Assignment 4 (Ch. 10 (end) and 12) Flashcards
What happens to sarcomere length if the zone of overlap is decreased?
-sarcomere length stays the same
-sarcomere length decreases
-sarcomere length increases
Sarcomere length increases.
Which of the following allows muscles to return to their original shape during relaxation?
-myosin binding
-opposing muscle contractions
-elastic forces
-gravity
-gravity, opposing muscle contractions, and elastic forces
Gravity, opposing muscle contractions, and elastic forces
The point in a muscle twitch when the troponin is bound to calcium is called the
-relaxation phase
-stimulus phase
-contraction phase
-isotonic period
-latent period
Contraction phase
The rapid rise and fall in force produced by a muscle fiber after a single action potential is a(n)
-muscle action potential
-tetanus
-twitch
-unfused tetanus
-motor end plate potential
Twitch
Detachment of myosin cross-bridges occurs during the
-relaxation phase
-stimulus phase
-contraction phase
-isotonic period
-latent period
Relaxation phase
To produce a contraction similar to a wave summation(b), the muscle…
-is excited by a stimulus of increasing intensity.
-generates more and more thin and thick filaments.
-must go through a rapid series of isolated twitches.
-must be stimulated to the point of fatigue.
-must be stimulated again before it has relaxed from the -previous stimulation.
Must be stimulated again before it has relaxed from the -previous stimulation.
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
-incomplete tetanus
-recruitment
-wave summation
-complete tetanus
Wave summation
What can the nervous system do to increase muscle tension?
-recruit larger motor units
-increase stimulation frequency
-increase the number of active motor units
-All of the listed responses can increase muscle tension.
All of the listed responses can increase muscle tension.
A weight-lifter strains to lift a heavy weight and there is no movement of the person’s arms holding on to the weight. This type of contraction is called a(n) ________ contraction.
-treppe
-isotonic
-concentric
-tetanus
-isometric
Isometric
A single motor neuron together with all the muscle fibers it innervates is called a(n)
-dermatome
-end foot
-myotome
-end plate
-motor unit
Motor unit
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
-recruitment
-a twitch.
-complete tetanus.
-incomplete tetanus.
-wave summation.
Complete tetanus
You try to pick up an object and discover that it is much heavier than you expected. Which process must occur in the muscle to increase tension so you can pick up the object?
-recruitment
-wave summation
-isotonic contraction
-treppe
-complete tetanus
Recruitment
In an isotonic contraction,
-tension rises and falls but the muscle length is constant.
-postural muscles stabilize the vertebrae.
-many twitches always fuse into one.
-muscle tension exceeds the load and the muscle lifts the load.
-the peak tension is less than the load.
Muscle tension exceeds the load and the muscle lifts the load.
Which of the following is not characteristic of smooth muscle?
-The thin filaments of smooth muscle fibers are attached to dense bodies.
-Neurons that innervate smooth muscles are under involuntary control.
-Smooth muscle cells are uninucleate.
-The striations are due to the orderly arrangement of actin and myosin.
-Smooth muscles do not contain sarcomeres.
The striations are due to the orderly arrangement of actin and myosin.
Smooth muscle contracts when calcium binds to __________ and activates __________.
-calmodulin; actin
-calmodulin; myosin light chain kinase
-troponin; myosin light chain kinase
-troponin; tropomyosin
calmodulin; myosin light chain kinase
Which of the following is true about the difference between cardiac muscle cells and skeletal muscle cells?
-Cardiac muscle cells does not have sarcomeres.
-Cardiac muscle cells have more nuclei in them than skeletal muscle cells.
-Cardiac muscle cells have intercalated discs where skeletal muscle cells do not.
-Cardiac muscle cells does not have striations like skeletal muscle cells.
-Cardiac muscle cells does not have t-tubules.
Cardiac muscle cells have intercalated discs where skeletal muscle cells do not.
The ________ division of the nervous system carries motor commands to muscles and glands.
-peripheral
-afferent
-efferent
-spinal
-autonomic
Efferent
The ________ nervous system provides involuntary regulation of smooth muscle, cardiac muscle, and glandular activity.
-peripheral
-autonomic
-somatic
-afferent
-motor
Autonomic
Which division of the PNS would contain sensory nerve fibers from special sensory receptors?
-efferent
-sympathetic
-parasympathetic
-afferent
Afferent
Neurons in which dendritic and axonal processes are continuous and the soma lies off to one side are called
-anaxonic
-unipolar
-bipolar
-tripolar
-multipolar
Unipolar
Which type of membrane channels are found at the axon?
-voltage-gated Ca2+ channels
-voltage-gated Na+ channels
-chemically-gated Na+ and K+ channels
-voltage-gated K+ channels
-both voltage-gated Na+ channels and voltage-gated K+ channels
Both voltage-gated Na+ channels and voltage-gated K+ channels
Which part of the neuron can propagate an action potential?
Axon
Most CNS neurons fall into which structural category?
-unipolar
-anaxonic
-bipolar
-multipolar
Multipolar
Which neuroglia myelinate CNS axons and which neuroglia myelinate PNS axons?
-oligodendrocytes; Schwann cells
-astrocytes; Schwann cells
-astrocytes; satellite cells
-satellite cells; astrocytes
-Schwann cells; oligodendrocytes
oligodendrocytes; Schwann cells
Small, wandering cells that engulf cell debris and pathogens in the CNS are called
-microglia
-satellite cells
-ependymal cells
-astrocytes
-oligodendrocytes
Microglia
Glial cells that surround the neurons in ganglia are
-satellite cells
-microglia
-oligodendrocytes
-ependymal cells
-astrocytes
Satellite cells
Damage to ependymal cells would most likely affect the
-formation of ganglia.
-formation of cerebrospinal fluid.
-formation of myelin sheaths.
-transport of neurotransmitters within axons.
-repair of axons.
Formation of cerebrospinal fluid.
Neuroglia perform all of these functions EXCEPT __________.
-release neurotransmitters
-regulate extracellular fluid composition
-provide supportive framework
-secrete CSF
release neurotransmitters
If the permeability of a resting axon to sodium ion increases,
-the membrane potential will hyperpolarize.
-inward movement of sodium ion will increase.
-inward movement of sodium will increase and the membrane will depolarize.
-outward movement of sodium ion will decrease.
-the membrane potential will repolarize.
Inward movement of sodium will increase and the membrane will depolarize.
Which of the following is not involved in creating the resting membrane potential of a neuron?
-membrane permeability for potassium ions greater than sodium ions
-membrane permeability for sodium ions greater than potassium ions
-diffusion of potassium ions out of the cell
-diffusion of sodium ions into the cell
-The interior of the plasma membrane has an excess of negative charges.
Membrane permeability for sodium ions greater than potassium ions
If the sodium-potassium pumps in the plasma membrane fail to function, all of the following occur except
-the neuron will slowly depolarize.
-the inside of the membrane will have a resting membrane potential that is more positive than normal.
-the membrane will slowly lose its capacity to generate action potentials.
-the intracellular concentration of potassium ions will increase.
-the intracellular concentration of sodium ions will increase.
The intracellular concentration of potassium ions will increase.
Graded potentials
-are often all-or-none.
-may be either a depolarization or a hyperpolarization.
-cause repolarization.
-produce an effect that spreads actively across the membrane surface.
-produce an effect that increases with distance from the point of stimulation.
may be either a depolarization or a hyperpolarization.
When potassium channels open and the ions diffuse through the membrane,
-there will be almost no effect on transmembrane potential.
-the inside of the membrane will become more negative.
-the membrane will depolarize to threshold.
-the inside of the membrane will become more positive.
-the membrane will become depolarized
The inside of the membrane will become more negative.
Ions can move across the plasma membrane in which of the following ways?
-through voltage-gated channels as in the action potential
-through passive or leak channels
-through chemically gated channels as in neuromuscular -transmission
-by ATP-dependent ion pumps like the sodium-potassium exchange pump
-All of the answers are correct.
All of the answers are correct.
The sodium–potassium exchange pump stabilizes resting potential of the neuron membrane at about __________.
- -70 mV
- -90 mV
- +66 mV
- -20 mV
-70 mV
The most abundant intracellular cation is __________, while the most abundant extracellular anion is __________.
-sodium, protein anions
-potassium, chloride
-potassium, protein anions
-sodium, chloride
potassium, chloride
Which type of ion channel is always open?
-chemically-gated
-leak
-mechanically-gated
-voltage-gated
Leak
The following are the main steps in the generation of an action potential.
1. Sodium channels are inactivated.
2. Voltage-gated potassium channels open and potassium moves out of the cell, initiating repolarization.
3. Sodium channels regain their normal properties.
4. A graded depolarization brings an area of an excitable membrane to threshold.
5. A temporary hyperpolarization occurs.
6. Sodium channel activation occurs.
7. Sodium ions enter the cell and depolarization occurs.
What is the proper sequence of these events?
4, 6, 7, 1, 2, 3, 5
The all-or-none principle states that
-the greater the magnitude of the stimuli, the greater the magnitude of the action potential.
-only sensory stimuli can activate action potentials.
-only motor stimuli can activate action potentials.
-all stimuli will produce identical action potentials.
-all stimuli great enough to bring the membrane to threshold will produce identical action potentials.
All stimuli great enough to bring the membrane to threshold will produce identical action potentials.
Which of the following statements about the action potential is false?
-During the repolarization phase, sodium channels close and potassium channels open.
-Repolarization occurs as potassium ions leave the axon.
-The rapid depolarization phase is caused by the entry of potassium ions.
-During the depolarization phase, membrane potential becomes positive.
-During the hyperpolarization phase, the ion pumps re-establish the sodium and potassium concentrations across the cell membrane.
The rapid depolarization phase is caused by the entry of potassium ions.
How would the absolute refractory period be affected if voltage-regulated sodium channels failed to inactivate?
-It would last indefinitely
-It would be much briefer
-It would basically be unaffected
It would last indefinitely
Puffer fish poison blocks voltage-gated sodium channels like a cork. What effect would this neurotoxin have on the function of neurons?
-The absolute refractory period would be shorter than normal.
-The axon would be unable to generate action potentials.
-Action potentials would lack a repolarization phase.
-Neurons would depolarize more rapidly.
-None, because the chemically gated sodium channels would still function.
The axon would be unable to generate action potentials.
Rapid impulse conduction from “node” to “node” is called
-spatial propagation.
-divergent propagation.
-saltatory propagation.
-continuous propagation.
-synaptic transmission.
saltatory propagation.
Which of the following does not influence the time necessary for a nerve impulse to be transmitted?
-whether or not the impulse begins in the CNS
-presence or absence of a myelin sheath
-presence or absence of nodes
-length of the axon
-diameter of the axon
whether or not the impulse begins in the CNS
In which of the following would the rate of impulse conduction be the greatest?
-a nonmyelinated fiber of 20-µm diameter
-a nonmyelinated fiber of 10-µm diameter
-a myelinated fiber of 10-µm diameter
-a myelinated fiber of 1-µm diameter
-It would be the same in all because of the all-or-none principle.
a myelinated fiber of 10-µm diameter
The period during which an excitable membrane cannot respond to further stimulation is the ________ period.
-lag
-absolute refractory
-resting
-stationary
-relative refractory
absolute refractory
Below are the events that occur during continuous propagation of action potential. Select the correct order in which the events occur.
- Adjacent membrane segment depolarizes.
- Local current spreads to adjacent voltage gated channel.
- Threshold is met.
- Local current develops due to sodium moving in the cytosol.
4, 2, 3, 1
What happens just after an axon is depolarized to threshold?
-Chemically-gated sodium channels open.
-Some potassium channels open.
-Voltage-gated sodium channels open.
-All potassium channels open.
Voltage-gated sodium channels open.
During propagation of the action potential, __________.
-after threshold is reached, voltage-gated sodium channels open rapidly
-local currents depolarize a spot adjacent to the active zone
-the axon hillock depolarizes the initial segment
-All of the listed responses are correct.
All of the listed responses are correct.
Compared to type A axons, type C axons are __________.
-smaller diameter
-slower propagating
-unmyelinated
-All of the listed responses are correct.
All of the listed responses are correct.
