Bms 333 Exam 2 Neuro
(241).webp "Bms 333 Exam 2 Neuro - Quiz")
- 1.
Which of the following best describes a neuron at the resting state?
- A.
Na+-K+ ATPase pumps are not active
- B.
The resting membrane potential is about +65 mV
- C.
K+ ions leak out of a neuron via nongated K+ channels
- D.
Voltage-gated K+ channels are open
- E.
The resting state represents the relative refractory period
Correct Answer
C. K+ ions leak out of a neuron via nongated K+ channelsExplanation
At the resting state, a neuron is not actively firing or transmitting signals. The Na+-K+ ATPase pumps are not active, meaning they are not actively pumping sodium and potassium ions across the cell membrane. The resting membrane potential is about +65 mV, indicating a positive charge on the outside of the cell compared to the inside. K+ ions leak out of the neuron via nongated K+ channels, which allows a slow and continuous leakage of potassium ions out of the cell. This leakage contributes to the establishment and maintenance of the resting membrane potential. The statement about voltage-gated K+ channels being open is incorrect because these channels are closed during the resting state. The resting state does not represent the relative refractory period, which is a different phase of the neuronal action potential.Rate this question:
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- 2.
A local anesthetics, lidocane, prevents generation of action potential by inactivating:
- A.
Receptors for gamma aminobutylic acid (GABA)
- B.
Nongated Na+ channels
- C.
Voltage-gated Ca++ channels
- D.
Voltage-gated Na+ channels
- E.
Release of neurotransmitter Ach
Correct Answer
D. Voltage-gated Na+ channelsExplanation
Lidocaine is a local anesthetic that works by preventing the generation of action potentials. It achieves this by inactivating voltage-gated Na+ channels. These channels are responsible for the rapid depolarization phase of the action potential, allowing sodium ions to enter the cell and initiate the electrical signal. By blocking these channels, lidocaine prevents the influx of sodium ions and inhibits the generation of action potentials, leading to local anesthesia.Rate this question:
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- 3.
Astrocytes:
- A.
Form choroid plexus that produce cerebrospinal fluid
- B.
Transport glucose from capillaries to neurons
- C.
Give rise to perivascular end feet in the dorsal root ganglion
- D.
Stop dividing shortly after birth
- E.
Promote intercellular accumulation of neurotransmitter glutamate
Correct Answer
B. Transport glucose from capillaries to neuronsExplanation
Astrocytes are a type of glial cells found in the brain and spinal cord. One of their important functions is to transport glucose from the capillaries to neurons. Glucose is the main source of energy for neurons, and astrocytes play a crucial role in ensuring that an adequate supply of glucose reaches the neurons for their proper functioning. This transport mechanism helps maintain the energy balance and supports the metabolic needs of neurons.Rate this question:
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- 4.
A lesion of the lateral funiculus is likely to affect:
- A.
Central canal
- B.
Neuronal perikarya
- C.
Ependymal cells
- D.
Schwann cells
- E.
Oligodendrocytes
Correct Answer
E. OligodendrocytesExplanation
A lesion of the lateral funiculus is likely to affect oligodendrocytes. Oligodendrocytes are a type of glial cell in the central nervous system that produce myelin, a fatty substance that insulates and protects nerve fibers. The lateral funiculus is a region of white matter in the spinal cord that contains nerve fibers. Therefore, a lesion in this area could damage or destroy the oligodendrocytes, leading to a disruption in the production of myelin and potentially affecting the transmission of nerve impulses.Rate this question:
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- 5.
When an excitatory synapse 'A' and inhibitory synapse 'B' are stimulated simultaneously, the postsynaptic neuron is likely to generate:
- A.
An excitatory postsynaptic potential only
- B.
An inhibitory poststynaptic potential only
- C.
No obvious overall changes in membrane potential
- D.
Hyperpolarizing potential
- E.
An action potential
Correct Answer
C. No obvious overall changes in membrane potentialExplanation
When an excitatory synapse 'A' and inhibitory synapse 'B' are stimulated simultaneously, the excitatory postsynaptic potential (EPSP) generated by synapse 'A' is balanced by the inhibitory postsynaptic potential (IPSP) generated by synapse 'B'. These opposing potentials cancel each other out, resulting in no obvious overall changes in the membrane potential of the postsynaptic neuron. Therefore, the postsynaptic neuron is unlikely to generate an action potential or hyperpolarizing potential in this scenario.Rate this question:
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- 6.
What do you expect to see in a dog with a large lesion affecting the intermediate substance of teh spinal cord?
- A.
Presence of quadriceps reflex
- B.
Absence of quadriceps reflex
Correct Answer
B. Absence of quadriceps reflexExplanation
A large lesion affecting the intermediate substance of the spinal cord can lead to disruption in the transmission of signals between the brain and the muscles. The quadriceps reflex, also known as the patellar reflex, is a reflex that involves the contraction of the quadriceps muscle in response to tapping the patellar tendon. If the lesion affects the pathway responsible for this reflex, it can result in the absence of the quadriceps reflex. Therefore, in a dog with a large lesion affecting the intermediate substance of the spinal cord, the expected finding would be the absence of the quadriceps reflex.Rate this question:
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- 7.
Demyelination of axon is likely to result in:
- A.
Slight increase in conduction velocity of action potential
- B.
Decreased conduction velocity to the speed typically seen in nonmyelinated nerve fibers
- C.
A loss of conduction of action potentials as local currents cannot reach the voltage-gated Na+ and K+ channels
- D.
Increased conduction velocity due to a loss of resistance imposed by axonal plasma membrane
- E.
No apparent change in conduction speed as voltage-gated Na+ and K+ channels are still available in the demyelinated area
Correct Answer
C. A loss of conduction of action potentials as local currents cannot reach the voltage-gated Na+ and K+ channelsExplanation
Demyelination of axon refers to the loss or damage of the myelin sheath, which is a protective covering around the axon. The myelin sheath plays a crucial role in facilitating the conduction of action potentials along the axon. Without the myelin sheath, the local currents generated during the action potential are unable to reach the voltage-gated Na+ and K+ channels, which are responsible for the propagation of the action potential. As a result, there is a loss of conduction of action potentials. Therefore, the correct answer is a loss of conduction of action potentials as local currents cannot reach the voltage-gated Na+ and K+ channels.Rate this question:
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- 8.
Which of the following is affected in a dog with tic paralysis?
- A.
Sensory neurons in the dorsal horn
- B.
Postsynaptic acetycholine receptors
- C.
Release of Ach at the neuromuscular junction
- D.
Release of glycine from the pre-synaptic site
- E.
Motor neurons in the ventral horn
Correct Answer
C. Release of Ach at the neuromuscular junctionExplanation
Tic paralysis in dogs is caused by the release of Ach (acetylcholine) at the neuromuscular junction. Acetylcholine is a neurotransmitter that is responsible for transmitting signals between nerve cells and muscle cells. In tic paralysis, there is an excessive release of Ach, leading to muscle spasms and paralysis. This excessive release of Ach can be caused by various factors, such as a tumor or inflammation in the area. Therefore, the correct answer is the release of Ach at the neuromuscular junction.Rate this question:
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- 9.
Which statement is true about the neuromuscular synapse?
- A.
Nerve fibers that form the neuromuscular synapse leave the spinal cord via the dorsal root
- B.
Terminal branches of the motor end plate release glutamate
- C.
Neuromuscular synapse is affected by myasthenia gravis
- D.
Postsynaptic membrane has receptors for gamma aminobutylic acid (GABA)
- E.
Axon terminals are covered with astrocytes
Correct Answer
C. Neuromuscular synapse is affected by myasthenia gravis -
- 10.
The pointed portion (depolarization) of an action potential is triggered by:
- A.
Inhibitory postsynaptic potentials
- B.
Na+-K+ ATPase pumps
- C.
Opening of voltage-gated K+ channels
- D.
Inactivation of voltage-gated Na+ channels
- E.
Activation of voltage-gated Na+ channels
Correct Answer
E. Activation of voltage-gated Na+ channelsExplanation
The depolarization phase of an action potential is triggered by the activation of voltage-gated Na+ channels. These channels open in response to a depolarizing stimulus, such as the binding of neurotransmitters to receptors on the postsynaptic membrane. When these channels open, Na+ ions rush into the cell, causing a rapid depolarization and the initiation of an action potential. The other options listed, such as inhibitory postsynaptic potentials, Na+-K+ ATPase pumps, opening of voltage-gated K+ channels, and inactivation of voltage-gated Na+ channels, are not directly responsible for triggering the depolarization phase of an action potential.Rate this question:
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- 11.
Which neurotransmitter generates excitatory postsynaptic potential (EPSP) that depolarizes the postsynaptic membrane during synaptic transmission?
- A.
Glycine
- B.
Ach
- C.
GABA
- D.
All of the above
Correct Answer
B. AchExplanation
Ach, or acetylcholine, generates excitatory postsynaptic potential (EPSP) that depolarizes the postsynaptic membrane during synaptic transmission. Ach is a neurotransmitter that is involved in various functions in the body, including muscle movement, memory, and learning. It acts as an excitatory neurotransmitter in many parts of the nervous system, including the neuromuscular junction, where it stimulates muscle contraction. Therefore, it is the correct answer for this question.Rate this question:
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- 12.
A nerve fiber is:
- A.
Made of an axon and endoneurium
- B.
Made of an axon and Schwann cells
- C.
Made of a myelinated axon and endoneurium
- D.
Made of a nerve fasicle surrounded by perineurium
- E.
Made of an axon and oligodendrocytes
Correct Answer
B. Made of an axon and Schwann cellsExplanation
A nerve fiber is made up of an axon and Schwann cells. The axon is the long, slender part of the nerve cell that transmits electrical signals, while the Schwann cells are specialized cells that wrap around the axon, providing insulation and support. This combination of the axon and Schwann cells allows for efficient and rapid transmission of nerve impulses along the nerve fiber.Rate this question:
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- 13.
For inhibitory graded potential (IPSP) to occur during synaptic transmission, an inhibitory neurotransmitter must bind to the:
- A.
Ligand-gated receptors to trigger influx of Cl-
- B.
Ligand-gated receptors to trigger influx of Na+
- C.
Voltage-gated Na+ channels to trigger influx of Na+
- D.
Voltage-gated K+ channels to trigger influx of K+
Correct Answer
A. Ligand-gated receptors to trigger influx of Cl-Explanation
Inhibitory graded potentials (IPSPs) occur when an inhibitory neurotransmitter binds to ligand-gated receptors. These receptors are specific to the inhibitory neurotransmitter and when they are activated, they open channels that allow the influx of chloride ions (Cl-) into the neuron. This influx of negatively charged ions hyperpolarizes the neuron, making it less likely to generate an action potential and therefore inhibiting the transmission of signals. Therefore, the correct answer is "ligand-gated receptors to trigger influx of Cl-".Rate this question:
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Apr 15, 2024Quiz Edited by
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Oct 08, 2012Quiz Created by
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