CH 7-10 Test Bank
Muscle cells
can only contract
Which of the following is characteristic of cardiac muscle?
cardiac muscle cells are striated
The term used to describe muscular growth in response to usage is
hypertrophy
A muscle producing almost peak tension during rapid cycles of contraction and relaxation is said to be in
incomplete tetanus
Most neurons in the brain are
multipolar
Exhaustion of energy reserves or decline in pH due to production and dissociation of lacticc acid causes
muscle fatigue
Which statement regarding the relaxation phase of a muscle twitch is true?
muscle tension falls to resting levels
The additional oxygen required during the recovery period to restore the normal pre-exertion levels is called the
oxygen debt
A traid is a
pair of terminal cisternae of the SR with a T tubule between them
All of the nervous tissue outside of the CNS comprises the
peripheral nervous system
Which property of the sarcolemma is affected by the neurotransmitter ACh?
permeability
The terminal cisternae are structural features of the
sarcoplasmic reticula
The skeletal muscles store calcium ions in the terminal cisternae of the
sarcoplasmic reticulum
Which of the following is a function of the efferent division of the nervous system?
sending signals to muscles
Which of the following statements describes how muscles help maintain homeostasis?
skeletal muscle contractions help maintain body temperature
Which statement regarding skeletal muscle is true?
skeletal muscles contain blood vessels
Nonstriated, involuntary muscle is
smooth
The suddent rush of which ion into the sarcoplasm produces an action potential in the sarcolemma?
sodium
As a skeletal muscle contraction is initiated, ACh binding alters the motor end plate membrane's permeability to
sodium ions
Creatine phosphate serves to
supply energy to synthesize ATP
The heart has to be able to regulate its contractions. Heart muscle, unlike skeletal muscle, cannot go into a tetanus. This is because
the heart muscle has to be able to consistently contract and pump blood in a controlled fashion
During a skeletal muscle contraction, calcium binds to which molecule?
troponin
Smooth muscle
uses primarily aerobic metabolism
The enzyme acetylcholinesterase causes ACh to
break down
During activities requiring anaerobic endurance
most of the muscle's energy is produced in mitochondria
The specialzied sarcolemma that contains ACh receptors is the ___
motor end plate
Neurotransmitters that cause skeletal muscle contraction are normally stored in:
motor neuron axon terminals
Which of the following helps maintain body position by tensing and firming a muscle even when the entire muscle is not contracting?
muscle tone
A sheath of connective tissue surrounding a bundle of striated muscle fibers is called
perimysium
The area between Z lines is the ___
sarcomere
The repeating functional unit of a myofibril is the
sarcomere
Acetylcholinesterase is found within the
synaptic cleft
Which of the following is one of the steps that ends a contraction?
ACh is broken down by acetylcholinesterase
Upon the nerve impulse arriving at the axon terminal
ACh is released
The stiffness that occurs at death, when actin and myosin molecules stay linked to each other in a contracted state, is due to a lack of
ATP
Which of the following statements describes the cause for the cessation of an action potential?
Acetylcholinesterase breaks down ACh
The brain and spinal cord comprise the
CNS
Which of the following structures is composed of proteins that connect the central portions of each thick filament to its neighbors?
M line
Which statement regarding "heat loss" is true?
Muscle contractions play an important role in the maintenance of normal body temperature
A resting muscle generates most of its ATP by
aerobic respiration
The ___ division of the nervous system brings sensory information to the central nervous
afferent
The part of the peripheral nervous system that brings information to the CNS is the
afferent division
A broad sheet formed by the collagen fibers of the connective tissues of skeletal muscle is called
an aponeurosis
Smooth muscle cells
are spindle-shaped
The glial cells responsible for maintaining blood-brain barrier are the
astrocytes
The largest and most numerous of the glial cells in the CNS are the
astrocytes
Which of the following phrases best describes the cyclical actions of a myosin cross-bridge during a muscle contraction?
attach, pivot, detach, and reactivate
The ___ nervous system provides involuntary regulation of smooth muscle, cardiac muscle, and glandular activity.
autonomic
Which of the following structures controls individual muscle fibers?
axon (nerve fiber)
The _____ contains vesicles filled with ACh
axon terminal
The active sites on actin molecules are usually covered up by other molecules. What is the critical material required to uncover the active sites on the actin molecules that will then bind to myosin heads?
calcium
In response to action potentials arriving from the transverse tubules, the sarcoplasmic reticulum releases
calcium ions
During moderate activity, which of the following is true regarding muscle metabolism?
glucose and fatty acids are catabolized
Regarding muscle fiber elongation:
gravity may help lengthen a muscle fiber after elongation
Fast fibers
have high glycogen reserves
Skeletal muscle fibers differ from "typical cells" in that these muscle fibers
have many nuclei
Which of the following occurs when tension production rises to a peak and very brief periods of relaxation occur?
incomplete tetanus
"Anaerobic endurance"
is exemplified by contractions of fast muscle fibers
In general, the nervous system
is fast acting
Which of the following statements correctly defines tension?
it is a force to an object that tneds to pull the object toward the source of the force
Which of the following occurs when glycolysis produces pyruvate faster than it can be used by the mitochondria?
lactic acid is produced
Calcium ions are released from the sarcoplasmic reticulum during the ____ phase of contraction
latent
In which of the following phases of a twitch is no tension produced by the muscle fiber?
latent period
Regarding lactic acid regulation, which cells in the body consume extra oxygen and produce ATP for the conversion of excess lactate absorbed from the blood back to glucose?
liver cells
Small phagocytic glial cells, which are derived from white blood cells are called
microglia
Muscle fasicles are separated by
perimysium
Which of the following is true about red muscles?
red muscles are slower than white muscles
Which of the following is an accurate characterisitc of slow fibers?
resting slow muscle fibers contain oxygen reserves, bound to myoglobin
The amount of tension produced by an individual muscle fiber depends solely upon which of the following factors?
the number of pivoting cross-bridges
Regarding a skeletal muscle fiber, wherever a T-tubule encircles a myofibril, the tuble is tightly bound to:
the sarcoplasmic reticulum
Which statement regarding isometric contractions is true?
the tension produced never exceeds the load
How do skeletal muscle contractions cause movement of the bones?
they pull on tendons
Myosin molecules are found in which of the following structures?
thick filaments
What is the function of the transverse tubules?
to transmit electrical impulses to the cell's interior
Tropomyosin strands are held in position by which of the following?
troponin molecules
A single stimulus-contraction-relaxation sequence in a muscle fiber is known as a
twitch
Muscular System Functions
1. move the skeleton 2. maintain posture and body position 3. support soft tissues 4. guard entrances and exits 5. maintain body temperature
Each myofibril consists of approximately ____ sarcomeres
10,000
Place these steps of muscle contraction in the correct order: 1. action potential is generated along the sarcolemma 2. nerve impulse arrives at synapse 3. calcium is released into muscle cell cytoplasm 4. ACh is produced 5. actin and myosin molecules continuously cross-link, with actin molecules being pulled inward
2, 4, 1, 3, 5
Choose the correct statement regarding motor units
a motor neuron may control only two or three muscle fibers of the eye muscles
Myofibrils are made primarily of
actin and myosin
Glycolysis
is an anaerobic process
The region of a sarcomere containing myosin, going from one end of the mysoin molecules to the other end of the myosin molecules, is the
A band
The thick filaments of sarcomeres are contained in which band?
A band
Which of the following structures is composed of a layer of collagen fibers that separates a muscle from surrounding tissues and organs?
Epimysium
The area of the sarcomere that is the light region between two successive A-bands is the
I band
The striated appearance of skeletal muscle results from
actin and myosin arrangement
During which phase is the stimulus frequency so high that the relaxation phase is eliminated?
complete tetanus
Which of the following terms defines a force that tends to push an object away from the source of the applied force?
compression
The branching structures that, together with the cell body, are sensitive to chemical, mechanical, or electrical stimulation are called
dendrites
Which of the following structures surrounds each skeletal muscle fiber and ties adjacent muscle fibers together?
endomysium
A layer of collagen fibers that surround an entire muscle is called:
epimysium
A bundle of muscle fibers is a
fascicle
A muscle ____ contains a sarcolemma, sarcoplasm, myofilaments, and myofibrils.
fiber
Which of the following parts of a neuromuscular junction is a specialized portion of the sarcolemma that contains receptors for ACh?
motor end plate
Why do individual muscle twitches have to be added together, as in summation or tetanus?
multiple twitches add up to an increase in muscle fiber tension, which increases the strength of the muscle
Which of the following occurs as a result of motor units in a particular muscle being always active, even though their contractions do not produce enough movement to cause contraction?
muscle tone
The myelin sheaths that surround the axon of some of the neurons in the CNS are formed by
oligodendrocytes
Which of the following structures is a specialized form of smooth endoplasmic reticulum that forms a tubular network around each myofibril?
sarcoplasmic reticulum
A person whose genetic makeup makes him or her a better marathon runner than a sprinter probably has more _____ in his or her leg muscles
slow fibers