Lecture 4 Synapses and transmission

Synapse

The primary location of neural communication with another cell; chemicals released by presynaptic cell influence the response of the postsynaptic cell.

Chemical Synaptic Transmission

Release of a chemical at a synapse whereby one cell influences another.

Postsynaptic Potential (PSP)

Local potential via changes in ion concentration across the postsynaptic membrane, which can be excitatory or inhibitory.

Excitatory Postsynaptic Potential (EPSP)

Local depolarization of the postsynaptic cell membrane that makes it more positive than the resting membrane potential.

Inhibitory Postsynaptic Potential (IPSP)

Local hyperpolarization that makes the postsynaptic membrane more negative than the resting potential, inhibiting neuron activation.

Presynaptic Facilitation

When neurotransmitter binding causes local depolarization of the postsynaptic axon terminal, resulting in increased release of neurotransmitter.

Presynaptic Inhibition

When neurotransmitter binding causes hyperpolarization of the postsynaptic axon terminal, resulting in decreased release of neurotransmitter.

Neurotransmitter

Chemicals released by a presynaptic neuron into the synaptic cleft that act directly on postsynaptic ion channels or indirectly activate proteins.

Neuromodulator

Chemicals released into the extracellular fluid that adjust the activity of many neurons.

Dopamine

A slow-acting inhibitory neurotransmitter involved in movement, motivation, and reward mechanisms; low levels are associated with Parkinson's disease.

Acetylcholine (ACh)

A major neurotransmitter of the PNS involved in neuromuscular junction activity and certain cognitive functions; linked to diseases like myasthenia gravis.

GABA

The most common fast-acting inhibitory neurotransmitter in the brain that opens Cl- channels to produce hyperpolarization.

Spatial Summation

The process where multiple different synapses produce EPSPs simultaneously at different locations in the postsynaptic cell's membrane.

Temporal Summation

Summation of EPSPs occurring at the same location on the postsynaptic cell membrane but at different times.

Myasthenia Gravis

An autoimmune disease where antibodies attack and destroy nicotinic receptors on muscle cells, leading to weakness.

Ionotropic Receptors

Fast-acting receptors that act directly and cause rapid transmission by forming ion channels.

Metabotropic Receptors

Slow-acting receptors that activate proteins inside the postsynaptic neuron indirectly and can trigger signal cascades.

Second-messenger Systems

Intracellular signaling pathways activated by G-proteins that can result in changes to gene expression or ion channel regulation.

Neurotransmitter Transporters

Proteins that remove neurotransmitters from the synaptic cleft; common targets for drugs.

Enzymatic Degradation

A process where neurotransmitters are broken down by enzymes, such as acetylcholinesterase.

Astrocytes

Glial cells that can take up neurotransmitters from the synaptic cleft, thus removing them from the synaptic space.