Muscular atrophy

____________ is considered the motor protein because it can hydrolyze ATP.

Myosin

which of the following functions as a motor protein in all three types of muscle tissue?

Myosin

For hypertrophy to occur in skeletal muscle fibers, which subcellular changes must be seen in a muscle cell? Select all of that apply

Myosin and action will increase in numbers Sarcoplasm increase

Lactic acid can be converted into all of the following except

Oxygen

Which connective tissue coat surrounds groups of muscle fibers, separating them into fascicles?

Perimysium bundles groups of muscle fibers into fascicles.

In a study with mice, satellite cells' productivity can increase in the presence of testosterone. What muscle type cross-section could increase?

Skeletal

Which disorder causes sustained contraction of skeletal muscles that usually affects neck and throat muscles first?

Tetanus

A large motor unit would control which body part? - a muscle required for back support - a muscle of the finger - a muscle involved in facial features - all of these

a muscle required for back support

wave summation is when

a second stimulus excites a partially relaxed muscle.

Which part of a somite differentiates into skeletal muscle?

The myotome of a somite differentiates into skeletal muscle.

What part of the sarcolemma contains acetylcholine receptors?

The part of the sarcolemma that contains acetylcholine receptors is the motor end plate.

Which structure releases calcium ions to trigger muscle contraction?

The sarcoplasmic reticulum releases calcium ions to trigger muscle contraction.

What are the three functions of ATP in muscle contraction?

Three functions of ATP in muscle contraction are the following: (1) Its hydrolysis by an ATPase activates the myosin head so it can bind to actin and rotate; (2) its binding to myosin causes detachment from actin after the power stroke; and (3) it powers the pumps that transport Ca2+ from the sarcoplasm back into the sarcoplasmic reticulum.

Human normally undergo a slow progressive loss of skeletal muscle mass after the age of 30.

True

T/F Alternate contractions allow for sustained contraction in a whole muscle

True

T/F Fused tetanus is caused by rapid muscle stimulations without muscle relaxation.

True

T/F In a motor unit, all muscle cells move together from a single stimulation.

True

T/F: Myofibrils are made of sarcomeres which are made of actin and myosin filaments

True

Which type of smooth muscle is more like cardiac muscle than skeletal muscle, with respect to both its structure and function?

Visceral smooth muscle is more like cardiac muscle; both contain gap junctions, which allow action potentials to spread from each cell to its neighbors.

This is the outermost layer of connective tissue surrounding a skeletal muscle.

epimysium

This is the property of muscle that gives it the ability to stretch without damage

extensibility

ATP is hydrolyzed by the myosin tail.

false

T/F Large motor units are required for the fine force control seen in the muscles of the hand.

false

T/F: Frequency of stimulation of a muscle cell is not a factor that influences tension

false

T/F: during a muscle contraction, actin binds to myosin

false

T/F: the myosin head detaches from the actin filament after new ATP binds to myosin

false

The perimysium surrounds

fascicles

muscles that tire quickly and rely on anaerobic glycolysis will have contractions that are

fast

What type of skeletal muscle fiber would an Olympic quality weight lifter specifically be developing during training, to enhance his or her weight lifting power?

fast glycolytic fibers

Leg muscles are predominantly composed of which type of muscle fiber

fast oxidative-glycolytic

A period of sustained skeletal muscle contraction in which individual twitches can not be detected is called

fused tetanus

After several visits to the gym and serious "iron pumping" (strength training) you notice that your biceps have enlarged. What has happened to your muscles?

hypertrophy

As one ages, the presence of slow oxidative fibers ....

increases

This structure is unique to cardiac muscle cells, and allows individual cells to be firmly attached to each other (to provide mechanical strength during contraction), and also allow the action potential to spread rapidly through the cardiac muscle tissue, so that contractions are smooth and coordinated.

intercalated discs

When oxygen is plentiful inside a skeletal muscle cell, what happens to the pyruvic acid that is formed during glycolysis?

it diffuses into mitochondria to be broken down to generate ATP

Which of the following is not a function of skeletal muscle tissue? 1) moving your eyes from left to right as you read this question 2) holding your head up 3) shivering to generate body heat when you've become chilled 4) stabilizing joints and helping to maintain body positions 5) moving food through the small intestine

moving food through the small intestine

A small amount of muscle tension and muscle definition (the appearance of muscle beneath the skin) is present even in a relaxed muscle. A person who is physically fit due to regular exercise, will have more of this characteristic of muscle tissue than someone who is not fit. What is this characteristic?

muscle tone

The contractile organelles of a skeletal muscle fiber are thread-like structures called

myofibrils

Which of the following molecules found in skeletal muscle cells binds oxygen that can later be used during aerobic metabolism to help generate ATP?

myoglobin

your patient has a large, soft lump in her thigh. after biopsy, you discover this is

myoma

A powerstroke is caused by the ATP hydrolysis and phosphate release, binding and movement of multiple _____ molecules.

myosin

During a muscle twitch, all of the following happens during the latent phase except: - Crossbridge Formation - Calcium Release - myosin contraction of actin filaments - Titin is stretched

myosin contraction of actin filaments

The site where a somatic motor neuron releases acetylcholine to stimulate a skeletal muscle fiber is called the

neuromuscular junction

Lactic acid can be converted into all of the following except

oxygen

because cardiac muscle depends on aerobic respiration to make atp, it requires a constant supply of

oxygen

Skeletal muscle is covered, surrounded and protected by various layers of connective tissue. Which layer of connective tissue would surround a bundle of muscle fibers (muscle cells)?

perimysium

Rotation of the myosin head toward the M line occurs during

power stroke

The basic functional unit of a myofibril is a/an

sarcomere

In smooth muscle most of the calcium comes from

sarcoplasmic reticulum and interstitial fluid

Regeneration of damaged skeletal muscle cells occurs via

satellite cells

The epimysium surrounds

skeletal muscle

If you are an endurance athlete, you especially rely on which type of skeletal muscle fiber to perform your sport?

slow oxidative fibers

Which muscle does not have a sarcomere?

smooth

Which of the following muscle types is responsible for controlling blood pressure?

smooth

Which type of muscle tissue is involuntary (can't be consciously controlled)? skeletal muscle smooth muscle cardiac muscle skeletal muscle and smooth muscle smooth muscle and cardiac muscle

smooth muscle and cardiac muscle

Depending on how specialized a type of muscle tissue is, the muscle fibers or cells of that tissue will have varied abilities to regenerate (healing and production of new cells). What type of muscle tissue has the greatest ability to regenerate?

smooth muscle cells have the greatest ability to regenerate

Smooth muscle fibers do not have striations like skeletal and cardiac muscle cells do. This is because:

smooth muscle fibers contain thin and thick filaments, as well as intermediate filaments, but none of them are arranged in sarcomeres

What features distinguish the three types of muscular tissue?

structure, location, function, and means of activation

In Neuromuscular Junctions, synaptic vesicles containing acetylcholine are found suspended in the cytosol of...

synaptic end bulbs

Release of calcium from these structures triggers skeletal muscle contraction

terminal cisterns of sarcoplasmic reticulum

The contractile organelle of skeletal muscle fibers is

the myofibril

What regulatory proteins can be found in the thin filaments of skeletal muscle fibers?

tropomyosin and troponin

which protein does calcium bind to?

troponin

T/F Titin is a very elastic molecule, which pulls the muscle back into its original position after contraction.

true

T/F: calcium binds to the troponin-tropomyosin complex and allows myosin to access the actin filaments

true

T/F: the myosin head detaches from the actin filament after new ATP binds to myosin

true

Which is the first step of a contraction cycle?

ATP is hydrolyzed by the myosin head

At what age does the slow, progressive loss of skeletal muscle mass occur?

30-50 years of age

How much of the total body weight of an average adult is muscle tissue?

40 - 50%

In what part of the sarcomere does actin and myosin overlapping?

A Band

Why is tension maximal at a sarcomere length of 2.2 μm?

A sarcomere length of 2.2 μm gives a generous zone of overlap between the parts of the thick filaments that have myosin heads and the thin filaments without the overlap being so extensive that sarcomere shortening is limited.

A treatment for myasthenia gravis is pyridostigmine which stops ACh from being broken down. Which does pyridostigmine inhibit?

AChE

What energizes the myosin head?

ATP hydrolysis reaction

Which somatic region will develop into the vertebrae?

C. sclerotome

Which ion is required for exocytosis of ACh?

Ca+2

Which event occurs during cardiac muscle cell contractions?

Ca2+ cause a conformational change in troponin, which moves tropomyosin.

What muscles have desmosomes and gap junctions?

Cardiac and smooth

Chicken breasts are composed of "white meat," whereas chicken legs are composed of "dark meat." The breasts and legs of migrating ducks are dark meat. The breasts of both chickens and ducks are used in flying. How can you explain the differences in the color of the meat (muscles)? How are they adapted for their particular functions?

The "dark meat" of both chickens and ducks is composed primarily of slow oxidative (SO) muscle fibers. These fibers contain large amounts of myoglobin and capillaries, which accounts for their dark color. In addition, these fibers contain large numbers of mitochondria and generate ATP by aerobic respiration. SO fibers are resistant to fatigue and can produce sustained contractions for many hours. The legs of chickens and ducks are used for support, walking, and swimming (in ducks), all activities in which endurance is needed. In addition, migrating ducks require SO fibers in their breasts to enable them to have enough energy to fly for extremely long distances while migrating. There may be some fast oxidative-glycolytic (FOG) fibers in the dark meat. FOG fibers also contain large amounts of myoglobin and capillaries, contributing to the dark color. They can use aerobic or anaerobic cellular respiration to generate ATP and have high‐to‐moderate resistance to fatigue. These fibers would be good for the occasional "sprint" that ducks and chickens undergo to escape dangerous situations. In contrast, the white meat of a chicken breast is composed primarily of fast glycolytic (FG) fibers. FG fibers have lower amounts of myoglobin and capillaries that give the meat its white color. There are also few mitochondria in FG fibers, so these fibers generate ATP mainly by glycolysis. These fibers contract strongly and quickly and are adapted for intense anaerobic movements of short duration. Chickens occasionally use their breasts for flying extremely short distances, usually to escape prey or perceived danger, so FG fibers are appropriate for their breast muscle.

What would happen if ATP suddenly were not available after the sarcomere had started to shorten?

The I bands and H zones disappear during muscle contraction; the lengths of the thin and thick filaments do not change.

What happens with the I band when the sarcomere contracts?

The I bands shortens during contraction

Which of the following is the smallest: muscle fiber, thick filament, or myofibril? Which is largest?

The following are arranged from smallest to largest: thick filament, myofibril, muscle fiber.

What are the main contractile proteins that thin and thick filament a sarcomere called

actin and myosin

a motor unit consists a motor neuron and ...

all the muscle fibers it innervates or supplies.

Which list of organs contains smooth muscle tissue? 1) blood vessels, stomach, esophagus 2) bladder, uterus, small intestine 3) biceps brachii, triceps brachii (muscles of the arm)heart 4) both blood vessels, stomach, esophagus and bladder, uterus, small intestine

both blood vessels, stomach, esophagus and bladder, uterus, small intestine

Autonomic motor neurons regulate:

both smooth and cardiac muscle

Calcium muscle contraction will continue to occur as long as the following chemicals are available in the cytosol of the muscle fiber

calcium ions and ATP

Which muscle(s) is/are controlled by the autonomic nervous system?

cardiac and smooth