Chapter 9 Flashcards
resting membrane potential
K is inside and negatively charged, NA is outside and positively charged
depolarization
NA channels open, NA goes inside and makes inside positively charged
repolarization
Na channels closed, K leaves, making inside negatively changed
repolarization
Na channels closed, K leaves, making inside negatively changed
Nerve signal arrives
Step 1
muscle fiber releases ACH
Step 2
ACH binds to receptors
Step 3
ligand-gated ion channel opens
Step 4
Action potentials occur
Step 5
action potentials enter T tubules
Step 6
calcium is released
Step 7
calcium binds to troponin
Step 8
complex reveals binding sites
Step 9
The junction between nerve endings and muscle fibers.
Neuromuscular junction
A rope-like organ that transfers information to the central nervous system.
Nerve
The enlargement at the end of an axon that secretes a neurotransmitter.
Synaptic knob
The vesicles in the axon containing neurotransmitters.
synaptic vesicles
A chemical in the neuromuscular junction that aids in stimulating or inhibiting muscle contraction.
neurotransmitter
A channel that opens or closes when a ligand is bound to the receptor site.
ligand-gated ion channel
The difference between the electric charge inside membrane and just outside the membrane.
RMP
A rapid change in membrane voltage.
EPP
A channel that opens or closes when a membrane reaches a certain voltage.
voltage-gated ion channel
The network of tubes and canals in the sarcolemma.
sarcoplasmic reticulum
A rapid change in a cell’s electrical charge that reverses the plasma membrane’s electrical polarity.
action potentials
Tube-like canals in the sarcolemma that deliver action potentials into the muscle fiber.
t tubules
Which of the following is NOT a function of skeletal muscle?
Select one:
a. body movement
b. maintenance of posture
c. Dilating and constricting the pupil of the eye
d. Carry out breathing movements
e. production of heat
c. Dilating and constricting the pupil of the eye
Smooth muscle is regulated by all of the following except
Select one:
a. the autonomic nervous system.
b. neurotransmitters.
c. the somatic nervous system.
d. hormones.
e. prostaglandins.
c. the somatic nervous system.
Which of the following statements concerning smooth muscle is true?
Select one:
a. It contains many sarcomeres.
b. Caveolae seem to take the place of the myofibrils.
c. A calcium-calmodulin complex initiates cross-bridge formation.
d. The cells are large and multinuclear.
e. It has a well developed sarcoplasmic reticulum.
c. A calcium-calmodulin complex initiates cross-bridge formation.
Which type of muscle tissue causes contraction of the heart?
Select one:
a. skeletal muscle
b. smooth muscle
c. cardiac muscle
c. cardiac muscle
Which of the following is true?
Select one:
a. Skeletal muscle is capable of spontaneous contraction.
b. Smooth muscle is found in the walls of hollow organs.
c. Cardiac muscle cells have multiple nuclei.
d. Smooth muscle cells are long and cylindrical.
e. There is a small amount of smooth muscle in the heart.
b. Smooth muscle is found in the walls of hollow organs.
List the following structures in order from smallest to largest.
(1) muscle fiber
(2) myofilament
(3) myofibril
(4) muscle fasciculus
Select one:
a. 4, 2, 3, 1
b. 2, 1, 4, 3
c. 3, 1, 4, 2
d. 2, 3, 1, 4
e. 1, 2, 3, 4
d. 2, 3, 1, 4
Why does muscle activity affect the temperature of the body?
Select one:
a. The rate of chemical reactions increases in muscle fibers during contraction, so the rate of heat production also increases.
b. Muscle contraction generates pyrogens which reset the body’s internal thermostat to a higher temperature.
c. Muscle activity directs more warm blood to the muscles away from the central core causing a cooling effect on your internal organs.
d. Increased muscle activity causes a rise in adipose stores which increases the insulation value of the body.
a. The rate of chemical reactions increases in muscle fibers during contraction, so the rate of heat production also increases.
Which of the following actions is caused by contraction of skeletal muscle?
Select one:
a. contraction of the heart
b. moving your feet in walking
c. movement of food through the digestive tract
d. emptying of the urinary bladder
e. vasoconstriction
b. moving your feet in walking
Muscles exhibit the property of excitability. This means that the muscle
Select one:
a. shortens its length.
b. recoils to its original resting length.
c. stretches beyond its normal length.
d. responds to stimulation by the nervous system.
e. excites itself.
d. responds to stimulation by the nervous system.
The capacity of a muscle cell to shorten forcefully is known as
Select one:
a. contractility.
b. excitability.
c. extensibility.
d. elasticity.
e. flexibility.
a. contractility.
Acetylcholine is released from the presynaptic terminal by the process of
Select one:
a. exocytosis.
b. diffusion.
c. phagocytosis.
d. active transport.
e. endocytosis.
a. exocytosis.
T tubules
Select one:
a. provide nutrients to the muscle fiber.
b. generate new muscle fibers.
c. conduct action potentials deep into the muscle cell.
d. release acetylcholine.
e. store calcium ions.
c. conduct action potentials deep into the muscle cell.
A sustained muscle contraction is known as
Select one:
a. tetanus
b. tone
c. treppe
d. twitch
e. paralysis
a. tetanus
After contraction has occurred, the calcium is
Select one:
a. destroyed by cholinesterase.
b. chemically bound to the cross bridges.
c. secreted by the Golgi apparatus to the outside of the cell.
d. released from troponin.
e. returned to the sarcolemma.
d. released from troponin.
The region of the sarcomere that contains both actin and myosin myofilaments is called the
Select one:
a. I band.
b. A band.
c. Z disk.
d. H zone.
e. M line.
b. A band.
Which of the following statements concerning fast-twitch muscle fibers is true?
Select one:
a. They split ATP rapidly.
b. They have large deposits of myoglobin.
c. They are well adapted to aerobic metabolism.
d. They have a well-developed blood supply.
e. They have many mitochondria.
a. They split ATP rapidly.
Maureen is hiking in the cold, and to maintain homeostasis her body begins to
Select one:
a. increase heat loss from the skin.
b. release chemicals to initiate a high fever.
c. shiver.
d. reduce her blood pressure.
e. vasodilate vessels in her head and neck
c. shiver.
A waste product of anaerobic respiration in muscle cells is
Select one:
a. uric acid.
b. hydrochloric acid.
c. lactic acid.
d. carbonic acid.
e. pyruvic acid.
c. lactic acid.
Rigor mortis occurs after death because
Select one:
a. cross-bridges form but can’t release.
b. calcium is actively transported back to the sarcoplasmic reticulum.
c. anaerobic respiration is occurring.
d. myosin levels decline at death.
e. cross-bridges never form.
a. cross-bridges form but can’t release.
Increased strength of a trained muscle is due to
Select one:
a. an increased number of muscle fibers.
b. the nervous system’s ability to recruit a large number of motor units simultaneously.
c. elimination of unnecessary enzymes and metabolic pathways.
d. elimination of all fat deposits.
e. elimination of unnecessary connective tissue.
b. the nervous system’s ability to recruit a large number of motor units simultaneously.
Which of the following is NOT a function of skeletal muscle?
Select one:
a. body movement
b. maintenance of posture
c. Dilating and constricting the pupil of the eye
d. Carry out breathing movements
e. production of heat
c. Dilating and constricting the pupil of the eye
Which type of muscle tissue would cause flexion and extension of the arm?
Select one:
a. skeletal muscle
b. smooth muscle
c. cardiac muscle
a. skeletal muscle
A fasciculus
Select one:
a. is a bundle of reticular fibers.
b. is surrounded by perimysium.
c. is only found in smooth muscle.
d. possesses an external lamina.
e. is a bundle of collagen fibers.
b. is surrounded by perimysium.
Which of the following connective tissue layers is outside all the others?
Select one:
a. perimysium
b. endomysium
c. epimysium
d. paramysium
e. sarcolemma
c. epimysium
Visceral smooth muscle
Select one:
a. may contain groups of cells that function as an independent unit.
b. occurs in sheets and exhibits numerous gap junctions.
c. contracts only when stimulated.
d. does not function as a unit.
e. All of these choices are correct.
b. occurs in sheets and exhibits numerous gap junctions.
Smooth muscle and cardiac muscle are similar in that they both
Select one:
a. are under involuntary control.
b. are striated.
c. are widely distributed in the body.
d. have multiple nuclei.
e. are under voluntary control.
a. are under involuntary control.
As muscle activity increases, the body temperature _____.
Select one:
a. decreases
b. increase
b. increase
Muscles exhibit the property of excitability. This means that the muscle
Select one:
a. shortens its length.
b. recoils to its original resting length.
c. stretches beyond its normal length.
d. responds to stimulation by the nervous system.
e. excites itself.
d. responds to stimulation by the nervous system.
Which of the following actions is caused by contraction of skeletal muscle?
Select one:
a. contraction of the heart
b. moving your feet in walking
c. movement of food through the digestive tract
d. emptying of the urinary bladder
e. vasoconstriction
b. moving your feet in walking
The capacity of a muscle cell to shorten forcefully is known as
Select one:
a. contractility.
b. excitability.
c. extensibility.
d. elasticity.
e. flexibility.
a. contractility.
When the myosin head flexes into a bend, pulling the actin filament along with it, this is called the
Select one:
a. action reaction.
b. power stroke.
c. recovery stroke.
d. muscle tone.
e. action potential.
b. power stroke.
The time between application of the stimulus to a motor neuron and the beginning of contraction is called the _____ phase.
Select one:
a. contraction
b. relaxation
c. latent or lag
d. refractory
e. threshold
c. latent or lag
The sarcoplasmic reticulum
Select one:
a. stores calcium ions.
b. shortens during muscle contraction.
c. transmits nerve impulses to the myofibrils.
d. connects adjacent sarcomeres.
e. covers the muscle fiber.
a. stores calcium ions.
Whole muscles can respond in a graded fashion to stimuli by varying
Select one:
a. the force of contraction of individual muscle fibers.
b. the number of motor units recruited.
c. the amplitude of the action potential.
d. the frequency of stimulus.
e. thresholds.
b. the number of motor units recruited.
The model that describes the contraction of the muscle is called the
Select one:
a. contraction cycle.
b. power stroke.
c. sliding filament model.
d. slipping fibril mechanism.
e. paddle model.
c. sliding filament model.
A lack of glycolytic enzymes within skeletal muscle cells would impair which type of ATP-yielding process?
Select one:
a. anaerobic respiration
b. aerobic respiration
c. both anaerobic and aerobic respiration
c. both anaerobic and aerobic respiration
Which of the following correctly describes myoglobin’s special function in muscle tissue?
Select one:
a. breaks down glycogen
b. synthesizes ATP
c. acts as a reservoir for oxygen
d. produces action potentials
e. stores glucose
c. acts as a reservoir for oxygen
Which type of respiration rapidly produces ATP for short time periods?
Select one:
a. anaerobic respiration
b. aerobic respiration
c. both anaerobic and aerobic respiration
a. anaerobic respiration
During resting conditions, _________ is synthesized to store energy?
Select one:
a. calcium
b. creatine phosphate
c. creatine
d. lactic acid
e. pyruvic acid
b. creatine phosphate
Which of the following is NOT an age related change in skeletal muscle?
Select one:
a. loss of muscle strength
b. loss of synapse surface area
c. loss of fast-twitch fibers
d. decreased recovery time
e. decrease in motor units
d. decreased recovery time
Which of these is true of skeletal muscle?
spindle-shaped cells
under involuntary control
many peripherally located nuclei per muscle fiber
forms the walls of hollow internal organs
may be autorhythmic
many peripherally located nuclei per muscle fibe
Which of these is not a major property of muscle?
contractility
elasticity
excitability
extensibility
secretability
secretability
Given these structures:
(1) whole muscle
(2) muscle fiber (cell)
(3) myofilament
(4) myofibril
(5) muscle fasciculus
Choose the arrangement that lists the structures in the correct order from largest to smallest.
1,2,5,3,4
1,2,5,4,3
1,5,2,3,4
1,5,2,4,3
1,5,4,2,3
1,5,2,4,3
Each myofibril
is made up of many muscle fibers.
contains sarcoplasmic reticulum.
is made up of many sarcomeres.
contains T tubules.
is the same thing as a muscle fiber.
is made up of many sarcomeres.
Myosin myofilaments are
attached to the Z disk.
found primarily in the I band.
thinner than actin myofilaments.
absent from the H zone.
attached to filaments that form the M line.
attached to filaments that form the M line.
Which of these statements about the molecular structure of myofilaments is true?
Tropomyosin has a binding site for Ca2+.
The head of the myosin molecule binds to an active site on G actin.
ATPase is found on troponin.
Troponin binds to the rodlike portion of myosin.
Actin molecules have a hingelike portion, which bends and straightens during contraction.
The head of the myosin molecule binds to an active site on G actin.
The part of the sarcolemma that invaginates into the interior of skeletal muscle fibers is the
T tubule system.
sarcoplasmic reticulum.
myofibrils.
terminal cisternae.
mitochondria.
T tubule system.
During the depolarization phase of an action potential, the permeability of the plasma membrane to
Ca2+ increases.
Na+ increases.
K+ increases.
Ca2+ decreases.
Na+ decreases.
Na+ increases.
During repolarization of the plasma membrane,
Na+ moves to the inside of the cell.
Na+ moves to the outside of the cell.
K+ moves to the inside of the cell.
K+ moves to the outside of the cell.
K+ moves to the outside of the cell.
Given these events:
(1) Acetylcholine is broken down into acetic acid and choline.
(2) Acetylcholine diffuses across the synaptic cleft.
(3) An action potential reaches the terminal branch of the motor neuron.
(4) Acetylcholine combines with a ligand-gated ion channel.
(5) An action potential is produced on the muscle fiber’s plasma membrane.
Choose the arrangement that lists the events in the order they occur at a neuromuscular junction.
2,3,4,1,5
3,2,4,5,1
3,4,2,1,5
4,5,2,1,3
5,1,2,4,3
3,2,4,5,1
Acetylcholinesterase is an important molecule in the neuromuscular junction because it
stimulates receptors on the presynaptic terminal.
synthesizes acetylcholine from acetic acid and choline.
stimulates receptors within the postsynaptic membrane.
breaks down acetylcholine.
causes the release of Ca2+ from the sarcoplasmic reticulum.
breaks down acetylcholine.
Given these events:
(1) The sarcoplasmic reticulum releases Ca2+.
(2) The sarcoplasmic reticulum takes up Ca2+.
(3) Calcium ions diffuse into the sarcoplasm.
(4) An action potential moves down the T tubule.
(5) The sarcomere shortens.
(6) The muscle relaxes.
Choose the arrangement that lists the events in the order they occur following a single stimulation of a skeletal muscle fiber.
1,3,4,5,2,6
2,3,5,4,6,1
4,1,3,5,2,6
4,2,3,5,1,6
5,1,4,3,2,6
4,1,3,5,2,6
Given these events:
(1) Calcium ions combine with tropomyosin.
(2) Calcium ions combine with troponin.
(3) Tropomyosin pulls away from actin.
(4) Troponin pulls away from actin.
(5) Tropomyosin pulls away from myosin.
(6) Troponin pulls away from myosin.
(7) Myosin binds to actin.
Choose the arrangement that lists the events in the order they occur during muscle contraction.
1,4,7
2,5,6
1,3,7
2,4,7
2,3,7
2,3,7
With stimuli of increasing strength, which of these is capable of a graded response?
neuron axon
muscle fiber
motor unit
whole muscle
whole muscle
Considering the force of contraction of a skeletal muscle fiber, multiple-wave summation occurs because of
increased strength of action potentials on the plasma membrane.
a decreased number of cross-bridges formed.
an increase in Ca2+ concentration around the myofibrils.
an increased number of motor units recruited.
increased permeability of the sarcolemma to Ca2+.
an increase in Ca2+ concentration around the myofibrils.
Which of these events occurs during the lag (latent) phase of muscle contraction?
cross-bridge movement
active transport of Ca2+ into the sarcoplasmic reticulum
Ca2+ binding to troponin
sarcomere shortening
breakdown of ATP to ADP
Ca2+ binding to troponin
A weight lifter attempts to lift a weight from the floor, but the weight is so heavy that he is unable to move it. The type of muscle contraction the weight lifter is using is mostly
isometric.
isotonic.
isokinetic.
concentric.
eccentric.
isometric.
Which of these types of fatigue is the most common?
muscular fatigue
psychological fatigue
synaptic fatigue
army fatigue
psychological fatigue
Given these conditions:
(1) low ATP levels
(2) little or no transport of Ca2+ into the sarcoplasmic reticulum
(3) release of cross-bridges
(4) Na+ accumulation in the sarcoplasm
(5) formation of cross-bridges
Choose the conditions that occur in both physiological contracture and rigor mortis.
1,2,3
1,2,5
1,2,3,4
1,2,4,5
1,2,3,4,5
1,2,4,5
Jerry Jogger’s 3-mile run every morning takes about 30 minutes. Which of these sources provides most of the energy for his run?
aerobic respiration
anaerobic respiration
creatine phosphate
stored ATP
aerobic respiration
Which of these conditions would you expect to find within the leg muscle fibers of a world-class marathon runner?
myoglobin-poor
contract very quickly
primarily anaerobic
numerous mitochondria
numerous mitochondria
Which of these increases the least as a result of muscle hypertrophy?
number of sarcomeres
number of myofibrils
number of fibers
blood vessels and mitochondria
connective tissue
number of fibers
Relaxation in smooth muscle occurs when
myosin kinase attaches phosphate to the myosin head.
Ca2+ binds to calmodulin.
myosin phosphatase removes phosphate from myosin.
Ca2+ channels open.
Ca2+ is released from the sarcoplasmic reticulum.
myosin phosphatase removes phosphate from myosin.
Compared with skeletal muscle, visceral smooth muscle
has the same ability to be stretched.
loses the ability to contract forcefully when stretched.
maintains about the same tension, even when stretched.
cannot maintain long, steady contractions.
can accumulate a substantial oxygen deficit.
maintains about the same tension, even when stretched.
Which of these statements concerning aging and skeletal muscle is correct?
A loss of muscle fibers occurs with aging.
Slow-twitch fibers decrease in number faster than fast-twitch fibers.
The loss of strength and speed is due mainly to loss of neuromuscular junctions.
The density of capillaries in skeletal muscle increases.
The number of motor neurons remains constant.
A loss of muscle fibers occurs with aging.
