Biology Unit 2: Synapses and Neurotransmitters
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Questions and Answers

What is the function of the axon terminal in the context of neuronal communication?

  • To receive signals from other neurons.
  • To release neurotransmitters into the synaptic cleft. (correct)
  • To generate action potentials.
  • To conduct action potentials along the neuron's length.

    • What is the role of neurotransmitters in communication between neurons?

  • They are responsible for generating action potentials at the axon hillock.
  • They serve as the electrical signal that travels down the axon.
  • They act as chemical messengers, transmitting signals across the synaptic cleft. (correct)
  • They are essential for the formation of myelin sheaths around axons.

    • What happens to the action potential as it reaches the axon terminal?

  • It is completely terminated, ending the signal transmission.
  • It is propagated along the dendrite of the receiving neuron.
  • It is converted into a chemical signal via the release of neurotransmitters. (correct)
  • It is amplified, increasing its strength before transmission to the next neuron.

    • How do neurotransmitters influence the receiving neuron?

    <p>They bind to receptors on the receiving neuron, triggering a specific cellular response. (C)</p> Signup and view all the answers

    What is the primary function of a synapse?

    <p>To allow communication between neurons or between a neuron and an effector cell. (A)</p> Signup and view all the answers

    How does the information travel through an electrical synapse?

    <p>Through gap junctions (B)</p> Signup and view all the answers

    What is the function of ligand-gated ion channels in a chemical synapse?

    <p>They open in response to a chemical messenger attaching to a receptor on the membrane (A)</p> Signup and view all the answers

    Which of the following is NOT a type of ion channel found on a membrane?

    <p>Pressure-gated (D)</p> Signup and view all the answers

    What is the difference between an excitatory postsynaptic potential (EPSP) and an inhibitory postsynaptic potential (IPSP)?

    <p>EPSPs increase the likelihood of an action potential while IPSPs decrease the likelihood (A)</p> Signup and view all the answers

    Which of the following neurotransmitters is most abundant in the brain?

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

    How does acetylcholine work to produce an EPSP?

    <p>By opening sodium channels (A)</p> Signup and view all the answers

    What is the function of neurotransmitters?

    <p>To transmit signals between neurons or effector organs (D)</p> Signup and view all the answers

    How does the release of neurotransmitters lead to the opening of ligand-gated ion channels?

    <p>Neurotransmitters bind to receptors which then activate the ion channels (B)</p> Signup and view all the answers

    Which neurotransmitter has a mainly inhibitory role in the CNS, is implicated in sleep regulation, migraines, appetite, and mood regulation, and is primarily found in the CNS?

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

    Which neurotransmitter is primarily found in the CNS, can be both excitatory or inhibitory, and is considered a "feel good" neurotransmitter?

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

    What is the primary difference between nicotinic and muscarinic acetylcholine receptors?

    <p>Their location within the nervous system (CNS vs PNS) (A)</p> Signup and view all the answers

    Which neurotransmitter is the main inhibitory neurotransmitter in the CNS?

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

    Which of the following neurotransmitters is NOT considered a "feel good" neurotransmitter?

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

    Flashcards

    Neurons

    Cells that transmit electrical signals in the nervous system.

    Action potentials

    Rapid electrical signals that travel along neurons.

    Synapse

    The junction between two neurons where communication occurs.

    Neurotransmitters

    Chemical messengers that transmit signals across synapses.

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    Effector cells

    Cells that respond to signals from neurons, like muscle or gland cells.

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    Acetylcholine

    A neurotransmitter in both CNS and PNS, binds to muscarinic and nicotinic receptors, can be excitatory or inhibitory.

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    Norepinephrine

    A neurotransmitter in both CNS and PNS, acts as a 'feel good' neurotransmitter, can be excitatory or inhibitory, major in sympathetic system.

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    Dopamine

    Mainly an excitatory or inhibitory neurotransmitter in CNS, associated with pleasure, affects mood and is linked to schizophrenia.

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    Serotonin

    A mainly inhibitory neurotransmitter, important for sleep regulation, appetite, and mood regulation in CNS.

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    GABA

    Main inhibitory neurotransmitter in CNS that opens chloride channels, creating an inhibitory postsynaptic potential (IPSP).

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    Presynaptic neuron

    The neuron that transmits signals before the synapse occurs.

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    Postsynaptic neuron

    The neuron that receives signals after the synapse occurs.

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    Electrical Synapses

    Less common synapses allowing signals to pass through gap junctions, found in brain and heart.

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    Chemical Synapses

    Common synapses where neurotransmitters are released to transmit signals between neurons.

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    Inhibitory Postsynaptic Potential (IPSP)

    Change in postsynaptic membrane that decreases the likelihood of an action potential.

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    Excitatory Postsynaptic Potential (EPSP)

    Change in postsynaptic membrane that increases the likelihood of an action potential.

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    Common Neurotransmitters

    Includes Acetylcholine, Norepinephrine, Dopamine, Serotonin, and GABA

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    Study Notes

    Unit 2: Part 3 - Synapses, Neuromuscular Junctions, and Neurotransmitters

    • The nervous system is a complex communication network
    • Communication between cells is crucial for homeostasis and response
    • Action potentials are essential for cellular communication, determined by the interaction between neurotransmitters (NT) and receptors.

    Synapses

    • Synapses allow communication between neurons and between neurons and effector cells (muscles or glands)
    • Two types of synapses:
      • Electrical synapses: Less common, found in brain and heart, signal travels through gap junctions
      • Chemical synapses: More common, found throughout the body, neurotransmitters are released from one neuron and bind to receptors on a neighboring neuron

    Chemical Synapse: Detailed Events

    • Action potential arrives at the axon terminal
    • Voltage-gated calcium channels open, allowing calcium ions (Ca2+) to enter
    • Calcium trigger exocytosis of synaptic vesicles containing neurotransmitters
    • Neurotransmitters diffuse across the synaptic cleft and bind to receptors on the postsynaptic membrane
    • Binding of neurotransmitters opens ion channels in the postsynaptic membrane. These channels are chemically-gated, or ligand-gated; they respond to specific ligands.
    • This causes a change in the postsynaptic membrane potential, either excitatory (EPSP) or inhibitory (IPSP).
    • Neurotransmitters are broken down or taken back into the presynaptic neuron to stop further signal transmission
    • Example: Acetylcholine (ACh) is released from presynaptic axon terminals and binds to receptors on postsynaptic membranes, triggering ion channel opening
    • Acetylcholinesterase (AChE) breaks down ACh

    Types of Neurotransmitters

    • Excitatory neurotransmitters: Increase the likelihood of an action potential. Example: Acetylcholine.
    • Inhibitory neurotransmitters: Decrease the likelihood of an action potential. Example: GABA

    Ion Channels

    • Four types:
      • Leak channels (always open)
      • Voltage-gated channels (open/close in response to membrane potential changes)
      • Ligand-gated channels (open/close in response to a specific molecule binding)
      • Mechanically-gated channels (open/close in response to mechanical stimuli)
      • Understanding ion channels is essential in understanding how nerve signals are propagated and muscle contractions occur

    Neurotransmitters: Specific Examples

    • Acetylcholine (ACh): Both CNS and PNS functions. Binds to muscarinic and nicotinic receptors, with effects dependent on binding type. A major component of neuromuscular junctions.
    • Norepinephrine: Both CNS and PNS functions. Can be excitatory or inhibitory; involved in the sympathetic nervous system, a "feel good" neurotransmitter.
    • Dopamine: Primarily CNS function. Excitatory or inhibitory; its neurotransmission is affected by drugs like cocaine and amphetamines, implicated in schizophrenia.
    • Serotonin: Primarily CNS function. Mainly inhibitory, regulating sleep, migraines, appetite, and mood.
    • GABA: Primarily CNS function. A major inhibitory neurotransmitter. Binding to its receptor opens chloride channels (Cl−), increasing negative charge inside the neuron, making it less likely to generate an action potential.

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    Unit 2 Part 3: Synapses, Neuromuscular Junction, and Neurotransmitters PDF

    Description

    Explore the intricate world of synapses and neurotransmitters in this quiz. Understand how communication between neurons and effector cells is vital for the nervous system's function. Test your knowledge on electrical and chemical synapses, and the events in chemical synapses.

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