Anatomy Chapters 10, 12, 13
moves a limb away
A distinction about the flexor reflex is that it __________. moves a limb away from a painful stimulus is an example of a monosynaptic reflex prevents a muscle from generating excessive tension prevents a muscle from overstretching
spinal nerve
A dorsal and ventral root of each spinal segment unite to form a spinal meninx. lumbar enlargement. spinal nerve. cervical enlargement. spinal ganglion.
neurotransmitter
A molecule that carries information across a synaptic cleft is a receiving neuron. neurotransmitter. sending neuron. synaptic cleft. synapse.
complete tetanus
A muscle producing its maximum tension is in __________. rigor mortis incomplete tetanus complete tetanus treppe
actin
A myosin head binds to which molecule to form a cross bridge? troponin actin tropomyosin
the postsynaptic neuron
A neuron that receives neurotransmitter from another neuron is called an oligodendrocyte. an interneuron. the postsynaptic neuron. the presynaptic neuron. the motor neuron.
reduces the muscle's ability for contraction
A patient takes a medication that blocks ACh receptors of skeletal muscle fibers. What is this drug's effect on skeletal muscle contraction? produces a strong, continuous state of contraction causes a strong contraction similar to a "charlie horse" cramp reduces the muscle's ability for contraction increases the muscle's excitability increases tone in the muscle
a reflex arc always includes all of these structures
A reflex arc always includes a(n) __________. sensory receptor afferent axon efferent axon A reflex arc always includes all of these structures.
aerobic metabolism of fatty acids
A resting muscle generates most of its ATP by the tricarboxylic acid cycle. aerobic metabolism of fatty acids. glycogenolysis. hydrolysis of creatine phosphate. anaerobic respiration.
a single pulse of calcium ion release
A single muscle action potential will normally be followed by __________. two pulses of calcium ion release incomplete tetanus treppe a single pulse of calcium ion release
perimysium
A thin layer of connective tissue that surrounds a muscle fascicle is called the __________. tendon perimysium epimysium endomysium
depolarization necessary to cause an action potential
A threshold stimulus is the resting potential. hyperpolarization of an axon. electrical current that crosses the synaptic cleft. depolarization necessary to cause an action potential. peak of an action potential.
a series of proteins that control calcium release
A triad is composed of a T-tubule and two adjacent terminal cisternae of the sarcoplasmic reticulum. How are these components connected? Voltage-gated sodium channels. Potassium leak channels. Myosin cross-bridge binding sites. A series of proteins that control calcium release.
detaching and resetting cross-bridges
ATP binding leads to which of the following actions? exposure of active sites on actin cross-bridge formation detaching and resetting cross-bridges pivoting of the myosin head
the opening of ligand-gated cation channels
Acetylcholine binds to its receptor in the sarcolemma and triggers __________. the opening of ligand-gated anion channels the opening of voltage-gated calcium channels the opening of calcium-release channels the opening of ligand-gated cation channels
on the motor end plate
Acetylcholine receptors are primarily located __________. inside vesicles inside the muscle fiber on the synaptic terminal on the motor end plate
initial segment
Action potential propagation begins (is first generated at) what region of a neuron? dendrite myelin node initial segment
Acetylcholine is degraded by acetylcholinesterase
Action potential propagation in a skeletal muscle fiber ceases when acetylcholine is removed from the synaptic cleft. Which of the following mechanisms ensures a rapid and efficient removal of acetylcholine? Acetylcholine diffuses away from the cleft. Acetylcholine is transported back into the axon terminal by a reuptake mechanism. Acetylcholine is degraded by acetylcholinesterase. Acetylcholine is transported into the postsynaptic neuron by receptor-mediated endocytosis.
extend from the brain or spinal cord to the sarcolemma of skeletal muscle fiber
Action potentials travel the length of the axons of motor neurons to the axon terminals. These motor neurons __________. extend from the spinal cord to the sarcolemma of a skeletal muscle fiber extend from the brain to the sarcolemma of a skeletal muscle fiber arise in the epimysium of a skeletal muscle and extend to individual skeletal muscle fibers extend from the brain or spinal cord to the sarcolemma of a skeletal muscle fiber
95
Aerobic metabolism normally provides ________ percent of the ATP demands of a resting muscle cell. 25 95 100 70 50
ATP binds to the myosin head
After a power stroke, the myosin head must detach from actin before another power stroke can occur. What causes cross bridge detachment? Calcium ions bind to troponin. ATP binds to the myosin head. ADP and inorganic phosphate are bound to the myosin head. Acetylcholine binds to receptors in the junctional folds of the sarcolemma.
rigor mortis
After death, muscle fibers run out of ATP and calcium begins to leak from the sarcoplasmic reticulum into the sarcoplasm. This results in a condition known as treppe. depolarization. rigor mortis. tetany. oxygen debt.
intercalated disks
All of the following are found in both skeletal and cardiac muscle fibers except __________. striations sarcomeres mitochondria intercalated disks
are arranged according to dermatomes
All of the following are true of polysynaptic reflexes, except that they have reverberating circuits that prolong the reflexive motor response. are arranged according to dermatomes. involve reciprocal innervation. are intersegmental in distribution. involve pools of interneurons.
the muscle fiber to contract
An action potential in the muscle fiber causes __________. acetylcholine to bind to receptors on the motor end plate acetylcholinesterase to break down acetylcholine the muscle fiber to contract the release of acetylcholine into the synaptic cleft
depolarizing currents established by the influx of Na+ flow down the axon and trigger an action potential at the next segment
An action potential is self-regenerating because __________. depolarizing currents established by the influx of K+ flow down the axon and trigger an action potential at the next segment depolarizing currents established by the influx of Na+ flow down the axon and trigger an action potential at the next segment repolarizing currents established by the efflux of Na+ flow down the axon and trigger an action potential at the next segment repolarizing currents established by the efflux of K+ flow down the axon and trigger an action potential at the next segment
voltage-gated Ca2+ channels
An action potential releases neurotransmitter from a neuron by opening which of the following channels? voltage-gated Na+ channels chemically gated Ca2+ channels voltage-gated K+ channels voltage-gated Ca2+ channels
all of the answers are correct
Any stimulus that opens ________ ion channel will produce a graded potential. ANSWER: a voltage-gated a mechanically-gated a sodium a chemically-gated All of the answers are correct.
1 meter per second
Approximately how fast do action potentials propagate in unmyelinated axons in humans? 120 meters per second 1 meter per second 0.1 meters per second 12 meters per second
-60mV
Around what transmembrane potential does threshold commonly occur? -60 mV -70 mV -60 V +60 mV
tendon
At each end of the muscle, the collagen fibers of the epimysium, and each perimysium and endomysium, come together to form a sheath. tendon. tenosynovium. satellite cell. ligament.
the membrane is much more permeable to potassium ions than to sodium ions
At rest, why is the transmembrane potential of a neuron (-70 mV) closer to the potassium equilibrium potential (-90 mV) than it is to the sodium equilibrium potential (+66 mV)? For each ATP hydrolyzed, the sodium-potassium exchange pump transports more sodium ions out of the cell (three) than it transports potassium ions into the cell (two). The concentration of potassium ions inside the cell is greater than the concentration of sodium ions outside the cell. There are more negatively charged proteins inside the cell than outside the cell. The membrane is much more permeable to potassium ions than to sodium ions.
chemically gated; postsynaptic
Binding of a neurotransmitter to its receptors opens __________ channels on the __________ membrane. chemically gated; postsynaptic voltage-gated; postsynaptic chemically gated; presynaptic voltage-gated; presynaptic
either depolarize or hyperpolarize
Binding of the neurotransmitter to its receptor causes the membrane to __________. either depolarize or hyperpolarize hyperpolarize depolarize
Synaptic vesicles fuse to the plasma membrane of the axon terminal and release acetylcholine
Calcium entry into the axon terminal triggers which of the following events? Cation channels open and sodium ions enter the axon terminal while potassium ions exit the axon terminal. Synaptic vesicles fuse to the plasma membrane of the axon terminal and release acetylcholine. Acetylcholine binds to its receptor. Acetylcholine is released into the cleft by active transporters in the plasma membrane of the axon terminal.
calcium ions are stored in the sarcoplasmic reticulum
Calcium ions couple excitation of a skeletal muscle fiber to contraction of the fiber. Where are calcium ions stored within the fiber? Calcium ions are stored in the transverse tubules. Calcium ions are stored in the sarcoplasmic reticulum. Calcium ions are stored in the nuclei. Calcium ions are stored in the mitochondria.
subarachnoid space
Cerebrospinal fluid flows within the pia mater. arachnoid mater. dura mater. subarachnoid space. filum terminale.
acetylcholine
Cholinergic synapses release the neurotransmitter adrenalin. serotonin. GABA. norepinephrine. acetylcholine.
in the same direction and of the same magnitude
Compared to the electrical gradient for sodium at rest, the electrical gradient for potassium at rest is __________. in the opposite direction but of the same magnitude. in the same direction and of the same magnitude. in the same direction but of greater magnitude. in the same direction but of lesser magnitude.
type C axons have all of these characteristics
Compared to type A axons, type C axons are __________. unmyelinated slower propagating smaller diameter Type C axons have all of these characteristics.
acts as an energy reserve in muscle tissue
Creatine phosphate is produced by the process of anaerobic respiration. is only formed during strenuous exercise. can replace ATP in binding to myosin molecules during contraction. cannot transfer its phosphate group to ADP. acts as an energy reserve in muscle tissue.
repeated cycling of cross-bridges causes all of these effects
Cycling of myosin cross-bridges results in ___________. force production ATP hydrolysis muscle shortening Repeated cycling of cross-bridges causes all of these effects.
most of the muscle's energy i produced in mitochondria
During activities requiring aerobic endurance fatigue occurs in a few minutes. glycogen and glycolysis are the primary sources of reserve energy. most of the muscle's energy is produced in mitochondria. oxygen is not required. oxygen debts are common.
the transmembrane potential (voltage)
During an action potential of a neuron, what directly causes the different channels to open and close? Sodium and potassium ions neurotransmitter binding to chemically gated channels the transmembrane potential (voltage) calcium ions
voltage-gated sodium channels begin to inactivate (close) and voltage-gated potassium channels begin to open
During an action potential, after the membrane potential reaches +30 mV, which event(s) primarily affect(s) the membrane potential? Voltage-gated potassium channels begin to open and the sodium-potassium exchange pump begins removing the excess Na+ ions from the inside of the cell. Voltage-gated sodium channels begin to inactivate (close) and voltage-gated potassium channels begin to open. Voltage-gated sodium channels begin to inactivate (close). Voltage-gated sodium channels begin to inactivate (close) and the sodium-potassium exchange pump begins removing the excess sodium ions from the inside of the cell.
all of the answers are correct
During anaerobic glycolysis ATP is produced. oxygen is not consumed. carbohydrate is metabolized. pyruvic acid is produced. All of the answers are correct.
both the electrical and chemical gradients
During depolarization, which gradient(s) move(s) Na+ into the cell? Na+ does not move into the cell. Na+ moves out of the cell. only the electrical gradient both the electrical and chemical gradients only the chemical gradient
acetylcholinesterase
During neuromuscular transmission, the axon terminals release __________. sodium ions acetylcholine calcium ions acetylcholinesterase
all of these events occur during propagation of the action potential
During propagation of the action potential, __________. the axon hillock depolarizes the initial segment local currents depolarize a spot adjacent to the active zone after threshold is reached, sodium channels open rapidly All of these events occur during propagation of the action potential.
glucose is produced from lactic acid
During the Cori cycle, in the liver glucose is produced from lactic acid. lactic acid is produced from pyruvic acid. lactic acid is shuffled to muscle cells. glucose is released from glycogen. lactic acid is produced from glucose.
additional oxygen is required o restore energy reserves consumed during exercise
During the recovery period the body's need for oxygen is increased because additional oxygen is required to restore energy reserves consumed during exercise. the muscles are not producing ATP. muscle cells are producing energy anaerobically. the individual is panting. the liver requires more oxygen to produce lactic acid.
neuromuscular junction
Each skeletal muscle fiber is controlled by a motor neuron at a single synaptic cleft. neuromuscular junction. sarcomere. synaptic knob. transverse tubule.
b-a-d-c
Events that occur at a cholinergic synapse are listed here, but they are arranged in an incorrect order. Choose the correct order of these events below. (a) Calcium influx triggers exocytosis of ACh. (b) An action potential depolarizes the synaptic terminal. (c) ACh is removed by AChE. (d) ACh binds to receptors on the postsynaptic membrane. b→ a→ d→ c c→ d→ b→ a a→ b→ d→ c b→ a→ c→ d
Calcium release from the sarcoplasmic reticulum initiates the contraction.
Excitation of the sarcolemma is coupled or linked to the contraction of a skeletal muscle fiber. What specific event initiates the contraction? Action potentials propagate into the interior of the skeletal muscle fiber. Voltage-sensitive proteins change shape. Sodium release from the sarcoplasmic reticulum initiates the contraction. Calcium release from the sarcoplasmic reticulum initiates the contraction.
excitation, in this case, refers to the propagation of the action potentials along the sarcolemma
Excitation-contraction coupling is a series of events that occur after the events of the neuromuscular junction have transpired. The term excitation refers to which step in the process? Excitation refers to the shape change that occurs in voltage-sensitive proteins in the sarcolemma. Excitation refers to the propagation of action potentials along the axon of a motor neuron. Excitation, in this case, refers to the propagation of action potentials along the sarcolemma. Excitation refers to the release of calcium ions from the sarcoplasmic reticulum.
conducting action potentials
Functions of astrocytes include all of the following, except guiding neuron development. maintaining the blood-brain barrier. responding to neural tissue damage. conducting action potentials. forming a three-dimensional framework for the CNS
satellite cells
Glial cells that surround the neurons in ganglia are oligodendrocytes. microglia. satellite cells. astrocytes. ependymal cells.
propagation is faster in myelinated axons
How do action potential propagation speeds in myelinated and unmyelinated axons compare? Propagation in myelinated axons is faster over short distances, but slower over long distances. Propagation speeds are similar in both axon types. Propagation is faster in unmyelinated axons. Propagation is faster in myelinated axons.
the energy comes from the hydrolysis of ATP
How does the myosin head obtain the energy required for activation? The energy comes from the direct phosphorylation of ADP by creatine phosphate. The energy comes from the hydrolysis of GTP. The energy comes from oxidative phophorylation. The energy comes from the hydrolysis of ATP.
acetylcholinesterase (AChE; n enzyme)
How is acetylcholine (ACh) removed from the synaptic cleft? a reuptake pump on the axon terminal diffusion away from the synaptic cleft acetylcholinesterase (AChE; an enzyme)
an influx of sodium ions from the current action potential depolarizes the adjacent area
How is an action potential propagated along an axon? Stimuli from the graded (local) potentials from the soma and dendrites depolarize the entire axon. An influx of sodium ions from the current action potential depolarizes the adjacent area. An efflux of potassium from the current action potential depolarizes the adjacent area.
slow closing of voltage-gated K+ channels
Hyperpolarization results from __________. slow closing of voltage-gated Na+ channels fast closing of voltage-gated K+ channels slow closing of voltage-gated K+ channels
the receiving neuron is less likely to generate an action potential
If a signal from a sending neuron makes the receiving neuron more negative inside, the receiving neuron is more likely to generate an action potential. the sending neuron becomes more positive inside. the sending neuron becomes more negative inside. the receiving neuron immediately generates an action potential. the receiving neuron is less likely to generate an action potential.
acetylcholine (ACh)
In a neuromuscular junction, synaptic vesicles in the motor neuron contain which neurotransmitter? serotonin acetylcholine (ACh) norepinephrine dopamine
the sodium concentration is higher outside the cell than inside the cell and the potassium concentration is higher inside the cell than outside the cell
In a neuron, sodium and potassium concentrations are maintained by the sodium-potassium exchange pump such that __________. the sodium concentration is higher inside the cell than outside the cell and the potassium concentration is higher outside the cell than inside the cell. both sodium and potassium concentrations are higher outside the cell compared to inside. the sodium concentration is higher outside the cell than inside the cell and the potassium concentration is higher inside the cell than outside the cell. the concentration of sodium outside the cell is equal to the concentration of potassium inside the cell.
presynaptic neuron
In a synapse, neurotransmitters are stored in vesicles located in the __________. presynaptic neuron postsynaptic neuron synaptic cleft
-90mV
In a typical neuron, what is the equilibrium potential for potassium? +66 mV -90 mV -70 mV 0 mV
+66mV
In a typical neuron, what is the equilibrium potential for sodium? -90 mV +66 mV +30 mV -70 mV
muscle tension exceeds the load and the muscle lifts the load
In an isotonic contraction, 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. tension rises and falls but the muscle length is constant.
the previous axonal segment is refractory
In an unmyelinated axon, why doesn't the action potential suddenly "double back" and start propagating in the opposite direction? Positive charges only move in one direction. New action potential generation near the soma repels previously generated action potentials. The previous axonal segment is refractory. The extracellular sodium concentration is too low around the previous axonal segment for an action potential to be (re)generated.
have lower membrane resistance to ion movement
In contrast to the internodes of a myelinated axon, the nodes __________. have higher membrane resistance to ion movement only occur at the beginning and end of the axon have lower membrane resistance to ion movement are wrapped in myelin
all of the answers are correct
In meningitis, bacteria can be the cause. CSF flow can be disrupted. viruses can be the cause. inflammation of the meninges occurs. All of the answers are correct.
calcium ions
In response to action potentials arriving along the transverse tubules, the sarcoplasmic reticulum releases hydrogen ions. potassium ions. sodium ions. acetylcholine. calcium ions.
sarcoplasmic reticulum
In response to an action potential along the transverse tubules, the __________ release(s) calcium ions into the sarcoplasm. troponin molecules sarcoplasmic reticulum thin filaments calcitonin
all of the answers are correct
In rigor mortis ATP is depleted. muscles are inextensible. the myosin heads are attached to actin. cross-bridge cycling is absent. All of the answers are correct.
initial segment of the axon
In what part of the neuron does the action potential typically initiate? dendrites soma (cell body) initial segment of the axon axon terminals
a polysynaptic reflex
In which of the following would the delay between stimulus and response be greater? a polysynaptic reflex a monosynaptic reflex
muscles that control the eyes
In which of the following would the motor units have the fewest muscle fibers? muscles of the neck postural muscles of the back thigh muscles calf muscles muscles that control the eyes
myelinated axons with the largest diameter
In which type of axon will velocity of action potential conduction be the fastest? Myelinated axons with the smallest diameters Unmyelinated axons with the largest diameter Unmyelinated axons of the shortest length Myelinated axons with the largest diameter
fascicles
Inside a muscle, bundles of single muscle fibers form __________. sarcomeres fascicles thick filaments T tubules
vesicles
Inside a neuron, acetylcholine is contained within __________. the motor end plate acetylcholine receptors vesicles the synaptic cleft
muscle contraction
Interactions between actin and myosin filaments of the sarcomere are responsible for the striped appearance of skeletal muscle. muscle relaxation. muscle fatigue. muscle contraction. the conduction of neural stimulation to the muscle fiber.
resting membrane potential (RMP)
Ions are unequally distributed across the plasma membrane of all cells. This ion distribution creates an electrical potential difference across the membrane. What is the name given to this potential difference? Resting membrane potential (RMP) Threshold potential Action potential Positive membrane potential
all of the answers are correct
Ions can move across the plasma membrane in which of the following ways? through passive or leak channels through chemically-gated channels as in neuromuscular transmission through voltage-gated channels as in the action potential by ATP-dependent ion pumps like the sodium-potassium exchange pump All of the answers are correct.
fast fibers
Large-diameter, densely packed myofibrils, large glycogen reserves, and few mitochondria are characteristics of fatty muscles. red muscles. fast fibers. intermediate fibers. slow fibers.
channel-mediated diffusion
Leak channels allow the movement of potassium and sodium ions by what type of membrane transport? channel-mediated diffusion facilitated diffusion simple diffusion active transport
the muscles would contract because of the calcium binding to troponin
Malignant hyperthermia (MH) is a rare genetic disease in which the sarcoplasmic reticulum leaks calcium when the patient is put under general anesthesia. Which of the following best describes how anesthesia would affect the skeletal muscles of a patient with MH? The muscles would contract because of increased action potential generation in the sarcolemma. The muscles would relax because of calcium being pumped back into the sarcoplasmic reticulum. The muscles would contract because of calcium binding to troponin. The muscles would contract because of increased nerve stimulation.
multipolar
Most CNS neurons fall into which structural category? anaxonic bipolar multipolar unipolar
without myelin, the internode membrane resistance decreases, preventing local currents from reaching adjacent nodes
Multiple sclerosis (MS) is a disease that stops action potential propagation by destroying the myelin around (normally) myelinated axons. Which of the following best describes how MS stops action potential propagation? Without myelin, the node membrane more easily becomes refractory. Without myelin, the internode membrane resistance decreases, preventing local currents from reaching adjacent nodes. Without myelin, the internode membrane resistance increases, preventing local currents from reaching adjacent nodes. Without myelin, the internode membrane is depolarized more easily.
lactic acid; decrease
Muscle fatigue occurs due to a buildup of __________ and __________ in pH. lactic acid; decrease lactic acid; increase creatine phosphate; decrease creatine phosphate; increase
have many nuclei
Muscle fibers differ from "typical cells" in that muscle fibers are very small. have large gaps in the cell membrane. have many nuclei. lack a plasma membrane. lack mitochondria.
contraction
Muscle tissue, one of the four basic tissue groups, consists chiefly of cells that are highly specialized for peristalsis. contraction. conduction. secretion cushioning.
aponeurosis
Muscles are attached to bones by tendons or __________. perimysium aponeuroses ligaments superficial fascia
made of a series of sarcomeres
Myofibrils are __________. proteins that cover active sites on actin made of a series of sarcomeres connections between actin and myosin bundles of muscle cells inside a whole muscle
actin
Myosin molecules form cross-bridges when they attach to __________. actin troponin tropomyosin calcium
thick filament
Myosin molecules form what part of the sarcomere? actin tropomyosin thin filament thick filament
unipolar
Neurons in which dendritic and axonal processes are continuous and the soma lies off to one side are called anaxonic. tripolar. unipolar. multipolar. bipolar.
anaxonic
Neurons that are rare, small, and lack features that distinguish dendrites from axons are called anaxonic. unipolar. multipolar. tripolar. bipolar.
bipolar
Neurons that have one axon and one dendrite, with the soma in between, are called bipolar. multipolar. anaxonic. tripolar. unipolar.
multipolar
Neurons that have several dendrites and a single axon are called tripolar. anaxonic. bipolar. unipolar. multipolar.
the inside surface of the plasma membrane is much more negatively charged than the outside surface
On average, the resting membrane potential is -70 mV. What does the sign and magnitude of this value tell you? The outside surface of the plasma membrane is much more negatively charged than the inside surface. The inside surface of the plasma membrane is much more positively charged than the inside surface. The inside surface of the plasma membrane is much more negatively charged than the outside surface. There is no electrical potential difference between the inside and the outside surfaces of the plasma membrane.
chemical and electrical gradients both going into the cell
Part G The electrochemical gradient for sodium ions in a neuron when the transmembrane potential is at the resting potential is caused by what? a chemical gradient going out of the cell and an electrical gradient going into the cell a chemical gradient going into the cell and an electrical gradient going out of the cell chemical and electrical gradients both going into the cell chemical and electrical gradients both going out of the cell
white
Regions of the CNS with an abundance of myelinated axons constitute the ________ matter.
plasticity
Resting smooth muscle can be stretched without developing much tension because of its __________. elasticity extensibility contractility plasticity
subarachnoid space
Samples of CSF for diagnostic purposes are normally obtained by placing the tip of a needle in the epidural space. arachnoid mater. dura mater. cerebral ventricles. subarachnoid space.
myoblasts
Skeletal muscle fibers are formed from embryonic cells called myofibrils. sarcomeres. myoblasts. myomeres. fascicles.
microglia
Small, wandering cells that engulf cell debris and pathogens in the CNS are called ependymal cells. microglia. oligodendrocytes. astrocytes. satellite cells.
leak channels
Sodium and potassium ions can diffuse across the plasma membranes of all cells because of the presence of what type of channel? Sodium-potassium ATPases Leak channels Ligand-gated channels Voltage-gated channels
The inside surface of the sarcolemma is negatively charged compared to the outside surface. Sodium ions diffuse inward along favorable chemical and electrical gradients.
Sodium and potassium ions do not diffuse in equal numbers through ligand-gated cation channels. Why? The outside surface of the sarcolemma is negatively charged compared to the inside surface. Sodium ions diffuse outward along favorable chemical and electrical gradients. The inside surface of the sarcolemma is negatively charged compared to the outside surface. Sodium ions diffuse inward along favorable chemical and electrical gradients. The outside surface of the sarcolemma is negatively charged compared to the inside surface. Potassium ions diffuse outward along favorable chemical and electrical gradients. The inside surface of the sarcolemma is negatively charged compared to the outside surface. Potassium ions diffuse inward along favorable chemical and electrical gradients.
both sensory and motor
Spinal nerves are involuntary. purely sensory. purely motor. both sensory and motor. interneuronal.
exocytosis
Synaptic vesicles contain neurotransmitters that are released by ________ when the action potential arrives. apoptosis endocytosis exocytosis hydrolysis sodium
triads
T tubules and the terminal cisternae are clustered into structures called __________. fascicles sarcomeres myofibrils triads
pyruvic acid is converted back to lactic acid
The "rest and recovery" period, where the muscle restores depleted reserves, includes all of the following processes EXCEPT __________. Pyruvic acid is converted back to lactic acid. Oxygen rebinds to myoglobin. ATP is used to rephosphorylate creatine into creatine phosphate. Glycogen is synthesized from glucose molecules.
Na+ is pumped out of the cell and K+ is pumped into the cell
The Na+-K+ pump actively transports both sodium and potassium ions across the membrane to compensate for their constant leakage. In which direction is each ion pumped? Both Na+ and K+ are pumped out of the cell. Na+ is pumped out of the cell and K+ is pumped into the cell. Both Na+ and K+ are pumped into the cell. K+ is pumped out of the cell and Na+ is pumped into the cell.
filum terminale
The ________ is a strand of fibrous tissue that provides longitudinal support as a component of the coccygeal ligament. ventral root cauda equina filum terminale conus medullaris dorsal root
somatic
The ________ nervous system controls the skeletal muscles. parasympathetic afferent somatic sympathetic autonomic
central
The ________ nervous system is composed of the brain and spinal cord. autonomic peripheral central afferent efferent
spinal cord; spinal nerve
The __________ is part of the CNS and the __________ is part of the PNS. cranial nerve; spinal nerve spinal cord; spinal nerve spinal nerve; spinal cord brain; spinal cord
crossed extensor
The __________ reflex involves activating muscles contralateral to the receptor. flexor crossed extensor tendon stretch
fast
The __________ type of muscle fiber has relatively few mitochondria. cardiac fast intermediate slow
sarcolemma
The action potential in skeletal muscle fibers is generated by the __________. sarcophagus sarcolemma sarcoplasmic reticulum sarcoplasm
terminal cisternae of the sarcoplasmic reticulum
The action potential on the muscle cell leads to contraction due to the release of calcium ions. Where are calcium ions stored in the muscle cell? terminal cisternae of the sarcoplasmic reticulum cytosol sarcolemma T tubule
carries sensory information
The afferent division of the PNS _____________. carries motor commands carries sensory information controls skeletal muscle controls smooth muscle
all stimuli great enough to bring the membrane to threshold will produce identical action potentials
The all-or-none principle states that all stimuli will produce identical action potentials. only motor stimuli can activate action potentials. the greater the magnitude of the stimuli, the greater the magnitude of the action potential. only sensory stimuli can activate action potentials. all stimuli great enough to bring the membrane to threshold will produce identical action potentials.
cell body (soma)
The axon hillock connects the axon with the __________. synapse telodendria cell body (soma) collaterals
all of the answers are correct
The axoplasm of the axon contains which of the following? mitochondria vesicles neurotubules neurofibrils All of the answers are correct.
neuron
The basic functional unit of the nervous system is the ________.
troponin
The binding of calcium to which molecule causes the myosin binding sites to be exposed? troponin tropomyosin actin
binding of the neurotransmitter causes chemically gated sodium channels to open in the motor end plate
The binding of the neurotransmitter to receptors on the motor end plate causes which of the following to occur? Binding of the neurotransmitter causes chemically gated sodium channels to open in the motor end plate. Binding causes potassium voltage-gated channels to open in the motor endplate. Binding causes voltage-gated sodium channels to open in the motor endplate. Binding causes chemically gated potassium channels to open in the motor end plate.
phrenic
The brachial plexus gives rise to all of the following nerves, except the musculocutaneous. radial. median. ulnar. phrenic.
tendon
The bundle of collagen fibers at the end of a skeletal muscle that attaches the muscle to bone is called a(n) myofibril. ligament. epimysium. tendon. fascicle.
endomysium
The capillaries that wrap around each muscle fiber are located within the __________. sarcolemma perimysium endomysium epimysium
subarachnoid space
The cerebrospinal fluid (CSF) circulates within the __________. dura mater subarachnoid space subdural space pia mater
Na+ and Cl-
The concentrations of which two ions are highest outside the cell. Na+ and A- (negatively charged proteins) K+ and A- (negatively charged proteins) Na+ and Cl- K+ and Cl-
endoneurium
The connective tissue layer that covers Schwann cells is the __________. endomysium epineurium perineurium endoneurium
a myosin head bound to actin
The cross bridge cycle is a series of molecular events that occur after excitation of the sarcolemma. What is a cross bridge? Calcium bound to troponin A myosin head bound to actin Troponin bound to tropomyosin ATP bound to a myosin head
acetylcholine
The cytoplasm of the neuromuscular terminal contains vesicles filled with molecules of the neurotransmitter epinephrine. acetylcholine. antidiuretic hormone. adrenaline. norepinephrine.
epimysium
The dense layer of connective tissue that surrounds an entire skeletal muscle is the fascicle. endomysium. epimysium. tendon. perimysium.
voltage-gated Na+ channels
The depolarization phase of an action potential results from the opening of which channels? chemically gated Na+ channels voltage-gated Na+ channels voltage-gated K+ channels chemically gated K+ channels
cell bodies of sensory neurons
The dorsal root ganglia mainly contain cell bodies of sensory neurons. cell bodies of motor neurons. axons of sensory neurons. synapses. axons of motor neurons.
all of these factors affect what happens at the postsynaptic neuron
The effect of a nerve impulse on a postsynaptic neuron depends on the __________. characteristics of the receptor on the postsynaptic neuron quantity of neurotransmitter released kind of neurotransmitter released by the presynaptic neuron All of these factors affect what happens at the postsynaptic neuron.
all of the answers are correct
The efferent division of the peripheral nervous system innervates: smooth muscle cells skeletal muscle cells heart muscle cells glandular cells All of the answers are correct.
a chemical gradient going out of the cell and an electrical gradient going into the cell
The electrochemical gradient for potassium ions when the transmembrane potential is at the resting potential (-70 mV) is caused by what? chemical and electrical gradients both going out of the cell chemical and electrical gradients both going into the cell a chemical gradient going out of the cell and an electrical gradient going into the cell a chemical gradient going into the cell and an electrical gradient going out of the cell
synaptic terminal
The end of a neuron, where acetylcholine-filled vesicles are located, is called the __________. synaptic terminal acetylcholine receptor synaptic cleft motor end plate
synaptic delay
The events that occur at a functioning cholinergic synapse cause _____________ . strengthening of the synapse a flow of acetylcholine (ACh) into the synaptic cleft that is removed only by simple diffusion synaptic delay loss of transmission of the action potential
all of the answers are correct
The function of the astrocytes in the CNS includes which of the following? maintaining the blood-brain barrier guiding neuron development adjusting the composition of the interstitial fluid repairing damaged neural tissue All of the answers are correct.
calcium
The ion that triggers the release of acetylcholine into the synaptic cleft is potassium. sodium. calcium. chloride. magnesium.
astrocytes
The largest and most numerous of the glial cells in the central nervous system are the ependymal cells. satellite cells. oligodendrocytes. microglia. astrocytes
pia mater
The layer of the meninges in direct contact with the spinal cord is the subarachnoid space. arachnoid. dura mater. pia mater. choroid plexus.
acetylcholine
The mechanism by which the neurotransmitter is returned to a presynaptic neuron's axon terminal is specific for each neurotransmitter. Which of the following neurotransmitters is broken down by an enzyme before being returned? acetylcholine glutamate
K+; Na+
The membranes of neurons at rest are very permeable to _____ but only slightly permeable to _____. Na+; Cl- K+; Na+ Na+; K+ K+; Cl-
multipolar
The most abundant class of neuron in the central nervous system is bipolar. multipolar. pseudopolar. anaxonic. unipolar.
potassium; chloride
The most abundant intracellular cation is __________ while the most abundant extracellular anion is __________. sodium; chloride potassium; protein anions sodium; protein anions potassium; chloride
sodium (Na+)
The movement of what ion is responsible for the local currents that depolarize other regions of the axon to threshold? calcium (Ca2+) voltage-gated sodium (Na+) channels sodium (Na+) Potassium (K+)
transverse tubules
The muscle action potential penetrates into a fiber along the __________. Z discs transverse tubules sarcoplasmic reticulum neuromuscular junction
T-tubules
The muscle action potentials that initiate contraction are transmitted from the sarcolemma into the interior of the muscle fiber by __________. T tubules myofilaments the sarcoplasmic reticulum myofibrils
loss of acetylcholine receptors in the end-plate membrane
The muscle weakness of myasthenia gravis results from insufficient acetylcholine release from presynaptic vesicles. inability of the muscle fiber to produce ATP. loss of acetylcholine receptors in the end-plate membrane. the motor neuron action potential being too small to shock the muscle fibers. excessive acetylcholinesterase that destroys the neurotransmitter
oligodendrocytes
The myelin sheath that covers many CNS axons is formed by oligodendrocytes. astrocytes. ependymal cells. satellite cells. microglia.
synaptic cleft
The narrow space between the synaptic terminal and the muscle fiber is the synaptic knob. synaptic cleft. motor unit. motor end plate. M line.
Schwann cells
The neurilemma of axons in the peripheral nervous system is formed by microglia. satellite cells. Schwann cells. oligodendrocytes. astrocytes.
astrocytes
The neuroglial cells that participate in maintaining the blood-brain barrier are the microglia. ependymal cells. oligodendrocytes. Schwann cells. astrocytes.
muscle fiber
The neuromuscular junction is a connection between a neuron and a __________. myofibril muscle fiber vesicle synaptic terminal
Acetylcholine is released by axon terminals of the motor neuron
The neuromuscular junction is a well-studied example of a chemical synapse. Which of the following statements describes a critical event that occurs at the neuromuscular junction? Acetylcholine is released by axon terminals of the motor neuron. When the action potential reaches the end of the axon terminal, voltage-gated sodium channels open and sodium ions diffuse into the terminal. Acetylcholine binds to its receptor in the junctional folds of the sarcolemma. Its receptor is linked to a G protein. Acetylcholine is released and moves across the synaptic cleft bound to a transport protein.
presynaptic inhibition
The neurotransmitter GABA blocks presynaptic voltage-gated calcium channels. Consequently, GABA produces __________. presynaptic inhibition EPSPs presynaptic facilitation IPSPs
EPSPs
The neurotransmitter glutamate opens channels that are permeable to sodium ions. What effect does glutamate produce on a postsynaptic neuron? both IPSPs and EPSPs EPSPs neither IPSPs nor EPSPs IPSPs
saltatory propagation
The node-to-node "jumping" regeneration of an action potential along a myelinated axon is called __________. local propagation continuous propagation myelinated propagation saltatory propagation
afferent
The part of the peripheral nervous system that carries sensory information to the CNS is designated afferent. motor. somatic. efferent. autonomic.
there are many more K+ leak channels than Na+ leak channels in the plasma membrane
The plasma membrane is much more permeable to K+ than to Na+. Why? The Na+-K+ pumps transport more K+ into cells than Na+ out of cells. Ligand-gated cation channels favor a greater influx of Na+ than K+. There are many more voltage-gated K+ channels than voltage-gated Na+ channels. There are many more K+ leak channels than Na+ leak channels in the plasma membrane.
sarcolemma
The plasma membrane of a skeletal muscle fiber is called the sarcoplasm. sarcomere. sarcosome. sarcolemma. sarcoplasmic reticulum.
retrograde axoplasmic transport
The rabies virus travels to the CNS via retrograde axoplasmic transport. subcutaneous connective tissue. anterograde axoplasmic transport. cerebrospinal fluid. blood vessels.
tendon
The reflex that limits muscle tension is the __________ reflex. tendon reciprocal flexor stretch
dermatome
The region of the body surface monitored by a pair of spinal nerves is known as a(n) __________. input domain dermatome segment dermal band
I band
The region of the sarcomere that always contains thin filaments is the I band. A band. M line. H band. Z line.
sarcomere
The repeating unit of a skeletal muscle fiber is the sarcomere. myofibril. myofilament. sarcolemma. sarcoplasmic reticulum.
the opening of voltage-gated K+ channels
The repolarization phase of an action potential results from __________. the opening of voltage-gated K+ channels the opening of voltage-gated Na+ channels the closing of voltage-gated K+ channels the closing of voltage-gated Na+ channels
the presence of concentration gradients and leak channels
The resting membrane potential depends on two factors that influence the magnitude and direction of Na+ and K+ diffusion across the plasma membrane. Identify these two factors. The presence of a resting membrane potential and leak channels The presence of concentration gradients and Na+-K+ pumps The presence of concentration gradients and leak channels The presence of concentration gradients and voltage-gated channels
remove acetylcholine from the synaptic cleft
The role of acetylcholinesterase in the neuromuscular junction is to __________. generate a muscle action potential release acetylcholine from the synaptic terminal increase the sodium permeability of the motor end plate remove acetylcholine from the synaptic cleft
calcium
The sarcoplasmic reticulum contains __________. T tubules myofilaments troponin calcium
synapse
The site of intercellular communication between a neuron and another cell is the telodendria. hillock. synapse. synaptic terminals. collateral.
a traverse tubule and two terminal cisternae
The skeletal muscle complex known as the triad consists of actin, myosin, and filaments. a transverse tubule and two terminal cisternae. actin, myosin, and sarcomeres. A bands, H bands, and I bands. filaments, myofibrils, and sarcomeres.
synaptic cleft
The small space between the sending neuron and the receiving neuron is the vesicle. synaptic terminal. synaptic cleft. neurotransmitter. calcium channel.
-70mV
The sodium-potassium exchange pump stabilizes resting potential at about __________. -90 mV -10 mV -70 mV +66 mV
sodium ions are transported out of the cell. potassium ions are transported into the cell
The sodium-potassium exchange pump transports potassium and sodium ions in which direction(s)? Sodium and potassium ions are both transported out of the cell. Sodium ions are transported into the cell. Potassium ions are transported out of the cell. Sodium and potassium ions are both transported into the cell. Sodium ions are transported out of the cell. Potassium ions are transported into the cell.
31
The spinal cord consists of __________ segments, each associated with two pairs of nerve roots. 5 12 31 29 to 31
4
The spinal cord stops elongating at about __________ years of age. 15 4 2 10
the dura mater and the arachnoid mater
The subdural space lies between the arachnoid mater and the pia mater. the dura mater and the arachnoid mater. the pia mater and the dura mater. the endosteum and the periosteum. the pia mater and the subarachnoid space.
dura mater
The tough, fibrous, outermost covering of the spinal cord is the dura mater. epidural block. pia mater. periosteum. arachnoid.
isometric
The type of contraction in which the muscle fibers do not shorten is called tetany. isometric. concentric. treppe. isotonic.
slow
The type of muscle fiber that is most resistant to fatigue is the ________ fiber. intermediate fast slow anaerobic high-density
a small myelinated axon
The velocity of the action potential is fastest in which of the following axons? a large unmyelinated axon a small unmyelinated axon a small myelinated axon
myelinated and unmyelinated axons
The white matter of the spinal cord is mainly Schwann cells. nodes of Ranvier. unmyelinated axons. neuroglia. myelinated and unmyelinated axons.
elastic protein
Titin is a(n) __________. calcium-binding protein elastic protein thin filament protein tropomyosin-binding protein
all of these can increase muscle tension
To increase muscle tension, the nervous system can __________. increase the number of active motor units increase the stimulation frequency recruit larger motor units All of these can increase muscle tension.
troponin
To what regulatory protein does calcium bind during the initiation of the contraction cycle in skeletal muscle fibers? actin troponin myosin tropomyosin
inactivation
Voltage-gated sodium channels have both an activation gate and a(n) ________ gate. repolarization ion swinging inactivation threshold
skin over the medial surface of the leg
What area of the body does the obturator nerve serve? skin over the medial surface of the leg muscles of the posterior thigh abdominal muscles skin over the posterior surface of the leg
potassium efflux (leaving cell)
What causes repolarization of the membrane potential during the action potential of a neuron? sodium influx (entering the cell) potassium efflux (leaving the cell) potassium influx (entering the cell) sodium efflux (leaving the cell)
binding of ATP
What causes the myosin head to disconnect from actin? binding of ATP binding of troponin binding of calcium hydrolysis of ATP
arrival of an action potential
What causes the release of calcium from the terminal cisternae of the sarcoplasmic reticulum within a muscle cell? ATP troponin arrival of an action potential calcium ion pump
an action potential in the neuron
What causes the vesicles inside a neuron to fuse with the plasma membrane? an action potential in the muscle fiber acetylcholine binding to acetylcholine receptors acetylcholine being broken down by acetylcholinesterase an action potential in the neuron
inactivation gates of voltage-gated Na+ channels close, while activation gates of voltage-gated K+ channels open
What changes occur to voltage-gated Na+ and K+ channels at the peak of depolarization? Activation gates of voltage-gated Na+ channels close, while activation gates of voltage-gated K+ channels open. Inactivation gates of voltage-gated Na+ channels close, while inactivation gates of voltage-gated K+ channels open. Activation gates of voltage-gated Na+ channels close, while inactivation gates of voltage-gated K+ channels open. Inactivation gates of voltage-gated Na+ channels close, while activation gates of voltage-gated K+ channels open.
the membrane potential changes from a negative value to a positive value
What characterizes depolarization, the first phase of the action potential? The membrane potential changes from a negative value to a positive value. The membrane potential changes to a much more negative value. The membrane potential changes to a less negative (but not a positive) value. The membrane potential reaches a threshold value and returns to the resting state.
once the membrane depolarizes to a peak value of +30mV, it repolarizes to its negative resting value of -70 mV
What characterizes repolarization, the second phase of the action potential? As the membrane repolarizes to a negative value, it goes beyond the resting state to a value of -80 mV. Once the membrane depolarizes to a threshold value of approximately -55 mV, it repolarizes to its resting value of -70 mV. Before the membrane has a chance to reach a positive voltage, it repolarizes to its negative resting value of approximately -70 mV. Once the membrane depolarizes to a peak value of +30 mV, it repolarizes to its negative resting value of -70 mV.
hydrolysis of ATP
What energizes the power stroke? hydrolysis of ATP binding of ATP calcium
the membrane potential must depolarize from the resting voltage of -70mV to threshold value of -55 mV
What event triggers the generation of an action potential? The membrane potential must depolarize from the resting voltage of -70 mV to a threshold value of -55 mV. The membrane potential must hyperpolarize from the resting voltage of -70 mV to the more negative value of -80 mV. The membrane potential must return to its resting value of -70 mV from the hyperpolarized value of -80 mV. The membrane potential must depolarize from the resting voltage of -70 mV to its peak value of +30 mV.
the myosin head pivots, moving the actin strand
What happens immediately after the myosin head binds to the active site on actin? ATP binds to the myosin head. The myosin head pivots, moving the actin strand. Tropomyosin moves away from the active site on actin. The myosin head detaches from the active site on actin.
K+ (potassium)
What ion causes repolarization of the neuron during an action potential? Na+ (sodium) Ca2+ (calcium) K+ (potassium) Mg2+ (magnesium)
Na+ (sodium)
What ion is responsible for the depolarization of the neuron during an action potential? Na+ (sodium) Cl- (chloride) Ca2+ (calcium) K+ (potassium)
transverse or T tubules
What is name given to the regularly spaced infoldings of the sarcolemma? transverse or T tubules sarcoplasmic reticulum terminal cisternae motor endplates
voltage-gated potassium channels taking some time to close in response to the negative membrane potential
What is primarily responsible for the brief hyperpolarization near the end of the action potential? the sodium/potassium exchange pump taking some time to restore the normal ion concentrations voltage-gated potassium channels taking some time to close in response to the negative membrane potential voltage-gated sodium channels taking some time to recover from inactivation voltage-gated potassium channels opening as the membrane potential becomes more negative (repolarized)
the sum of the electrical and chemical gradients for that ion
What is the electrochemical gradient of an ion? the transmembrane potential at which the electrical and chemical gradients are equal in magnitude, but opposite in direction the difference between the concentrations of an ion inside and outside the cell The electrochemical gradient is the direction an ion would diffuse (either outward or inward) when the neuron is at rest, regardless of the transmembrane potential. the sum of the electrical and chemical gradients for that ion
voltage-gated Na+ channels change shape and their activation gates open
What is the first change to occur in response to a threshold stimulus? Voltage-gated Na+ channels change shape, and their inactivation gates close. Voltage-gated Na+ channels change shape, and their activation gates open. Voltage-gated K+ channels change shape, and their activation gates open. Voltage-gated Ca2+ channels change shape, and their activation gates open.
making of ATP- the "power house" of the cell
What is the function of the muscle cell feature indicated by the arrow? (mitochondria) houses the genetic material of the cell part of coupling the action potential to contraction making of ATP - the "power house" of the cell storage of calcium
houses the genetic material of the cell
What is the function of the muscle cell feature indicated by the arrow? (nucleus) part of coupling the action potential to contraction storage of calcium making of ATP - the "power house" of the cell houses the genetic material of the cell
storage of calcium
What is the function of the muscle cell feature indicated by the arrow? (sarcoplasmic reticulum) making of ATP - the "power house" of the cell part of coupling the action potential to contraction storage of calcium houses the genetic material of the cell
part of coupling the action potential to contraction
What is the function of the muscle cell feature indicated by the arrows? (t-tubules) storage of calcium houses the genetic material of the cell part of coupling the action potential to contraction making of ATP - the "power house" of the cell
the myelin sheath increases the speed of action potential conduction from the initial segment to the axon terminals
What is the function of the myelin sheath? The myelin sheath increases the insulation along the entire length of the axon. The myelin sheath decreases the speed of action potential conduction from the initial segment to the axon terminals. The myelin sheath decreases the resistance of the axonal membrane to the flow of charge. The myelin sheath increases the speed of action potential conduction from the initial segment to the axon terminals.
100mV
What is the magnitude (amplitude) of an action potential? 30 mV 100 mV 70 mV
degrades acetylcholine in the synaptic cleft
What is the primary role of the enzyme acetylcholinesterase (AChE) at a cholinergic synapse? AChE binds to ACh receptors, causing them to open. AChE degrades acetylcholine in the synaptic cleft. AChE depolarizes the postsynaptic cell. AChE releases acetylcholine into the synaptic cleft.
Typically, hundreds of skeletal muscle fibers are innervated by a single motor neuron
What is the relationship between the number of motor neurons recruited and the number of skeletal muscle fibers innervated? Typically, hundreds of skeletal muscle fibers are innervated by a single motor neuron. A motor neuron typically innervates only one skeletal muscle fiber. A skeletal muscle fiber is innervated by multiple motor neurons. Motor neurons always innervate thousands of skeletal muscle fibers.
neurotransmitter binds to receptors on the postsynaptic cell membrane
What is the role of neurotransmitter at a chemical synapse? Neurotransmitter causes vesicles to fuse with the presynaptic membrane. Neurotransmitter binds to receptors on the postsynaptic cell membrane. Neurotransmitter causes an action potential in the presynaptic cell. Neurotransmitter causes calcium to enter the presynaptic cell.
the space between the synaptic terminal and the motor end plate
What is the synaptic cleft? the step where acetylcholinesterase (AChE) breaks down, or cleaves, acetylcholine the space between the synaptic terminal and the motor end plate the border between the motor end plate and the sarcolemma the region of the neuron containing synaptic vesicles
dehydration synthesis
What is the type of chemical reaction used to rebuild ADP into ATP? rehydration synthesis dehydration synthesis hydrolysis
2 ms
What is the typical duration of a nerve action potential? 200 ms 2 ms 20 ms 0.2 ms
-70mV
What is the value for the resting membrane potential for most neurons? -90 mV +30 mV -70 mV
exocytosis
What means of membrane transport is used to release the neurotransmitter into the synaptic cleft? a channel exocytosis a protein carrier
exocytosis
What mechanism releases neurotransmitter from presynaptic neurons? exocytosis endocytosis phagocytosis pinocytosis
voltage-gated Na+ channels
What opens first in response to a threshold stimulus? Voltage-gated K+ channels Ligand-gated Cl- channels Voltage-gated Na+ channels Ligand-gated cation channels
Na+-K+ ATPase
What prevents the Na+ and K+ gradients from dissipating? Na+ cotransporter Na+ and K+ leaks Na+-K+ ATPase H+-K+ ATPase
synaptic cleft
What separates the presynaptic and postsynaptic cells at a chemical synapse? synaptic cleft chemically gated ion channels vesicles filled with neurotransmitter calcium channels
Calcium ions bind to troponin and change its shape
What specific event triggers the uncovering of the myosin binding site on actin? Calcium ions bind to tropomyosin and change its shape. Sodium ions bind to troponin and change its shape. Calcium release channels open in the sarcoplasmic reticulum, and calcium levels rise in the sarcoplasm. Calcium ions bind to troponin and change its shape.
the sarcomere
What structure is the functional unit of contraction in a skeletal muscle fiber? The sarcomere The junctional folds of the sarcolemma The cross bridge The triad
a chemically gated channel
What type of channel in the postsynaptic membrane binds neurotransmitter? a chemically gated channel a voltage-gated channel a leakage channel a mechanically gated channel
continuous conduction
What type of conduction takes place in unmyelinated axons? Continuous conduction Electrical conduction Saltatory conduction Synaptic transmission
diffusion
What type of membrane transport causes the depolarization phase of the action potential in neurons? filtration active transport diffusion facilitated diffusion
All of the answers are correct
When a skeletal muscle fiber contracts, the H bands and I bands get smaller. the Z lines get closer together. the width of the A band remains constant. the zones of overlap get larger. All of the answers are correct.
voltage-gated calcium channels
When an action potential arrives at the axon terminal of a motor neuron, which ion channels open? voltage-gated potassium channels voltage-gated sodium channels chemically gated calcium channels voltage-gated calcium channels
tropomyosin moves into the groove between the helical actin strands
When calcium ion binds to troponin, tropomyosin moves into the groove between the helical actin strands. actin heads will bind to myosin. muscle relaxation occurs. myosin shortens. active sites on the myosin are exposed.
they cause vesicles containing neurotransmitter molecules to fuse to the plasma membrane of the sending neuron
When calcium ions enter the synaptic terminal, they cause an action potential in the sending neuron. the inside of the receiving neuron becomes more positive. neurotransmitter molecules are quickly removed from the synaptic cleft. the inside of the receiving neuron becomes more negative. they cause vesicles containing neurotransmitter molecules to fuse to the plasma membrane of the sending neuron.
troponin
When calcium is released inside a muscle cell, what does it bind to? actin tropomyosin myosin troponin
all of the answers are correct
When comparing slow muscle fibers to fast muscle fibers, slow fibers are rich in the red protein myoglobin. have much smaller fiber diameters. generate much less tension. take about three times as long to reach peak tension. All of the answers are correct.
all of the answers are correct
When contraction occurs, the H bands get smaller. the Z lines move closer together. the I bands get smaller. the width of the A band remains constant. All of the answers are correct.
cross bridge cycling ends when sufficient calcium has been actively transported back into the sarcoplasmic reticulum to allow calcium to unbind from troponin
When does cross bridge cycling end? Cross bridge cycling ends when calcium ions are passively transported back into the sarcoplasmic reticulum. Cross bridge cycling ends when ATP binds to the myosin head. Cross bridge cycling ends when sufficient calcium has been actively transported back into the sarcoplasmic reticulum to allow calcium to unbind from troponin. Cross bridge cycling ends when calcium release channels in the sarcoplasmic reticulum open.
ion channels in the plasma membrane of the receiving neuron open
When neurotransmitter molecules bind to receptors in the plasma membrane of the receiving neuron, vesicles in the synaptic terminal fuse to the plasma membrane of the sending neuron. the receiving neuron becomes more negative inside. the receiving neuron becomes more positive inside. ion channels in the plasma membrane of the receiving neuron open. ion channels in the plasma membrane of the sending neuron open.
tropomyosin
When the sarcomere is at rest, what is covering the active sites on actin? tropomyosin troponin cross-bridges myosin
at the nodes
Where are action potentials regenerated as they propagate along a myelinated axon? at the internodes at myelin at the nodes at every segment of the axon
at every segment of the axon
Where are action potentials regenerated as they propagate along an unmyelinated axon? at the nodes at the internodes at myelin at every segment of the axon
initial segment
Where do most action potentials originate? Nodes of Ranvier Initial segment Cell body Axon terminal
axon hillock
Where in the neuron is an action potential initially generated? soma and dendrites axon hillock anywhere on the axon
the region of the resting sarcomere that only contains thick filaments
Which arrangement of the sarcomere gives rise to the structure (band or line) indicated by the arrow? (H-band) the region of the sarcomere that contains only thin filaments is the point of connection for adjacent thick filaments the region of the resting sarcomere that only contains thick filaments the boundary between adjacent sarcomeres
the region of the sarcomere that contains only thin filaments
Which arrangement of the sarcomere gives rise to the structure (band or line) indicated by the arrow? (I-band) the region of the resting sarcomere that only contains thick filaments the boundary between adjacent sarcomeres the region of the sarcomere that contains only thin filaments is the point of connection for adjacent thick filaments
is the point of connection for adjacent thick filaments
Which arrangement of the sarcomere gives rise to the structure (band or line) indicated by the arrow? (M-line) the region of the sarcomere that contains only thin filaments the boundary between adjacent sarcomeres is the point of connection for adjacent thick filaments the region of the resting sarcomere that only contains thick filaments
the boundary between adjacent sarcomeres
Which arrangement of the sarcomere gives rise to the structure (band or line) indicated by the arrow? (Z-line) the region of the sarcomere that contains only thin filaments the boundary between adjacent sarcomeres is the point of connection for adjacent thick filaments the region of the resting sarcomere that only contains thick filaments
troponin
Which component of a thin filament binds to calcium once the calcium ion is released from the sarcoplasmic reticulum? tropomyosin troponin actin myosin
astrocytes
Which is the largest and most abundant type of neuroglia? satellite cells ependymal cells astrocytes oligodendrocytes
obturator nerve
Which nerve does NOT belong to the sacral plexus? obturator nerve sciatic nerve fibular nerve tibial nerve
brachial plexus
Which nerve plexus innervates the pectoral girdle and upper limbs? brachial plexus lumbar plexus cervical plexus sacral plexus
the head portion of the myosin molecule
Which of the following acts as an ATPase during the contraction cycle of muscle? tropomyosin molecules troponin molecules the head portion of the myosin molecule actin molecules the tail portion of the myosin molecule
calcium influx into the synaptic terminal causes vesicle fusion with the plasma membrane and the release of neurotransmitter
Which of the following best describes the role of calcium in synaptic activity? Calcium diffuses across the synaptic cleft and binds to chemically gated channels on the postsynaptic cell. Calcium breaks down acetylcholine. Calcium influx into the axon causes an action potential to propagate into the synaptic terminal. Calcium influx into the synaptic terminal causes vesicle fusion with the plasma membrane and the release of neurotransmitter.
repeating unit of striated myofibrils
Which of the following best describes the term sarcomere? repeating unit of striated myofibrils protein that accounts for elasticity of resting muscle largely made of myosin molecules thin filaments are anchored here storage site for calcium ions
storage and release site for calcium ions
Which of the following best describes the term sarcoplasmic reticulum? repeating unit of striated myofibrils storage and release site for calcium ions protein that accounts for elasticity of resting muscle thin filaments are anchored here largely made of myosin molecules
tropomyosin shifting position
Which of the following causes the active site on actin to be exposed or uncovered? cross-bridge formation calcium entering the sarcoplasmic reticulum tropomyosin shifting position troponin releasing calcium
whether or not the impulse begins in the CNS
Which of the following does not influence the time necessary for a nerve impulse to be transmitted? diameter of the axon length of the axon presence or absence of a myelin sheath whether or not the impulse begins in the CNS presence or absence of nodes
all of the answers are correct
Which of the following is a recognized class of opioid neuromodulators? dynorphins endomorphins endorphins enkephalins All of the answers are correct.
all of the answers are correct.
Which of the following is a recognized function of skeletal muscle? guard body entrances and exits produce movement maintain body temperature maintain posture All of the answers are correct.
satellite cells
Which of the following is a type of glial cell found in the peripheral nervous system? microglia oligodendrocytes astrocytes ependymal cells satellite cells
a neuron
Which of the following is an example of a presynaptic cell? a secretory cell a muscle cell a neuron a Schwann cell
myosin
Which of the following is involved in the power stroke? myosin tropomyosin myofibrils Z lines
Calcium ions
Which of the following is most directly responsible for the coupling of excitation to contraction of skeletal muscle fibers? Acetylcholine. Action potentials. Sodium ions. Calcium ions.
direct long-term functions, such as growth
Which of the following is not a function of the nervous system? control peripheral effectors coordinate voluntary and involuntary activities sense the internal and external environments direct long-term functions, such as growth integrate sensory information
change the type of receptor found in the postsynaptic membrane
Which of the following is not a possible drug effect on synaptic function? interfere with neurotransmitter synthesis prevent neurotransmitter inactivation interfere with neurotransmitter reuptake block neurotransmitter binding to receptors change the type of receptor found in the postsynaptic membrane
pseudopolar
Which of the following is not a recognized structural classification for neurons? bipolar multipolar anaxonic unipolar pseudopolar
it is more positive than the resting potential
Which of the following is true about threshold for an action potential? The membrane begins to hyperpolarize. Voltage-gated potassium channels begin to open. Threshold for a typical neuron is approximately -30 mV. It is more positive than the resting potential. Voltage-gated potassium channels begin to close.
all of the answers are correct
Which of the following is true regarding an epidural block? It can provide mainly sensory anesthesia, depending on the anesthetic selected. It can provide sensory and motor anesthesia, depending on the anesthetic selected. It is commonly used as a method of pain control during labor and delivery. It affects only the spinal nerves in the immediate area of the injection. All of the answers are correct.
the generation of the action potential in the sarcolemma
Which of the following most correctly describes excitation in the context of excitation-contraction coupling in skeletal muscle? the formation of cross-bridges the generation of an action potential in the sarcolemma the binding of calcium to troponin the release of calcium by the sarcoplasmic reticulum
through calcium release from the sarcoplasmic reticulum
Which of the following phrases best describes how excitation is coupled to contraction in skeletal muscle fibers? through cross-bridge formation through T tubules through electrical impulses travelling along the sarcolemma through calcium release from the sarcoplasmic reticulum
Krebs cycle and oxidative phosphorylation
Which of the following processes produces 36 ATP? glycolysis Krebs cycle and oxidative phosphorylation hydrolysis of creatine phosphate
glycolysis
Which of the following processes produces molecules of ATP and has two pyruvic acid molecules as end products? hydrolysis of creatine phosphate glycolysis Krebs cycle and oxidative phosphorylation
actin
Which of the following proteins contains the active site involved in cross-bridge formation? actin tropomyosin troponin myosin
all of the answers are correct
Which of the following statements is (are) true regarding human muscles? Most have both slow and fast fibers. Slow fibers are abundant in the back muscles. Slow fibers are abundant in the calf muscles. Eye muscles are composed entirely of fast fibers. All of the answers are correct.
cardiac muscle stimulation is neural
Which of the following statements is false? Cardiac muscle stimulation is neural. Cardiocytes are interconnected through intercalated discs. Skeletal muscle stimulation is neural. Cardiac muscle contractions cannot be summated. Skeletal muscle contractions may be summated.
type A fiber
Which of these axons will conduct an action potential most quickly? Type C fiber Type B fiber Type A fiber All fibers have the same propagation speed.
phrenic nerve
Which of these cervical plexus nerves innervates the diaphragm? lesser occipital nerve phrenic nerve great auricular nerve transverse cervical nerve
centrioles
Which of these components is usually absent from a neuron? axons dendrites centrioles cell body
psuedopolar
Which of these is not a neuron structural category? multipolar bipolar unipolar pseudopolar
they are large in diameter
Which of these is not a property of slow muscle fibers? They contract slowly. They resist fatigue. They are rich in myoglobin. They are large in diameter.
sodium channels open
Which of these is the earliest step in the generation of an action potential? Sodium channels open. Potassium channels open. Potassium channels inactivate. Sodium channels inactivate.
all of these are true of cardiac fibers
Which of these is true of cardiac muscle fibers? Cardiac fibers branch. Cardiac fibers have a long twitch duration compared to skeletal fibers. Cardiac fibers have a single nucleus. All of these are true of cardiac fibers.
norepinephrine
Which of these neurotransmitters do adrenergic synapses use? GABA nitric oxide norepinephrine acetylcholine
nitric oxide
Which of these neurotransmitters does not bind to a plasma membrane receptor? GABA norepinephrine nitric oxide serotonin
norepinephrine
Which of these neurotransmitters is released at CNS adrenergic synapses? adrenaline serotonin GABA norepinephrine
satellite cells
Which of these types of neuroglia are abundant in peripheral ganglia? satellite cells microglia astrocytes oligodendrocytes
sarcoplasmic reticulum
Which organelle completely surrounds each myofibril inside a muscle fiber? sarcoplasmic reticulum nucleus calcium fascicle
all of these processes are part of every reflex arc
Which processes are always part of a reflex arc? receptor activation afferent action potential efferent action potential All of these processes are part of every reflex arc.
all of the answers are correct
Which statement about the microscopic anatomy of skeletal muscle fibers is true? Each fiber has many nuclei. Muscle fibers are continuous from tendon to tendon. Cross striations result from the lateral alignment of thick and thin filaments. Tubular extensions of the sarcolemma penetrate the fiber transversely. All of the answers are correct.
myosin
Which thick filament binds to actin once its active binding sites are exposed? myosin actin troponin tropomyosin
passive
Which type of ion channel is always open? mechanically gated passive voltage-gated chemically gated
white fast twitch fibers
Which type of muscle fiber has a large quantity of glycogen and mainly uses glycolysis to synthesize ATP? red slow twitch fibers white fast twitch fibers
skeletal
Which type of muscle tissue has the greatest effect on the body's heat production? skeletal cardiac smooth All of these muscle types have about the same effect on the body's heat production.
chemical
Which type of synapse is most common in the nervous system? chemical electrical mechanical radiative processing
the inactivation gates of voltage-gated Na+ channels close in the node, or segment, that has just fired an action potential
Why does regeneration of the action potential occur in one direction, rather than in two directions? The activation gates of voltage-gated K+ channels open in the node, or segment, that has just depolarized. The activation gates of voltage-gated Na+ channels close in the node, or segment, that has just depolarized. The inactivation gates of voltage-gated Na+ channels close in the node, or segment, that has just fired an action potential. The inactivation gates of voltage-gated K+ channels close in the node, or segment, that has just fired an action potential.
the areas that have had the action potential are refractory to a new action potential
Why does the action potential only move away from the cell body? The flow of the sodium ions only goes in one direction—away from the cell body The areas that have had the action potential are refractory to a new action potential.
sarcomeres
Z lines define the edges of which of the following? sarcomeres cross-bridges myofibrils myosin
neuroglia
________ account for roughly half of the volume of the nervous system. Axons Dendrites Synapses Neuroglia Efferent fibers
mechanically-gated
________ channels open or close in response to physical distortion of the membrane surface. Mechanically-gated Active Leak Voltage-gated Chemically-gated
ependymal cells
________ line the brain ventricles and spinal canal. Satellite cells Astrocytes Oligodendrocytes Microglia Ependymal cells
multipolar
________ neurons are the most common class in the CNS. Bipolar Anaxonic Multipolar Sensory Unipolar
sensory
________ neurons form the afferent division of the PNS. Somatic sensory Neural sensory Motor Sensory Visceral sensory
chemically-gated channels
________ open or close in response to binding specific molecules. Voltage-gated and chemically-gated channels Chemically-gated channels Voltage-gated channels Leak channels Activated channels