Neuroscience: Synapse Structure and Function

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Questions and Answers

What role does caffeine play with adenosine receptors in the brain?

  • It slows down the cell's activity.
  • It enhances the binding of adenosine to its receptors.
  • It blocks adenosine from binding to its receptors. (correct)
  • It amplifies the sensation of tiredness.

Which statement correctly describes what happens during sleep?

  • The binding of adenosine signals increased alertness.
  • Neurons become more active.
  • Cellular waste products like adenosine are reabsorbed and recycled. (correct)
  • Caffeine enhances the likelihood of action potentials.

Which of the following is NOT a fate of neurotransmitters in a synaptic cleft?

  • Binding to a receptor in the postsynaptic cell membrane.
  • Reuptake by the presynaptic neuron.
  • Inactivation by serotonin in the synaptic cleft. (correct)
  • Enzymatic breakdown in the synaptic cleft.

What fundamental effect does caffeine have on the perception of tiredness?

<p>Prevents the brain's ability to sense tiredness. (C)</p> Signup and view all the answers

Why does a person feel 'refreshed' in the morning after a good night's sleep?

<p>Cellular waste products, such as adenosine, are recycled. (D)</p> Signup and view all the answers

What is the main effect of dopamine in the brain?

<p>It influences behavior, mood, and attention. (C)</p> Signup and view all the answers

Which enzyme is responsible for the breakdown of acetylcholine?

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

What role do selective serotonin reuptake inhibitors (SSRIs) play in the treatment of depression?

<p>They block serotonin reuptake transporters. (A)</p> Signup and view all the answers

What happens to dopamine levels when a person engages in addictive behaviors?

<p>They increase and cause feelings of pleasure. (C)</p> Signup and view all the answers

Which substance is particularly associated with blocking dopamine reuptake transporters?

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

What effect does adenosine have on the body?

<p>It promotes drowsiness by slowing nerve activity. (D)</p> Signup and view all the answers

What is the primary function of serotonin in the context of mood regulation?

<p>Maintains mood balance and supports bodily functions. (C)</p> Signup and view all the answers

What is the purpose of neurotransmitter transporters?

<p>To recycle neurotransmitters for reuse. (B)</p> Signup and view all the answers

What occurs first when an action potential arrives at the axon terminal?

<p>Calcium channels open and calcium rushes in (D)</p> Signup and view all the answers

Which neurotransmitter is primarily associated with muscle contraction?

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

What type of neurotransmitter decreases the likelihood of an action potential in the postsynaptic neuron?

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

What is the function of ligand-gated receptors at the postsynaptic cell?

<p>They open ion channels upon binding with a neurotransmitter (A)</p> Signup and view all the answers

What happens to the sodium ions when excitatory neurotransmitters bind to the postsynaptic receptors?

<p>Sodium ions flow into the neuron (D)</p> Signup and view all the answers

How do inhibitory neurotransmitters affect the postsynaptic membrane?

<p>They open channels for negative ions to enter (C)</p> Signup and view all the answers

What is the correct sequence of neurotransmission events after calcium rushes into the terminal?

<p>Vesicles fuse, neurotransmitters are released, neurotransmitters bind to receptors (C)</p> Signup and view all the answers

Which of the following describes the synaptic cleft?

<p>Gap between the axon terminal and the postsynaptic neuron (A)</p> Signup and view all the answers

Flashcards

Synapse Definition

The space between the axon terminal of one neuron and the dendrites of another.

Signal Change at Synapse

Electrical signals change to chemical signals at the synapse.

Neurotransmitter

Chemical messengers that carry signals across the synaptic cleft.

Excitatory Neurotransmitter

Increases the likelihood of an action potential in the postsynaptic neuron by making the cell more positive.

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Inhibitory Neurotransmitter

Decreases the likelihood of an action potential in the postsynaptic neuron by making the cell more negative.

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Postsynaptic Receptor

A receptor on the postsynaptic neuron that binds to neurotransmitters.

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Synaptic Transmission Steps

Action potential arrives, calcium enters, vesicles fuse, neurotransmitter released, NT binds to postsynaptic receptor, causing response.

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Ligand-Gated Receptor

A receptor that opens when a ligand (neurotransmitter binds)

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Adenosine's Role

Adenosine is a chemical that accumulates in the brain during wakefulness and signals tiredness by binding to receptors. This binding slows down cellular activity, making us feel drowsy.

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Caffeine's Trick

Caffeine blocks adenosine receptors, preventing adenosine from binding and signaling tiredness. This is why caffeine makes us feel more alert and awake.

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Neurotransmitter Fates

Neurotransmitters released into the synaptic cleft can be reabsorbed by the presynaptic neuron, broken down by enzymes, or bind to postsynaptic receptors.

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Reuptake

The process by which neurotransmitters are reabsorbed by the presynaptic neuron after being released into the synaptic cleft.

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Enzymatic Breakdown

Enzymes in the synaptic cleft can break down neurotransmitters, making them inactive.

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Neurotransmitter Re-uptake

The process where neurotransmitters are reabsorbed by the presynaptic neuron after being released into the synapse.

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Neurotransmitter Breakdown

The process where neurotransmitters are broken down by enzymes in the synapse.

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Dopamine

A neurotransmitter associated with pleasure, motivation, attention, and learning.

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Serotonin

A neurotransmitter involved in mood regulation, sleep, and digestion.

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Adenosine

A cellular waste product produced when cells use energy, known to cause tiredness.

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Adenosine Receptors

Receptors on neurons that bind to adenosine, leading to drowsiness when activated.

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Cocaine's Effect

Cocaine blocks dopamine re-uptake transporters, causing dopamine to build up in the synapse, leading to increased pleasure and euphoria.

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SSRIs (Selective Serotonin Reuptake Inhibitors)

Antidepressants that work by blocking the re-uptake of serotonin, increasing serotonin levels in the synapse and improving mood.

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Study Notes

Synapse Structure and Function

  • A synapse is a space between the axon terminal and dendrites
  • In an action potential, the signal changes from electrical to chemical as it crosses the synapse
  • Synaptic communication involves a presynaptic cell, a synaptic cleft, and a postsynaptic cell

Typical Synaptic Function

  • Action potential arrives at the axon terminal
  • Calcium channels open, calcium rushes into the cell
  • Vesicles fuse with the membrane, releasing neurotransmitters into the synaptic cleft
  • Neurotransmitters bind to receptors on the postsynaptic cell
  • Postsynaptic response: excitatory (positive charge; increases likelihood of reaching threshold) or inhibitory (negative charge, decreases likelihood)
  • Neurotransmitters are removed from the cleft through reuptake, enzyme breakdown, or both

Neurotransmitters

  • Neurotransmitters are chemical messengers that travel across the synaptic cleft
  • Examples include acetylcholine, GABA, dopamine, glutamate, endorphins, and others
  • Neurotransmitters can be either excitatory or inhibitory; excitatory makes a cell more positive and inhibitory makes it more negative.

Postsynaptic Responses

  • Binding of neurotransmitters to receptors can cause muscle contraction, or an action potential
  • Receptors can be ligand-gated channels, which open up when a neurotransmitter attaches
  • Ions like sodium (Na+) or chloride (Cl-) can flow in or out of the cell

Neurotransmitter Removal

  • Neurotransmitters are often removed from the synaptic cleft via reuptake or enzymatic breakdown (e.g.,acetylcholine (ACh) is broken down by acetylcholinesterase)
  • This process clears the signaling pathway to prepare for the next action potential.

Pleasure Centers in the Brain

  • Brain pleasure centers are stimulated by pleasurable experiences
  • These are associated with activity of dopamine which helps regulate mood, attention, memory and emotions.
  • Drugs can affect these centers, leading to potentially addictive behavior.

Adenosine and Caffeine

  • Adenosine is a byproduct of cell energy use
  • Accumulating adenosine signals our body to slow down (drowsiness) by binding to receptors
  • Caffeine blocks adenosine receptors preventing feelings of tiredness.

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