BMS 300 Exam 2

The Nernst potential equation depends on:

- Charge on ions - Concentration of ions outside the cell - Concentration of ions inside the cell - Temperature

Astrocytes

- regulate extracellular K+ concentrations - clear out excess amounts of neurotransmitters - surround the synaptic cleft between neurons

Dorsal column medial lemniscus

Ascend the spinal cord in the dorsal columns

Location of the output region of a sensory neuron

CNS

Third order neuron

Cell body in the thalamic relay nucleus, axon extends up to the somatosensory cortex.

Graded

ESPS

The membrane potential is returned to rest by the opening of voltage-gated _____ channels.

K+

Location of the conductile region of a sensory neuron

PNS

What two ions are responsible for establishing an equilibrium between the electrical and chemical gradients?

Potassium (K+) and Anions

Cellularists

Santiago Roman y Cajal

_____________ ____________ are located in the peripheral nervous system (PNS) and _______________________ are found in the central nervous system (CNS).

Schwann cells; oligodendrocytes

In the vertebrate peripheral nervous system, _________________________________ cells wrap around the ____________________ region of neurons to generate concentric layers of _______________________.

Schwann; axon (conductile); myelin

Spinothalamic tract

Synapses on a second order neuron in the dorsal horn

This ion depolarizes the membrane at the site where the plasma membrane of the __________________________ approaches the membrane of the _______________________________ to cause the __________________________ channels to remove their blockade of the ___________________________ and permit ___________ ions to enter the _________________ where it binds to __________________ on thin filaments.

T-tubule; sarcoplasmic reticulum; DHP receptors; ryanodine receptor; Ca2+; cytoplasm; troponin c

What channels are located exclusively at the Nodes of Ranvier?

VG K+ and Na+ channels

During depolarization, the dominant channel that is open is the ______________________ . During repolarization, the dominant channel that is open is the _______________________.

Voltage gated Na+ channels; Voltage gated K+ channels

What is/are true statements about Action Potentials? a. they always have the same amplitude and duration b. information is coded through the frequency of Action Potentials c. they always have a different amplitude and duration

a and b

With respect to the lateral corticospinal tract (LCST) the cell bodies of the upper motor neurons are located in the ______________. Select all that apply. a. Primary motor cortex b. Somatosensory cortex c. Precentral gyrus d. Postcentral gyrus

a and c

To clear neurotransmitter from the synaptic cleft in the central nervous system, there are cells that contain transmembrane proteins that simultaneously bind Na + and the neurotransmitter glutamate. This transmembrane protein then simultaneously transports them into the cell's cytoplasm. The cell type where you would expect to find such transporters would be the: a. Astrocyte b. Oligodendrocyte c. Schwann d. Neuron

a. Astrocyte

Cells that maintain the extracellular environment in the central nervous system by pumping sodium and potassium ions and mopping up excess neurotransmitter are: a. Astrocytes b. Schwaan Cells c. Microglia d. Oligodendrocytes

a. Astrocytes

In resting condition, _________ is high outside the cell and ________ is high inside the cell. a. Na+, K+ b. K+, Na+

a. Na+, K+

The fast axoplasmic transport includes proteins from the __________ and transported on ___________. The slow axoplasmic transport includes proteins from the ____________. a. RER, microtubules, cytoplasm b. microtubules, cytoplasm, RER c. cytoplasm, RER, microtubules

a. RER, microtubules, cytoplasm

Action potentials will pass much more _________ along a myelinated axon, as opposed to an unmyelinated axon. This is because myelin ______________ membrane resistance. a. Rapidly, increases b. Slowly, increases c. Rapidly, decreases d. Slowly, decreases

a. Rapidly, increases

EPSPs from numerous synaptic sites providing the necessary charge to bring the membrane potential to threshold is an example of: a. Spatial Summation b. Temporal Summation c. Action Potential d. Adding summation e. I don't know

a. Spatial Summation

Ca2+ binds to ____________________, which rolls __________________ out of the way. This allows myosin to bind the myosin binding sites located on the actin thin filaments. a. Troponin C, Tropomyosin b. Tropomyosin, Troponin C c. Troponin C, actin d. Tropomyosin, myosin

a. Troponin C, Tropomyosin

A motor unit is defined as a lower motor neuron and the group of muscle fibers it innervates. a. True b. False

a. True

All good primary sensory afferents leave their cell bodies outside the central nervous system in a dorsal root ganglion and do not cross the midline. a. True b. False

a. True

Increasing membrane resistance will increase the time it takes for an electrical potential to decay (AKA increase tau) a. True b. False

a. True

Myelin reduces membrane capacitance by increasing the thickness of the membrane and thus increasing the separation of cations and anions. a. True b. False

a. True

Only the dendrite or input region of a neuron has ion channels. a. True b. False

a. True

The membrane potential seeks the equilibrium potential of the ion whose permeability is dominant. a. True b. False

a. True

The channel that delivers positive charge to the narrow gap between the T-tubule membrane and the sarcoplasmic reticulum is: a. Voltage Gated Na+ channel. b. Acetylcholine receptor c. Dihydropyridine (DHP) receptor d. Ryanodine receptor e. Voltage gated K+ channel.

a. Voltage Gated Na+ channel.

In regards to the spinothalamic tract, where does the second order neuron cross the midline? a. at the spinal cord segment b. at the brainstem c. at the thalamus d. never crosses the midline

a. at the spinal cord segment

Protein synthesis occurs in the a. cell body b. axon c. dendrite d. terminal

a. cell body

The tendon tap reflex can be elicited by a stretch in a muscle. What is the order of information flow from the primary sensory afferent to the lower motor neuron? a. dorsal root ganglion, dorsal horn, ventral horn b. dorsal horn, dorsal root, ventral horn c. ventral root, ventral horn, dorsal horn, dorsal root

a. dorsal root ganglion, dorsal horn, ventral horn

At chemical synapses, neurotransmitter predominantly opens _____________ in the ___________. a. ligand-gated channels, postsynaptic element b. neurotransmitter release sites, presynaptic element c. synaptic vesicles, postsynaptic element d. voltage-gated Calcium channels that govern neurotransmitter release, presynaptic element e. ligand-gated channels, presynaptic element

a. ligand-gated channels, postsynaptic element

A hyperpolarized cell can be generated when: a. ligand-gated ionotropic channels for Cl- open b. voltage-gated Cl- channels in the postsynaptic membrane open c. Na + flows into the cell down its concentration gradient d. an action potential is generated in the postsynaptic membrane. e. two of the answers are correct

a. ligand-gated ionotropic channels for Cl- open

The colliculus is located in a part of the brain known as the midbrain. The colliculospinal tract controls reflexive movements via somatic efferents to the head and neck in response to visual or auditory (afferent) input. This tract is responsible for orienting to a sound in the environment. You would expect neurons in this tract to have their input regions in the ________________ and their output regions in the ________________________. a. midbrain, gray matter of the spinal cord b. dorsal horn of the spinal cord, midbrain c. colliculus, dorsal columns d. midbrain, dorsal root ganglion e. ventral horn, colliculus

a. midbrain, gray matter of the spinal cord

There is a type of toxin found in the liver of the puffer fish that prevents the opening of voltage-gated Na+ channels in neurons. The effect of this toxin is to: a. prevents the initiation of the action potential b. depolarizes the membrane potential and maintains it depolarized c. prolongs the return of the membrane potential to the resting level d. increases the duration of the action potential e. All answers are correct

a. prevents the initiation of the action potential

Each year, an estimated 250,000 people die from envenomation by snake bite. Many of these deaths are caused by snakes in the family elapidae including the mambas, cobras, and kraits. The venoms of these snakes contain numerous toxins that work at different sites and through different mechanisms which converge on blocking synaptic transmission at the neuromuscular synapse. A proposed treatment for envenomation by cobras is a nasal spray containing neostigmine, a drug that blocks acetylcholinesterase. You would expect this treatment to be effective because it would: a. prolong the availability of acetylcholine at the neuromuscular synapse. b. increase the availability of choline and acetate in the synaptic cleft to open nicotinic acetylcholine receptor channels. c. increase Na+ permeability in the muscle T-tubule system. d. prolong the duration of individual action potentials propagating along the sarcolemma. e. All of the above are correct.

a. prolong the availability of acetylcholine at the neuromuscular synapse.

Osmium is a heavy metal that binds to lipid and turns black. Which of the following would you expect to be labeled most darkly? a. the decussation of the pyramids. b. the dorsal horn of the spinal cord c. the somatosensory cortex. d. the ventral horn of the spinal cord e. b and d are correct.

a. the decussation of the pyramids.

Proteins are transported via axoplasmic transport at slow rates (0.5 to 2 mm per day) and fast rates (200 to 400 mm per day). The difference in transport rate directly results from: a. the difference in the time spent per day in transport by kinesin on microtubules b. the site where the protein is synthesized c. the substrate molecule used by the motor protein d. the motor protein used to transport the proteins

a. the difference in the time spent per day in transport by kinesin on microtubules

Nerve agents such as sarin and VX bind acetylcholinesterases, enzymes that cleave acetylcholine into a molecule of acetate and a molecule of choline, to permanently inactivate the enzyme. From what you know of synaptic transmission, which of the following sites would be targets for these nerve agents? a. the synapse between the lower motor neuron and muscle. b. the synapse between an inhibitory interneuron and a lower motor neuron c. the synapse between a primary sensory afferent and an excitatory interneuron. d. the synapse between second and third order sensory neurons. e. all except a are correct.

a. the synapse between the lower motor neuron and muscle.

The cell bodies of neurons whose conductile processes are located in spinal nerves and conduct action potentials away from the central nervous system are located in the: a. the ventral horn of the spinal cord b. the dorsal horn of the spinal cord c. dorsal root ganglia d. ventral root ganglia e. dorsal columns

a. the ventral horn of the spinal cord

For a disease where only motor neurons (somatic efferent neurons) die, you would expect to observe neuronal cell death in the: a. ventral horn of the spinal cord b. dorsal horn of the spinal cord c. in the dorsal columns of the spinal cord d. dorsal root

a. ventral horn of the spinal cord

Vagus stuff

acetylcholine

All or nothing

action potential

Opening these channels reinitiates the _______________ at each of these sites which results in a type of conduction known as __________________________ conduction which comes from the Latin, meaning to hop.

action potential; salutatory

unmyelinated axons

action potentials propagate at 1 m/s (slow)

K+ leak channels

always open

conductile

axon

output

axon terminal

If you have a lesion affecting the entire left side of the spinal cord, as is the case with Brown Sequard Syndrome, what symptoms would you expect to see? Select all that apply. a. loss of proprioception on the right b. loss of Proprioception on the left c. Loss of pain on the right d. Loss of pain on the left

b and c

When measurements are taken along an unmyelinated axon where the voltage gated channels are clustered at one site, we see a decrease in voltage as we move down the axon. Why do we see this decrease? a. Charge leaves through V-gated Na+ channels b. Charge leaves through K+ leak channels c. Charge enters through V-gated K+ channels d. Charge enters through K+ leak channels e. Charge leaves through V-gated K+ channels

b. Charge leaves through K+ leak channels

Membranes that are "leaky" due to a large number of K+ leak channels or the opening on Cl- channels has what effect on membrane resistance? a. Increases b. Decreases c. No change

b. Decreases

The ion that is responsible for vesicular release at the axon terminal is: a. Extracellular Na+ b. Extracellular Ca2+ c. Intracellular K+

b. Extracellular Ca2+

An adequate amount of negative charge must arrive at the trigger zone in order to reach threshold. a. True b. False

b. False

Voltage and membrane resistance are inversely proportional to each other. (V= IR) a. True b. False

b. False

When ______ binds to enough ligand-gated ionotropic channels, Cl- becomes the ion with the dominant permeability a. Glutamate b. GABA c. Dopamine d. Acetylcholine

b. GABA

The Bark Scorpion, is a highly venomous scorpion of Arizona. Its sting is exceptionally painful to mammals, yet the Grasshopper Mouse readily preys on these arachnids. Videos show the mice being stung repeatedly without demonstrating pain. Molecular analyses of the mouse show a single amino acid change in a voltage-gated channel specific to pain sensing neurons in the peripheral nervous system; the scorpion toxin binds to this channel, and prevents it from opening. This mutation allows the Grasshopper Mouse to be stung by the scorpion, but feel no pain. The ion most likely prevented from flowing through this channel by the toxin is: a. Cl- b. Na+ c. K+ d. Ca2+ e. b and c are correct

b. Na+

If the resting membrane potential of a cell was +70 mv, the electrical driving force on sodium would be... a. Into the neuron b. Out of the neuron c. Balanced

b. Out of the neuron

The opening of axon membrane voltage-gated potassium channels is responsible for which part of the action potential? a. Depolarization of the axon b. Repolarization of the axon c. Signaling neurotransmitter release

b. Repolarization of the axon

The Bark Scorpion, is a highly venomous scorpion of Arizona. Its sting is exceptionally painful to mammals, yet the Grasshopper Mouse readily preys on these arachnids. Videos show the mice being stung repeatedly without demonstrating pain. Molecular analyses of the mouse show a single amino acid change in a voltage-gated channel specific to pain sensing neurons in the peripheral nervous system; the scorpion toxin binds to this channel, and prevents it from opening. This mutation allows the Grasshopper Mouse to be stung by the scorpion, but feel no pain. In mice other than the Grasshopper Mouse, action potentials would propagate toward the brain in the spinal cord in the : a. Dorsal (posterior) columns b. Spinothalamic tract c. Corticospinal tract d. Dorsal horn e. Ventral horn

b. Spinothalamic tract

According to the SNARE hypothesis, Ca2+ binds to ______________ which is the calcium sensor. a. SNAP-25 b. Synaptotagmin c. Syntaxin d. VAMP/Synaptobrevin

b. Synaptotagmin

Where did transmembrane channels in the axon terminal come from? a. They were synthesized on bound ribosomes in the cell body and carried via slow axoplasmic transport b. They were synthesized on bound ribosomes in the cell body and carried via fast axoplasmic transport c. They were synthesized on bound ribosomes in the axon and carried via fast axoplasmic transport d. They were synthesized on free ribosomes in the cell body and carried via slow axoplasmic transport

b. They were synthesized on bound ribosomes in the cell body and carried via fast axoplasmic transport

The point at which K+ efflux equals Na+ influx is known as: a. Capacitance b. Threshold c. Resistance d. Action Potential

b. Threshold

Synaptic potentials produced in the input region of motor neurons: a. are invariant, always reaching the same amplitude. b. are graded so that their amplitude depends on the number of ligand-gated channels that open. c. result only once the membrane potential has reached threshold d. require the opening of voltage-gated Ca2+ channels e. all except b are correct.

b. are graded so that their amplitude depends on the number of ligand-gated channels that open.

The conductile regions of neurons whose cell bodies are in the peripheral nervous system and enter the central nervous system in the _________________ and are examples of ________________. a. ventral horn, somatic efferents b. dorsal horn, primary sensory afferents c. ventral root, motor efferents d. dorsal column nuclei, second order neurons e. a and c are correct.

b. dorsal horn, primary sensory afferents

You would expect to find the highest density of Schwann cells in: a. nuclei b. nerves c. gray matter d. tracts e. b and d are correct

b. nerves

Fish hunting snails are commonly found in the South China Sea. These animals attract fish with a lure, and harpoon them. At the base of the harpoon there is a venom sac that contains several toxins. After harpooning the fish, the snail injects the venom to immobilize the fish. Among the toxins are alpha, omega, mu, kappa, and delta conotoxins. Recordings taken from muscle fibers poisoned with omega conotoxin show that an action potential arrives at the output region of the lower motor neuron, but no EPSP is generated even though the application of acetylcholine to the neuromuscular synapse from an extracellular pipet generates a depolarization leading to muscle contraction. Labeling neuromuscular synapses with fluorescently labeled omega conotoxin would likely be found bound to: a. voltage-gated Na+ channels in skeletal muscle sarcolemma. b. voltage-gated Ca2+ channels at neurotransmitter release sites. c. dihydropyridine receptors at the junction between the transverse tubules and the sarcoplasmic reticulum. d. ryanodine receptors at the junction between the transverse tubules and the sarcoplasmic reticulum. e. the postsynaptic membrane at the neuromuscular junction.

b. voltage-gated Ca2+ channels at neurotransmitter release sites.

Fish hunting snails are commonly found in the South China Sea. These animals attract fish with a lure, and harpoon them. At the base of the harpoon there is a venom sac that contains several toxins. After harpooning the fish, the snail injects the venom to immobilize the fish. Among the toxins are alpha, omega, mu, kappa, and delta conotoxins. The effect of kappa conotoxins on action potentials propagating in lower motor neurons is to increase their duration. In these preparations, the Na+ permeability turns off normally. You would expect the kappa conotoxins to block the activation of: a. voltage-gated Na+ channels. b. voltage-gated K+ channels. c. voltage-gated Ca2+ channels. d. voltage-gated Na+ channels. e. K+ leak channels. 21.

b. voltage-gated K+ channels.

The resting membrane potential is approximately: a. +40 mv b. -40 mv c. - 70 mv d. + 70 mv

c. - 70 mv

What would the equilibrium potential be for K+ if there were equal concentration inside and outside the cell? (Hint: Think about the Nernst equation) a. +40 b. -70 c. 0

c. 0

The Bark Scorpion, is a highly venomous scorpion of Arizona. Its sting is exceptionally painful to mammals, yet the Grasshopper Mouse readily preys on these arachnids. Videos show the mice being stung repeatedly without demonstrating pain. Molecular analyses of the mouse show a single amino acid change in a voltage-gated channel specific to pain sensing neurons in the peripheral nervous system; the scorpion toxin binds to this channel, and prevents it from opening. This mutation allows the Grasshopper Mouse to be stung by the scorpion, but feel no pain. Assuming uniform distribution of the scorpion toxin in the central and peripheral nervous system, you would expect labeled scorpion toxin to be found: a. On the imput regions of neurons in the central nervous system b. Along the internodal regions of myelinated neurons. c. At the nodes of Ranvier of myelinated neurons d. Uniformly distributed along the conductile regions of myelinated neurons. e. c and d are correct.

c. At the nodes of Ranvier of myelinated neurons

In skeletal muscle, relaxation occurs when: a. The action potential propagates down the t-tubule b. Ca2+ is released from the sarcoplasmic reticulum c. Ca2+ is pumped from the cytoplasm back into the sarcoplasmic reticulum d. Ca2+ is removed from the muscle cytoplasm through the t-tubule membrane e. Ca2+ is pumped across the sarcolemma into the extracellular space

c. Ca2+ is pumped from the cytoplasm back into the sarcoplasmic reticulum

The resting membrane potential in neurons largely results from a gradient of ___ ions and open _____. a. Na+, Na+ leak channels b. impermeant anions, impermeant anion channels c. K+, K+ leak channels d. Cl−, Cl− leak channels e. Na+, voltage-gated Na+ channels

c. K+, K+ leak channels

The resting membrane potential in neurons largely results from a gradient of __________ ions and open _______________. a. Na+, Na+ leak b. impermeant anions, impermeant anion channels c. K+, K+ leak channels d. Cl-, Cl- leak channels e. Na+, voltage-gated Na+ channels

c. K+, K+ leak channels

The concentric rings formed by oligodendrocytes are called: a. Schwann cells b. Astrocytes c. Myelin

c. Myelin

When gated Na+ channels close, what ion is responsible for bringing the membrane back to resting membrane potential? a. Chloride (Cl-) b. Sodium (Na+) c. Potassium (K+) d. Anions

c. Potassium (K+)

At rest, the membrane potential is maintained near -70 mV. In order to fire an action potential, enough positive charge has to enter the cell to reach threshold ( around -55mV). What is true regarding the amount and form of that positive charge? a. Proportionally, large amounts of Na+ have to enter the cell. This results in drastic changes in Na+ concentration within the cell. b. Proportionally, large amounts of K+ have to enter the cell. This results in drastic changes in K+ concentration within the cell. c. Proportionally, very little Na+ has to enter the cell in order to achieve threshold and therefore an action potential. d. Proportionally, very little K+ has to enter the cell in order to achieve threshold and therefore an action potential.

c. Proportionally, very little Na+ has to enter the cell in order to achieve threshold and therefore an action potential.

Which of the following is correct when describing ion distributions in neurons? a. The concentration of Ca+ is lower in the extracellular space than in the cytoplasm. b. The concentration of K+ is higher in the extracellular space than in the cytoplasm. c. The concentration of Na+ is higher in the extracellular space than in the cytoplasm.

c. The concentration of Na+ is higher in the extracellular space than in the cytoplasm.

The input region lacks _________________, but contains _____________________. a. Ligand-gated channels, voltage gated channels b. K+ leak channels, voltage gated channels c. Voltage-gated channels, ligand gated channels d. Ligand-gated channels, K+ leak channels

c. Voltage-gated channels, ligand gated channels

Neurotransmitter is removed from the synaptic cleft by transmembrane proteins that bind Na+ ion and a molecule of neurotransmitter in the extracellular space and simultaneously transport the ion and the neurotransmitter into the cell, You would expect to find this form of transport on: a. oligodendrocytes b. Schwann cells at the neuromuscular synapse c. astrocytes d. microglial cells b and c are correct

c. astrocytes

Neurotransmitter is removed from the synaptic cleft by transmembrane proteins that bind a Na+ ion and a molecule of neurotransmitter in the extracellular space and simultaneously transport the ion and the neurotransmitter into the cell. You would expect to find this form of transport on: a. oligodendrocytes b. Schwann cells at the neuromuscular synapse c. astrocytes d. microglial cells e. b and c are correct.

c. astrocytes

Each year, an estimated 250,000 people die from envenomation by snake bite. Many of these deaths are caused by snakes in the family elapidae including the mambas, cobras, and kraits. The venoms of these snakes contain numerous toxins that work at different sites and through different mechanisms which converge on blocking synaptic transmission at the neuromuscular synapse. Alpha-bungarotoxin, which is a component of the venom of the banded krait (Bungarus multicinctus), prevents nicotinic acetylcholine receptors from opening. You would expect this toxin to: a. decrease the amount of neurotransmitter released at the neuromuscular synapse. b. decrease the duration of the presynaptic action potential c. decrease the amplitude of the excitatory postsynaptic potential d. d. generate an action potentials whose amplitude is smaller than normal. e. b and d are correct.

c. decrease the amplitude of the excitatory postsynaptic potential

Extracellular K+ concentrations are normally between 4 and 5 millimolar, but in animals and people in renal failure, this value can rise above 7 to 8 milimolar. You would expect such the increased extracellular K+ levels to: a. make the new resting membrane potential more negative than the original resting membrane potential b. make the membrane potential more negative than the original resting membrane potential c. drive the resting membrane potential toward the new equilibrium potential for K+ d. drive the resting membrane potential toward the equilibrium potential for Cl- e. a and c are correct

c. drive the resting membrane potential toward the new equilibrium potential for K+

In the somatosensory system, the neurons whose conductile processes cross the midline always: a. have their cell bodies in the dorsal horn of the spinal cord b. have their cell bodies in the dorsal column nuclei c. form synapses in the thalamus d. have their conductile process in the spinothalamic tract e. all except c are correct

c. form synapses in the thalamus

In the somatosensory system, the neurons whose conductile processes cross the midline always: a. have their cell bodies in the dorsal horn of the spinal cord. b. have their cell bodies in the dorsal column nuclei. c. form synapses in the thalamus. d. have their conductile process in the spinothalamic tract. e. All except c are correct.

c. form synapses in the thalamus.

In the central nervous system, you would expect to see summation of EPSPs and IPSPs in: a. ganglia b. white matter c. gray matter d. tracts e. nerves

c. gray matter

In the central nervous system, you would expect to see summation of EPSPs and IPSPs in: a. ganglia. b. white matter. c. gray matter. d. tracts. e. nerves.

c. gray matter.

Slow axon-axoplasmic transport of cytoplasmic proteins is a result of: a. kinesin being slower in neurons b. continuous fast transport c. intermittent fast transport

c. intermittent fast transport

In the input region of neurons, the membrane resistance (Rm) typically decreases when: a. voltage-gated Cl- channels in the postsynaptic membrane open b. ligand-gated ionotropic channels for cations open c. ligand-gated ionotropic channels for Cl- open d. an action potential is generated in the postsynaptic membrane e. a and d are correct

c. ligand-gated ionotropic channels for Cl- open

In the input region of neurons, the membrane resistance (Rm) typically decreases to inhibit the cell when: a. voltage-gated Cl─ channels in the postsynaptic membrane open. b. ligand-gated ionotropic channels for cations open. c. ligand-gated ionotropic channels for Cl─ open. d. an action potential is generated in the postsynaptic membrane. e. a and d are correct

c. ligand-gated ionotropic channels for Cl─ open.

Inhibitory postsynaptic potentials (IPSPs) are generated when: a. voltage-gated Cl─ channels in the postsynaptic membrane open. b. Na+ flows into the cell down its concentration gradient. c. ligand-gated ionotropic channels for Cl─ open. d. an action potential is generated in the postsynaptic membrane. e. a and d are correct

c. ligand-gated ionotropic channels for Cl─ open.

The chemical connection between the output and input regions of two neurons is called a __________. a. cell body b. gap junction c. synapse d. axon terminal

c. synapse

Proteins are transported via axoplasmic transport at slow rates (.5 to 2 mm/day) and fast rates (200- 400 mm per day). The difference in transport rates results form: a. the motor protein used to transport the proteins b. the substrate molecule usde by the motor protein c. the difference in the time spent per day in transport by kinesin on microtubules d. the site where protein is synthesized e. a and b are correct

c. the difference in the time spent per day in transport by kinesin on microtubules

Proteins are transported via axoplasmic transport at slow rates (0.5 to 2 mm per day) and fast rates (200 to 400 mm per day). The difference in transport rate results from: a. the motor protein used to transport the proteins b. the substrate molecule used by the motor protein c. the difference in the time spent per day in transport by kinesin on microtubules. d. the site where the protein is synthesized. e. a and b are correct.

c. the difference in the time spent per day in transport by kinesin on microtubules.

Reticularists

camillo golgi

cell body

characterized protein synthesis organelles

axon

conductile region, characterized by voltage gated channels

What channel is responsible for setting the resting membrane potential? a. Voltage-gated K+ channel b. Voltage-gated Na+ channel c. Voltage-gated Cl- channel d. K+ leak channel

d. K+ leak channel

For an excitatory synapse _________________ is released from the presynaptic cell and binds to ligand-gated ionotropic channels in the postsynaptic cell. This allows for ___________ ions to enter the postsynaptic cell. a. GABA, Cl- b. Neurotransmitter, Cl- c. GABA, Na+ d. Neurotransmitter, Na+

d. Neurotransmitter, Na+

For an excitatory synapse _________________ released from the presynaptic cell binds to ligand-gated ionotropic channels in the postsynaptic cell allowing for ___________ ion to enter the postsynaptic cell. a. Gaba, Cl- b. Neurotransmitter, Cl- c. Gaba, Na+ d. Neurotransmitter, Na+

d. Neurotransmitter, Na+

Which of the following is not true about muscle cells? a. Muscle cells are multinucleated b. Muscle cells contain t-tubules c. The plasma membrane of muscle cells is called the sacrolemma d. The sarcoplasmic reticulum and the t-tubules are physically fused with one another e. The sarcoplsamic reticulum contains a high concentration of Ca2+

d. The sarcoplasmic reticulum and the t-tubules are physically fused with one another

On Febraury 13, 2017, Kim Jong Nam, the half-brother of Kim Jong Um, the Supreme Leader of the Democratic People's Republic of Korea, was assinated in a Malaysian airport. The cause of his death appears to be VX, a nerve agent that inactivates acetylcholinesterase by irreversibly binding to the active site of this enzyme and preventing the conversion of acetylcholine to its inactive components, choline and acetate. High concentrations of acetylcholine at synapses that use this neurotransmitter first cause receptor activation followed by the closing of the receptor ion channel in a process called receptor inactivation. You would expect the enzyme inactivated by VX to be found in: a. Glial cells surrounding the neuromuscular synapse b. The cytoplasm of the muscle cell c. The sarcoplasmic reticulum d. The synaptic cleft e. Synaptic vesicles

d. The synaptic cleft

Neurotransmitters that open ligand-gated ionic channels which are permeable to Cl- are inhibitory when: a. the ECl is more negative than the resting membrane potential and the IPSPs hyperpolarize the membrane potential b. the ECl is the same as the resting membrane potential and the IPSPs do not change the resting membrane potential c. the ECl is more positive than the resting membrane potential and the IPSPs depolarize the membrane potential d. a,b, or c may be correct as long as the threshold is more positive than the ECl

d. a,b, or c may be correct as long as the threshold is more positive than the ECl

In the accompanying diagram, the neurotransmitter that is released at the synapse labeled 9 is: a. glutamate b. GABA c. glycine d. acetylcholine e. b or c could be correct.

d. acetylcholine

The spinotectal tract carries information to a region of the midbrain called the tectum, and is responsible for providing a reflexive orientation to touch. You would expect neurons to have their input regions in the __________ and their output regions in the ___________. a. tectum in the midbrain, dorsal horn of the spinal cord b. ventral horn of the spinal cord, tectum in the midbrain c. tectum of the midbrain, white matter of the spinal cord d. dorsal horn of the spinal cord, tectum of the midbrain e. dorsl column nuclei, tectum of the midbrain

d. dorsal horn of the spinal cord, tectum of the midbrain

There are several toxins from Clostridium bacteria that affect neuronal function. All of these toxins are proteolytic enzymes that specifically attack proteins in the SNARE complex. The most immediate effect of these toxins is to prevent: a. the opening of ligand-gated ionotropic channels in the postsynaptic cell. b. the opening of voltage-gated Na+ channels in the postsynaptic cell. c. the opening of voltage-gated Ca2+ channels in the presynaptic cell. d. neurotransmitter release by exocytosis. e. neurotransmitter uptake by glial cells.

d. neurotransmitter release by exocytosis.

In the functional classification of the neuron, neurons with their cell bodies in the dorsal root ganglion have their input regions in the: a. gray matter of the spinal cord b. dorsal root ganglion c. ventral horn of the spinal cord d. peripheral nervous system e. a and d are correct

d. peripheral nervous system

A tumor pressing agains the spinal cord blocks action potential propagation in the white matter. You find that all somatosensory modalities from the arms remain intact. The patient feels no pain in the left leg and no fine touch in the right leg. (Sensory information enters the spinal cord from the arms in the cervical region and from the legs in the lumbar regions). You can conclude that the tumor is located on the: a. right side of the spinal cord blow the lumbar region b. left side of the spinal cord above the cervical region c. left side of the spinal cord between the lumbar and cervical regions d. right side of the spinal cord between the lumbar and cervical regions e. on the ventral aspect of the spinal cord

d. right side of the spinal cord between the lumbar and cervical regions

In synaptic transmission between the lower motor neuron and the muscle cell, the source of Ca2+ ions responsible for neurotransmitter release is the: a. sarcoplasmic reticulum b. t-tubules c. synaptic vesicles d. synaptic cleft e. mitochondria

d. synaptic cleft

The trigger zone for the 3rd order neuron in the somatosensory system would be located in the: a. dorsal root ganglion b. dorsal horn of the spinal cord c. dorsal column nuclei d. thalamic relay nucleus e. cerebral cortex

d. thalamic relay nucleus

The trigger zones for the third order neurons in the somatosensory system would be located in the: a. dorsal root ganglion b. dorsal horn of the spinal cord c. dorsal column nuclei d. thalamic relay nucleus e. cerebral cortex

d. thalamic relay nucleus

Fish hunting snails are commonly found in the South China Sea. These animals attract fish with a lure, and harpoon them. At the base of the harpoon there is a venom sac that contains several toxins. After harpooning the fish, the snail injects the venom to immobilize the fish. Among the toxins are alpha, omega, mu, kappa, and delta conotoxins. The effect of delta conotoxin is to prolong the duration of action potentials that propagate in the lower motor neuron conductile regions. Preparations poisoned with this conotoxin show normal K+ permeability after the peak of the action potential. You would expect the delta conotoxin to affect: a. the activation of voltage-gated Na+ channels. b. the activation of voltage-gated K+ channels. c. the activation of voltage-gated Ca2+ channels. d. the inactivation of voltage-gated Na+ channels. e. K+ leak channels.

d. the inactivation of voltage-gated Na+ channels.

Cresyl violet, sometimes known as a Nissl Stain, preferentially labels nucleic acids (RNA and DNA). Which of the following would you expect to be predominantly labeled by cresyl violet staining? a. the spinothalamic tract of the anterolateral system b. the dorsal columns of the dorsal column nuclei c. the internal capsule d. the somatosensory cortex e. all except d are correct

d. the somatosensory cortex

You would expect to find the highest density of Oligodendrocytes in: a. nuclei b. nerves c. gray matter d. tracts e. b and d are correct.

d. tracts

Fish hunting snails are commonly found in the South China Sea. These animals attract fish with a lure, and harpoon them. At the base of the harpoon there is a venom sac that contains several toxins. After harpooning the fish, the snail injects the venom to immobilize the fish. Among the toxins are alpha, omega, mu, kappa, and delta conotoxins. Mu conotoxins block muscle contraction in response to nerve stimulation. Recordings in the muscle fiber show an EPSP that exceeds threshold, but no action potential. The mu conotoxins block the: a. voltage-gated Na+ channels in the motor neuron. b. voltage-gated Ca2+ channels in the axon terminal c. release of neurotransmitter from the lower motor neuron output region. d. voltage-gated Na+ channels in the sarcolemma. e. b and c are correct

d. voltage-gated Na+ channels in the sarcolemma.

input

dendrite

Molecules transported in the fast phase of axoplasmic transport are: a) cytoplasmic proteins b) transported in vesicles. c) synthesized on free ribosomes. d) synthesized on rough endoplasmic reticulum. e) b and d are correct

e) b and d are correct

Each year, an estimated 250,000 people die from envenomation by snake bite. Many of these deaths are caused by snakes in the family elapidae including the mambas, cobras, and kraits. The venoms of these snakes contain numerous toxins that work at different sites and through different mechanisms which converge on blocking synaptic transmission at the neuromuscular synapse. The Green and Black Mambas of Africa of the genus Dendroaspis produce a toxin called Dendrotoxin. This small protein inserts into the voltage-gated K+ channel and blocks it in the conductile region of the lower motor neuron. You would expect this toxin to: a. increase the amount of neurotransmitter released at the neuromuscular synapse. b. increase the duration of the presynaptic action potential c. increase the number of open nicotinic acetylcholine receptors. d. initially increase Na+ influx into the muscle cell. e. All of the above are correct.

e. All of the above are correct.

_____________ nerves carry information ___________ the brain. a. afferent; toward b. afferent; away from c. efferent; away from d. efferent; toward e. Choices A and C are both correct f. Choices B and D are both correct

e. Choices A and C are both correct

On Febraury 13, 2017, Kim Jong Nam, the half-brother of Kim Jong Um, the Supreme Leader of the Democratic People's Republic of Korea, was assinated in a Malaysian airport. The cause of his death appears to be VX, a nerve agent that inactivates acetylcholinesterase by irreversibly binding to the active site of this enzyme and preventing the conversion of acetylcholine to its inactive components, choline and acetate. High concentrations of acetylcholine at synapses that use this neurotransmitter first cause receptor activation followed by the closing of the receptor ion channel in a process called receptor inactivation. 6. The initial effects of VX at the neuromuscular synapse would be to: a. Increase the amplitude of EPSPs in the muscle fiber b. Increase the duration of EPSPs in the muscle fiber c. Increase the duration of each action potential in the muscle fiber d. Increase the amount of neurotransmitter released e. a and b are correct

e. a and b are correct

Which are true about myelinating glial cells? Select all that is true. a. They provide insulation b. They process information c. They physically surround neurons d. They protect the cells from viruses e. a and c f. b and d

e. a and c

Following extended periods of muscle activation, extracellular K+ concentrations are sometimes higher than normal. You would expect the increased extracellular K+ to: (If this helps, remember that EK = 58 log [Ko]/[Ki] and that the log of 1 = 0. If it doesn't help, you do not need to plug the numbers into the Nernst equation, just know the trends.) a. make the new resting membrane potential more positive than the original resting membrane potential. b. make the membrane potential more negative than the original resting membrane potential. c. drive the resting membrane potential to the new equilibrium potential for K+. d. drive the resting membrane potential toward the equilibrium potential for Cl-. e. a and c are correct

e. a and c are correct

Assuming the following were synthesized simultaneously, which would be the last to arrive at the output region of a neuron? a. proteins synthesized on free ribosomes b. voltage-gated calcium channels c. tubulin on microtubules d. proteins synthesized on rough endoplasmic reticulum e. a and c would be the last to arrive

e. a and c would be the last to arrive

Assuming the following were synthesized simultaneously, which would be the last to arrive at the output region of a neuron? a. proteins synthesized on free ribosomes. b. voltage-gated calcium channels. c. globular actin to be incorporated into the cortical actin cytoskeleton. d. V-SNAREs e. a and c would be the last to arrive.

e. a and c would be the last to arrive.

The Bark Scorpion, is a highly venomous scorpion of Arizona. Its sting is exceptionally painful to mammals, yet the Grasshopper Mouse readily preys on these arachnids. Videos show the mice being stung repeatedly without demonstrating pain. Molecular analyses of the mouse show a single amino acid change in a voltage-gated channel specific to pain sensing neurons in the peripheral nervous system; the scorpion toxin binds to this channel, and prevents it from opening. This mutation allows the Grasshopper Mouse to be stung by the scorpion, but feel no pain. The toxin in the Bark Scorpion venom most likely binds to a: a. Primary sensory afferent b. Stretch receptor neuron c. Second order neuron d. a neuron that forms its first synapse in the dorsal horn of the spinal cord e. a and d are correct

e. a and d are correct

The ligand-gated channels activated by somatic afferent neurons would be found in: a. in the dorsal root ganglia. b. the ventral horn. c. dorsal horn. d. dorsal column nuclei. e. all except a are correct.

e. all except a are correct.

Voltage-gated Na+ channels are.... a. Opened by the presence of negative charge b. Opened by the presence of positive charge c. Always open d. Gated e. b and d

e. b and d (opened by positive charge and gated)

The Bark Scorpion, is a highly venomous scorpion of Arizona. Its sting is exceptionally painful to mammals, yet the Grasshopper Mouse readily preys on these arachnids. Videos show the mice being stung repeatedly without demonstrating pain. Molecular analyses of the mouse show a single amino acid change in a voltage-gated channel specific to pain sensing neurons in the peripheral nervous system; the scorpion toxin binds to this channel, and prevents it from opening. This mutation allows the Grasshopper Mouse to be stung by the scorpion, but feel no pain. In comparison to a normal house mouse: a. The amplitude of the generator potential produced by the scorpion venom would be smaller in the Grasshopper Mouse b. The Grasshopper Mouse would lack action potentials in the second order neuron produced by a pin prick c. The amplitude of the action potential would exceed the equilibrium potential for Na+ in the Grasshopper Mouse d. The Grasshopper Mouse would lack action potentials produced by the scorpion venom in the pain sensitive primary sensory afferent e. b and d are correct

e. b and d are correct

As compared to putting your cell phone in your pocket, hoisting your carryon luggage into the overhead compartment would activate: a. a greater number of lower motor neurons innervating each muscle fiber b. a greater number of voltage gated Na+ channels in each muscle fiber c. a greater number of motor units in each activated muscle d. larger motor units in each activated muscle e. c and d are correct

e. c and d are correct

On Febraury 13, 2017, Kim Jong Nam, the half-brother of Kim Jong Um, the Supreme Leader of the Democratic People's Republic of Korea, was assinated in a Malaysian airport. The cause of his death appears to be VX, a nerve agent that inactivates acetylcholinesterase by irreversibly binding to the active site of this enzyme and preventing the conversion of acetylcholine to its inactive components, choline and acetate. High concentrations of acetylcholine at synapses that use this neurotransmitter first cause receptor activation followed by the closing of the receptor ion channel in a process called receptor inactivation. You would expect the channels that are intially open and then are closed to be: a. Voltage-gated Na+ channels b. Voltage-gated Ca2+ channels c. Activated (opened) by nicotine d. Ligand gated ionotropic channels e. c and d are correct

e. c and d are correct

The bearded guy running the camera in the back of the room (as opposed to the bearded guy blathering at the front of the room) fancies himself a strong individual. If the cameraman were to go to the gym and squat lift 300 pounds, you would expect his nervous system to activate __________________ than when he adjusts the dials on the camera. a. a greater number of lower motor neurons innervating each muscle fiber b. a greater number of voltage gated Na+ channels in each muscle fiber c. a greater number of motor units d. larger motor units e. c and d are correct

e. c and d are correct

Under circumstances where ATP is depleted and there is a high concentration of intracellular Ca2+ in a muscle fiber: a. Myosin heads are detached from the actin filaments b. Myosin heads are cycling on and off the actin filament c. Myosin heads are firmly attached to the thin filaments d. tropomyosin has moved to uncover the underlying myosin binding sites e. c and d are correct

e. c and d are correct

Under circumstances where ATP is depleted and there is a high concentration of intracellular Ca2+ in a muscle fiber: a. myosin heads are detached from the actin filaments. b. myosin heads are cycling on and off the actin filaments. c. myosin heads are firmly attached to the thin filaments. d. tropomyosin has moved to uncover the underlying myosin binding sites. e. c and d are correct.

e. c and d are correct.

Fish hunting snails are commonly found in the South China Sea. These animals attract fish with a lure, and harpoon them. At the base of the harpoon there is a venom sac that contains several toxins. After harpooning the fish, the snail injects the venom to immobilize the fish. Among the toxins are alpha, omega, mu, kappa, and delta conotoxins. The alpha conotoxins block nicotinic acetylcholine receptors. You would expect fluorescently labeled alpha conotoxins to be found: a. uniformly distributed on the skeletal muscle sarcolemma. b. confined to the transverse tubule (T-tubule) membrane. c. confined to the junction between the transverse tubule and sarcoplasmic reticulum. d. uniformly distributed on the sarcoplasmic reticulum. e. confined to the postsynaptic membrane at the neuromuscular junction.

e. confined to the postsynaptic membrane at the neuromuscular junction.

You would expect that VAMP and Syntaxin, which are examples of SNARE proteins, to be synthesized on: a. rough ER in the axon b. free ribosomes in the neuronal cell body c. free ribosomes in the axon terminal d. rough ER in the axon terminal e. rough ER in the neuronal cell body

e. rough ER in the neuronal cell body

You would expect that VAMP and Syntaxin, which are examples of SNARE proteins, to be synthesized on: a. rough endoplasmic reticulum in the axon. b. free ribosomes in the neuronal cell body. c. free ribosomes in the axon terminal. d. rough endoplasmic reticulum in the axon terminal. e. rough endoplasmic reticulum in the neuronal cell body.

e. rough endoplasmic reticulum in the neuronal cell body.

Number of action potentials per second

frequency coding

Collection of neuronal cell bodies in the PNS

ganglion

Dendrite

input region, usually characterized by ligand gated channels

Concentric layers are found in the __________________________ regions located between the _______________________________ where _________________________ Na+ channels are clustered.

intermodal; nodes of Ranvier; voltage-gated

internodal region

lacks voltage gated Na+ and K+ channels

Bundle of conductile regions in the PNS

nerves

Where the neuron innervates the muscle fiber

neuromuscular junction

Collection of neuronal cell bodies in the CNS

nucleus

axon terminal

output region, characterized by SNARE proteins

capacitor

storage of charge across a non-conducting medium

Site where neurons communicate with each other

synapse

Bundle of conductile regions in the CNS

tracts

syntaxin

transmembrane protein in plasma membrane

VAMP

transmembrane protein in vesicle

To initiate an action potential at the neuromuscular synapse, the local depolarization opens _____________________ channels that admit the ion, ______________.

voltage-gated; Na+