Neuro - Quiz 1
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Questions and Answers

Which of the following sensory modalities includes the perception of pain?

  • Proprioceptive sensations
  • Thermal sensations
  • Equilibrium
  • Somatic sensory modalities (correct)

    • What is the function of visceral senses?

  • They provide information about conditions within internal organs. (correct)
  • They detect external stimuli like light and sound.
  • They measure body temperature and pain.
  • They allow perception of joint movements.

    • Which sensory receptor process involves converting energy from a stimulus into a graded potential?

  • Sensory adaptation
  • Transmission of the signal
  • Stimulation of the sensory receptor
  • Transduction of the stimulus (correct)

    • Which type of sensation does NOT belong to the general senses?

    <p>Hearing (D)</p> Signup and view all the answers

    What allows proprioceptive sensations to provide information about body position and movement?

    <p>Conscious and unconscious perception (C)</p> Signup and view all the answers

    What characterizes an electrical synapse?

    <p>The membranes of two cells are in tight contact to allow electrical coupling. (D)</p> Signup and view all the answers

    Which of the following cells can serve as target cells in synaptic connections?

    <p>Nerves, muscles, and glands (A)</p> Signup and view all the answers

    How do electrical synapses compare to chemical synapses in terms of speed?

    <p>They are faster than chemical synapses. (C)</p> Signup and view all the answers

    What is the primary structural difference between chemical and electrical synapses?

    <p>Chemical synapses have the presynaptic and postsynaptic cells separated by a gap. (D)</p> Signup and view all the answers

    Which statement about synapses is correct?

    <p>Chemical synapses allow for complex signaling due to the presence of a synaptic cleft. (B)</p> Signup and view all the answers

    What type of sensory receptor adapts slowly to a stimulus and continues to transmit signals?

    <p>Tonic receptors (A), Proprioceptors (B)</p> Signup and view all the answers

    Which of the following statements accurately describes phasic receptors?

    <p>They rapidly adapt and mainly signal changes in the stimulus. (A)</p> Signup and view all the answers

    What happens to sensory receptors during adaptation?

    <p>Their responsiveness typically diminishes while the stimulus is maintained. (B)</p> Signup and view all the answers

    Which receptor type is known for not adapting to stimuli?

    <p>Nociceptors (B)</p> Signup and view all the answers

    Which of the following examples correctly illustrates rapid adaptation in sensory receptors?

    <p>Realizing a bad smell disappears over time (C)</p> Signup and view all the answers

    What type of sensory neurons carry impulses from the peripheral nervous system into the central nervous system?

    <p>First order neurons (B)</p> Signup and view all the answers

    Which type of receptor is primarily responsible for detecting mechanical stress such as pressure and vibration?

    <p>Mechanoreceptors (C)</p> Signup and view all the answers

    What happens when graded potentials in sensory neurons reach the threshold level?

    <p>They generate impulses (B)</p> Signup and view all the answers

    Which type of receptors lack structural specialization and are responsible for detecting pain and temperature?

    <p>Free nerve endings (C)</p> Signup and view all the answers

    Which statement regarding the integration of sensory input is correct?

    <p>Conscious sensations are integrated in the cerebral cortex. (D)</p> Signup and view all the answers

    What is the primary role of nociceptors in the human body?

    <p>To detect potential damage to tissues (C)</p> Signup and view all the answers

    What type of receptors are responsible for detecting light and are found in the retina?

    <p>Photoreceptors (D)</p> Signup and view all the answers

    What phenomenon occurs when initial pain stimuli lead to increased sensitivity to further painful stimuli?

    <p>Hyperalgesia (D)</p> Signup and view all the answers

    Which type of response illustrates the inhibition of pain transmission through descending pathways?

    <p>Stimulation-produced analgesia (A)</p> Signup and view all the answers

    Which receptor type detects changes in temperature and has two distinct types for hot and cold stimuli?

    <p>Thermoreceptors (D)</p> Signup and view all the answers

    Which classification of receptors responds primarily to external stimuli like touch and temperature?

    <p>Exteroceptors (B)</p> Signup and view all the answers

    What characterizes encapsulated nerve endings compared to free nerve endings?

    <p>They have specialized connective tissue capsules. (C)</p> Signup and view all the answers

    What type of sensory receptor is responsible for responding to electromagnetic waves?

    <p>Electromagnetic receptors (A)</p> Signup and view all the answers

    What type of neurotransmitter is classified as an endorphin?

    <p>Neuropeptide (C)</p> Signup and view all the answers

    Which receptor does morphine primarily act on?

    <p>Opiate receptors (D)</p> Signup and view all the answers

    How does cocaine affect dopamine in the synaptic cleft?

    <p>Blocks the reuptake system (A)</p> Signup and view all the answers

    What is the primary effect of nerve gas (Sarin) on neurotransmission?

    <p>Blocks acetylcholine removal (C)</p> Signup and view all the answers

    What autoimmune condition is characterized by antibodies that antagonistically affect acetylcholine receptors?

    <p>Myasthenia Gravis (B)</p> Signup and view all the answers

    Which component is NOT considered a basic constituent of neural circuits?

    <p>Muscle fibers (A)</p> Signup and view all the answers

    What type of neurotransmission is primarily implicated in epilepsy?

    <p>Reduced inhibitory transmission (B)</p> Signup and view all the answers

    What structure provides the primary location for synaptic connectivity?

    <p>Neuropil (C)</p> Signup and view all the answers

    Which of the following is an example of a neuronal pool?

    <p>A group of connected interneurons (C)</p> Signup and view all the answers

    In the myotatic reflex, sensory neurons transmit information in which direction?

    <p>Toward the central nervous system (D)</p> Signup and view all the answers

    Which psychiatric condition is linked with low levels of serotonin?

    <p>Depression (D)</p> Signup and view all the answers

    What term describes neurons that only participate in local aspects of a circuit?

    <p>Interneurons (A)</p> Signup and view all the answers

    What is the effect of cold on endorphin levels?

    <p>Increases endorphin levels (C)</p> Signup and view all the answers

    What is one function of endorphins?

    <p>Reduce stress (D)</p> Signup and view all the answers

    What is the primary role of neurotransmitters at synapses?

    <p>To facilitate the transmission of action potentials (D)</p> Signup and view all the answers

    What determines the amplitude of an excitatory postsynaptic potential (EPSP)?

    <p>The number of vesicles released from the presynaptic cell (C)</p> Signup and view all the answers

    How do inhibitory neurotransmitters affect the postsynaptic cell?

    <p>They lead to hyperpolarization of the cell (C)</p> Signup and view all the answers

    What is the primary excitatory neurotransmitter in the central nervous system (CNS)?

    <p>Glutamate (D)</p> Signup and view all the answers

    What enzyme is responsible for degrading serotonin in the synaptic cleft?

    <p>Monoamine oxidase (MAO) (D)</p> Signup and view all the answers

    Which neurotransmitter is primarily involved in muscle contraction?

    <p>Acetylcholine (C)</p> Signup and view all the answers

    What happens to the membrane potential when excitatory neurotransmitters bind to their receptors?

    <p>The membrane potential becomes more positive (B)</p> Signup and view all the answers

    Which of the following is NOT an example of an inhibitory neurotransmitter?

    <p>Acetylcholine (D)</p> Signup and view all the answers

    How do modulating neurotransmitters differ from fast-acting neurotransmitters?

    <p>They act more slowly and have longer-lasting effects (D)</p> Signup and view all the answers

    Which neurotransmitter is synthesized from the amino acid tryptophan?

    <p>Serotonin (D)</p> Signup and view all the answers

    What is the function of the receptor channels in nerve synapses?

    <p>To facilitate ion movement across the membrane (B)</p> Signup and view all the answers

    What role does vitamin B6 play in serotonin production?

    <p>It helps synthesize serotonin (B)</p> Signup and view all the answers

    Which of the following neurotransmitters can act both as a neurotransmitter and a modulator?

    <p>Serotonin (C)</p> Signup and view all the answers

    How is the action potential concluded at the presynaptic cell?

    <p>By degradation of the neurotransmitter (D)</p> Signup and view all the answers

    What is divergence in neuronal pools?

    <p>The spread of information from one pool to multiple pools (D)</p> Signup and view all the answers

    How does convergence affect motor neurons?

    <p>It allows conscious control over the same motor neurons (A)</p> Signup and view all the answers

    What characterizes serial processing in neurons?

    <p>Information is relayed in a stepwise fashion from one pool to another (B)</p> Signup and view all the answers

    What does parallel processing allow in the context of sensory information?

    <p>Simultaneous processing of information by several neuronal pools (D)</p> Signup and view all the answers

    What is reverberation in a neural circuit?

    <p>A feedback loop that continues to stimulate itself (B)</p> Signup and view all the answers

    Which of the following best defines sensation?

    <p>Any stimulus the body is aware of through its receptors (C)</p> Signup and view all the answers

    What distinguishes perception from sensation?

    <p>Perception involves the storage of sensory memories in the cortex (C)</p> Signup and view all the answers

    Which of the following is NOT a characteristic of divergence?

    <p>Restricting the information to a few options (C)</p> Signup and view all the answers

    What can occur when sensory impulses reach the spinal cord?

    <p>Only simple reflex actions like the stretch reflex (B)</p> Signup and view all the answers

    Which pattern of interaction among neurons allows for the same inputs to produce different outputs?

    <p>Convergence (D)</p> Signup and view all the answers

    In which situation is serial processing primarily observed?

    <p>When relaying information between different hemispheres of the brain (A)</p> Signup and view all the answers

    What type of feedback is involved in maintaining normal breathing according to reverberation?

    <p>Negative feedback (C)</p> Signup and view all the answers

    What is NOT a sensory modality?

    <p>X-rays (C)</p> Signup and view all the answers

    What mechanism allows a sharp stimulus to produce multiple simultaneous reactions?

    <p>Divergence (B)</p> Signup and view all the answers

    Which of the following best describes the relationship between sensation and perception?

    <p>Sensation is the physical input; perception is the interpretation of that input (C)</p> Signup and view all the answers

    Study Notes

    Synapses

    • Synapses are specialized junctions where neurons communicate with target cells.
    • Target cells include nerves, muscles, and glands.
    • Two types of synapses: electrical and chemical.

    Electrical Synapses

    • Rare in vertebrates.
    • Membranes of the two cells are in close contact, creating electrical coupling.
    • Enables fast and reliable transmission of nerve impulses (action potentials).
    • Faster than chemical synapses.
    • More synchronized.

    Chemical Synapses

    • More common.
    • Presynaptic and postsynaptic cells are separated by a synaptic cleft (10-15 times wider than electrical synapses).
    • Transmission relies on neurotransmitters released from the presynaptic cell.
    • Allows for precise control of neurotransmitter release.

    Neurotransmitters

    • Neurotransmitters and their receptors have a lock-and-key fit.
    • At nerve-muscle and many nerve-nerve synapses, receptors act as ion channels.
    • Binding of a neurotransmitter changes the receptor shape, opening an intrinsic pore.

    Excitatory Postsynaptic Potentials (EPSPs)

    • Excitatory neurotransmitters open ion channels allowing positively charged sodium ions to enter the cell.
    • This depolarizes the postsynaptic membrane, creating an EPSP.
    • EPSP amplitude is roughly proportional to the number of released vesicles.
    • Sufficiently large EPSPs trigger an action potential in the target cell.

    Inhibitory Transmitters

    • Inhibitory neurotransmitters make the postsynaptic cell less excitable.
    • Often associated with chloride or potassium channels, leading to hyperpolarization (making the interior more negative).
    • Examples include glycine and GABA.

    Acetylcholine and Glutamate

    • Acetylcholine is excitatory at nerve-skeletal muscle synapses.
    • Glutamate is the main excitatory neurotransmitter in the central nervous system.

    Serotonin (5-hydroxytryptamine, 5-HT)

    • Synthesized from tryptophan, with vitamin B6 aiding the process.
    • Predominantly found in the gut.
    • Stored in vesicles in the presynaptic terminals.
    • Action potential triggers exocytosis of serotonin into the synaptic cleft.
    • Serotonin binds to receptors on the postsynaptic cell, depolarizing it.
    • Reaching threshold initiates an action potential in the postsynaptic cell.
    • Remaining serotonin is degraded by monoamine oxidase (MAO).
    • MAO also degrades reabsorbed serotonin, terminating nerve signals and preparing the synapse for subsequent impulses.
    • Catechol-O-methyl transferase (COMT) targets catecholamines (not serotonin).
    • MAOIs are antidepressants.
    • Serotonin can act as a modulator.

    Modulation

    • Slower and longer-lasting than fast neurotransmitters.
    • Often involve activation of intracellular messengers (not directly opening ion channels).
    • Can affect gene expression.
    • Multiple neurotransmitters/modulators can be released by a single nerve terminal.

    Enkephalins (Opiates/Endorphins)

    • Neuropeptide.
    • Inhibitory effect.
    • Located in the brain and spinal cord.
    • Functions: stress reduction, promoting calmness, natural pain killer.
    • Cold and exercise likely increase endorphin production.

    Synapse Abuse

    • Many drugs affect synapses.
    • Nicotine activates nicotinic acetylcholine receptors, causing dopamine release.
    • Curare is an antagonist of acetylcholine receptors, blocking neuromuscular transmission.
    • Morphine/Heroin act on opiate receptors.
    • Cannabis acts on cannabinoid receptors.
    • Cocaine blocks dopamine reuptake (prolonged dopamine in the cleft).
    • Nerve gas (Sarin) blocks acetylcholine removal, causing spastic paralysis.

    Disorders of Synaptic Function

    • Myasthenia Gravis: Autoantibodies antagonize acetylcholine receptors, leading to reduced neurotransmission and fatigue.
    • Graves Disease: Autoantibodies agonistically bind to the thyroid gland.
    • Epilepsy: Possibly linked to decreased inhibitory transmission (GABA).
    • Depression/Schizophrenia: Likely involve serotonin/dopamine synapse disruptions.

    Neural Circuits

    • Neurons function in ensembles.
    • Synaptic connections form a neuropil, a dense network between cell bodies, where most connections occur.
    • Afferent neurons carry information to the CNS.
    • Efferent neurons carry information away from the CNS.
    • Interneurons participate in local circuits.
    • Example: stretch reflex circuit (sensory afferents, interneurons, motor efferents).

    Neuronal Pools

    • Groups of interconnected neurons with specific functions.
    • Defined functionally, not anatomically.
    • Five circuit patterns: divergence, convergence, serial processing, parallel processing, reverberation.

    Sensation

    • Conscious/unconscious awareness of stimuli.
    • Nature of sensation depends on impulse destination and receptor type.
    • Can range from simple reflexes to complex perceptions.

    Sensation vs. Perception

    • Sensation: Awareness of any stimulus detected by receptors.
    • Perception: Conscious awareness and interpretation of a sensation.

    Sensory Modality

    • Property differentiating one sensation from another.
    • General senses (somatic & visceral) and special senses (smell, taste, vision, hearing, equilibrium).

    General Senses

    • Somatic senses: tactile (touch, pressure, vibration, itch), thermal (temperature), pain, proprioceptive (joint/muscle position).
    • Visceral senses: Conditions within internal organs (e.g., pressure, pain).

    Special Senses

    • Smell, taste, vision, hearing, equilibrium (cranial nerves).

    Process of Sensation

    • 4 steps: stimulation of sensory receptor, transduction into a graded potential (generator or receptor potential), generation of impulses (action potentials), and integration by the CNS.

    Sensory Receptors

    • Range from simple to complex structures.
    • Classified by structure, stimulus type, response to stimulus, and location.

    Types of Receptors

    • Free nerve endings: Bare dendrites (pain, temperature, itch, light touch).
    • Encapsulated nerve endings: Dendrites in connective tissue capsules (pressure, vibration, deep touch).
    • Separate sensory cells: Specialized cells that synapse onto neurons (vision, taste, hearing, equilibrium - except smell).

    Stimulus Types of Receptors

    • Mechanoreceptors: Detect physical or mechanical stress.
    • Thermoreceptors: Detect temperature changes (hot/cold).
    • Nociceptors: Detect potential tissue damage (intense mechanical deformation, excessive heat, chemicals).
    • Chemoreceptors: Detect chemicals (taste, smell, blood oxygen, pH).
    • Photoreceptors: Detect light (rods/cones).
    • Other: Electromagnetic receptors, baroreceptors.

    Hyperalgesia/Stimulation-produced analgesia

    • Hyperalgesia: Increased sensitivity to pain after initial stimulus.
    • Stimulation-produced analgesia: Descending pathways inhibiting pain signals; opioids involved.
    • Referred pain: Pain felt at site different from actual injury location.

    Pain-Gate Theory

    • Stimulation of non-pain afferents can inhibit pain pathways (TENS).

    Receptor Potential

    • A graded potential in receptors in the special senses.

    Receptor Location

    • Exteroceptors: External stimuli.
    • Interoceptors: Internal stimuli (e.g., blood pressure).
    • Proprioceptors: Body position (muscles, tendons, joints).

    Adaptation

    • Most receptors adapt (decrease sensitivity to maintained stimuli).
    • Tonic receptors: Adapt slowly, provide information about stimulus duration.
    • Phasic receptors: Adapt rapidly, signal changes in stimulus intensity.

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    Description

    Explore the fascinating world of synapses, the specialized junctions where neurons communicate with various target cells. This quiz dives into the two main types of synapses, electrical and chemical, detailing their characteristics and functions. Test your knowledge on neurotransmitters and their crucial role in neural communication.

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