Ch. 10a HW SmartBook

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

A; H

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

Blank 1: fatigue

A single motor neuron and the skeletal muscle fibers it controls is called a ______.

motor unit

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

reduced stimulation

Somatic motor neurons innervate ______ muscle.

skeletal

The expanded tip of an axon is called a ______.

synaptic knob

A skeletal muscle cell is also called a muscle _____.

Blank 1: fiber or fibers

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

more

Skeletal muscle contraction is controlled by _____ neurons.

motor

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

motor end plate

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

motor neuron

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

Blank 1: myoglobin

Contraction of specific skeletal muscles stabilizes joints and helps maintain the body's _____ by holding the head and truck erect.

Blank 1: posture, position, or structure

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

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.

When an action potential travels down T-tubules to the terminal cisternae of the SR, what ion is released into the sarcoplasm?

calcium

The synaptic knob of the neuron is a(n) ______ of an axon.

expanded tip

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

What part of a myosin molecule does ATP bind to?

head

Eccentric contractions actively ______ a muscle.

lengthen

Thick filaments are assembled from bundles of the protein called _____.

myosin

A nerve impulse travels through an axon to its ______.

synaptic knob

Which can cause muscle fatigue?

-build up of intracellular P1 - insufficient Ca2+ - Na+ or K+ imbalances (357)

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

Excitability

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

True

True or false: Postural muscles contract continuously when a person is awake to prevent collapse of the body.

True

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

glycolytic; oxidative

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

head

An increase in muscle fiber number is called ______.

hyperplasia

A type of muscle contraction in which there is no movement of the muscle is an ______ contraction.

isometric

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

elasticity

True or false: A byproduct of anaerobic respiration is lactic acid.

True

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 motor neuron axon travels through the epimysium and perimysium and enters the ______, where it delivers a nerve impulse to an individual ______.

endomysium; muscle fiber

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

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

mitochondria

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

muscle tension

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

myofilaments

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

myosin heads

Where a motor neuron axon terminal and a muscle cell meet is called a _____ junction.

neuromuscular

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

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

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

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

two

Thick filaments are about ______ the diameter of thin filaments.

two times

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

Each muscle fiber is controlled by one ______ neuron.

motor

Myofibrils consist of bundles of short ______.

myofilaments

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

sarcomeres

At the end of contraction, when the stimulation from the nerve impulse ceases, calcium ions are pumped back into the ______.

sarcoplasmic reticulum

Attached to the skeleton and surrounding the openings of the urinary and gastrointestinal traces are locations of ______ muscle.

skeletal

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

troponin

Skeletal muscle fibers are classified into three types based on what two characteristics?

type of contraction and ATP supply

The cyclic events of "attach, pivot, detach, return" continue as long as _____ ions remain bound to the troponin.

Blank 1: calcium, Ca, Ca2+, or Ca++

The enzyme acetylcholinesterase resides in the synaptic _____.

Blank 1: cleft

The sarcoplasm of a skeletal muscle fiber contains hundreds to thousands of long, cylindrical structures called _____ that extend the length of the cell.

Blank 1: myofibrils

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

Blank 1: phosphate

A (An) _______ contraction of the arm muscles allows you to lift a book from the table, whereas a (an) ______ contraction of the arm muscles allows you to lower the book back down to the table.

concentric; eccentric

The expansive sheet of dense irregular connective tissue that separates individual muscles is called the ______.

deep fascia

In an isometric contraction, the muscle ______ body movement.

does not produce

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

elasticity

An increase in muscle fiber size is called _____.

hypertrophy

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

Blank 1: isometric or Isometric

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 _____.

Blank 1: recruitment

According to the sliding filament theory, when a muscle contracts, thick and thin filaments _____ past each other, and the _____ shortens.

Blank 1: slide or move Blank 2: sarcomere, muscle, or myofibril

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

Blank 1: summation

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

Blank 1: twitch

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

Sarcoplasm

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: 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

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

To start a muscle contraction, a nerve impulse causes ______ release at a neuromuscular junction.

acetylcholine

To stop motor end plate stimulation, usually acetylcholine is quickly broken down and removed from the receptor by ______.

acetylcholinesterase

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

Each myosin head in a thick filament can bind to the protein in a thin filament called _____.

actin

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

aerobic respiration

A muscle cell obtains ATP in the short term via what process?

anaerobic respiration

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

areolar

Functionally, troponin provides a binding site for ______ ions.

calcium

Hyperplasia is an increase is muscle ______.

cell numbers

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

There are two types of isotonic contractions, which include eccentric and _____.

concentric

The diameter of a muscle fiber will predict ______.

how much power it will produce

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

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

into

In the picture of the adult holding the baby in a steady or constant position, the type of contraction that is represented is an _____ contraction.

isometric

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

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

sarcoplasmic

A neuromuscular junction contains a(n) ______.

synaptic knob, motor end plate, synaptic cleft

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

t

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

tension

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

their ATPase which splits ATP

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

In a muscle cell at rest, the myosin heads of a thick filament point ______ the sarcomere.

toward the ends of

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

Concentric isotonic contractions actively ______ a muscle.

shorten

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

ATP

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

Blank 1: sliding

Muscle cells store oxygen bound to a _____ molecule?

Blank 1: Myoglobin or myoglobin

Thick myofilaments are composed of bundles of _____ protein molecules.

Blank 1: Myosin or myosin

The arrival of a nerve impulse at the synaptic knob of a motor neuron causes synaptic vesicles to release _____ into the synaptic cleft.

Blank 1: acetylcholine, ACh, or neurotransmitter

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

Heat production

True or false: Atrophy is a wasting of tissue that results in a reduction in muscle size, tone, and power.

True

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

aerobic

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

aerobic

The ATP needed to fuel a 100m sprint would be supplied primarily from ______.

anaerobic respiration

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

anaerobic/ aerobic

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

fast/intermediate

Aerobic respiration requires the presence of what molecule?

oxygen

The immediate supply of ATP for use in muscle contraction is generated by the ______ system.

phosphagen

The plasma membrane of a skeletal muscle fiber is called the _____.

sarcolemma

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

ACh