Ch. 8 Human Anatomy Test
The segment of a muscle fiber that contains both actin and myosin is the
A band
The dark bands in skeletal muscle that contribute to its striated appearance are known as
A bands
What are fascicles?
A small bundle of muscle fiber
A person feels out of breath after vigorous exercise because of oxygen debt. Which of the following statements helps explain this phenomenon?
Anaerobic respiration increases during strenuous activity, Conversion of lactic acid to glycogen occurs in the liver and requires energy, Priority in energy use is given to ATP synthesis
A motor neuron connects to a single muscle fiber.
False
An influx of potassium ions into the muscle fiber is responsible for cross-bridging of actin and myosin filaments.
False
Layers of connective tissue that extend into muscle and form compartments within the muscle are fascicles.
False
Much of the heat of the body is produced by the metabolic activities of viscera.
False
Oxygen is stored in muscle tissue in molecules of located near mitochondria.
False
The energy source for conversion of ADP to ATP in an actively contracting muscle is creatine phosphate.
False
The sarcoplasmic reticulum is composed of invaginations of the muscle cell membrane that contain extracellular fluid.
False
List the three types of muscle
Skeletal, smooth, cardiac
A skeletal muscle fiber is an individual cell that contracts and shortens when stimulated.
True
During muscle contraction, the head of myosin cross-bridges attach to actin binding sites and bend slightly pulling the actin filament toward the center of the sarcomere
True
Muscle fatigue is the inability to contract after a period of sustained, strenuous exercise.
True
Skeletal muscle is composed of multiple layers surrounded by connective tissue.
True
Skeletal muscle is composed of skeletal muscle tissue, nervous tissue, blood, and connective tissue.
True
The severity of muscle strain depends on the number of muscle fibers that are damaged.
True
The sarcomere, the basic unit of skeletal muscle extends from
Z line to Z line
Describe the structure and function of a sarcomere
a contractile unit in a striated muscle fiber (cell) extending from one Z line to the next Z line
What is a cross-bridge?
a myosin molecule composed of two twisted protein strands with globular parts
Define all-or-none response
a skeletal muscle fiber normally does not contract partially; if it contracts at all, it contracts fully
Muscle tone refers to
a state of sustained, partial contraction of muscles that is necessary to maintain posture
The chemical that is necessary for the transmission of an impulse from a nerve to a muscle fiber is
acetylcholine
When a nerve impulse reaches the end of a motor neuron,
acetylcholine is released
Two neurotransmitters that affect smooth muscle are ___________ and ____________
acetylcholine, norepinephrine
The action of acetylcholine is halted by the enzyme
acetylcholinesterase
The characteristic striated appearance of skeletal muscle is due to the arrangement of alternating protein filaments composed of __________ and __________
actin, myosin
What is the function of these channels?
activate the muscle contraption mechanism when the fiber is stimulated
The energy used in muscle contraction is supplied by the decomposition of
adenosine triphosphate (ATP)
myosin filaments contain
an enzyme ATPase
During high intensity exercise, muscle fibers rely upon what process for energy?
anaerobic respiration
Smooth body movements depend on _____________ giving way to prime movers
antagonists
When this tissue extends beyond the muscle to form a sheetlike structure, it is called a(n) _____________
aponeuroses
A fibrous, flattened, sheet-like tendon is known as
aponeurosis
The muscle that compresses the cheeks inward when it contracts is the
buccinator
The ion necessary to link myosin and actin is
calcium
Peristalsis is due to which of the following characteristics of smooth muscle?
capacity of smooth muscle fibers to excite each, rhythmicity
The kind of energy that muscles use to contract is
chemical
A substance that stores energy released when stores of the substance in number 10 are in low supply is ____________ __________
creatine phosphate
Opposing ends of cardiac muscle fibers are connected by ____ - ____ ____________
cross-bands intercalated discs
Atrophy refers to a(n) (increase, decrease) in the size and strength of a muscle
decrease
The muscle that abducts the upper arm and can both flex and extend the gamers is the
deltoid
The muscle that abducts the upper arm and can both flex and extend the humerus is the
deltoid
The connective tissue that surrounds individual muscle fibers is
endomysium
A skeletal muscle is held in position by layers of fibrous connective tissue called _________
fascia
An individual skeletal muscle is separated from adjacent muscles by
fascia
Which of the following muscles produce plantar flexion?
gastrocnemius
The heaviest muscle in the body, which serves to straighten the leg at the hip during walking is the
gluteus maximus
Less than half the energy released by cellular respiration is available for metabolic processes. The rest is lost as _________
heat
Where is multiunit smooth muscle found?
in the irises of the eyes and the walls of blood vessels
Describe recruitment
increase in the number of motor units being activated
Oxygen debt secondary to strenuous exercise is due to
insufficient oxygen to promote conversion of lactic acid to glucose, lack of available oxygen to convert ADP to ATP
The rapidity with which an impulse spreads in cardiac muscle is due to
intercalated disks between muscle fibers
After prolonged muscle use, muscle fatigue occurs due to an accumulation of ________ ________
lactic acid
The period of time between a stimulus to a muscle and muscle response is called the
latent period
The band of tough connective tissue that extends from the xiphoid process to the symphysis pubis and serves as an attachment for muscles of the abdominal wall is the _________ ___________
linea alba
Muscles that are involved in chewing are attached to the
mandible
The insertion of the sternocleidomastoid is the
mastoid process of the temporal bone
An injury in which a few muscle fibers are torn but the fascia is left intact is called a _________ __________ __________
mild muscle strain
Define threshold stimulus
minimal strength required to cause a contraction
Smooth muscle contracts (more slowly, more rapidly) than skeletal muscle following stimulation
more slowly
A motor neuron and the muscle fibers it controls are called a ________ _________
motor unit
Two types of smooth muscle are __________ muscle and ____________ muscle
multiunit, visceral
What substance in muscle seems able to store oxygen temporarily?
myoglobin
Rhythmicity is a property of
neither
The union between a nerve fiber and a muscle fiber is the
neuromuscular junction
Skeletal muscle cells contain many
nuclei and mitochondria
The strength of a muscle in response to different levels of stimulation is determined by the
number of motor units receiving a threshold stimulus
The strength of a muscle contraption in response to different levels of stimulation is determined by the
number of motor units stimulated
The attachment of a muscle to a relatively fixed part is called the _________; the attachment to a relatively movable part is called the ____________
origin, insertion
The muscles that flex, extend, and rotate the head include all of the following except
pectoralis minor
Antagonistic muscles
perform functions opposite to those performed by the prime mover
The toxin of clostridium botulinum causes death by
preventing the release of acetylcholine
Impulses travel relatively (rapidly, slowly) through cardiac muscle
rapidly
The network of membranous channels in the cytoplasm of muscle fibers is the ___________ ___________. The other channels found in the cytoplasm are the _________ _________.
sarcoplasmic reticulum, transverse tubules
When the cross-bridge of the myosin molecule forms linkages with actin filaments, the result is
shortening of the muscle fiber
List the tissues found in skeletal muscle
skeletal muscle tissue, blood, nervous tissue, connective tissue
List the kinds of tissue present in skeletal muscle
skeletal muscle tissue, nervous tissue, blood, connective tissue
The muscle that moves the head to one side is the
sternocleidomastoid
The result of summation and recruitment together is
sustained tetanic contraction
Which of the following is not characteristic of the motor end plate on a muscle fiber?
synaptic vesicles
Muscles that assist the prime mover in producing a movement are called
synergists
This tissue extends beyond the end of a skeletal muscle to form a cordlike _________
tendon
Layers of connective tissue extending into the muscle to form partitions between muscle bundles are continuous with attachments of muscle to periosteum called
tendons
The primary extensors of the upper arm are the
teres major and latissimus dorsi
ATPase is stored in
the globular portion of the myosin filament
Where is visceral smooth muscle found?
the walls of hollow organs such as stomach, intestines, urinary bladder, uterus
two major protein filaments
thick filament myosin, thin filament actin
Describe a single muscle fiber
thin, elongated cylinder with rounded ends. Contracts in response to stimulation, relaxes when stimulation ends
The minimal strength stimulus needed to elicit contraction of a single muscle fiber is called a(n) __________ ___________
threshold stimulus
The properties of smooth muscle that allows peristalsis are ____________ and ____________
transmission of impulses, rhythmicity
Actin filament contain
troponin and tropomyosin
Describe summation
when the degree of change in membrane potential directly correlates with stimulation frequency