Synapses and Neuromuscular Control & Nervous System Disorders

Flashcards covering synapses, neurotransmitters, and nervous system disorders.

Electrical Synapse

An electric current passes directly from the pre- to postsynaptic cell through gap junctions.

Chemical Synapse

An electrical signal is converted into a chemical signal that is released from the presynaptic cell and acts on receptors on the postsynaptic cell.

Gap Junction

Intercellular channel formed by the docking of two hemichannels composed of connexin or innexin proteins.

Neurotransmitter

Chemical messenger released from a neuron that transmits a signal to another neuron or target cell.

Acetylcholine (ACh)

A classical neurotransmitter synthesized from choline and acetyl coenzyme A, and degraded by acetylcholinesterase.

Excitatory Postsynaptic Potential (EPSP)

Depolarization of the postsynaptic membrane, making it more likely to fire an action potential.

Inhibitory Postsynaptic Potential (IPSP)

Hyperpolarization of the postsynaptic membrane, making it less likely to fire an action potential.

Ionotropic Receptor

Receptor that directly opens ion channels upon ligand binding, leading to rapid response.

Metabotropic Receptor

Receptor that activates second messenger pathways upon ligand binding, leading to slower, longer-lasting effects.

Neuromuscular Junction

Synapse between a motor neuron and a muscle fiber.

Myasthenia Gravis (MG)

Autoimmune disorder where auto-antibodies attack nicotinic ACh receptors at the neuromuscular junction, leading to muscle weakness.

Lambert-Eaton Myasthenic Syndrome (LEMS)

Autoimmune disorder where auto-antibodies attack voltage-gated Ca++ channels in the motor neuron presynaptic terminal, reducing ACh release.

Depression

Mood disorder associated with imbalances in monoaminergic and cholinergic pathways in the limbic system.

Monoamine Oxidase (MAO) Inhibitors

Drugs that prevent the breakdown of monoamine neurotransmitters, used to treat depression.

Reuptake Inhibitors

Drugs that block the reuptake of neurotransmitters into the nerve terminal, increasing their concentration in the synaptic cleft.

Somatic Motor Pathway

Controls skeletal muscle; single neurons originate in CNS; release ACh which acts on nicotinic ACh receptors.

Autonomic Nervous System

Controls involuntary actions; primary transmitters are ACh and NA; innervates tissues via two groups of neurones connected in series and separated by ganglia