Autonomic Nervous System & Limbic System – Core Vocabulary

A comprehensive set of 50 vocabulary flashcards covering key structures, pathways, neurotransmitters, disorders, and functions of the Autonomic Nervous System and Limbic System, designed to reinforce critical terminology for exam preparation.

Autonomic Nervous System (ANS)

Involuntary division of the PNS that controls visceral functions such as heart rate, digestion, respiration, pupillary size, and sexual arousal.

Sympathetic Nervous System (SNS)

Thoracolumbar division of the ANS that produces the "fight-or-flight" response; mobilizes energy, increases heart rate, dilates bronchi and pupils, and inhibits digestion.

Parasympathetic Nervous System (PSNS)

Craniosacral division of the ANS that promotes "rest-and-digest" activities; slows heart rate, stimulates digestion, and conserves energy.

Enteric Nervous System

Neural network within the gut sometimes considered part of the ANS; controls gastrointestinal motility and secretion.

Preganglionic Neuron

First efferent neuron in an autonomic pathway; its cell body is in the CNS and its axon synapses in an autonomic ganglion.

Postganglionic Neuron

Second efferent neuron in an autonomic pathway; its cell body is in an autonomic ganglion and its axon innervates the target organ.

Thoracolumbar Outflow

Origin of sympathetic preganglionic neurons in spinal cord segments T1–L2/3.

Craniosacral Outflow

Origin of parasympathetic preganglionic neurons in cranial nerves III, VII, IX, X and spinal cord segments S2–S4.

Adrenergic Neuron

Autonomic neuron that releases norepinephrine (and sometimes epinephrine) at its synapse with target tissues.

Cholinergic Neuron

Autonomic neuron that releases acetylcholine at its synapse (both preganglionic of ANS and postganglionic of PSNS).

Fight-or-Flight Response

Physiological state produced by sympathetic activation preparing the body for immediate action or stress.

Rest-and-Digest Response

Physiological state produced by parasympathetic activation that promotes maintenance and restorative functions.

Autonomic Ganglion

Cluster of neuronal cell bodies outside the CNS where pre- and post-ganglionic ANS neurons synapse.

White Ramus Communicans

Myelinated pathway that carries sympathetic preganglionic fibers from spinal nerve to sympathetic chain ganglion.

Gray Ramus Communicans

Unmyelinated pathway that carries sympathetic postganglionic fibers back to the spinal nerve for distribution.

Splanchnic Nerves

Preganglionic sympathetic fibers that pass through the sympathetic chain without synapsing and terminate in prevertebral ganglia.

Celiac Ganglion

Prevertebral sympathetic ganglion that supplies stomach, liver, adrenal medulla, kidneys, and portions of intestine.

Hypogastric Plexus

Autonomic plexus supplying pelvic organs, receiving lumbar splanchnic sympathetic fibers.

Vagus Nerve (CN X)

Major parasympathetic cranial nerve providing ~75 % of PSNS outflow to thoracic and abdominal organs.

Pelvic Splanchnic Nerves

Parasympathetic nerves arising from S2–S4 that innervate distal colon, bladder, and genitalia.

Orthostatic Hypotension

Drop in blood pressure upon standing due to impaired autonomic regulation, causing dizziness or light-headedness.

Vasovagal Reflex

Exaggerated parasympathetic response leading to bradycardia, hypotension, and fainting (syncope) in response to triggers.

Autonomic Dysreflexia

Life-threatening hypertensive episode in individuals with spinal cord lesions above T6 caused by unchecked sympathetic discharge.

Referred Pain

Perception of visceral pain at a somatic location supplied by the same spinal segments as the affected organ.

Limbic System

Interconnected brain structures supporting emotion, motivation, learning, memory, olfaction, and visceral responses.

Hippocampus

Medial temporal lobe structure essential for forming explicit long-term memories and spatial navigation.

Amygdala

Almond-shaped nuclei in the temporal lobe that coordinate emotional processing, fear responses, and emotional memory.

Cingulate Gyrus

Limbic cortical belt involved in emotional regulation, autonomic control, and attentional processing.

Fornix

C-shaped fiber tract conveying hippocampal outputs to mammillary bodies and septal nuclei.

Mammillary Bodies

Hypothalamic structures that relay hippocampal signals to the anterior thalamic nuclei; involved in memory circuits.

Septal Nuclei

Limbic nuclei anterior to the septum pellucidum that modulate reward and autonomic responses.

Parahippocampal Gyrus

Cortical region aiding spatial memory and part of the limbic lobe.

Dentate Gyrus

Hippocampal sub-region where adult neurogenesis occurs, contributing to pattern separation in memory.

Entorhinal Cortex

Interface between hippocampus and neocortex; gateway for memory consolidation and retrieval.

Nucleus Accumbens

Ventral striatum structure central to reward, pleasure, and addiction pathways.

Orbitofrontal Cortex

Prefrontal region essential for decision making, judgment, and emotional regulation.

Prefrontal Cortex

Anterior frontal lobe area governing executive functions, insight, motivation, and mood; interconnected with limbic system.

Basal Ganglia

Subcortical nuclei directing intentional movement; dopamine depletion here contributes to Parkinson’s disease.

Papez Circuit

Hippocampus–mammillary body–anterior thalamus–cingulate gyrus loop originally linked to emotion, now known for memory.

Explicit (Declarative) Memory

Memory of facts and events that can be consciously recalled; hippocampus-dependent.

Implicit (Non-declarative) Memory

Unconscious memory of skills, habits, and conditioned responses independent of hippocampus.

Neurogenesis

Birth of new neurons, notably in the adult dentate gyrus; supports learning and memory.

Allocortex

Phylogenetically older, three-layered cortical regions such as olfactory cortex within the limbic system.

Klüver-Bucy Syndrome

Behavioral syndrome (docility, hypersexuality, oral exploration) resulting from bilateral temporal lobe lesions.

Stria Terminalis

Fiber bundle connecting amygdala to hypothalamus and septal area, influencing autonomic and emotional responses.

Non-adrenergic Non-cholinergic (NANC) Neurons

Autonomic neurons that use nitric oxide instead of acetylcholine or norepinephrine, especially in gut and lungs.

Anterior Thalamic Nucleus

Thalamic relay in the Papez circuit involved in memory processing.

Suprachiasmatic Nucleus

Hypothalamic clock that synchronizes circadian rhythms to light–dark cycles.

Subcallosal Area

Medial frontal limbic region implicated in mood regulation; hyperactivity linked to depression.

Hypothalamus

about the size of a pearl, this structure directs a multitude of important functions. It wakes you up in the morning, and gets the adrenaline flowing. The hypothalamus is also an important emotional center, controlling the molecules that make you feel exhilarated, angry, or unhappy

Olfactory Cortex

Receives sensory info from the olfactory bulb and is involved in the identification of odors

Thalamus

a large, dual lobed mass of grey matter cells that relay sensory signals to and from the spinal cord and the cerebrum. Specific nuclei are involved with the limbic system