Exam 2 Flashcards
Which fibers generate more force?
fast-twitch fibers
slow-twitch fibers
ultra slow fibers
fast-twitch fibers
The AV node is important because it
- directs electrical impulses from the ventricles to the atria.
- delays the transmission of the electrical impulses to the ventricles in order for the atria to finish contracting.
- serves as the normal pacemaker in a heart.
- electrically opens the AV valves.
- None of the other answers are correct.
delays the transmission of the electrical impulses to the ventricles in order for the atria
to finish contracting.
Within a single fiber, the tension developed during a twitch depends upon the
- amplitude of the action potential.
- length of the action potential
- length of the sarcomeres prior to contraction.
- duration of the initial stimulus.
length of the sarcomeres prior to contraction.
The theory that explains how a muscle fiber contracts is called the ________ theory.
- sliding filament
- neuromuscular
- action-myosin interaction hypothesis
- muscle contraction undertaking
- excitation-contraction coupling
sliding filament
A motor unit consists of
- one neuron and all the skeletal muscle fibers it controls.
- one skeletal muscle fiber and the neuron that controls that fiber.
- one skeletal muscle fiber and all the neurons that control that fiber.
- one axon terminal branch and the myofibrils it controls.
one neuron and all the skeletal muscle fibers it controls.
Motor units that control skeletal muscles involved with fine motor movements (eye muscles or
the hands) have ________ muscle fibers than motor units that control more gross movements
(gastrocnemius muscle of the lower leg).
*fewer
*more
*the same number of
more
The force generated by a single muscle fiber can be increased by increasing
- frequency of action potentials and increasing muscle length beyond optimal only.
- the asynchrony of recruitment
- muscle length beyond optimal
- frequency of action potentials
frequency of action potentials
Contraction of a skeletal muscle cell is initiated by the
- release of calcium ions by the neuron into the neuromuscular junction.
- release of sodium ions by the neuron into the neuromuscular junction.
- electrical current traveling from the neuron directly into the muscle cell.
- hormones delivered by the blood supply to the nearby tissue.
- release of acetylcholine by a neuron terminating at the neuromuscular junction.
release of acetylcholine by a neuron terminating at the neuromuscular junction.
An intracellular signal molecule that translates a signal from a neurotransmitter or hormone into
an intracellular response is called a
second messenger
Compared to skeletal muscle, contraction of smooth muscle cells is
*a slower response to a stimulus and sustained without fatigue.
*a slower response to a stimulus, sustained without fatigue, and controlled by the
somatic nervous system.
*only sustained without fatigue.
*only a slower response to a stimulus.
*only controlled by the somatic nervous system.
a slower response to a stimulus and sustained without fatigue
Semilunar valves are found between the_____________:
- ventricle and the vessels leaving from the ventricles
- atria and large blood vessels leading to the heart
- atria and ventricles
atria and large blood vessels leading to the heart
A ventricle with cells contracting rapidly in a disorganized manner, with no effective pumping
action, is said to be in
fibrillation
If a second stimulus arrives before the relaxation phase has ended, a second, more powerful
contraction occurs. This addition of one twitch to another is called
*treppe.
*complete tetanus.
*recruitment.
*incomplete tetanus.
*wave summation.
wave summation.
When a skeletal muscle cell contracts and the muscle shortens,
- some myosin heads are forming crossbridges as others are releasing them.
- the actin molecule swivels during the power stroke.
- the actin ATPase allows the actin molecule to swivel.
- each myosin head generates a single power stroke.
- the position of an actin molecule relative to a myosin molecule does not change
some myosin heads are forming crossbridges as others are releasing them.
If the signal molecule acts on the cell that secreted it, the chemical is called a(n)
autocrine
The term used to describe the volume of blood in the ventricle POTENTIALLY available to be
pumped out of the heart during the next contraction is
*cardiac output (CO).
*heart rate (HR).
*end-diastolic volume (EDV).
*stroke volume (SV).
*end-systolic volume (ESV).
end-diastolic volume (EDV).
The rapid depolarization phase of the action potentials of myocardial CONTRACTILE cells is due to which ion(s)? *Na+ only *Ca2+ only *K+ only *both Ca2+ and K+ *both Na+ and K+
Na+ only
All molecules secreted by nerve cells (neuromodulators, neurotransmitters, and neurohormones)
are known as ________.
neurocrines
If the concentration of a ligand decreases, the target cell may insert more receptors into the cell
membrane in an attempt to keep its response at a normal level, in a process known as
up-regulation
Systolic blood pressure is the pressure measured in_____________.
- capillaries.
- veins.
- major arteries.
- ventricles
major arteries
Striated muscles are so-called because of a repeating pattern of light and dark bands. One repeating unit of the banding pattern is called a
- sarcomere.
- sarcofibril.
- myomere.
- myofilament.
- crossbridge.
sarcomere
Most of the time, the parallel thick and thin filaments of the myofibrils are connected by
________ that span the space between myosin and actin molecules.
*crossbridges
*nebulin molecules
*calcium ions
*tropomyosin molecules
*sarcomeres
crossbridges
Normally, the right side of the heart
- will pump less blood volume than the left side
- pumps the same volume of blood from the atria as it does from the ventricle
- pumps the same volume of blood as the left side of the heart
pumps the same volume of blood as the left side of the heart
Skeletal muscle differs from smooth muscle in that skeletal muscle in that
*skeletal is under voluntary control.
*skeletal muscle is excitable and can shorten.
*cardiac muscle is capable of relaxation.
skeletal muscle gets *longer rather than shorter when excited.
skeletal is under voluntary control.
The normal primary pacemaker of the human heart:
- is also known as the atrioventricular (AV) node.
- is located in the right ventricle
- is also known as the sinoatrial (SA) node
- sends out a signal for contraction once every 2 minutes
is also known as the sinoatrial (SA) node
If the radius of a blood vessel is reduced from a value of 2 to value of 1 we should expect blood flow to be:
- reduced to half of the previous value
- reduced to 1/16th of the previous value
- increased by 2X the previous value
- increased 16X the previous value
reduced to 1/16th of the previous value
Which is NOT a common property of single-unit smooth muscles?
- Each cell functions independent of its neighbor.
- Electrical responses travel directly between cells.
- Their contraction occurs in a coordinated manner.
- Only some of the smooth muscle cells are associated with autonomic neuron axon terminals.
- Smooth muscle cells are connected by gap junctions.
Each cell functions independent of its neighbor.
The speed with which force is developed by skeletal muscles is determined by the
- myosin ATPase isoform.
- Ca2+ ATPase activity.
- sarcoplasmic calcium concentration.
- Ca2+ ATPase activity and sarcoplasmic calcium concentration.
myosin ATPase isoform.
Central skeletal muscle fatigue likely arises mainly from
- high levels of by contraction products such as lactate or ADP
- calcium pumps in the skeletal muscles.
- failure in neuromuscular transmission.
- excitation-contraction coupling.
- failure in signal relay from brain to spinal cord.
high levels of by contraction products such as lactate or ADP .
A chemical that is secreted by a cell to act on cells in its immediate vicinity is called a(n)
paracrine
The I band contains
- thick filaments only.
- myosin only.
- thin filaments only.
- thick and thin filaments.
thin filaments only.
The function of transverse tubules is to
- conduct ATP molecules out of the mitochondria throughout the sarcoplasm.
- rapidly move action potentials to the interior of the muscle fiber.
- store Ca2+ ions inside the muscle fiber.
- ensure a supply of glycogen throughout the muscle sarcoplasm.
rapidly move action potentials to the interior of the muscle fiber.
An Electrical shock delivered externally to the heart is usually used to treat
- ventricular fibrillation.
- atrial fibrillation.
- heart block.
- heart murmur
ventricular fibrillation.
When a muscle is stimulated repeatedly at a high rate, the amount of tension gradually increases
to a steady maximum tension. This state of maximum tension is called
*wave summation.
*incomplete tetanus.
*recruitment.
*a twitch.
*complete (fused) tetanus.
complete (fused) tetanus.
Which is NOT a basic method of cell-to-cell communication?
- cytoplasmic transfer of signals
- contact-dependent signals
- diffused chemical signals
- nerve and blood-transported signals
- mechanical signals
mechanical signals
Cross bridge detachment is caused by ________ binding to the myosin head.
- acetylcholine
- calcium
- magnesium
- easy off
- ATP
ATP
If or “funny” channels are permeable to which of the following ions?
- Ca2+ only.
- Na+ only.
- Na+ and K+.
- K+ only.
Na+ and K+.
The function of the titin protein is to
- cover the myosin binding site on the actin molecule.
- stabilize the position of the contractile filaments.
- interact with actin during contraction.
- release calcium during contraction.
- pull Z lines together during contraction
stabilize the position of the contractile filaments.
Which is a characteristic of slow-twitch oxidative skeletal muscle fibers?
- long contraction duration only
- few mitochondria only
- high capillary density only
- long contraction duration and high capillary density
- long contraction duration, few mitochondria, and high capillary density
long contraction duration and high capillary density
The left ventricular wall of the heart is thicker than the right wall in order to ________.
- accommodate a greater volume of blood
- may it look more attractive in photos of the heart
- pump blood through a smaller valve
- pump blood with greater pressure
pump blood with greater pressure
Which major blood circuit has the highest pressure?
- Systemic
- Pulmonic
Systemic
When a skeletal muscle generates enough force during contraction to shorten,
- the sarcomere, the A band, and the I band will shorten.
- only the sarcomere will shorten.
- only the A band will shorten.
- the sarcomere and the I band will shorten.
- only the I band will shorten.
the sarcomere and the I band will shorten. The A band will not shorten
This protein is activated by the Ca2+-calmodulin complex to phosphorylate the myosin light chain protein. *myosin light chain phosphatase *tropomyosin *myosin heavy chain *myosin light chain kinase
myosin light chain kinase
Which is NOT TRUE of Duchene Muscular Dystrophy?
- it is an inherited disorder
- dystrophin is a structural protein
- many patients with this disorder die before the age of thirty
- ALL of the answers are true
ALL of the answers are true
An intracellular signal molecule that translates a signal from a neurotransmitter or hormone into
an intracellular response is called a ________.
*second messenger
*suspender
*translator
*dynamic operator
second messenger
________ is made up of multiple globular molecules polymerized to form long chains or filaments.
- Troponin
- Tropomyosin
- Actin
- Titin
- Myosin
Actin
One of the first steps in the contraction process for smooth muscle is that Calcium binds to:
- the dense bodies
- troponin
- actin
- calmodulin
calmodulin
The function of the titin protein is to
A) stabilize the position of the contractile filaments.
B) pull Z lines together during contraction.
C) interact with actin during contraction.
D) release calcium during contraction.
E) cover the myosin binding site on the actin molecule.
stabilize the position of the contractile filaments.
When a muscle fiber contracts, the I bands diminish in size, the H zones may disappear, and the A bands
do not diminish in length. TRUE OR FALSE
TRUE
Continued sustained smooth contraction due to rapid stimulation is called:
- Multiple motor unit summation
- Muscle tone
- Maximal Stimulus
- Wave Summation
- Tetanus
Tetanus
Which of the following receive(s) blood during ventricular systole?
- pulmonary arteries only
- pulmonary veins only
- aorta only
- both the aorta and pulmonary trunk
both the aorta and pulmonary trunk
Prevents backflow into the left atrium.
- Mitral valve
- Aortic semilunar valve
- Tricuspid valve
- Pulmonary semilunar valve
Mitral valve
Which of the following is the correct sequence of events for muscle contractions?
A) neurotransmitter release, muscle cell action potential, motor neuron action potential, release of calcium ions from SR, sliding of myofilaments, ATP-driven power stroke
B) muscle cell action potential, neurotransmitter release, ATP-driven power stroke, calcium ion release from SR, sliding of myofilaments
C) motor neuron action potential, neurotransmitter release, muscle cell action potential, release of calcium ions from SR, ATP-driven power stroke, sliding of myofilaments
D) neurotransmitter release, motor neuron action potential, muscle cell action potential, release of
calcium ions from SR, ATP-driven power stroke
motor neuron action potential, neurotransmitter release, muscle cell action potential, release of
calcium ions from SR, ATP-driven power stroke, sliding of myofilaments
Prevents backflow into the right atrium.
- Pulmonary semilunar valve
- Mitral valve
- Aortic semilunar valve
- Tricuspid valve
Tricuspid valve
Cardiac output PER MINUTE at rest is approximately_______ liter(s):
5.0
Typically, when steroid hormones bind to their receptors,
- adenylyl cyclase is activated.
- cyclic nucleotides are formed.
- G proteins are inhibited.
- gene transcription may increase or decrease.
- protein kinases are activated.
gene transcription may increase or decrease.
The volume of blood left in the ventricle after it contracts is called the
end systolic volume)
Immediately following the arrival of the stimulus at a skeletal muscle cell there is a short period called
the ________ period during which the neurotransmitter is released by exocytosis, diffuses across the
synaptic cleft, and binds to its receptors.
*contraction
*relaxation
*latent
*refractory
latent
Hypothetically, if a muscle were stretched to the point where thick and thin filaments no longer
overlapped, ________.
*cross bridge attachment would be optimum because of all the free binding sites on actin
*no muscle tension could be generated
*maximum force production would result because the muscle has a maximum range of travel
*ATP consumption would increase because the sarcomere is “trying” to contract
no muscle tension could be generated
Determined by alternating motor units of a muscle organ even when the muscle is at rest.
- Muscle tone
- Tetanus
- Multiple motor unit summation
- Maximal Stimulus
- Wave Summation
Muscle tone
Normal heart sounds are mainly caused by which of the following events?
- excitation of the sinoatrial (SA) node
- closure of the heart valves
- friction of blood against the chamber walls
- opening of the heart valves
closure of the heart valves
What is the primary function of wave summation?
- prevent muscle fatigue
- increase muscle tension
- prevent muscle relaxation
- produce smooth, continuous muscle contraction
produce smooth, continuous muscle contraction
The thicker filaments are the ________ filaments.
- A band(s)
- Z discs
- Myosin molecules
- I band(s)
Myosin molecules
The volume of blood left in the ventricle before it contracts is called the
end diastolic volume)
During muscle contraction, myosin cross bridges attach to which active sites?
- intermediate filaments
- Z discs
- myosin filaments
- actin filaments
actin filaments
The stimulus above which no stronger contraction can be elicited, because all motor units are firing in the muscle. *Muscle tone *Multiple motor unit summation *Wave Summation *Tetanus *Maximal Stimulus
Maximal Stimulus
Reduction in blood flow to a muscle fiber would have the greatest effect on ________.
- fast glycolytic
- both slow and fast oxidative
- slow oxidative fibers
- fast oxidative fibers
slow oxidative fibers
The situation in which contractions become stronger due to stimulation before complete relaxation occurs. *Wave Summation *Multiple motor unit summation *Maximal Stimulus *Muscle tone *Tetanus
Wave Summation
During isometric contraction, the energy used appears as movement. TRUE OR FALSE
FALSE
An electrocardiogram (ECG) provides direct information about valve function. TRUE OR FALSE
FALSE
What is the role of tropomyosin in skeletal muscles?
*Tropomyosin is the chemical that activates the myosin heads.
*Tropomyosin serves as a contraction inhibitor by blocking the myosin binding sites on the actin
molecules.
*Tropomyosin serves as a contraction inhibitor by blocking the actin binding sites on the myosin molecules.
*Tropomyosin is the receptor for the motor neuron neurotransmitter.
Tropomyosin serves as a contraction inhibitor by blocking the myosin binding sites on the actin
molecules.
During the period of ventricular filling ________.
*pressure in the heart is at its peak
*the atria remain in diastole
*blood flows mostly passively through the atria and the open atrioventricular (AV) valves into
the ventricles
*the aortic and pulmonary semilunar valves are open
blood flows mostly passively through the atria and the open atrioventricular (AV) valves into
the ventricles
