Neuroscience Reflex Mechanisms Quiz
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Questions and Answers

What does synaptic delay in reflexes suggest about neural pathways?

  • They are primarily influenced by effector responses.
  • They involve synaptic gaps that necessitate delays in transmission. (correct)
  • They are solely dependent on sensory receptors.
  • They consist of continuous circuits without interruptions.

    • Which of the following components is NOT involved in the reflex arc as identified by Sherrington?

  • Control centers in the nervous system
  • Psychological triggers (correct)
  • Sensory neurons
  • Efferent neural pathways

    • In Sherrington's findings, which response type indicates a more complex interaction at synapses?

  • Inhibitory responses exclusively
  • Automatic responses without delay
  • Excitatory and inhibitory responses (correct)
  • Reflex responses only

    • What phenomenon demonstrates that small stimuli can combine to enhance a response?

    <p>Spatial and temporal summation (A)</p> Signup and view all the answers

    Which of these accurately describes the role of motor neurons in reflex actions as examined by Sherrington?

    <p>They transmit responses from the CNS to effectors. (A)</p> Signup and view all the answers

    What does Neuron Theory propose about the nature of neurons?

    <p>Neurons are the functional units of the nervous system. (D)</p> Signup and view all the answers

    What is the primary role of the soma in a neuron?

    <p>To synthesize proteins and perform metabolic work. (A)</p> Signup and view all the answers

    Which type of neuron carries sensory information toward the central nervous system?

    <p>Afferent neurons. (A)</p> Signup and view all the answers

    What distinguishes oligodendrocytes from Schwann cells?

    <p>Oligodendrocytes can myelinate multiple axons, while Schwann cells typically myelinate one. (D)</p> Signup and view all the answers

    Which component of a neuron is primarily responsible for receiving signals?

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

    What is a common characteristic of microglia in the nervous system?

    <p>They eliminate waste and harmful agents. (B)</p> Signup and view all the answers

    In which way do Purkinje cells contribute to the nervous system?

    <p>They have branching structures that facilitate complex connections. (C)</p> Signup and view all the answers

    What is the primary function of Schwann cells in the peripheral nervous system?

    <p>They form the myelin sheath around axons. (A)</p> Signup and view all the answers

    What role do oligodendrocytes play in the central nervous system?

    <p>They form myelin sheaths around axons. (D)</p> Signup and view all the answers

    How does the process of saltatory conduction enhance signal transmission?

    <p>By allowing action potentials to skip nodes. (B)</p> Signup and view all the answers

    What is characteristic of the resting membrane potential in neurons?

    <p>It is maintained by ion distribution across the membrane. (C)</p> Signup and view all the answers

    Which statement best describes the membrane structure of neurons?

    <p>It is a phospholipid bilayer with distinct hydrophilic heads and hydrophobic tails. (B)</p> Signup and view all the answers

    Which factor primarily determines the permeability of the cell membrane to a compound?

    <p>The molecular size and lipid solubility of the compound. (A)</p> Signup and view all the answers

    What role do ligand-gated channels play in neuron function?

    <p>They open or close in response to neurotransmitter binding. (C)</p> Signup and view all the answers

    Which type of glial cells is responsible for the immune response in the CNS?

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

    What initiates the generation of action potentials in excitable cells?

    <p>Changes in the membrane potential due to stimulation. (B)</p> Signup and view all the answers

    What role do sodium channels play during the generation of a nerve impulse?

    <p>They enable the influx of sodium ions into the cell. (B)</p> Signup and view all the answers

    What characterizes the absolute refractory period?

    <p>Sodium channels are inactivated, preventing action potential generation. (D)</p> Signup and view all the answers

    What happens to potassium channels after an action potential?

    <p>They open to help restore the resting state of the neuron. (D)</p> Signup and view all the answers

    What is a consequence of excessive activation of neurons?

    <p>Sodium buildup within the axon leading to potential neuron death. (A)</p> Signup and view all the answers

    How does the sodium-potassium pump restore ion distribution?

    <p>By moving ions against their concentration gradients over time. (C)</p> Signup and view all the answers

    Why do local anesthetics block sodium channels?

    <p>To prevent the generation of action potentials and stop pain sensation. (A)</p> Signup and view all the answers

    What occurs during the relative refractory period?

    <p>A stronger stimulus is necessary to trigger another action potential. (B)</p> Signup and view all the answers

    What is the major risk associated with tetrodotoxin (TTX)?

    <p>It blocks sodium channels, preventing action potentials and causing respiratory failure. (C)</p> Signup and view all the answers

    What mechanism helps prevent sodium buildup after rapid action potentials?

    <p>The sodium-potassium pump restores the ion distribution. (C)</p> Signup and view all the answers

    What triggers the opening of voltage-activated channels?

    <p>Changes in the membrane potential due to action potentials. (A)</p> Signup and view all the answers

    What occurs during hyperpolarization of a neuron's membrane potential?

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

    What primary role does the Na⁺/K⁺ pump play in maintaining resting membrane potential?

    <p>It pumps 3 Na⁺ ions out and 2 K⁺ ions in. (A)</p> Signup and view all the answers

    Which factor primarily determines the resting membrane potential (RMP)?

    <p>The unequal distribution of ions across the membrane. (B)</p> Signup and view all the answers

    How does an increase in Na⁺ permeability affect the membrane potential?

    <p>It results in a more positive membrane potential. (D)</p> Signup and view all the answers

    Which statement about the electrical gradient in neurons is accurate?

    <p>It promotes the influx of Na⁺ ions. (A)</p> Signup and view all the answers

    What is the resting membrane potential (RMP) typically characterized by?

    <p>Negative inside the membrane and positive outside. (C)</p> Signup and view all the answers

    What effect does the electrical gradient have on K⁺ ions during resting potential?

    <p>It repels K⁺ ions out of the cell. (D)</p> Signup and view all the answers

    What happens to the membrane potential during repolarization?

    <p>The membrane potential returns to its resting state. (C)</p> Signup and view all the answers

    Which ion's permeability change most significantly influences the resting membrane potential?

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

    What is the primary function of the sodium-potassium pump?

    <p>To establish and maintain the ion concentration gradients across the membrane. (B)</p> Signup and view all the answers

    What is the primary action of inhibitory postsynaptic potentials (IPSPs) on a neuron's membrane potential?

    <p>They hyperpolarize the membrane, making it more negative. (D)</p> Signup and view all the answers

    Which of the following best describes the integration of excitatory and inhibitory postsynaptic potentials?

    <p>They combine algebraically, determining the probability of generating an action potential. (A)</p> Signup and view all the answers

    In pain response feedback mechanisms, what role does the interneuron play?

    <p>It inhibits the main neuron to reduce the pain signal over time. (A)</p> Signup and view all the answers

    Which synaptic type is characterized by a connection between an axon terminal and a neuronal cell body?

    <p>Axo-somatic. (C)</p> Signup and view all the answers

    How do excitatory postsynaptic potentials (EPSPs) affect a neuron's activity?

    <p>They depolarize the membrane, increasing the likelihood of firing an action potential. (D)</p> Signup and view all the answers

    What is the primary function of myelin in the nervous system?

    <p>To insulate axons and speed up signal transmission. (A)</p> Signup and view all the answers

    How do Schwann cells differ from oligodendrocytes?

    <p>Schwann cells form myelin in the peripheral nervous system, while oligodendrocytes do so in the central nervous system. (D)</p> Signup and view all the answers

    What role do microglia play in the central nervous system?

    <p>They carry out immune responses and clean cellular debris. (C)</p> Signup and view all the answers

    What characterizes the resting membrane potential of excitable cells?

    <p>It is around -70mV due to unequal ion distribution across the membrane. (B)</p> Signup and view all the answers

    Which statement accurately describes saltatory conduction?

    <p>Action potentials jump from one node of Ranvier to the next along myelinated axons. (C)</p> Signup and view all the answers

    What property of phospholipid bilayers affects the permeability of the neuron membrane?

    <p>Permeability primarily depends on the size and lipid solubility of molecules. (D)</p> Signup and view all the answers

    What mechanism facilitates the transport of ions across the neuron's membrane?

    <p>Membrane transporters that move ions and large molecules across the membrane. (B)</p> Signup and view all the answers

    What primarily drives the movement of molecules in facilitated diffusion?

    <p>The chemical gradient (A)</p> Signup and view all the answers

    Which statement accurately describes the function of the sodium-potassium pump?

    <p>It maintains the concentration gradients of sodium and potassium using ATP. (C)</p> Signup and view all the answers

    What is the primary consequence of increased sodium permeability during an action potential?

    <p>A significant depolarization of the membrane potential (C)</p> Signup and view all the answers

    Which factor significantly influences the resting membrane potential (RMP)?

    <p>The permeability of potassium at rest (C)</p> Signup and view all the answers

    What characterizes equilibrium potential for an ion?

    <p>It is when chemical and electrical gradients are equal. (A)</p> Signup and view all the answers

    What is the effect of the electrochemical gradient on ion movement?

    <p>It dictates the direction and rate of ion movement across the membrane. (C)</p> Signup and view all the answers

    What happens when a potassium leak channel opens?

    <p>The membrane potential becomes more negative. (C)</p> Signup and view all the answers

    In the context of ion conductance, which statement is true?

    <p>Higher ion permeability leads to higher conductance. (D)</p> Signup and view all the answers

    Which function is NOT associated with the resting membrane potential?

    <p>It is primarily influenced by sodium permeability. (A)</p> Signup and view all the answers

    What characterizes the trigger zone in sensory neurons?

    <p>It is where the dendrites meet the axon. (C)</p> Signup and view all the answers

    Which feature of action potentials ensures they travel in one direction?

    <p>Absolute refractory period. (C)</p> Signup and view all the answers

    During which period can a stronger-than-normal stimulus generate an action potential?

    <p>Relative refractory period. (B)</p> Signup and view all the answers

    What does the All or None Law imply about action potentials?

    <p>Once triggered, they always reach the same depolarization value. (D)</p> Signup and view all the answers

    What physiological function does back-propagation of the action potential serve?

    <p>It contributes to synaptic plasticity and Long-Term Potentiation. (A)</p> Signup and view all the answers

    What major factor allows action potentials to maintain a consistent speed during propagation?

    <p>Sequential opening of sodium channels. (C)</p> Signup and view all the answers

    In which type of neuron does the action potential primarily originate from the dendrites?

    <p>Unipolar sensory neurons. (B)</p> Signup and view all the answers

    What role does the absolute refractory period play in action potentials?

    <p>It prevents the generation of new action potentials. (C)</p> Signup and view all the answers

    What initiates the domino effect of action potentials along the axon?

    <p>Activation of sodium channels due to depolarization. (A)</p> Signup and view all the answers

    Which statement regarding the speed of action potentials is accurate?

    <p>It can vary due to resting membrane potential. (D)</p> Signup and view all the answers

    What distinguishes graded potentials from action potentials?

    <p>Graded potentials can vary in amplitude and polarity. (B)</p> Signup and view all the answers

    What determines the amplitude of a graded potential?

    <p>The strength of the triggering stimulus. (C)</p> Signup and view all the answers

    Where do graded potentials primarily occur within a neuron?

    <p>In the soma or dendrites. (C)</p> Signup and view all the answers

    What occurs during temporal summation of graded potentials?

    <p>Two graded potentials from one neuron happen close in time. (D)</p> Signup and view all the answers

    What happens to the amplitude of graded potentials as they propagate?

    <p>They decrease in amplitude with distance. (B)</p> Signup and view all the answers

    What triggers the opening of ion channels in graded potentials?

    <p>Interaction between neurotransmitters and receptors. (B)</p> Signup and view all the answers

    What is a critical threshold for generating an action potential?

    <p>The specific strength needed in a graded potential at the axon hillock. (D)</p> Signup and view all the answers

    What is the difference between depolarization and hyperpolarization in graded potentials?

    <p>Depolarization increases the likelihood of an action potential, while hyperpolarization decreases it. (D)</p> Signup and view all the answers

    In what way do graded potentials differ from action potentials regarding summation?

    <p>Graded potentials can sum to trigger action potentials while action potentials cannot. (B)</p> Signup and view all the answers

    What role does the axon hillock play in neuronal signaling?

    <p>It integrates inputs to decide if an action potential should be generated. (A)</p> Signup and view all the answers

    What is the primary role of radial glia during embryonic development?

    <p>To guide neuron migration and facilitate axon/dendrite growth (C)</p> Signup and view all the answers

    Which statement accurately describes the function of astrocytes?

    <p>They regulate material exchange between blood and brain extracellular fluid (B)</p> Signup and view all the answers

    Which characteristic best describes the structure of the blood-brain barrier?

    <p>It is composed of endothelial cells with tight junctions (A)</p> Signup and view all the answers

    How does active transport facilitate the function of the blood-brain barrier?

    <p>It requires energy to move chemicals against their concentration gradient. (B)</p> Signup and view all the answers

    Which nutrient is primarily relied upon by vertebrate neurons for energy?

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

    What distinguishes the function of Schwann cells from that of oligodendrocytes?

    <p>Oligodendrocytes can support multiple axons, while Schwann cells support a single axon. (D)</p> Signup and view all the answers

    What is a significant challenge presented by the blood-brain barrier?

    <p>It complicates the delivery of certain therapeutic drugs to the brain. (A)</p> Signup and view all the answers

    Which class of receptors is coupled to G-proteins and does not control ion channels directly?

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

    Which second messenger is activated by metabotropic receptors and is primarily involved in memory regulation?

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

    What type of receptors does acetylcholine utilize within both the neuromuscular junction and the autonomic nervous system?

    <p>Both Nicotinic and Muscarinic (D)</p> Signup and view all the answers

    Which of the following is NOT a class of metabotropic receptors mentioned?

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

    What processes are primarily affected by transcription factors activated through signaling pathways from metabotropic receptors?

    <p>Gene expression and regulation (B)</p> Signup and view all the answers

    What distinguishes electrical synapses from chemical synapses?

    <p>Electrical synapses allow action potential transmission without neurotransmitter release. (C)</p> Signup and view all the answers

    Which statement about the pre-synaptic terminal is correct?

    <p>It is responsible for storing neurotransmitters. (B)</p> Signup and view all the answers

    What effect do gap junctions have on neuron behavior?

    <p>They synchronize the activity of connected neurons. (A)</p> Signup and view all the answers

    Which type of synapse is more common in the nervous system?

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

    What determines whether a synaptic signal will be excitatory or inhibitory?

    <p>The type of neurotransmitter released and its receptor type. (C)</p> Signup and view all the answers

    What primary role do connexins play in gap junctions?

    <p>They form channels that allow ions to flow between neurons. (D)</p> Signup and view all the answers

    How does an action potential influence neurotransmitter release at a chemical synapse?

    <p>It must arrive at the terminal to facilitate neurotransmitter release. (C)</p> Signup and view all the answers

    What characterizes the synaptic release influenced by background activity?

    <p>It results in miniature potentials due to constant neurotransmitter release. (B)</p> Signup and view all the answers

    What is a key feature of axo-secretory synapses?

    <p>They release neurohormones for hormonal signaling into the bloodstream. (D)</p> Signup and view all the answers

    What is the role of astrocytes in tripartite synapses?

    <p>They buffer neurotransmitter release and generate internal calcium signals. (D)</p> Signup and view all the answers

    Which neurotransmitter is primarily associated with excitatory synapses that astrocytes modulate?

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

    What primarily triggers the release of neurotransmitters from synaptic vesicles?

    <p>An increase in calcium concentration within the pre-synaptic membrane (D)</p> Signup and view all the answers

    What is the significance of Long-Term Potentiation (LTP) in synaptic function?

    <p>It indicates a stronger response after repeated activation of a synapse. (C)</p> Signup and view all the answers

    Which structures are responsible for storing neurotransmitters before their release?

    <p>Storage granules and synaptic vesicles (D)</p> Signup and view all the answers

    How do glial transmitters affect synaptic communication?

    <p>They can increase or decrease the excitability of both pre- and post-synaptic terminals. (D)</p> Signup and view all the answers

    What is a primary function of mitochondria in synaptic terminals?

    <p>To generate ATP needed for neurotransmitter release processes. (B)</p> Signup and view all the answers

    What role do microtubules play in the synaptic process?

    <p>They transport neurotransmitter vesicles from the cell body to the synapse. (C)</p> Signup and view all the answers

    What effect do astrocytes have on the concentration of neurotransmitters in the synaptic cleft?

    <p>They buffer excess neurotransmitter levels to prevent overstimulation. (D)</p> Signup and view all the answers

    What distinguishes metabotropic receptors from ionotropic receptors in terms of response speed?

    <p>Metabotropic receptors have a slow response, while ionotropic receptors respond quickly. (C)</p> Signup and view all the answers

    Which mechanism correctly describes the action of a second messenger like cAMP in the context of metabotropic receptors?

    <p>It activates G-proteins and influences cellular processes. (B)</p> Signup and view all the answers

    What type of ion channel is primarily involved in the fast response mechanism of ionotropic receptors?

    <p>Ligand-gated channels that open upon neurotransmitter binding. (C)</p> Signup and view all the answers

    What effect does the activation of G-proteins have on cellular processes regarding metabotropic receptors?

    <p>It initiates the formation of second messengers like cAMP. (D)</p> Signup and view all the answers

    In terms of neurotransmitter effects, which statement is true regarding the multiple receptor activation?

    <p>The same neurotransmitter can activate both types for different cellular effects. (A)</p> Signup and view all the answers

    What is the impact of a second messenger like cAMP on potassium channels upon activation?

    <p>It can either open or close potassium channels, depending on the signaling pathway. (D)</p> Signup and view all the answers

    How does the structure of ionotropic receptors differ from metabotropic receptors?

    <p>Ionotropic receptors are made of 5 subunits forming a pore, metabotropic receptors are not channel-forming. (C)</p> Signup and view all the answers

    What physiological changes does the opening of potassium channels induce following cAMP activation?

    <p>It causes hyperpolarization, decreasing neuronal excitability. (D)</p> Signup and view all the answers

    What process is initiated when a neurotransmitter binds to a metabotropic receptor?

    <p>G-protein activation following receptor binding. (D)</p> Signup and view all the answers

    In the context of neuromodulation, how do metabotropic receptors impact communication efficiency?

    <p>They can modulate communication by altering membrane polarization or gene expression. (D)</p> Signup and view all the answers

    What does the GHK equation primarily calculate?

    <p>The overall membrane potential based on ion equilibrium and permeabilities (C)</p> Signup and view all the answers

    How does the sodium-potassium pump contribute to maintaining resting membrane potential?

    <p>By using ATP to pump 3 Na⁺ out and 2 K⁺ in (D)</p> Signup and view all the answers

    What role do potassium channels play in establishing resting membrane potential?

    <p>They allow K⁺ to leak out of the cell, contributing to the negative inside potential. (A)</p> Signup and view all the answers

    What is a direct consequence of the sodium-potassium pump stopping due to the lack of ATP?

    <p>The membrane potential dissipates or fades. (D)</p> Signup and view all the answers

    When sodium channels open, what is the effect on the membrane potential?

    <p>The inside of the cell becomes less negative due to Na⁺ influx. (A)</p> Signup and view all the answers

    Which of the following correctly describes the role of ion gradients at resting potential?

    <p>K⁺ is high inside the cell while Na⁺ is high outside. (D)</p> Signup and view all the answers

    What establishes the equilibrium potential for potassium specifically?

    <p>Potassium channels alone. (D)</p> Signup and view all the answers

    What is the primary function of the cerebrospinal fluid (CSF)?

    <p>To act as a cushion for the brain (C)</p> Signup and view all the answers

    Which layer of the meninges is considered the strongest?

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

    What space lies between the dura mater and the arachnoid mater?

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

    How does the blood-brain barrier function in relation to brain tissue?

    <p>It prevents direct communication between blood vessels and brain tissue (A)</p> Signup and view all the answers

    What is the main consequence of meningitis?

    <p>Inflammation of the meninges (B)</p> Signup and view all the answers

    What occurs immediately after the membrane potential reaches its peak during an action potential?

    <p>Sodium channels inactivate and potassium channels open (B)</p> Signup and view all the answers

    During repolarization, which direction do potassium ions primarily move?

    <p>Out of the cell (A)</p> Signup and view all the answers

    What is the main consequence of the absolute refractory period in neural signaling?

    <p>No action potential can be triggered, regardless of stimulus (B)</p> Signup and view all the answers

    What characteristic distinguishes the relative refractory period from the absolute refractory period?

    <p>Some sodium channels have recovered to an active state (D)</p> Signup and view all the answers

    What maintains the resting membrane potential in neurons?

    <p>Potassium leak channels (A)</p> Signup and view all the answers

    What drives the initial depolarization during an action potential?

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

    What phenomenon occurs during hyperpolarization in a neuron?

    <p>The membrane potential becomes more negative than resting values (D)</p> Signup and view all the answers

    What primarily ensures unidirectional propagation of the action potential along the axon?

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

    Which type of channels are activated based on the membrane voltage difference?

    <p>Voltage-activated channels (B)</p> Signup and view all the answers

    What is the function of autoreceptors in the brain?

    <p>Detect neurotransmitter levels and inhibit release (A)</p> Signup and view all the answers

    What type of signaling do endocannabinoids utilize?

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

    Which neurotransmitter is a precursor to serotonin?

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

    What is the role of cannabinoid receptors when cannabinoids bind to them?

    <p>Inhibit further neurotransmitter release (B)</p> Signup and view all the answers

    Which of the following neurotransmitter classes does NOT include endocannabinoids?

    <p>Modified Amino Acids (A)</p> Signup and view all the answers

    How do cannabinoids primarily affect neuronal communication?

    <p>By reducing both excitatory and inhibitory messages (C)</p> Signup and view all the answers

    Which statement describes the effect of cannabinoid binding on neurotransmitter release?

    <p>It inhibits neurotransmitter release from presynaptic terminals (D)</p> Signup and view all the answers

    What lipid is primarily involved in the endogenous cannabinoid system?

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

    Which neurotransmitter is classified as a purine?

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

    What characterizes post-synaptic neurons' role in the feedback mechanism?

    <p>Inhibiting further neurotransmitter release from the presynaptic terminal (C)</p> Signup and view all the answers

    What distinguishes the synthesis of neuropeptides from other neurotransmitters?

    <p>Neuropeptides are synthesized in the cell body. (B)</p> Signup and view all the answers

    What triggers the release of neuropeptides?

    <p>Repeated depolarization. (B)</p> Signup and view all the answers

    Which statement accurately describes the duration of effects for neuropeptides compared to other neurotransmitters?

    <p>Neuropeptides have effects lasting many minutes. (C)</p> Signup and view all the answers

    How do lipid transmitters like endocannabinoids differ from classical neurotransmitters?

    <p>Lipid transmitters are derived from membrane phospholipids or cholesterol. (A)</p> Signup and view all the answers

    Which of the following is NOT a characteristic of gaseous transmitters?

    <p>They are actively transported into vesicles. (A)</p> Signup and view all the answers

    Regarding the action of neuropeptides as neuromodulators, which of the following is true?

    <p>They can diffuse widely and influence multiple neurons. (B)</p> Signup and view all the answers

    How does the binding of endocannabinoids to receptors impact synaptic transmission?

    <p>It inhibits the release of other neurotransmitters. (B)</p> Signup and view all the answers

    What factor determines whether a neurotransmitter is excitatory or inhibitory?

    <p>The receptor type on the postsynaptic neuron. (B)</p> Signup and view all the answers

    Which characteristic is true of ion transmitters like Zinc (Zn2+)?

    <p>They are released into the synaptic cleft with other transmitters. (B)</p> Signup and view all the answers

    Which of the following components differentiates metabotropic receptors from ionotropic receptors?

    <p>Metabotropic receptors lead to slower, longer-lasting effects. (D)</p> Signup and view all the answers

    Flashcards

    Neuron Theory

    A theory stating that neurons are the fundamental units of the nervous system, communicating independently and not merging.

    Neuron

    A specialized cell that receives and transmits signals within the nervous system.

    Dendrites

    Branching structures in a neuron that receive incoming signals from other neurons.

    Soma (Cell Body)

    The main body of a neuron containing the nucleus and other essential organelles.

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    Axon

    A long, slender projection of a neuron that transmits nerve impulses away from the cell body.

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    Oligodendrocytes

    A type of glial cell that wraps around axons, providing insulation and speeding up signal transmission.

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    Microglia

    Specialized glial cells responsible for removing cellular debris and pathogens in the brain.

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    Myelin Sheath

    The fatty, white substance that wraps around axons, providing insulation and speeding up signal transmission. It is essential for the proper functioning of the nervous system.

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    Myelination

    The process of forming the myelin sheath around axons. It is crucial for the development of the nervous system and efficient signal transmission.

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    Saltatory Conduction

    The mechanism by which action potentials propagate along myelinated axons by jumping from one node of Ranvier to the next. This significantly increases conduction velocity.

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    Resting Membrane Potential

    The resting membrane potential is the electrical charge across the cell membrane when the cell is inactive. It is typically around -70mV.

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    Membrane Transporters

    A type of membrane transporter that allows ions and large, non-lipophilic molecules to cross the plasma membrane. They play a crucial role in various cellular processes, including signal transduction and nutrient uptake.

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    Ligand-Gated Channels

    Channels that are activated by the binding of a specific neurotransmitter. They are essential for synaptic transmission.

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    Membrane Potential

    The difference in charge between the inside and outside of a cell membrane. It can change in response to stimulation, generating action potentials.

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    Excitable Cells

    Specialized cells, like neurons and muscle cells, that can change their membrane potential in response to stimulation, generating electrical signals.

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    Resting Membrane Potential (RMP)

    The difference in electrical charge across a neuron's membrane, measured in millivolts (mV). It's typically negative on the inside compared to the outside.

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    Depolarization

    A change in the membrane potential, making it less negative (closer to zero).

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    Repolarization

    The membrane potential returning back to its resting state after depolarization.

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    Hyperpolarization

    A change in the membrane potential, making it more negative.

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    Electrical Gradient

    The electrical gradient across the neuron's membrane, caused by the unequal distribution of ions, making the inside negative relative to the outside.

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    Concentration Gradient

    The difference in concentration of ions across the neuron's membrane, driving the movement of ions from high to low concentration.

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    Sodium-Potassium Pump

    A protein complex embedded in the neuron's membrane. It actively pumps three sodium ions (Na+) out and two potassium ions (K+) into the cell, maintaining the electrical and concentration gradients.

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    Equilibrium Potential

    The potential across the membrane at which the electrical and concentration gradients for a specific ion are balanced, resulting in zero net movement of that ion.

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    Action Potential (AP)

    The rapid electrical signal traveling along an axon, allowing communication between neurons.

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    Synaptic Delay

    The time delay between a stimulus and the resulting reflex response, which indicates the presence of synaptic gaps between neurons.

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    Spatial/Temporal Summation

    The mechanism by which multiple small stimuli, applied at different locations (spatial) or at different times (temporal), can combine to produce a stronger response.

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    Reflex Arc

    A neural pathway that responds automatically to a stimulus without conscious control.

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    Double Nature of Reflex

    A neuronal circuit where a stimulus can produce both excitatory and inhibitory effects on different muscles, leading to complex coordinated movements.

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    Sensory Receptors

    Specialized receptors in the nervous system that detect specific stimuli, such as pain, temperature, pressure, or light.

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    How do sodium channels work?

    Sodium channels are activated by voltage changes across the membrane, allowing an influx of positive sodium ions. This triggers a nerve impulse, a rapid change in electrical potential that travels along the neuron.

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    What are the refractory periods?

    The absolute refractory period occurs immediately after an action potential, where the neuron is unable to generate another action potential. The relative refractory period follows, where a much stronger stimulus is needed to trigger an action potential.

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    How does a neuron return to its resting state?

    Sodium channels close quickly after an action potential, and potassium channels open. Potassium ions flow out of the neuron due to their concentration gradient, carrying positive charge. This process restores the neuron's resting membrane potential.

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    What is the sodium-potassium pump?

    The sodium-potassium pump uses energy to actively transport sodium ions out of the neuron and potassium ions back in. This maintains the concentration gradients crucial for generating action potentials.

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    What can happen when a neuron is overstimulated?

    Excessive action potentials can overwhelm the sodium-potassium pump's ability to maintain the balance of ions. This can lead to toxic buildup of sodium within the axon, potentially damaging or even killing the neuron.

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    What are the effects of blocking sodium channels?

    Some drugs block sodium channels, preventing nerve impulses from being generated. This can lead to a loss of sensation, muscle paralysis, or even death.

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    How do local anesthetics work?

    Local anesthetics, like lidocaine and novocaine, block sodium channels, preventing pain signals from reaching the brain. They are used to numb specific areas during medical procedures.

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    What is tetrodotoxin (TTX)?

    Tetrodotoxin (TTX) is a potent sodium channel blocker found in pufferfish. It can cause paralysis and respiratory failure, leading to death.

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    What is myelin?

    Myelin is a fatty substance that wraps around axons, acting like an insulator to speed up nerve signal transmission.

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    Who forms myelin?

    Schwann cells are responsible for myelinating axons in the peripheral nervous system, while oligodendrocytes myelinate axons in the central nervous system.

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    What are microglia?

    Microglia are specialized immune cells that patrol the brain, removing debris and pathogens.

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    What are excitable cells?

    Excitable cells, like neurons and muscle cells, can change their membrane potential in response to stimulation, producing signals like action potentials.

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    Explain the resting membrane potential.

    The resting membrane potential is the electrical charge difference across a cell membrane when it's inactive, usually around -70mV.

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    How do ions cross the cell membrane?

    Ions need specific transporters to cross the cell membrane, acting like doors that allow only certain molecules to pass through.

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    What are ligand-gated channels?

    Ligand-gated channels are proteins that open or close in response to a specific molecule binding to them. These are crucial for communication between neurons.

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    What is a Voltage-Gated Channel?

    Voltage-gated channels are unique membrane channels that open or close based on the electrical charge across the plasma membrane.

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    How does Facilitated Diffusion work?

    Facilitated diffusion is passive transport where molecules move down a concentration gradient without requiring energy. It uses carrier proteins to speed up the movement.

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    What is Active Transport?

    Active transport is a process that consumes energy to move substances against a concentration gradient. It uses pumps to move substances from low to high concentration.

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    What is Conductance?

    Conductance measures how easily ions can flow through a channel. Higher permeability means higher conductance, allowing more ions to pass through.

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    How are ion channels selective?

    Ion channels are often ion-selective, meaning they allow specific types of ions to pass through, such as sodium, potassium, chloride, or calcium.

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    What is an Electrochemical Gradient?

    Electrochemical gradient is the combined force of chemical gradient (concentration difference) and electrical gradient (charge difference) that drives ion movement across the membrane.

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    What is Equilibrium Potential?

    The equilibrium potential is the voltage difference across the membrane when the electrical and chemical gradients for a specific ion are balanced.

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    What is Resting Membrane Potential (RMP)?

    The resting membrane potential (RMP) is the electrical potential difference across a cell membrane at rest. This is the result of all ion equilibrium potentials, weighted by their permeability.

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    How does the Sodium-Potassium Pump work?

    The sodium-potassium pump is an active transport protein that uses energy to maintain the concentration gradients of sodium and potassium. It pumps out 3 sodium ions for every 2 potassium ions pumped in.

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    Where do action potentials originate?

    Action potentials are initiated at the axon hillock, a specialized region rich in sodium channels. This is where the cell body transitions into the axon.

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    Why does the action potential start at the axon hillock?

    Although sodium channels are present throughout the neuron, the axon hillock has a higher concentration and specific types of voltage-gated channels necessary for AP generation.

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    What direction do action potentials travel?

    Action potentials travel in a specific direction along the axon, from the trigger zone towards the axon terminal. They cannot travel backwards.

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    What is the 'all-or-none' law?

    This means that the action potential either fires fully or not at all. Once triggered, it always reaches the same depolarization value and returns to resting potential.

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    What is the absolute refractory period?

    The absolute refractory period occurs immediately after an action potential, where the neuron cannot respond to stimulation, regardless of strength.

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    What is the relative refractory period?

    The relative refractory period follows, where a stronger stimulus is required to trigger another action potential.

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    What is depolarization?

    Depolarization is a change in the membrane potential, making it less negative. It is crucial for generating action potentials.

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    What is repolarization?

    Repolarization returns the membrane potential to its resting state after depolarization.

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    What is hyperpolarization?

    Hyperpolarization makes the membrane potential more negative, making it less likely that an action potential will fire.

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    Where is the trigger zone?

    The trigger zone, where the dendrites meet the axon, is the starting point for the action potential.

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    What are Inhibitory Postsynaptic Potentials (IPSPs)?

    Inhibitory postsynaptic potentials (IPSPs) are signals that make a neuron less likely to fire an action potential. They work by hyperpolarizing the membrane, making it more negative.

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    What is the difference between EPSPs and IPSPs?

    Excitatory postsynaptic potentials (EPSPs) increase the likelihood of a neuron firing an action potential by depolarizing the membrane, making it less negative. Inhibitory postsynaptic potentials (IPSPs) decrease the likelihood by hyperpolarizing the membrane.

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    How do EPSPs and IPSPs influence a neuron's firing?

    The balance between EPSPs and IPSPs determines the final output of a neuron. If the sum of EPSPs is greater than the sum of IPSPs, the neuron will likely fire, and vice versa.

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    What is the Spontaneous Firing Rate of a neuron?

    The spontaneous firing rate refers to the baseline rate at which a neuron fires action potentials independently of any synaptic input. EPSPs increase this rate, while IPSPs decrease it.

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    What are the different types of synapses?

    The different types of synapses based on the location of the connection are: dendro-dendritic, axo-dendritic, axo-extracellular, axo-somatic, and axo-synaptic. The most common is the axo-dendritic type.

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    Graded potential: Amplitude Variation

    Graded potentials vary in amplitude based on the strength of the stimulus, unlike action potentials which have a constant amplitude.

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    Graded potential: Triggering Stimulus

    Graded potentials are triggered by neurotransmitters binding to receptors, opening ion channels like sodium (Na+), potassium (K+), and chloride (Cl-).

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    Graded potential: Propagation

    Graded potentials propagate like waves, gradually decreasing in amplitude as they travel across the cell.

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    Graded potential: Summation

    Graded potentials can sum up, meaning multiple weak stimuli can combine to reach the threshold and trigger an action potential.

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    Graded potential: Threshold

    If a graded potential is strong enough, it reaches the axon hillock (the trigger zone), potentially generating an action potential.

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    Temporal Summation

    Temporal summation occurs when two graded potentials from the same neuron arrive close together in time and combine.

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    Action potential: No Summation

    Action potentials cannot sum due to their refractory period, a period where the neuron cannot fire another action potential.

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    Graded potential: No Summation

    If two graded potentials are too far apart in time, they do not sum, and their individual contributions to the total potential are not added together.

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    Graded potential: Summation (Close in Time)

    When stimuli are close in time, graded potentials can sum up, making it more likely for the potential to reach the threshold and trigger an action potential.

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    Graded Potential: Amplitude Proportionality

    Graded potential amplitude is proportional to the strength of the stimulus and the distance from its origin: stronger stimuli create larger potentials, and the potential decreases with distance.

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    Schwann Cells

    A type of glial cell that forms myelin sheaths around axons in the peripheral nervous system (PNS), speeding up electrical conduction.

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    Astrocytes

    A specialized type of glial cell that forms a tight seal around blood vessels in the brain, regulating what substances can pass between the blood and the brain.

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    Active Transport

    A protein-mediated process that requires energy to move substances across the blood-brain barrier.

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    Cerebrospinal Fluid (CSF)

    A salty fluid produced by the choroid plexus and circulates around the brain and spinal cord, providing protection and transporting nutrients.

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    Blood-Brain Barrier

    A barrier formed by astrocytes and endothelial cells that protects the brain from harmful toxins and pathogens in the bloodstream.

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    Glucose

    The primary nutrient for neurons, able to cross the blood-brain barrier.

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    GABA Ionotropic Receptor

    A type of receptor that binds to GABA, a major inhibitory neurotransmitter in the brain. They work by opening ion channels, allowing the flow of negatively charged chloride ions into the neuron. This makes the neuron less likely to fire an action potential, leading to inhibition of neural activity.

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    Nicotinic Receptors

    A type of receptor that binds to acetylcholine, a neurotransmitter involved in muscle contraction, learning, and memory. They open ion channels, allowing the flow of sodium ions into the neuron. This depolarizes the neuron, making it more likely to fire an action potential.

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    Metabotropic Receptors

    Receptors that are not directly coupled to ion channels. They work indirectly by activating a chain of intracellular events involving second messengers. These messengers amplify the signal and lead to a variety of cellular responses.

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    cAMP (cyclic adenosine monophosphate)

    A key second messenger involved in many metabotropic receptor pathways. It is produced from ATP by adenylyl cyclase and activates protein kinase A, leading to changes in gene expression and cellular activity.

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    Transcription Factors

    A group of transcription factors that play a crucial role in regulating gene expression. They are activated by various signals, including stress and second messengers, and control the production of proteins essential for cellular functions.

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    Synaptic Cleft

    The narrow gap between the pre-synaptic and post-synaptic terminals where neurotransmitters are released.

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    Post-synaptic Membrane

    The membrane on the post-synaptic neuron or dendritic spine where neurotransmitters bind.

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    Post-synaptic Receptors

    Specialized proteins on the post-synaptic membrane that bind to neurotransmitters, triggering a response, either excitatory or inhibitory.

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    Neurotransmitter-receptor Interaction

    Each neurotransmitter has specific receptors. Each receptor can have different subtypes.

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    Storage Granules & Synaptic Vesicles

    Vesicles store neurotransmitters and transport them to the pre-synaptic membrane to release them.

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    Calcium's Role in Neurotransmitter Release

    Calcium triggers the release of neurotransmitters by causing vesicles to fuse with the pre-synaptic membrane.

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    Mitochondria's Role in Synapses

    Mitochondria provide the energy (ATP) required for neurotransmitter release.

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    Microtubules' Function in Synapses

    Microtubules transport vesicles filled with neurotransmitters from the cell body to the synapse.

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    Tripartite Synapse

    A type of synapse involving three components: presynaptic terminal, postsynaptic terminal, and astrocytes.

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    Role of Astrocytes

    Astrocytes surround synapses and help modulate their activity by regulating neurotransmitter release.

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    Passive (Leak) Channels

    These channels are always open, allowing ions to passively flow across the membrane, balancing concentration & electrical gradients. Think of them as 'leaky faucets' always letting some water through.

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    Active (Gated) Channels

    These channels open in response to specific stimuli. Think of them as 'gated doors' allowing only specific things through.

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    Ionotropic Receptors

    Neurotransmitters binding to these receptors directly open ion channels. This leads to rapid changes in membrane potential (e.g., EPSP). Think of them as 'direct communication' allowing immediate signals.

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    Second Messengers (e.g., cAMP)

    Second messengers like cAMP are molecules that trigger various downstream effects. They act as 'internal messengers' amplifying signals within the cell.

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    Neurotransmitter Modulation

    This refers to the ability of neurons to produce different responses to the same neurotransmitter depending on the type of receptor activated. Think of it as 'multitasking', with one signal causing different effects.

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    Axo-axonic Synapse

    A synapse formed directly between two axons, allowing for rapid communication between neurons.

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    Axo-secretory Neurons

    Neurons that release neurohormones, which are hormones released into the bloodstream to trigger physiological changes.

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    Electrical Synapse

    Electrical synapses allow for direct current flow between neurons through gap junctions, resulting in rapid signal transmission.

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    Gap Junctions

    Gap junctions are channels between neurons that allow ions to flow directly, enabling rapid signal propagation.

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    Chemical Synapse

    Chemical synapses use neurotransmitters to transmit information between neurons. Neurotransmitter release depends on the arrival of an action potential.

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    Pre-synaptic Terminal

    The pre-synaptic terminal is the part of the neuron where neurotransmitters are stored and released.

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    Pre-synaptic Membrane

    The pre-synaptic membrane is the membrane of the pre-synaptic terminal.

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    Inhibitory Postsynaptic Potentials (IPSPs)

    Inhibitory postsynaptic potentials (IPSPs) are signals that make a neuron less likely to fire an action potential.

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    Excitatory Postsynaptic Potentials (EPSPs)

    Excitatory postsynaptic potentials (EPSPs) make a neuron more likely to fire an action potential by depolarizing the membrane.

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    Goldman-Hodgkin-Katz (GHK) Equation

    Calculates the overall membrane potential by considering the equilibrium potentials of all ions and their permeabilities. It simplifies to the Nernst equation when one ion's permeability dominates.

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    Electrochemical Gradient

    The movement of ions across the membrane due to both concentration and electrical gradients.

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    Absolute Refractory Period

    The time immediately following an action potential where no new action potential can be triggered, regardless of stimulus strength.

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    Relative Refractory Period

    The period after the absolute refractory period where another action potential can be generated, but only with a stronger-than-usual stimulus.

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    Peak of Action Potential

    Sodium permeability is at its highest, and sodium ions flood into the cell, driving the membrane potential towards a positive value.

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    Threshold of Action Potential

    A slow depolarization brings the membrane potential to the threshold, the point where voltage-gated sodium channels open.

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    Voltage-Activated Channels

    Channels whose permeability depends on the voltage difference across the membrane.

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    Dura Mater

    A tough membrane that forms the outermost layer of the meninges. It encases and protects the brain. It has two layers: outer and inner.

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    Arachnoid

    A thinner layer of the meninges located beneath the dura mater. It is marked by a space called the subarachnoid space, which contains cerebrospinal fluid.

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    Pia mater

    The innermost layer of the meninges, closely adhering to the brain's surface, following its folds and grooves.

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    Subdural space

    The space between the dura mater and the arachnoid. It is a potential space that can fill with blood in case of trauma, leading to a subdural hematoma.

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    Subarachnoid space

    A larger space below the arachnoid. It is filled with cerebrospinal fluid and contains major blood vessels supplying the brain.

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    What is the role of autoreceptors in negative feedback?

    Neurons use autoreceptors to sense the levels of neurotransmitters they release. When levels are high, the autoreceptors signal back to the neuron to stop releasing more neurotransmitters. This keeps neurotransmitter levels in check.

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    What are cannabinoids?

    Cannabinoids are a group of chemicals found in marijuana that interact with the body's natural cannabinoid system. Key neurotransmitters in this system include anandamide and 2-AG.

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    How does the endocannabinoid system work?

    The endocannabinoid system uses "retrograde signaling" to adjust neurotransmitter release. After a strong signal, postsynaptic neurons send endocannabinoids back to the presynaptic neuron to inhibit further release.

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    How do some drugs affect the endocannabinoid system?

    Certain drugs, like marijuana, interact with the endocannabinoid system by binding to receptors for anandamide or 2-AG. This can reduce neurotransmitter release in various parts of the brain.

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    What are neurotransmitters?

    Neurotransmitters are chemicals that neurons use to communicate with each other. There are many types, each with a specific role in the nervous system.

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    What are glutamate and GABA, and why are they important?

    Glutamate is the primary excitatory neurotransmitter in the brain, involved in learning and memory. GABA is the primary inhibitory neurotransmitter, calming the nervous system.

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    What is acetylcholine?

    Acetylcholine, a modified amino acid, plays a key role in muscle movement, learning, and memory. It's also linked to attention.

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    What are monoamines?

    Monoamines are a group of neurotransmitters derived from amino acids. They include dopamine, norepinephrine, epinephrine, and serotonin. Dopamine is involved in reward and motivation.

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    What are neuropeptides and what are endorphins?

    Neuropeptides are a diverse group of neurotransmitters that are made from chains of amino acids. Endorphins are neuropeptides that play a role in reducing pain and producing feelings of pleasure.

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    How are neurotransmitters made?

    Neurons synthesize neurotransmitters from substances we get from our diet. For example, tryptophan is a precursor to serotonin, and choline is needed to make acetylcholine.

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    Neuropeptides

    Synthesized in the cell body and released from dendrites, cell body, and sides of the axon by repeated depolarization. They diffuse widely and affect many neurons via metabotropic receptors, causing long-lasting effects.

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    Endocannabinoids

    Lipid-based neurotransmitters synthesized from membrane phospholipids or cholesterol, they easily pass through membranes and bind to CB1 and CB2 receptors.

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    Neurotransmitter Receptor Specificity

    The effect of a neurotransmitter on a postsynaptic neuron depends on the type of receptor it binds to. The same neurotransmitter can be excitatory or inhibitory depending on the receptor type.

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    Gaseous Transmitters

    Gaseous transmitters are not stored in vesicles and are synthesized as needed. They easily cross the cell membrane.

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    Zinc as a Transmitter

    Zinc is a transmitter that is actively transported and packaged into vesicles, often with another transmitter like glutamate. It is released into the synaptic cleft.

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    Precursors for Neurotransmitters

    Tryptophan and phenylalanine are essential amino acids, needed for the synthesis of certain neurotransmitters like dopamine and serotonin.

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    Tryptophan and Serotonin

    The lack of Tryptophan leads to lower levels of serotonin, a neurotransmitter often associated with mood and sleep regulation.

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    Neuropeptide Release

    Repeated depolarization triggers the release of neuropeptides. They are released from dendrites, cell body, and sides of the axon, unlike other neurotransmitters released from the axon terminal.

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    Study Notes

    Biological Psychology

    • Biological psychology studies the biological mechanisms behind behavior and experience, focusing on the brain and body.
    • The goal is to relate brain function to behavior, understanding that every action has a biological cause.

    Mind-Body Problem

    • Historical roots: Greek-Roman mythology connected behavior to the psyche, not the brain.
    • Mentalism: The mind controls behavior, but how does a non-material entity direct the body?
    • Dualism (Descartes): Mind and body are separate but connected via the brain; the pineal gland acts as a bridge. Descartes suggested that the pineal gland was the bridge between the non-material mind and the material body.
    • Materialism: Behavior is wholly explained by the nervous system, rooted in evolutionary theories.
    • Gall's Localization: Specific brain areas control particular behaviors (supported by phrenology).

    Nervous System

    • The central nervous system (CNS) includes the brain and spinal cord; the peripheral nervous system (PNS) connects the brain to the body.
    • The nervous system has functional divisions including the somatic (voluntary) and autonomic (involuntary) nervous systems.
    • The autonomic nervous system further breaks down into the sympathetic ("fight or flight") and parasympathetic ("rest and digest") divisions. The enteric nervous system (ENS) is also present.
    • Different structures are connected to different parts of the body.

    Brain

    • The brain interprets sensory information, regulates bodily functions, and supports thinking, learning, memory, and emotions.
    • Major brain regions include the corpus callosum (connects hemispheres), cerebral cortex (planning, reasoning, language), brainstem (heart rate, breathing), cerebellum (coordination), diencephalon (thalamus, hypothalamus, pineal gland), and the spinal cord.

    Neurons

    • Structure: Nucleus, cell body, dendrites, myelin sheath, axons, and nerve endings.
    • Communication: Neurons rely on electrical and chemical processes.
    • Action Potential: Electrical signals travel along axons to send information.
    • Behavior Control: Influences thoughts, feelings, and responses to rewards and stimuli.
    • First Recorded Action Potential: By Hodgkin and Huxley in 1939.

    Cells of the Nervous System

    • Neurons (transmit electrical impulses) and glial cells (support and nourish neurons) are interconnected to create mental experiences.
    • The brain contains about 100 billion neurons.
    • Santiago Ramón y Cajal's work (late 1800s) proved neurons are separate cells.

    Neuron Structure

    • Neurons are specialized, polarized nerve cells that receive and transmit signals.
    • Neurons require oxygen and glucose.
    • They have a high metabolic rate.
    • Neurons can't be replaced, except by stem cells.

    Neuron Components

    • Dendrites: Receive signals; contain synaptic receptors/dendritic spines (increase surface area).
    • Soma (Cell Body): Contains nucleus, mitochondria, ribosomes, and manages metabolic tasks.
    • Axon: Transmits impulses; may be myelinated with nodes of Ranvier/releases chemicals at terminals.
    • Afferent, Efferent, Intrinsic Neurons: Sensory inputs, motor output, and local connections.
    • Variations: Vary in size, shape, and function, influencing their connections.

    Glial Cells

    • Astrocytes: Synchronize axon activity, support neurons, form the blood-brain barrier, and take up neurotransmitters.
    • Microglia: Remove waste, viruses, fungi.
    • Oligodendrocytes & Schwann Cells: Form myelin sheaths around axons (CNS vs. PNS).
    • Radial Glia: Guide neuron migration during development.
    • Ependymal Cells: Secrete cerebrospinal fluid (CSF) and help with ion regulation.

    Action Potential

    • Action potential (AP) is an electrical signal propagating along an axon.
    • Phases: Depolarization, repolarization, hyperpolarization, resting potential.
    • Refractory Periods: Absolute (no AP is possible) and relative (stronger stimulus needed for AP).
    • Saltatory Conduction: Faster AP transmission in myelinated axons.

    Exitable Cells

    • Membrane potential changes due to stimulation, generating APs.
    • Voltage-gated ion channels facilitate these changes.
    • Resting membrane potential (-70 mV) due to unequal ion distribution.
    • Neuron membrane: Phospholipid bilayer.
    • Membrane permeability depends on lipid solubility and molecular size.
    • Membrane transporters move ions and molecules.
    • Ligand-gated channels (ionotropic receptors) involved in synaptic transmission.
    • Voltage-gated channels crucial for generating action potentials.
    • Facilitated diffusion (passive) and active transport (e.g., Na+/K+ pump) regulate ion movements.
    • Electrochemical gradients and equilibrium potentials influence ion movement.
    • Nernst and GHK equations calculate equilibrium and membrane potentials.

    Sodium-Potassium Pump (Na+/K+)

    • Maintains resting membrane potential.
    • Actively pumps 3 Na+ out and 2 K+ in using ATP.
    • Essential to sustain resting potential during neural activity when Na+ influx intensifies; necessary to maintain ion gradients for action potentials.

    Ion Movements and Channels

    • Ion channels are essential for selective ion passage.
    • K+ channels are open at rest, allowing K+ leakage.
    • Na+ channels are mainly closed at rest.
    • Chemical and electrical gradients balance ion movement.
    • Equilibrium potential exists for each ion.
    • Resting membrane potential (-70 mV) is influenced by K+ high permeability.

    Graded Potentials (GPs)

    • Graded potentials are changes in membrane potential that vary in size, unlike action potentials (APs).
    • Stimuli at the synapse, dendrites, or cell body generate them.
    • They can be depolarizing (+) or hyperpolarizing (-).
    • They diminish in amplitude as they spread.
    • Temporal summation: Summation of potentials from one neuron, close together in time.
    • Spatial summation: Summation of potentials from multiple neurons, nearly simultaneous.
    • Integration: Summation of EPSPs or IPSPs to determine if the threshold for an AP has been reached.

    Synapses

    • Neurons communicate at synapses (gaps between neurons, discovered by Charles Scott Sherrington in 1906).
    • Synaptic delay: Delay in communication between neurons, indicating the presence of synapses.
    • Spatial and temporal summation: Multiple small stimuli can combine to trigger a response, especially as they occur in quick succession.
    • Excitatory and inhibitory responses: Synapses can cause opposing effects.
    • Reflex arc: Neural pathway for automatic muscle responses (e.g., withdrawal reflex).

    Tripartite Synapses

    • Synapses and astrocytes collaborate to modulate synaptic activity. Astrocytes take up and release glial transmitters influencing synaptic communication. They also buffer neurochemicals, like glutamate.
    • This tripartite interaction enhances synaptic plasticity via changes in receptors' expression and sensitivity.

    Quadpartite Synapses

    • Includes microglia enhancing or suppressing synaptic activity.
    • Dysfunctional glial cells are associated with aberrant synaptic plasticity in psychological disorders, like depression.

    Neurons and Neurotransmission

    • Neurons communicate via neurotransmitters (chemicals).
    • Neurotransmitters work with receptors to generate an active response.
    • Types of receptors:
      • Ionotropic: Fast, direct effects on ion channels.
      • Metabotropic: Slow, involve signalling cascades via secondary messengers.
    • Synaptic transmission: 5 steps (synthesis, packaging, transport and release, binding, and termination of signaling).
    • Neurotransmitter inactivation: Occurs via diffusion, degradation, or reuptake.
    • Types of neurotransmitters: Amino acids (glutamate, GABA), amines (dopamine, serotonin, norepinephrine), neuropeptides, gases, and lipids (endocannabinoids).
    • Quantal release suggests that neurotransmitter release occurs in discrete packets (quanta).
    • Different classes of neurotransmitters have varying impact on the brain (speed, pathways, and role in different systems).
    • Drugs often act as agonists or antagonists influencing neurotransmitter activity.

    Neuron Structure (Electrical and Chemical Signals)

    • Neuron membrane structure: Phospholipid bilayer, crucial for regulating movement of ions and larger/larger molecules.
    • Channels and pumps: Essential for maintaining resting potential and rapid, graded potentials; neurons respond to and send signals electrochemically.
    • Two types of receptors (speed, pathways, final activity)
      • Ionotropic: Fast effects through direct ion channel opening.
      • Metabotropic: Slow effects through secondary messenger systems like cAMP modulation, affecting various neural functions.
    • G-proteins: Relay transmitters' signals inside the cell.

    Anatomy of the Nervous System

    • Central Nervous System (CNS) components: Brain, spinal cord.
    • Peripheral Nervous System (PNS) function: Connects CNS to body; includes somatic (voluntary) and autonomic (involuntary) divisions.
    • Directional terms: Rostral/caudal, ventral/dorsal, anterior/posterior, superior/inferior, lateral/medial and ipsilateral/contralateral are used to reference locations and directions in the nervous system; also included are coronal, horizontal, and sagittal planes to visualize the brain.
    • Neural structures: Laminae (layer), columns (organization structure), tract (axons), nerve (axon/dendrite bundles).

    Meninges

    • Meninges: Protective coverings (dura mater, arachnoid mater, pia mater) around the brain and spinal cord.
    • CSF circulation and its role in protection and support; also CSF cushioning of the brain and spinal cord.

    The Brain Stem

    • Structures: Medulla, pons, midbrain.
    • Functions: Control of vital reflexes, pathways for signals, sleep-wake cycles, movement regulation; integrates movement and sensory data.

    Cerebellum

    • Location: Back of the brain, above the pons.
    • Structure: Highly folded structure.
    • Functions: Motor learning, timing, coordination of movements, balance, attention shifts; also important for motor learning and error correction, contributing to smooth, coordinated movements.
    • Cerebellar homunculus: Representation of body parts in cerebellum.

    Diencephalon

    • Structures: Thalamus, hypothalamus, pineal gland.
    • Functions: Relay station for sensory information (thalamus), maintains homeostasis (hypothalamus), hormone function (hypothalamus), sleep cycles/circadian rhythms (pineal gland).

    Forebrain (Cerebrum)

    • Organization: Two hemispheres; layers.
    • Functions: Higher cognitive functions (perception, planning, emotions, personality, and personality), integrating sensory input; includes allocortex and neocortex.
    • Allocortex: Important for motivation, emotion, and memory.
    • Neocortex: Critical for complex cognitive tasks.
    • Basal ganglia: Structures underneath the cortex, involved in motor control, memory, and emotional expression (e.g., initiation of skilled movement, reward); important for selection and execution of movements.

    Spinal Cord

    • Location: Central nervous system; within the spinal column.
    • Structure: Segmented; grey and white matter.
    • Signals: Relay signals for sensory and motor functions via dorsal and ventral roots; also crucial for spinal reflexes.
    • Spinal reflexes (e.g., knee-jerk reflex, crossed extensor reflex): Control rapid, automatic responses without conscious engagement from the brain (sensory & motor involvement).
    • Neural pathways moving motor and sensory information along the length of the spinal cord.

    Peripheral Nervous System (PNS)

    • PNS components: Motor and sensory neurons bundled in nerves, somatic (voluntary) and autonomic (involuntary).
    • Motor nerves: Carry signals for muscle contraction.
    • Sensory nerves: Carry sensory information.
    • Mixed nerves: Contain both motor and sensory fibers.
    • Nerve structure: Myelinated axons bundled with connective tissue; different types of nerves exist (motor, sensory, or mixed), based on function.

    Autonomic Nervous System (ANS)

    • The autonomic nervous system controls involuntary bodily functions.
    • Divisions: Sympathetic (stimulatory, "fight or flight") and parasympathetic (inhibitory, "rest and digest").
    • Anatomical differences: Ganglia location (near spinal cord vs. near target organs), length of pre- and post-ganglionic fibers.
    • Neurotransmitters: Acetylcholine and norepinephrine.
    • Receptors: Varying receptor types on target tissues, resulting in different effects; receptors present on the target tissues are either nicotinic or muscarinic (sympathetic/parasympathetic, respectively).

    Senses

    • Sensory division of the peripheral nervous system collects information from the external and internal environment and sends it to the brain.
    • Sensory receptors transduce stimuli (converting physical energy into electrical signals).
    • Different receptors respond to distinct types of stimuli; a primary sensory receptor converts stimuli of a particular kind to a nerve impulse.
    • Pathways: From receptors/ganglia to the brain, crossing the midline (opposite) in many cases.
    • Coding: Converts stimuli to patterns of neural activity.
    • Adaptation: Receptors adjust to sustained stimuli.

    Auditory System

    • Detects sound waves (periodic air compressions).
    • Ear anatomy: Outer, middle, inner ear structures.
    • Cochlea: Transduces sound waves into electrical signals.
    • Hair cells: Sound detectors in the cochlea, bending in response to vibrations that activate neural signals.
    • Auditory pathways/cortex: Process and code auditory information (frequency, loudness).
    • Tonotopic organization: Specifies frequency-specific areas in the auditory cortex.
    • Sound localization: Identifies the source of sounds by analyzing differences in arrival time and intensity between ears.
    • Pathways: Cochlea→ brain stem → inferior colliculus in midbrain → medial geniculate nucleus (thalamus) → auditory cortex (processing and analysis).
    • Processing pathway differences: "What" pathway identifies sounds; "how" pathway facilitates movement in response to sounds.

    Visual System

    • Perceives light energy in the visible spectrum (400-700 nm).
    • Eye structure: Cornea, pupil/iris, lens, retina.
    • Retina: Convert light energy to electrical signals (transduction from light to electrical signals).
    • Fovea: Region of sharpest vision, contains cones, and each cone activates one bipolar neuron).
    • Rods: High sensitivity to dim light; located peripherally, many rods converge onto a single neuron).
    • Cones: High acuity and color vision; concentrated in the fovea, each cone activates one bipolar neuron.
    • Phototransduction: Converts light into electrical signals.
    • Visual pathways: Optic nerve, optic chiasm, lateral geniculate nucleus (thalamus), visual cortex (processing and analysis).
    • Dorsal and ventral streams: Separate visual processing pathways ("where" and "what").
    • Visual fields and receptive fields: Define visual region/stimulation to activate a neuron.
    • Color vision: Trichromatic and opponent-process theories explain color perception.
    • Blind spot: Region of the retina lacking photoreceptors where the optic nerve exits the eye.

    Movement

    • Hierarchical motor system organization: Cerebral cortex plans and initiates movement, with brainstem and spinal cord executing the action.
    • Parallel processing: Allows the brain to coordinate several independent actions simultaneously.
    • Feedback mechanisms: Continuously adapt movement based on sensory information.
    • Muscles, muscle fibers, and motor units enable movement.
    • Antagonistic muscle pairs (e.g., biceps and triceps) enable coordinated movement.
    • Proprioceptors (muscle spindles and Golgi tendon organs) provide feedback for movement accuracy.
    • Pathways through the spinal cord, brain stem, and cerebellum refine movement.
    • Motor and Sensory areas receive information from each other, allowing for the development of a response. Motor and Somatosensory cortices work together in parallel to coordinate movements and sensations.

    Neurotransmitters and Psychoactive Drugs

    • Many psychoactive drugs influence neurotransmitters and receptors in the nervous system which alters the behaviour; drugs can act as agonists or antagonists for specific neurotransmitters.
    • Studying drug actions involves understanding neurotransmitter systems and their influence on various brain functions; drugs affect different neurotransmitter systems and vary in their effects (doses, timing, frequency of exposure, and route of administration).
    • Tolerance and sensitization are critical concepts indicating adaptations to drug use. The brain adapts to the presence of the drug leading to tolerance. The brain also adapts to the constant presence of the drug, leading to sensitization.

    Brain Development

    • Brain development involves processes across the entire body which affect the entire CNS.
    • Neuronal development: Proliferation, migration, differentiation, maturation (axon/dendrite growth), synaptogenesis, apoptosis, and myelination.
    • Neurogenesis: The creation of new neurons.
    • Migration: Neurons move to their destinations.
    • Differentiation: Neurons specialize into specific types.
    • Maturation: Refinement of neurons that happen throughout the entire body.
    • Synaptogenesis: Formation of synapses.
    • Apoptosis: Programmed neuron death.
    • Myelination: Formation of the myelin sheath around axons.
    • Neural Darwinism: Neurons competing for resources and connections.
    • Neurotrophic factors (NGF): Support neuron survival and growth.
    • Experience and neural connectivity: Experience during development significantly shapes neural connections through physical and chemical effects (chemical gradients, signalling, etc.)
    • Enriched environments promote brain development.
    • Sensitive periods: Specific developmental windows when experiences have greater impacts.

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    Biology Notes - Biological Psychology, PDF

    Description

    Test your knowledge on the reflex arc, synaptic delay, and neuronal structures based on Sherrington's findings in neuroscience. This quiz will cover the roles of different neurons and glial cells, and explore the principles of Neuron Theory. Challenge yourself and strengthen your understanding of neural pathways and reflexes.

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