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One way in which neuronal pools can process incoming signals is by amplifying them, which is known as divergence.
One way in which neuronal pools can process incoming signals is by amplifying them, which is known as divergence.
False
A reverberatory circuit is a mechanism by which a neuron in a pool can re-excite itself, leading to prolonged output discharge.
A reverberatory circuit is a mechanism by which a neuron in a pool can re-excite itself, leading to prolonged output discharge.
True
One example of a reverberatory circuit functioning in the body is during respiration, where the inspiratory neuronal pool in the medulla remains excited for approximately 2 seconds per respiratory cycle.
One example of a reverberatory circuit functioning in the body is during respiration, where the inspiratory neuronal pool in the medulla remains excited for approximately 2 seconds per respiratory cycle.
True
A parallel circuit for after-discharge involves the input signal spreading through a series of neurons in the neuronal pool, with impulses converging on a single output neuron.
A parallel circuit for after-discharge involves the input signal spreading through a series of neurons in the neuronal pool, with impulses converging on a single output neuron.
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One theory suggests that wakefulness is maintained by continual reverberation within a specific area of the brain stem.
One theory suggests that wakefulness is maintained by continual reverberation within a specific area of the brain stem.
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Some neuronal pools are capable of emitting output signals continuously even without excitatory input signals, potentially due to their rhythmical property or reverberating circuits.
Some neuronal pools are capable of emitting output signals continuously even without excitatory input signals, potentially due to their rhythmical property or reverberating circuits.
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Inhibitory mechanisms in the nervous system destabilize neuronal circuits, making them more susceptible to uncontrolled excitation.
Inhibitory mechanisms in the nervous system destabilize neuronal circuits, making them more susceptible to uncontrolled excitation.
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Recurrent inhibition involves a collateral terminal returning from the pathway to excite an inhibitory interneuron, which then inhibits the initial excitatory neuron of the same pathway.
Recurrent inhibition involves a collateral terminal returning from the pathway to excite an inhibitory interneuron, which then inhibits the initial excitatory neuron of the same pathway.
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The fatigue mechanism for adjusting pathway sensitivity is a long-term mechanism, affecting the number of synaptic receptors.
The fatigue mechanism for adjusting pathway sensitivity is a long-term mechanism, affecting the number of synaptic receptors.
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Sensory receptors transduce environmental signals into electrical signals, which are then transmitted as action potentials.
Sensory receptors transduce environmental signals into electrical signals, which are then transmitted as action potentials.
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Pain signals originating from the visceral pain fibers terminate in the intermediate gray region of the spinal cord.
Pain signals originating from the visceral pain fibers terminate in the intermediate gray region of the spinal cord.
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The parenchyma of the liver is highly sensitive to pain.
The parenchyma of the liver is highly sensitive to pain.
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Mechanoreceptors are responsible for detecting stimuli related to light, sound, and chemicals.
Mechanoreceptors are responsible for detecting stimuli related to light, sound, and chemicals.
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The somatosensory system primarily deals with the sense of smell and taste.
The somatosensory system primarily deals with the sense of smell and taste.
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Distention of a hollow viscus can cause pain.
Distention of a hollow viscus can cause pain.
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The axons of the second order neurons in the visceral pain pathway travel through the anterolateral white matter of the spinal cord.
The axons of the second order neurons in the visceral pain pathway travel through the anterolateral white matter of the spinal cord.
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Proprioceptors are specialized sensory receptors that provide information about joint position, muscle tension, and muscle contraction.
Proprioceptors are specialized sensory receptors that provide information about joint position, muscle tension, and muscle contraction.
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The Golgi tendon organ is a type of proprioceptor found in muscle spindles, responsible for sensing muscle stretch.
The Golgi tendon organ is a type of proprioceptor found in muscle spindles, responsible for sensing muscle stretch.
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The cerebral cortex is the final destination of the visceral pain pathway.
The cerebral cortex is the final destination of the visceral pain pathway.
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Pain perception is not affected by psychological factors.
Pain perception is not affected by psychological factors.
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Overuse of a neural circuit can lead to an upregulation of synaptic receptors, increasing its sensitivity.
Overuse of a neural circuit can lead to an upregulation of synaptic receptors, increasing its sensitivity.
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Inhibitory interneurons are responsible for enhancing and amplifying signals in a neural pathway.
Inhibitory interneurons are responsible for enhancing and amplifying signals in a neural pathway.
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The threshold for pain increases under "fight or flight" conditions.
The threshold for pain increases under "fight or flight" conditions.
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Individual variations in pain response are influenced by genetic makeup, cultural background, age, and gender.
Individual variations in pain response are influenced by genetic makeup, cultural background, age, and gender.
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The brain cannot control the degree of pain signal input to the nervous system.
The brain cannot control the degree of pain signal input to the nervous system.
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Stimulation of large sensory fibers from peripheral tactile receptors can contribute to a decrease in pain perception.
Stimulation of large sensory fibers from peripheral tactile receptors can contribute to a decrease in pain perception.
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The velocities of transmission in the anterolateral pathway are similar to those in the dorsal column-medial lemniscal system.
The velocities of transmission in the anterolateral pathway are similar to those in the dorsal column-medial lemniscal system.
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Layer IV of the cerebral cortex is primarily responsible for receiving diffuse, nonspecific input signals.
Layer IV of the cerebral cortex is primarily responsible for receiving diffuse, nonspecific input signals.
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The cerebral cortex contains eight layers of neurons.
The cerebral cortex contains eight layers of neurons.
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Neurons in layer V of the cerebral cortex are generally smaller and project to nearby areas.
Neurons in layer V of the cerebral cortex are generally smaller and project to nearby areas.
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The ability to transmit rapidly changing signals is a strong feature of the anterolateral pathway.
The ability to transmit rapidly changing signals is a strong feature of the anterolateral pathway.
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A sudden onset of painful stimulus results in a single pain sensation.
A sudden onset of painful stimulus results in a single pain sensation.
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Chemosensitive pain receptors respond to mechanical stress.
Chemosensitive pain receptors respond to mechanical stress.
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Ischemia can cause pain due to the accumulation of lactic acids.
Ischemia can cause pain due to the accumulation of lactic acids.
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Pain receptors are primarily found as free nerve endings.
Pain receptors are primarily found as free nerve endings.
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Prostaglandins play a role in sensitizing pain nerve fibers.
Prostaglandins play a role in sensitizing pain nerve fibers.
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Aspirin and other non-steroidal anti-inflammatory drugs promote the formation of prostaglandins.
Aspirin and other non-steroidal anti-inflammatory drugs promote the formation of prostaglandins.
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Referred pain is felt in the same area as the tissue causing the pain.
Referred pain is felt in the same area as the tissue causing the pain.
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Thermosensitive pain receptors respond to extreme temperatures.
Thermosensitive pain receptors respond to extreme temperatures.
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Muscle spasm causes pain only through mechanical stimulation.
Muscle spasm causes pain only through mechanical stimulation.
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Substance P is a chemical that directly damages pain nerve endings.
Substance P is a chemical that directly damages pain nerve endings.
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Study Notes
Nervous System Functions
- Coordinates activities of other systems (endocrine) to maintain homeostasis via sensory and motor functions of the CNS.
- Stores experiences (memory) and establishes response patterns through prior experiences (learning).
Functional Levels of CNS
- Intercommunication between external and CNS is mediated by the sensory-somatic peripheral nervous system.
- Intercommunication between internal environment and CNS is mediated by autonomic peripheral nervous systems.
- CNS can be divided into three functional levels:
1. Spinal Cord Level
- Acts as a conduit for signals between the periphery of the body and the brain, and in the opposite direction.
- Contains reflex control centers.
- Controlled by higher levels of the CNS.
2. Lower Brain Level (Subcortical)
- Houses centers for subconscious bodily functions (medulla, pons, epencephalon, hypothalamus, thalamus, cerebellum, basal ganglia).
- Regulates arterial pressure, respiration, equilibrium control, feeding reflexes, and many emotional/behavioral patterns.
3. Higher Brain Level (Cortical)
- Translates lower CNS functions into precise actions.
- Large storehouse for memory and involved in higher-level thought processes.
- Essential for most thought processes, working alongside lower CNS centers.
Neuronal Pools
- Collections of interconnected neurons.
- Process signals in specialized ways (e.g., basal ganglia, thalamus nuclei, cerebellum).
- Input signals can excite, inhibit, or facilitate neurons within the pool.
- Signal processing can be serial (sequential) or parallel (simultaneous)
- Amplification and divergence of signals possible.
- Convergence allows summation of multiple signals onto a single pool.
- After-discharge: sustained output even after incoming signals cease.
Synaptic After-Discharge
- Excitatory synapses trigger long-acting synaptic transmitters on postsynaptic neurons.
Parallel Circuit for After-Discharge
- Input signals spread through multiple neurons, converging on an output neuron.
- Impulses within the pool keep re-exciting the output neuron.
Reverberatory Circuit for After-Discharge
- Excitation of a neuron in a pool feeds back to re-excite itself.
- Example: respiratory cycle. Mechanisms for extended wakefulness from continuous reverberation might exist in the brainstem.
Stabilization of Neuronal Circuits
- Inhibition prevents uncontrolled signal cycling throughout the brain.
- Gross inhibitory control is exerted in widespread areas (e.g., basal ganglia).
Presynaptic Inhibition
- Inhibits signal transmission before reaching the synapse.
- Mechanisms:
- Opening chloride and potassium channels at the presynaptic terminal.
- Blocking calcium channels.
Postsynaptic Inhibition
- Inhibits signal transmission at the synapse.
- Mechanisms could involve IPSP generation or synaptic fatigue.
Lateral Inhibition
- Collateral fibers from a pathway synapse with an inhibitory neuron.
- The inhibitory neuron then inhibits adjacent neurons (prevents signal spread).
Recurrent Inhibition
- Collateral fibers return to synapse with an inhibitory interneuron.
- This inhibitory neuron then inhibits the initial excitatory neuron in the pathway.
Adjustment of Pathway Sensitivity
- Automatic Short-Term Adjustment (fatigue): Overused pathways become less sensitive; underused, more sensitive.
- Automatic Long-Term Adjustment (downgrading/upgrading): Receptor proteins are altered to increase or decrease sensitivity based on usage.
Somatosensory Functions
- Specialized receptors detect stimuli (mechanical, thermal, etc.) and convert them into action potentials.
- Types of receptors: mechanoreceptors, thermoreceptors, nociceptors (pain receptors), electromagnetic/photoreceptors, chemoreceptors.
- Types of sensations: somatic (skin, muscle, joints), special (vision, smell, taste, etc.), and visceral (internal environment).
General Properties of Receptors
- Sensitivity: Receptors are exceptionally sensitive to specific types of stimuli.
- Specificity: Specific nerve fibers transmit particular modalities.
- Ability to generate receptor potentials (electrical potentials): Stimulus excites the receptor and produces an electrical change (graded potential).
Adaptation (Desensitization)
- Tonic receptors: Slowly or incompletely adapt.
- Phasic receptors: Rapidly adapt.
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Description
This quiz explores the mechanisms of neuronal pools and how they process incoming signals. It covers concepts such as divergence, reverberatory circuits, and the role of neuronal pools in respiratory cycles and wakefulness. Test your understanding of these critical functions in the nervous system.
