Ch. 12 - Nervous System and Nervous Tissue Flashcards
Which of the following cavities contains a component of the central nervous system?
A) Abdominal.
B) Pelvic.
C) Cranial.
D) Thoracic.
C) Cranial.
Explanation: The cranial cavity contains the brain, which is a core component of the central nervous system (CNS). The CNS consists of the brain and spinal cord, located in the cranial and vertebral cavities respectively.
Incorrect:
A) Abdominal: Contains digestive organs—not part of the CNS.
B) Pelvic: Contains bladder and reproductive organs—not CNS structures.
D) Thoracic: Contains lungs and heart—again, not CNS-related.
Which structure predominates in the white matter of the brain?
A) Myelinated axons.
B) Neuronal cell bodies.
C) Ganglia of the parasympathetic nerves.
D) Bundles of dendrites from the enteric nervous system.
A) Myelinated axons.
Explanation: White matter is composed mainly of myelinated axons, which are responsible for fast signal conduction between neurons. Myelin gives white matter its characteristic pale appearance.
Incorrect:
B) Neuronal cell bodies: These are mostly found in gray matter, not white.
C) Ganglia of the parasympathetic nerves: Ganglia are part of the peripheral nervous system (PNS), not the brain’s white matter.
D) Bundles of dendrites from the enteric nervous system: The enteric system is part of the digestive tract, not the brain.
Which part of a neuron transmits an electrical signal to a target cell?
A) Dendrites.
B) Soma.
C) Cell body.
D) Axon.
D) Axon.
Explanation: The axon is the long projection of the neuron that carries electrical impulses away from the cell body toward a target, such as another neuron, muscle, or gland.
Incorrect:
A) Dendrites: Receive signals, they don’t transmit them to targets.
B) Soma / C) Cell body: Integrates input but doesn’t conduct the signal to the next cell.
Which term describes a bundle of axons in the peripheral nervous system?
A) Nucleus.
B) Ganglion.
C) Tract.
D) Nerve.
D) Nerve.
Explanation: In the PNS, a bundle of axons is called a nerve. In the CNS, the equivalent structure is called a tract.
Incorrect:
A) Nucleus: Group of cell bodies in the CNS.
B) Ganglion: Group of cell bodies in the PNS, not axons.
C) Tract: Bundle of axons in the CNS, not PNS.
Which functional division of the nervous system would be responsible for the physiological changes seen during exercise (e.g., increased heart rate and sweating)?
A) Somatic.
B) Autonomic.
C) Enteric.
D) Central.
B) Autonomic.
Explanation: The autonomic nervous system regulates involuntary physiological responses like heart rate and sweat production, especially under stress or exercise.
Incorrect:
A) Somatic: Controls voluntary movement, not autonomic responses.
C) Enteric: Manages digestion.
D) Central: Refers to CNS structures, not functional roles.
What type of glial cell provides myelin for the axons in a tract?
A) Oligodendrocyte.
B) Astrocyte.
C) Schwann cell.
D) Satellite cell.
A) Oligodendrocyte.
Explanation: Oligodendrocytes are the myelinating glial cells of the CNS, including axons within tracts.
Incorrect:
B) Astrocyte: Supports neurons and helps form the blood-brain barrier, but doesn’t myelinate.
C) Schwann cell: Myelinates axons in the PNS, not CNS tracts.
D) Satellite cell: Supports PNS cell bodies, not involved in myelination.
- Which part of a neuron contains the nucleus?
A) Dendrite.
B) Soma.
C) Axon.
D) Synaptic end bulb.
B) Soma.
Explanation: The soma, or cell body, contains the nucleus and most of the organelles of the neuron.
Incorrect:
A) Dendrite / D) Synaptic end bulb: Don’t contain the nucleus.
C) Axon: Conducts signals, but does not contain the nucleus.
Which of the following substances is least able to cross the blood-brain barrier?
A) Water.
B) Sodium ions.
C) Glucose.
D) White blood cells.
D) White blood cells.
Explanation: The blood-brain barrier (BBB) is designed to prevent most immune cells, including white blood cells, from entering the CNS to protect the brain’s delicate environment.
Incorrect:
A) Water, B) Sodium ions, C) Glucose: These can cross the BBB via specific transport mechanisms.
What type of glial cell is the resident macrophage behind the blood-brain barrier?
A) Microglia.
B) Astrocyte.
C) Schwann cell.
D) Satellite cell.
A) Microglia.
Explanation: Microglia are the immune cells of the CNS, acting as phagocytes behind the BBB.
Incorrect:
B) Astrocyte: Supports neurons and the BBB, not immune defense.
C) Schwann cell / D) Satellite cell: Found in the PNS, not CNS.
What two types of macromolecules are the main components of myelin?
A) Carbohydrates and lipids.
B) Proteins and nucleic acids.
C) Lipids and proteins.
D) Carbohydrates and nucleic acids.
C) Lipids and proteins.
Explanation: Myelin is composed primarily of lipids (for insulation) and proteins (for structure and function).
Incorrect: A, B, D: These do not match the dominant molecular composition of myelin.
If a thermoreceptor is sensitive to temperature sensations, what would a chemoreceptor be sensitive to?
A) Light.
B) Sound.
C) Molecules.
D) Vibration.
C) Molecules.
Explanation: Chemoreceptors detect chemical stimuli, such as molecules in the air (smell) or in food (taste), or changes in blood chemistry.
Incorrect:
A) Light: Detected by photoreceptors.
B) Sound / D) Vibration: Detected by mechanoreceptors.
Which of these locations is where the greatest level of integration is taking place in the example of testing the temperature of the shower?
A) Skeletal muscle.
B) Spinal cord.
C) Thalamus.
D) Cerebral cortex.
D) Cerebral cortex.
Explanation: The cerebral cortex is where conscious perception and complex processing occur—making it the site of highest integration during the shower scenario.
Incorrect:
A) Skeletal muscle: Responsible for executing movement, not integration.
B) Spinal cord: Handles basic reflexes, not complex sensory processing.
C) Thalamus: Relays signals but doesn’t perform the final integration.
How long does all the signaling through the sensory pathway, within the central nervous system, and through the motor command pathway take?
A) 1 to 2 minutes.
B) 1 to 2 seconds.
C) Fraction of a second.
D) Varies with graded potential.
C) Fraction of a second.
Explanation: Neural signaling is extremely fast. From sensory detection to CNS integration and back through motor output, the process occurs in fractions of a second.
Incorrect:
A & B: Far too slow for nervous system responses.
D: Graded potentials influence signal strength but not total response time.
What is the target of an upper motor neuron?
A) Cerebral cortex.
B) Lower motor neuron.
C) Skeletal muscle.
D) Thalamus.
B) Lower motor neuron.
Explanation: Upper motor neurons originate in the cerebral cortex and synapse on lower motor neurons, which then activate skeletal muscle.
Incorrect:
A) Cerebral cortex: The origin, not the target.
C) Skeletal muscle: Target of the lower motor neuron.
D) Thalamus: Involved in sensory relay, not motor control.
What ion enters a neuron causing depolarization of the cell membrane?
A) Sodium.
B) Chloride.
C) Potassium.
D) Phosphate.
A) Sodium.
Explanation: Sodium ions (Na⁺) rush into the neuron when voltage-gated channels open, depolarizing the membrane by making the inside more positive.
Incorrect:
B) Chloride: Usually causes hyperpolarization.
C) Potassium: Exits during repolarization.
D) Phosphate: Not directly involved in depolarization.
Voltage-gated Na⁺ channels open upon reaching what state?
A) Resting potential.
B) Threshold.
C) Repolarization.
D) Overshoot.
B) Threshold.
Explanation: Voltage-gated sodium channels open once the membrane reaches the threshold potential (typically around -55 mV), initiating the action potential.
Incorrect:
A) Resting potential: No channel opening.
C) Repolarization / D) Overshoot: Occur after Na⁺ channels have already opened and inactivated.
What does a ligand-gated channel require in order to open?
A) Increase in concentration of Na⁺ ions.
B) Binding of a neurotransmitter.
C) Increase in concentration of K⁺ ions.
D) Depolarization of the membrane.
B) Binding of a neurotransmitter.
Explanation: Ligand-gated channels open in response to a chemical signal—typically the binding of a neurotransmitter like acetylcholine.
Incorrect:
A & C: Changes in ion concentration don’t directly open ligand-gated channels.
D: That describes voltage-gated channels.
What does a mechanically gated channel respond to?
A) Physical stimulus.
B) Chemical stimulus.
C) Increase in resistance.
D) Decrease in resistance.
A) Physical stimulus.
Explanation: Mechanically gated channels open in response to physical deformation, such as touch, pressure, or stretch.
Incorrect:
B) Chemical stimulus: Relevant to ligand-gated channels.
C & D: Resistance is not a direct trigger for these channels.
Which of the following voltages would most likely be measured during the relative refractory period?
A) +30 mV.
B) 0 mV.
C) -45 mV.
D) -80 mV.
D) -80 mV.
Explanation: The relative refractory period occurs during hyperpolarization, when the membrane potential is more negative than usual—around -80 mV.
Incorrect:
A & B: Too positive.
C) -45 mV: Close to threshold; not typical of the relative refractory state.
Which of the following is probably going to propagate an action potential fastest?
A) A thin, unmyelinated axon.
B) A thin, myelinated axon.
C) A thick, unmyelinated axon.
D) A thick, myelinated axon.
D) A thick, myelinated axon.
Explanation: Thick, myelinated axons conduct signals fastest due to both low internal resistance and saltatory conduction.
Incorrect:
A & C: Lack myelin; slower conduction.
B: Myelinated but thin; not as fast as thick and myelinated.
How much of a change in the membrane potential is necessary for the summation of postsynaptic potentials to result in an action potential being generated?
A) +30 mV.
B) +15 mV.
C) +10 mV.
D) -15 mV.
C) +10 mV.
Explanation: To reach threshold from a resting potential of about -70 mV, a depolarization of about +10 to +15 mV is typically needed.
Incorrect:
A) +30 mV: This is the peak of the action potential, not the threshold.
B) +15 mV: Acceptable, but +10 mV is the minimum common value.
D) -15 mV: Hyperpolarization, not depolarization.
A channel opens on a postsynaptic membrane that causes a negative ion to enter the cell. What type of graded potential is this?
A) Depolarizing.
B) Repolarizing.
C) Hyperpolarizing.
D) Non-polarizing.
C) Hyperpolarizing.
Explanation: When negative ions (like Cl⁻) enter the cell, the inside becomes more negative, which is hyperpolarization—moving further from threshold.
Incorrect:
A) Depolarizing: Would involve positive ions entering.
B) Repolarizing: Refers to return to resting after an action potential.
D) Non-polarizing: Not a standard term in this context.
What neurotransmitter is released at the neuromuscular junction?
A) Norepinephrine.
B) Serotonin.
C) Dopamine.
D) Acetylcholine.
D) Acetylcholine.
Explanation: Acetylcholine (ACh) is the neurotransmitter released by motor neurons at the neuromuscular junction, where it stimulates muscle contraction.
Incorrect:
A) Norepinephrine: Involved in autonomic responses (especially sympathetic).
B) Serotonin: Affects mood and emotion, not muscle contraction.
C) Dopamine: Linked to reward and motor control in the CNS, not the NMJ.
What type of receptor requires an effector protein to initiate a signal?
A) Biogenic amine.
B) Ionotropic receptor.
C) Cholinergic system.
D) Metabotropic receptor.
D) Metabotropic receptor.
Explanation: Metabotropic receptors are indirect-acting receptors that use effector proteins like G-proteins and second messengers to initiate intracellular responses.
Incorrect:
A) Biogenic amine: A class of neurotransmitters, not a receptor type.
B) Ionotropic receptor: Directly opens ion channels without secondary messengers.
C) Cholinergic system: Refers to neurons that use ACh, not a specific receptor mechanism.
Which of the following neurotransmitters is associated with inhibition exclusively?
A) GABA.
B) Acetylcholine.
C) Glutamate.
D) Norepinephrine.
A) GABA.
Explanation: GABA (gamma-aminobutyric acid) is the brain’s primary inhibitory neurotransmitter, causing hyperpolarization of the postsynaptic membrane.
Incorrect:
B) Acetylcholine: Can be excitatory or inhibitory depending on the receptor.
C) Glutamate: Primarily excitatory.
D) Norepinephrine: Typically excitatory in the sympathetic nervous system.
