Chemical Synapses and Neurotransmission

These flashcards cover key concepts and mechanisms involved in chemical synapses, neurotransmitter function, and the generation of postsynaptic potentials.

What is the presynaptic neuron responsible for in a chemical synapse?

The presynaptic neuron releases neurotransmitters into the synaptic cleft.

What does the term 'synapse' refer to?

The junction between two neurons where neurotransmission occurs.

What is the role of calcium voltage-gated channels in neurotransmission?

They open when an action potential arrives, allowing calcium to rush in and trigger neurotransmitter release.

What neurotransmitter is primarily discussed in this lecture?

Acetylcholine (ACh).

What happens during exocytosis in the presynaptic neuron?

Synaptic vesicles filled with neurotransmitter fuse with the membrane and release their contents into the synaptic cleft.

What are ligand-gated receptor channels?

Receptor channels that open in response to the binding of a neurotransmitter, allowing ions to flow through.

What ion is associated with the excitatory postsynaptic potential (EPSP)?

Sodium (Na+).

What is generated when sodium rushes into the postsynaptic neuron?

Excitatory postsynaptic potential (EPSP).

What is the threshold potential needed to trigger an action potential?

Negative 55 millivolts.

What are muscarinic ACh receptors associated with?

Potassium (K+) efflux, leading to inhibitory postsynaptic potential (IPSP).

What does IPSP stand for?

Inhibitory postsynaptic potential.

What effect does potassium efflux have on the membrane potential?

It makes the membrane more negative, leading to hyperpolarization.

How does the binding of acetylcholine to nicotinic receptors affect the postsynaptic neuron?

It allows sodium to flow in, depolarizing the neuron and generating an EPSP.

What occurs if the EPSP is strong enough in the postsynaptic neuron?

It can lead to an action potential if the threshold is reached.

What is a hyperpolarizing graded potential associated with?

Inhibitory postsynaptic potential (IPSP).

Describe the sequence of events that occur when an action potential reaches the axon terminals.

It opens calcium channels, calcium influx occurs, stimulating synaptic vesicles to release neurotransmitter.

What is the function of the synaptic end bulb?

It stores synaptic vesicles filled with neurotransmitters at the presynaptic neuron.

What effect does sodium influx have on the postsynaptic membrane potential?

It depolarizes the membrane and contributes to generating EPSP.

What occurs to the membrane potential during an EPSP?

The membrane potential becomes less negative.

What does 'calcium influx' refer to in the context of neurotransmission?

The rapid entry of calcium ions into the presynaptic terminal, triggering neurotransmitter release.