chapter 9

Thin filaments composed primarily of the protein Intracellular

Actin

A _________ works against the action

Antagonist

Shortening occurs

Concentric

________ muscle cells are shorter than the fibers of skeletal muscle, and they have single, centrally located nuclei.

Smooth

The striations seen in skeletal muscle consist of alternating dark bands, called the ____ bands, and light bands, called the ____ bands.

A & I

Composed of thick myosin filaments overlapping thin actin filaments

A bands (dark bands)

The site of this functional connection is called a _______.

Synapse

bundles of skeletal muscle fibers within a muscle Surrounded by perimysium

fascicles

In general, oxygen debt develops as a result of:

strenuous exercise

________ _________ that forms the connective tissue layer of the serous membranes covering organs in various body cavities and lining those cavities.

subserous fascia

In order for a skeletal muscle fiber to contract, calcium must bind to

troponin

Name the functional units of contraction in a muscle fiber

Sarcomeres

Fulcrum-resistance-force

Second class lever

In ____ muscle, myofilaments are arranged into sarcomeres

cardiac and skeletal

In _____ muscle, some calcium needed for contraction is from the extracellular fluid

cardiac and visceral smooth

In ______ muscle, muscle impulses pass freely from cell to cell, resulting in contraction of the entire muscle, not just individual fibers

cardiac and visceral smooth

Which of the following best describes myofibrils?

comprised of thick and thin filaments

Which of the following equations best describes how the muscle cell can replenish ATP when ATP levels are low?

creatine phosphate + ADP → creatine + ATP

The force that shortens the sarcomeres comes from

cross-bridges pulling on the thin filaments.

the portion of the network that surrounds the muscles is called deep _________ ________.

deep fascia

Which muscle is the prime mover of shoulder abduction (abduction of the arm)?

deltoid

Of the energy released during cellular respiration, less than half is used to produce ATP. What is the fate of the rest of the released energy?

it becomes heat

Describe the role of acetylcholinesterase in stimulation of a muscle

it is the enzyme that breaks down acetylcholine in the synaptic cleft, ending stimulation of the muscle fiber.

Which type of muscle is most likely found in the walls of large blood vessels?

malunit smooth muscle

A ______ includes a motor neuron and all of the muscle fibers that it controls

motor unit

The inability of a muscle to contract after rigorous exercise is the definition of:

muscle fatigue

What word segment means "muscle"?

myo-

the sarcoplasm also has abundant long parallel structures called

myofibrils

thick filaments composed of the protein Intracellular

myosin

Name of the type of synapse that occurs between a motor neuron and a muscle fiber

neuromuscular junction

Compared to skeletal muscle, smooth muscle:

takes longer to contract and can stay contracted longer

_________ affects the tendon and ___________ affects the connective tissue sheath of the tendon.

tendinitis, tenosynovitis.

fibers in a _____ may intertwine with those in the periosteum of a bone, attaching the muscle to the bone.

tendon

What is necessary for both muscle contraction and muscle relaxation

ATP

The neurotransmitter that is released at neuromuscular junctions and that stimulates skeletal muscle to contract is ______.

Acetylcholine

What is the name of the neurotransmitter used at a skeletal neuromuscular junction?

Acetylcholine

_______________ is the neurotransmitter that motor neurons use to control skeletal muscle contraction.

Acetylcholine

_____ molecules are globular, and each has a binding site to which the heads of the myosin molecule can attach

Actin

Each neuron has a process called an axon, which extends from the cell body and can conduct electrical impulses called ________ __________.

Action potentials

A _______ causes an action

Agonist

An action, such as flexing the knee, is caused by the contraction of a muscle acting as an ______ and is opposed by a muscle acting as an ______.

Agonist; antagonist

Which of the following is an effect of exercise on the muscular system?

An increase in proimflammatory molecules that can result in the formation of new muscle cells

Which of the following is an effect of exercise on the muscular system?

An increase in proimflammatory molecules that can result in the formation of new muscle cells.

Muscles that flex the wrist are found on the _____ side of the forearm while those that extend the wrist are found on the _____ side of the forearm.

Anterior; posterior

Are composed of thin actin filaments held by direct attachments to structures called z lines.

I bands (light bands)

The opposing ends of cardiac muscle cells are connected by cross hands called

Intercalated disc

These fibers have the fast-twitch speed associated with white fibers with an intermediate oxidative capacity

Intermediate fibers

When a muscle contracts, its ___________ is pulled toward the _______.

Intersection; origin

Equal length, change in force

Isometric

Equal force, change in length

Isotonic

Smooth muscles don't have troponin, instead they use a protein called

Calmodulin

when the resulting forceful, sustained contraction lacks even partial relaxation, it is called a ___________ __________ ____________.

Complete tetanic contraction

What are intercalated discs found in cardiac muscle cells?

Complex membrane junctions that include desmosomes and gap junctions.

Which muscle group is composed of mainly slow-twitch (type I) fibers?

Erector spinae muscles of the back

Are also called white fibers because they have less myoglobin and have a poorer blood supply than red fibers.

Fast twitch glycolic fibers (type 2b)

Which muscle fiber type is most fatigable?

Fast-twitch (Type IIb)

May be primarily glycolic (fatiguable) or primarily oxidative (fatigue resistant)

Fast-twitch (type 1)

Which of the following describes smooth muscle contraction but not skeletal muscle contraction?

Hormones can inhibit muscle contraction

When skeletal muscles may not be able to supply enough oxygen to sustain aerobic reactions of cellular respiration. Might be limited to anaerobic reactions to produce ATP

Lactic acid threshold or anaerobic threshold

The A band includes a thickening known as the ___ ______ which consists of proteins that help hold thick filaments in place.

M line

The muscle cells are less well organized and function as separate units, independent of neighboring cells.

Malunit smooth muscle

Neurons that control effectors, including skeletal muscle fibers, are called _________ _____________.

Motor neurons

What is the result of a muscle contraction

Movement within the myofibrils in which the filaments of actin and myosin slide past one another, shortening the sarcomeres.

A bundle of fascicles Surrounded by epimysium

Muscle

The body attacks the muscular system, the name means grave muscular weakness, the body produces antibodies that target receptors for the neurotransmitter acetylcholine on skeletal muscle cells at neuromuscular junctions.

Myasthenia Gravis

Is synthesized in muscle cells and imparts the reddish brown color of skeletal muscle tissue Temporarily stores oxygen

Myoglobin

During the contraction cycle, what is the result of ATP binding to myosin?

Myosin heads release from the binding site on actin

The synapse where a motor neuron axon and a skeletal muscle fiber meet is called a

Neuromuscular junction

Neurons communicate with the cells that they control by releasing chemicals called _____________________, at a synapse.

Neurotransmitters

At higher frequencies of stimulation, as the time spent in relaxation becomes very brief, a condition called __________ ___________ results.

Partial tetany

Consists of alternate contractions and relaxations of the longitudinal and circular muscles

Peristalsis

Fibers, such as those in the long muscles of the back, are also called red fibers because they contain the red oxygen storing pigment myoglobin.

Slow-twitch (type 1)

Always oxidative and are therefore resistant to fatigue

Slow-twitch fibers (type 1)

In a sustained contraction , the force of individual twitches combines by the process of ____________.

Summation

A small gap called the _________ ___________ separates the membrane of the neuron and the membrane of the muscle fiber.

Synaptic cleft

Contribute to an action by helping the agonist

Synergists

An ion will diffuse across a cell membrane only if two conditions are met

There is a concentration gradient and the membrane is permeable to that ion

The smallest stimulus strength that triggers a contraction in a muscle fiber is called a ______ stimulus.

Threshold

__________ molecules are rod shaped and occupy the longitudinal grooves of the actin helix

Tropomyosin

________ molecules have three protein subunits and are attached to actin

Troponin

According to sliding filament model

When sarcomeres shorten, the thick and thin filaments do not change length.

Appear in the center of I bands

Z lines

A contractile response of a single muscle fiber to a single muscle impulse is called

a twitch

In general, oxygen debt develops as a result of:

actin

may attach to bone or the coverings of adjacent muscles.

aponeuroses

Muscle contractions that generate less force than the resistance and result in lengthening of the muscle are called:

eccentric contraction

each muscle fiber within a fascicle lies within a layer of connective tissue in the form of a thin covering called ________.

endomysium

the layer of connective tissue that closely surrounds a skeletal muscle is called the ____________.

epimysium

The connection between stimulation of a muscle fiber and contraction is called ________________________, and it involves an increase in calcium ions in the cytosol.

excitation-contraction coupling

an individual skeletal muscle is separated from adjacent muscles and held in position by layers of dense connective tissue called __________.

fascia

Muscles that move the thigh have their insertions on the

femur

Which class of lever has the fulcrum in the center with resistance and the force being on opposite ends?

first class lever

The metabolic process that generates a net of two ATP molecules in the cytosol of a muscle fiber is called:

glycolosis

Contraction of the splenius capitis and semispinalis capitis will move the:

head

At what level of organization is a skeletal muscle, such as the biceps brachii?

organ

Another layer of connective tissue, called the _______, extends inward from the epimysium and separates the muscle tissue into small sections.

perimysium

Within a skeletal muscle, fascicles are separated from each other by connective tissue called the _____, and muscle fibers are separated from each other by connective tissue called the _____.

perimysium; endomysium

muscle cell membrane

sarcolemma

The striations form a repeating pattern of units called

sarcomeres

The amount of oxygen needed to repay the oxygen debt includes

the amount of oxygen that muscle cells need to resynthesize ATP

Define muscle tone.

the contraction of muscle while at rest

The type of smooth muscle in which all of cells contract together is ______ smooth muscle

visceral

The type of smooth muscle in which all of cells contract together is ______ smooth muscle.

visceral