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