Neuroscience Chapter on Sensation and Synapses
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Questions and Answers

Which of the following is NOT included in the general senses?

  • Pain sensations
  • Smell sensations (correct)
  • Temperature sensations
  • Proprioceptive sensations

    • What type of sensation allows perception of body position and movement?

  • Tactile sensations
  • Visceral sensations
  • Proprioceptive sensations (correct)
  • Thermal sensations

    • Which step in the process of sensation involves converting energy from a stimulus into a graded potential?

  • Interpretation of the sensation
  • Transmission of the signal
  • Stimulation of the sensory receptor
  • Transduction of the stimulus (correct)

    • Which one of the following is considered a special sense?

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

    Visceral senses provide information regarding:

    <p>Conditions within internal organs (B)</p> Signup and view all the answers

    What characterizes tonic receptors?

    <p>They provide information on the duration of a stimulus. (C)</p> Signup and view all the answers

    What happens to sensory receptors during adaptation?

    <p>They exhibit a decrease in responsiveness to long-lasting stimuli. (C)</p> Signup and view all the answers

    What is a synapse primarily involved in?

    <p>Facilitating communication between a neuron and a target cell (C)</p> Signup and view all the answers

    Which characteristic distinguishes electrical synapses from chemical synapses?

    <p>Electrical synapses allow direct physical contact between the two cells (B)</p> Signup and view all the answers

    Which of the following is an example of a phasic receptor?

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

    Which statement is true about chemical synapses compared to electrical synapses?

    <p>Chemical synapses have a gap that is 10-15 times larger than electrical synapses (A)</p> Signup and view all the answers

    Which type of receptor is specialized for detecting changes rather than duration?

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

    What types of cells can synapses connect to?

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

    What is the primary role of proprioceptors?

    <p>Indicate background level stimuli. (D)</p> Signup and view all the answers

    What is a notable advantage of electrical synapses over chemical synapses?

    <p>Electrical synapses are more synchronized and operate faster (C)</p> Signup and view all the answers

    What is the role of the sensory neurons in the myotatic spinal reflex?

    <p>They carry signals from the dorsal root ganglion to the spinal cord. (A)</p> Signup and view all the answers

    Which type of neuron is responsible for inhibiting the activity of flexor muscles in the reflex arc?

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

    What defines a neuronal pool?

    <p>A group of interconnected neurons with specific functions. (B)</p> Signup and view all the answers

    In the concept of divergence within neural circuits, what does it allow?

    <p>The distribution of input to multiple neuronal pools. (C)</p> Signup and view all the answers

    Which processing pattern involves several neurons synapsing on the same postsynaptic neuron?

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

    Which pattern of neuronal processing is characterized by relaying information in a stepwise manner?

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

    What is a significant characteristic of internal and external signals processed simultaneously in the brain?

    <p>They are processed by divergent pools. (B)</p> Signup and view all the answers

    How many sensory neurons are estimated to exist in the human body?

    <p>10 million (C)</p> Signup and view all the answers

    What does the output of a neuronal pool influence?

    <p>Motor neurons or peripheral effectors. (A)</p> Signup and view all the answers

    Which neuronal processing method allows simultaneous responses during reflex actions?

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

    What occurs when excitatory neurotransmitters bind to receptors on the postsynaptic cell?

    <p>Local depolarization known as EPSP (A)</p> Signup and view all the answers

    Which neurotransmitter is primarily responsible for excitation at the neuromuscular junction?

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

    What effect do inhibitory neurotransmitters generally have on the postsynaptic cell?

    <p>Make the cell less likely to generate an action potential (B)</p> Signup and view all the answers

    What is the primary role of monoamine oxidase (MAO) in neurotransmission?

    <p>Degrade remaining serotonin after its action (A)</p> Signup and view all the answers

    What is unique about modulators like serotonin compared to fast neurotransmitters?

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

    Which enzyme specifically targets catecholamines in neurotransmission?

    <p>Catechol-o-methyl transferase (COMT) (D)</p> Signup and view all the answers

    How does the release of neurotransmitters occur at the presynaptic cell during an action potential?

    <p>Vesicles fuse with the membrane and release neurotransmitters (B)</p> Signup and view all the answers

    What was once believed about neurotransmitter release in relation to nerve fibers?

    <p>All nerve fibers released the same neurotransmitter (D)</p> Signup and view all the answers

    What is the function of the neurotransmitter glycine?

    <p>Acts as an inhibitory neurotransmitter (D)</p> Signup and view all the answers

    Which of the following statements is true regarding the action of neurotransmitters?

    <p>Modulators can cause changes in gene activation (B)</p> Signup and view all the answers

    What is the primary distinction between sensation and perception?

    <p>Sensation is the awareness of stimuli, while perception involves interpretation. (A)</p> Signup and view all the answers

    Which type of feedback loop is involved in positive reverberation?

    <p>Reinforcing the initial stimulus to increase response. (C)</p> Signup and view all the answers

    What role do sensory receptors play in the process of sensation?

    <p>They convert sensory energy into graded potential for transduction. (A)</p> Signup and view all the answers

    Which types of sensations fall under the category of general senses?

    <p>Touch, temperature, and proprioception. (C)</p> Signup and view all the answers

    How is consciousness maintained according to the discussed mechanisms?

    <p>Using reverberation in neural circuits. (A)</p> Signup and view all the answers

    Which of the following is an example of a visceral sense?

    <p>Awareness of hunger and fullness. (D)</p> Signup and view all the answers

    In the process of sensation, what does the term 'transduction' refer to?

    <p>The conversion of energy from a stimulus into a graded potential. (C)</p> Signup and view all the answers

    What is NOT a requirement for a sensation to occur?

    <p>Conscious awareness of the stimulus. (C)</p> Signup and view all the answers

    What distinguishes special senses from general senses?

    <p>Special senses are located solely in the face. (A)</p> Signup and view all the answers

    Which example illustrates a complex reflex elicited by sensory impulses reaching the lower brain stem?

    <p>Adjustments in heart rate during exercise. (A)</p> Signup and view all the answers

    What pattern of neural interaction allows information to spread from one pool to multiple pools?

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

    Which circuit pattern involves several neurons synapsing on the same postsynaptic neuron?

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

    What is the term for the process where information is relayed in a stepwise fashion from one neuronal pool to another?

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

    In which pattern does the same information get processed simultaneously by several neurons or pools?

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

    Which pattern of neural interaction can involve feedback loops that may produce positive or negative effects?

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

    What are the impulses called that can lead to spinal reflexes when relayed to the spinal cord?

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

    Which of the following stimuli might we be aware of due to having specific receptors?

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

    What role do sensory modalities serve in distinguishing various sensations?

    <p>They categorize sensations based on distinct properties. (A)</p> Signup and view all the answers

    What happens when sensory impulses reach the cerebral cortex?

    <p>They generate complex sensory experiences and identifications. (A)</p> Signup and view all the answers

    Which of the following best describes the nature of reverberation in neural circuits?

    <p>It helps in maintaining complex functions like consciousness. (B)</p> Signup and view all the answers

    Which statement is true regarding both conscious and subconscious control of motor neurons?

    <p>Convergence allows for both types of control on the same neurons. (A)</p> Signup and view all the answers

    How does divergence play a role in sensory perception?

    <p>It allows the same sensory input to reach multiple processing areas. (A)</p> Signup and view all the answers

    What is the primary role of endorphins in the body?

    <p>Act as natural painkillers (D)</p> Signup and view all the answers

    Which neurotransmitter is involved in the mechanism of reward associated with nicotine?

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

    What effect does curare have on the body?

    <p>Paralyzes muscle by blocking ACh receptors (A)</p> Signup and view all the answers

    Cocaine functions primarily by which mechanism?

    <p>Blocking reuptake of dopamine (B)</p> Signup and view all the answers

    Which condition is characterized by the antibody-mediated reduction of acetylcholine receptors?

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

    What role do interneurons play in neural circuits?

    <p>Only participate locally in circuits (D)</p> Signup and view all the answers

    Which disorder is primarily linked to an increase in dopamine activity?

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

    Which neurotransmitter is typically involved in inhibitory transmission in the brain?

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

    What characterizes a neuronal pool?

    <p>It's a group of interconnected interneurons with specific functions. (C)</p> Signup and view all the answers

    What is the primary function of afferent neurons?

    <p>Transmit sensory information to the CNS (D)</p> Signup and view all the answers

    What is the main effect of MAOIs in the context of antidepressant treatment?

    <p>They increase serotonin levels. (A)</p> Signup and view all the answers

    How do endorphin levels typically change with exercise or cold exposure?

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

    In which of the following disorders is there evidence of reduced serotonin levels?

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

    Which action characterizes fast neurotransmitters?

    <p>They unbind quickly from their receptors. (B)</p> Signup and view all the answers

    What typically happens during the activation of inhibitory interneurons in a reflex circuit?

    <p>Flexor muscles are less active. (C)</p> Signup and view all the answers

    Which neurotransmitter is primarily associated with inhibitory effects in the brain?

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

    What is a common characteristic of neurotransmitters that act as modulators?

    <p>They trigger longer-lasting responses. (B)</p> Signup and view all the answers

    What is a key characteristic of neural circuits?

    <p>They are composed of afferent, efferent, and interneurons. (C)</p> Signup and view all the answers

    What is the primary effect of nicotine on neurotransmission?

    <p>Activates nicotinic acetylcholine receptors. (D)</p> Signup and view all the answers

    Which condition is linked with an autoimmune response affecting acetylcholine receptors?

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

    What neurotransmitter is linked to excessive excitation in epilepsy?

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

    Which statement accurately describes the function of interneurons?

    <p>They participate in local circuits. (D)</p> Signup and view all the answers

    What is one function of enkephalins, related to their classification as neuropeptides?

    <p>Act as natural painkillers. (A)</p> Signup and view all the answers

    Which of the following drugs acts on cannabinoid receptors?

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

    What condition is characterized by having too much dopamine in the system?

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

    In which part of the nervous system do afferent neurons primarily function?

    <p>They carry information toward the central nervous system. (C)</p> Signup and view all the answers

    What is the role of GABA in synaptic function?

    <p>To inhibit neurotransmission. (B)</p> Signup and view all the answers

    Which type of receptor adapts quickly to stimuli and does not provide information on the duration of the stimulus?

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

    What is the role of a tonic receptor?

    <p>To indicate background stimulus levels (C)</p> Signup and view all the answers

    Which neurotransmitter is primarily excitatory at nerve-skeletal muscle synapses?

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

    Which of the following statements is true regarding adaptation in sensory receptors?

    <p>Tonic receptors do not adapt. (D)</p> Signup and view all the answers

    What triggers the generation of impulses in sensory neurons?

    <p>Graded potentials reaching a threshold (B)</p> Signup and view all the answers

    What distinguishes electrical synapses from chemical synapses?

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

    How does the postsynaptic cell become depolarized upon receiving neurotransmitters?

    <p>By allowing positively charged sodium ions to enter (B)</p> Signup and view all the answers

    Which type of sensory receptors lack any structural specialization?

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

    What type of receptor is primarily responsible for detecting potential damage to tissues?

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

    What is a characteristic of phasic receptors?

    <p>They adapt quickly and diminish responses. (A)</p> Signup and view all the answers

    Which of the following neurotransmitters is categorized as inhibitory?

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

    Which part of the central nervous system integrates sensory inputs for conscious perception?

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

    What phenomenon occurs when initial pain leads to heightened sensitivity to subsequent painful stimuli?

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

    What happens when serotonin binds to receptors on the postsynaptic cell?

    <p>It initiates a new action potential. (D)</p> Signup and view all the answers

    Which type of receptors provide information about the body’s position?

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

    Which receptors are specifically designed to detect chemicals in the body?

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

    What is the main function of mechanoreceptors?

    <p>Detection of physical stress (A)</p> Signup and view all the answers

    What is the main effect of inhibitory neurotransmitters on a postsynaptic cell?

    <p>To decrease its chances of firing an action potential (B)</p> Signup and view all the answers

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

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

    What is a generator potential?

    <p>A graded potential produced by sensory receptors (D)</p> Signup and view all the answers

    What can lead to the sensation of a bad smell disappearing after constant exposure?

    <p>It is a function of tonic receptors. (C)</p> Signup and view all the answers

    Which type of sensory receptor is specialized and separate from neurons?

    <p>Separate sensory cells (C)</p> Signup and view all the answers

    Which type of receptor responds primarily to light?

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

    What type of synapse involves communication between neurons via the release of neurotransmitters?

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

    What effect does TENS (transcutaneous electric nerve stimulation) rely on?

    <p>Inhibition of pain pathways via non-pain fibers (C)</p> Signup and view all the answers

    What type of receptors are responsible for detecting the internal environment, such as blood pressure?

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

    What is the role of the first-order neurons in sensory pathways?

    <p>They conduct impulses from PNS to CNS (B)</p> Signup and view all the answers

    Which type of receptors can detect changes in temperature?

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

    What type of assessments do amplifiers of Lorenzini primarily perform?

    <p>Response to electrical fields, salinity, and temperature (B)</p> Signup and view all the answers

    What occurs when graded potentials reach the threshold?

    <p>Impulses are generated and propagated. (C)</p> Signup and view all the answers

    What is the primary function of nociceptors?

    <p>Signal potential tissue damage. (C)</p> Signup and view all the answers

    What distinguishes encapsulated nerve endings from free nerve endings?

    <p>Encapsulated endings are enclosed in a connective tissue capsule. (A)</p> Signup and view all the answers

    Which type of receptor is responsible for detecting visible light?

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

    What is the role of first-order neurons in the sensory pathway?

    <p>They conduct impulses from the PNS to the CNS. (C)</p> Signup and view all the answers

    Which receptor type responds to mechanical stress such as touch or pressure?

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

    What phenomenon describes increased sensitivity to pain following an initial painful stimulus?

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

    Which of the following receptors responds primarily to pressure and vibration?

    <p>Encapsulated nerve endings (B)</p> Signup and view all the answers

    What type of receptor potential is generated by special senses like vision and taste?

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

    Which receptor is responsible for detecting changes in temperature?

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

    How do descending pathways influence pain perception?

    <p>They inhibit transmission of pain stimuli. (A)</p> Signup and view all the answers

    What type of sensory receptor monitors the internal environment?

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

    What is the initial response mechanism for sensory receptors to a stimulus?

    <p>Production of graded potentials. (D)</p> Signup and view all the answers

    What leads to referred pain in the body?

    <p>Convergence of visceral and somatic afferents. (C)</p> Signup and view all the answers

    Study Notes

    Synapses

    • A synapse is the connection point between two cells, specifically a neuron and another cell (e.g., nerve, muscle, gland).
    • Two types of synapses exist: electrical and chemical.

    Electrical Synapses

    • Rare in vertebrates.
    • Cell membranes are in close contact, enabling rapid and reliable impulse transmission.
    • The action potential directly passes from one cell to the next.
    • Faster than chemical synapses.
    • More synchronized than chemical synapses.

    Chemical Synapses

    • More common than electrical synapses.
    • Presynaptic and postsynaptic cells are separated by a synaptic cleft (gap).
    • Transmission occurs via neurotransmitter release from the presynaptic cell.
    • Synapses can regulate the amount of neurotransmitter released.
    • This offers more control over transmission compared to electrical synapses.

    Neurotransmitters

    • Neurotransmitters are chemical messengers.
    • Some neurotransmitters cause excitation in the postsynaptic cell (EPSP).

    Excitatory Postsynaptic Potential (EPSP)

    • The postsynaptic membrane depolarizes (becomes less negative).
    • Positively charged sodium ions move into the cell.
    • EPSP amplitude relates to the number of vesicles released by the presynaptic cell.
    • A large enough EPSP can trigger an action potential in the postsynaptic cell.
    • Resulting in a nerve impulse propagated along the neuron or muscle contraction.

    Inhibitory Transmitters

    • Some neurotransmitters inhibit the postsynaptic cell.
    • These transmitters cause hyperpolarization (making the cell's interior even more negative).
    • They often affect channels for chloride or potassium ions.
    • Resulting in a reduced likelihood of triggering an action potential.

    Examples of Neurotransmitters

    • Excitatory: Acetylcholine, Glutamate
    • Inhibitory: Glycine, GABA

    Serotonin

    • Synthesized from tryptophan.
    • Often packaged in vesicles.
    • Vitamin B6 aids in synthesis.
    • Found predominantly in the gut.
    • Released into the synaptic cleft upon stimulation.
    • Binds to receptors on the postsynaptic cell, triggering depolarization.
    • Cleared from the synaptic cleft by degradation via enzymes MAO and COMT, (MAOI can target serotonin).

    Modulation

    • Slower acting, longer lasting influence than 'fast' neurotransmitters.
    • Receptors often activate intracellular messenger molecules.
    • Can affect gene expression.
    • One neuron can release multiple neurotransmitters/modulators.
    • Dale's principle is not universally applicable.

    Enkephalin/Endorphins

    • Opiate-type neuropeptide type.
    • Primarily found in the brain and spinal cord.
    • Inhibitory postsynaptic effect.
    • Natural pain relievers, reducing stress, and promoting calm.
    • Cold and exercise can increase their levels.

    Synapse Abuse

    • Many drugs affect synaptic processes.
    • Nicotine: Activates acetylcholine receptors, leading to dopamine release (euphoria).
    • Curare: Blocks acetylcholine receptors, causing paralysis.
    • Morphine/Heroin: Target opiate receptors.
    • Cannabis: Acts on cannabinoid receptors in the brain.
    • Cocaine: Blocks dopamine re-uptake, prolonging its activity (stimulant effect).
    • Nerve gas (Sarin): Blocks acetylcholine removal, causing muscle contraction paralysis.

    Disorders of Synaptic Function

    • Myasthenia Gravis: Autoimmune disorder affecting acetylcholine receptors at neuromuscular junctions.
    • Graves Disease: Autoimmune disease linked to thyroid.
    • Epilepsy: Potentially linked to decreased inhibitory transmission (GABA).
    • Depression/Schizophrenia: Possible involvement of imbalances in serotonin and dopamine systems respectively.

    Neural Circuits

    • Neurons are organized into circuits to process information, and these circuits greatly vary according to the intended functions.
    • Neuropil is dense tangle of dendrites, axon terminals, and glial cells in between neurons.
    • Circuits contain: afferent, efferent, and interneurons.
    • The afferent limb brings information into the CNS.
    • The efferent limb sends information away from the CNS.
    • Interneurons relay information within the circuit.
    • Ex: Knee-jerk reflex.
      • Afferent limb: sensory neurons.
      • Efferent limb: motor neurons controlling flexor and extensor muscles.
      • Interneurons: Integrate & modify responses.
      • The result is reciprocal action between complementary muscles.

    Neuronal Pools

    • Groups of interconnected interneurons.
    • Defined by function.
    • May be diffuse or localized.
    • Each pool has a limited number of input sources & output destinations, containing both excitatory & inhibitory neurons.
    • The output of a pool can affect other pools or control effectors.

    Circuit Patterns

    • Divergence: One input to multiple outputs.
      • Sensory information distributed throughout the brain. E.g., visual info.
    • Convergence: Multiple inputs to a single output.
      • Conscious and subconscious control of the same motor activity. E.g, breathing.
    • Serial Processing: Step-by-step relay of information between pools.
      • e.g. information crossing the hemispheres
    • Parallel Processing: Multiple pools processing the same info at once.
      • Stepping on a sharp object.
    • Reverberation: Feedback loops.
      • maintaining consciousness, muscular coordination. Ex: Breathing.

    Sensation and Perception

    • Sensation: Conscious or unconscious awareness of stimuli.
    • Perception: Conscious interpretation of sensations.
    • Sensory Modality: The different types of sensations.
    • General Senses: Somatic (touch, temperature, pain, proprioception), visceral.

    Sensory Receptors

    • General Sensory Receptors: Free nerve endings, encapsulated nerve endings.
    • Special Sensory Receptors: Specialized cells for vision, hearing, taste, equilibrium.
    • Classifying Sensory Receptors: Structural, type of stimulus detected, location and response to stimuli.
    • Stimulus types: Mechanoreceptors, thermoreceptors, nociceptors (pain), chemoreceptors, photoreceptors (light).

    The Process of Sensation

    • Four steps: 1.Stimulation of receptor. 2. Transduction (conversion to electrical signal). 3. Generation of impulses if graded potentials reach threshold (Action Potential). 4. Integration of info in CNS.
    • First-Order neurons: Sensory neurons conducting impulses to CNS.

    Sensory Receptor Adaptation

    • Tonic: Respond continuously and slowly. Convey the duration of a stimulus. Ex: pain, body position.
    • Phasic: Respond rapidly to changes and quickly stop. Convey changes in the stimulus. Ex: touch, pressure.

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    Description

    Test your knowledge on the general and special senses, sensory receptors, and the functions of synapses in neuroscience. This quiz covers important concepts regarding sensory adaptation, proprioception, and the differences between electrical and chemical synapses. Challenge yourself and see how well you understand these fundamental topics!

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