Introduction to the Autonomic Nervous System (Part 1)

Vocabulary practice flashcards covering neurotransmission, receptors, enzymes, transporters, and physiological branches in the autonomic nervous system.

Sympathetic Cholinergic Effectors

Exceptional sympathetic effectors innervated by acetylcholine rather than norepinephrine, specifically sweat glands and piloerector muscles.

Norepinephrine Synthesis Site

The final synthesis step of norepinephrine occurs inside synaptic vesicles (catalyzed from dopamine), not outside the vesicle.

Acetylcholine (ACh) Synthesis Site

Synthesized in the cytoplasm outside the vesicle prior to vesicular storage.

Cocaine (Adrenergic Mechanism)

Inhibits the norepinephrine transporter (NET), resulting in an increase of NE at the synapse.

MAO-A Inhibitors

Enzyme inhibitors primarily utilized in the therapeutic treatment of depression.

MAO-B Inhibitors

Enzyme inhibitors primarily utilized in the clinical treatment of Parkinson's disease.

Tyrosine Hydroxylase Enzyme

The enzyme responsible for catalyzing the rate-limiting step in the biosynthesis of norepinephrine.

Norepinephrine Transporter (NET)

The presynaptic transporter directly targeted and inhibited by cocaine as well as tricyclic antidepressants.

Somatic Nervous System Architecture

A motor pathway composed of a single lower motor neuron connecting the central nervous system directly to effector skeletal muscle (does not consist of two neurons in series).

Sympathetic Nervous System Neuronal Lengths

Autonomic division characteristically structured with short preganglionic neurons and long postganglionic neurons.

Fight or Flight Response

Acute physiological stress response controlled by the sympathetic branch of the autonomic nervous system.

Parasympathetic Nervous System

Autonomic branch responsible for regulating resting and vegetative functions of the heart, lungs, and gastrointestinal tract (GIT).

Parasympathetic Neurotransmitter

Acetylcholine (ACh), which is released by both preganglionic and postganglionic parasympathetic neurons.

Muscarinic Receptors (Ligand Affinity)

Cholinergic receptors that exhibit high binding affinity for muscarine and acetylcholine, but low affinity for nicotine.

Preganglionic Sympathetic Neurotransmitter

Acetylcholine (ACh), released at the sympathetic ganglia to activate postganglionic neurons.

Adrenal Medulla Hormonal Output

Endocrine catecholamine secretion consisting of approximately $80\%$ epinephrine (EPI) and $20\%$ norepinephrine (NE).

SNAP-25

SNARE complex protein destroyed by botulinum toxin (BOTOX) to inhibit the exocytotic release of acetylcholine.

Nicotinic (Nn) Receptors

Neuronal-type nicotinic cholinergic receptors localized at autonomic ganglia and the adrenal medulla.

Vesicular Acetylcholine Transporter (VAChT)

Carrier protein responsible for transporting synthesized acetylcholine from the cytoplasm into storage vesicles.

Reuptake-1 by NET

Primary neurochemical termination pathway responsible for clearing $90\%$ of norepinephrine (NE) activity at the synapse.

Acetylcholinesterase Enzyme

Hydrolytic enzyme responsible for rapid termination of the vast majority of acetylcholine (ACh) synaptic activity.

M1, M3, and M5 Muscarinic Signaling

Signal transduction pathway mediated by the $IP_3$ and DAG cascade via $G_q$ protein activation.

M2 and M4 Muscarinic Signaling

Signal transduction pathway resulting in the inhibition of adenylyl cyclase and subsequent decrease in cAMP via $G_i$ protein activation.

Nicotinic Receptor Signal Transduction

Ligand-gated mechanism characterized by direct opening of $Na^+/K^+$ ion channels leading to cellular membrane depolarization.

Tricyclic Antidepressants (Mechanism)

Pharmacological agents that inhibit the norepinephrine transporter (NET) to block catecholamine reuptake.

Alpha2 Receptor

Presynaptic inhibitory adrenergic autoreceptor that downregulates further release of norepinephrine.