5.3.3 Synaptic transmission

• Key steps in synaptic transmission

  1️⃣ Action potential arrives at presynaptic terminal

  2️⃣ Neurotransmitter molecules are released from synaptic vesicles

  3️⃣ Neurotransmitter binds to receptors on postsynaptic membrane

  4️⃣ Ion channels open, generating a postsynaptic potential

  5️⃣ If the postsynaptic potential is strong enough, it triggers a new action potential
• The synaptic cleft is approximately 20-40 nanometers wide.


  True
• Match the step of neurotransmitter release with its description:

  Synaptic vesicles fuse with presynaptic membrane ↔️ Exocytosis

  Calcium ions enter the presynaptic terminal ↔️ Influx of Ca2+
• The synaptic cleft is the space between the presynaptic and postsynaptic membranes
• Match the type of neurotransmitter with its function or example:

  Acetylcholine ↔️ Muscle contraction

  Dopamine ↔️ Pleasure and reward

  Serotonin ↔️ Mood regulation
• When an action potential arrives at the presynaptic terminal, it causes an influx of calcium ions.
• Match the type of neurotransmitter with its example and function:

  Amino Acids ↔️ Glutamate, GABA || Glutamate is excitatory, GABA is inhibitory

  Monoamines ↔️ Dopamine, Serotonin, Norepinephrine || Involved in mood, cognition, motor control

  Acetylcholine ↔️ Acetylcholine || Crucial for neuromuscular function

  Neuropeptides ↔️ Endorphins, Substance P || Regulate pain perception and mood
• Monoamines such as dopamine are involved in motor control and mood regulation.


  True
• Match the receptor type with its definition and function:

  Ionotropic ↔️ Directly opens ion channels || Causes rapid postsynaptic potentials

  Metabotropic ↔️ Indirectly activates signaling cascades || Modulatory effects on the postsynaptic neuron
• Metabotropic receptors trigger more gradual, long-lasting changes through secondary messenger systems.
• Synaptic transmission converts an electrical signal into a chemical signal at the synapse.
• Match the structure of the synapse with its description:

  Presynaptic terminal ↔️ Contains synaptic vesicles filled with neurotransmitters

  Synaptic cleft ↔️ Small gap between presynaptic and postsynaptic membranes

  Postsynaptic membrane ↔️ Contains specialized receptor proteins
• The fusion of synaptic vesicles with the presynaptic membrane is triggered by an increase in intracellular calcium ions.


  True
• Acetylcholine is crucial for neuromuscular function and some cognitive processes.
• Which amino acid neurotransmitter is excitatory?

  Glutamate
• Ionotropic receptors directly open ion channels upon neurotransmitter binding.


  True
• Ionotropic receptors generate rapid EPSPs or IPSPs.
• What specialized proteins are responsible for reuptake of neurotransmitters?

  Transporter proteins
• Higher neurotransmitter concentrations in the synaptic cleft lead to stronger postsynaptic responses.
• Key steps in synaptic transmission

  1️⃣ Action potential arrives at presynaptic terminal

  2️⃣ Neurotransmitter molecules are released

  3️⃣ Neurotransmitters bind to postsynaptic receptors

  4️⃣ Excitatory or inhibitory postsynaptic potential is generated

  5️⃣ New action potential may be initiated
• When an action potential arrives, calcium ions trigger the fusion of vesicles with the presynaptic membrane.
• What is the basis for classifying neurotransmitters?

  Chemical structure and function
• GABA is an inhibitory neurotransmitter.


  True
• Acetylcholine is crucial for neuromuscular function and some cognitive processes
• What is the defining characteristic of ionotropic receptors?

  Directly open ion channels
• Metabotropic receptors indirectly activate signaling cascades
• How does neurotransmitter concentration affect synaptic transmission?

  Higher concentration, stronger response
• What role does synaptic transmission play in learning and memory?

  Modifies strength of connections
• Synaptic transmission is only electrical in nature.

  False
• Synaptic transmission is the process by which an electrical signal (action potential) is converted into a chemical signal at the synapse
• The presynaptic terminal contains synaptic vesicles filled with neurotransmitter
• Synaptic vesicles release neurotransmitter molecules into the synaptic cleft via exocytosis.


  True
• Steps of neurotransmitter release

  1️⃣ Synaptic vesicles move to the presynaptic membrane

  2️⃣ Calcium ions enter the presynaptic terminal

  3️⃣ Synaptic vesicles fuse with the membrane

  4️⃣ Neurotransmitter molecules are released into the synaptic cleft
• Arrange the following steps in the mechanism of neurotransmitter release at the synapse:

  1️⃣ Synaptic vesicles are stored in the presynaptic terminal

  2️⃣ Action potential arrives at the presynaptic terminal

  3️⃣ Calcium ions (Ca2+) influx through voltage-gated channels

  4️⃣ Synaptic vesicles fuse with the presynaptic membrane

  5️⃣ Neurotransmitters are released into the synaptic cleft
• Exocytosis is the process by which synaptic vesicles fuse with the presynaptic membrane to release neurotransmitters.

  True
• Glutamate is an example of an excitatory neurotransmitter.
• Acetylcholine is crucial for neuromuscular function and some cognitive processes.
• Ionotropic receptors cause rapid excitatory or inhibitory postsynaptic potentials by directly opening ion channels.


  True
• Arrange the following steps in the process of synaptic transmission:

  1️⃣ Action potential reaches presynaptic terminal

  2️⃣ Neurotransmitters are released into the synaptic cleft

  3️⃣ Neurotransmitters bind to postsynaptic receptors

  4️⃣ EPSP or IPSP is generated in the postsynaptic neuron

  5️⃣ New action potential may be initiated
• Neurotransmitters are released from synaptic vesicles into the synaptic cleft during synaptic transmission.


  True