The Autonomic Nervous System and Higher-Order Functions

A comprehensive set of vocabulary flashcards covering the Autonomic Nervous System, neurotransmitters, receptors, higher-order functions, and the effects of aging.

Autonomic Nervous System (ANS)

Also known as the visceral motor system, it provides involuntary control over glands, cardiac muscle, smooth muscle, and adipocytes to coordinate vital functions.

Autonomic Ganglia

Peripheral clusters of visceral motor neuron cell bodies that provide innervation to visceral effectors.

Preganglionic Neurons

Visceral motor neurons with cell bodies located in the brainstem and spinal cord whose axons project to autonomic ganglia.

Postganglionic Neurons

Also called ganglionic neurons, these cells have bodies within autonomic ganglia and axons that extend to peripheral target organs.

Sympathetic Division

Often called the 'fight or flight' system, it prepares the body for stress or emergencies by increasing metabolic rate and mental alertness.

Parasympathetic Division

Referred to as the 'rest and digest' system, it focuses on energy conservation and maintaining the resting metabolic rate.

Thoracolumbar Division

Another name for the sympathetic division, reflecting the location of its preganglionic neuron cell bodies in the thoracic and lumbar spinal segments.

Craniosacral Division

A synonym for the parasympathetic division, as its preganglionic neurons originate in the brainstem and sacral spinal segments.

Collateral Ganglia

Prevertebral ganglia located anterior to the vertebral column that innervate abdominopelvic tissues to reduce blood flow and release stored energy.

Adrenal Medullae

Modified sympathetic ganglia that release epinephrine and norepinephrine into the bloodstream as hormones to produce long-lasting metabolic changes.

Varicosities

Swollen segments along postganglionic neuron telodendria that store and release neurotransmitters like norepinephrine.

Alpha-1 Receptors

The most common type of adrenergic receptor, primarily found in smooth muscle, where stimulation causes an excitatory effect via $Ca^{2+}$ release.

Alpha-2 Receptors

Inhibitory adrenergic receptors found on both pre- and postsynaptic neurons that lower $cAMP$ levels to coordinate ANS activities.

Beta-1 Receptors

Adrenergic receptors located in the heart and muscles that trigger an increase in metabolic activity when stimulated.

Beta-2 Receptors

Receptors that, when stimulated, cause the relaxation of smooth muscles along the respiratory tract, leading to bronchodilation.

Beta-3 Receptors

Receptors found in adipocytes that, when stimulated, lead to the breakdown of triglycerides through lipolysis.

Nitroxidergic Synapses

Synapses that release nitric oxide ($NO$) to produce vasodilation and increased blood flow in the brain and skeletal muscles.

Vagus Nerve ($CN\text{ X}$)

The cranial nerve responsible for approximately $75\,$ of all parasympathetic output.

Intramural Ganglia

Parasympathetic ganglia embedded within the tissues of the specific target organs they innervate.

Nicotinic Receptors

Cholinergic receptors found on postganglionic neurons of both ANS divisions; they act as chemically gated $Na^+$ channels and are always excitatory.

Muscarinic Receptors

G protein-coupled cholinergic receptors at parasympathetic target organs whose response can be either excitatory or inhibitory.

Autonomic Tone

The background level of activity maintained by autonomic motor neurons, allowing for a greater range of control through increase or decrease in activity.

Visceral Reflex Arc

A polysynaptic reflex consisting of a receptor, sensory neuron, processing center, two visceral motor neurons, and a peripheral effector.

Short Reflexes

Visceral reflexes that bypass the CNS entirely, with sensory and interneurons located within autonomic ganglia to control localized responses.

Enteric Nervous System

A specialized network capable of controlling digestive functions independently of the CNS through nerve nets in the digestive tract walls.

Fact Memories

Specific bits of factual information stored through experience.

Skill Memories

Learned motor behaviors, such as complex patterns involving the basal nuclei and cerebellum, often performed at an unconscious level.

Memory Consolidation

The process of converting short-term memories into long-term memories, often requiring repetition.

Memory Engram

A single neural circuit that corresponds to a specific long-term memory, typically taking at least an hour to form.

Deep Sleep

Also known as slow-wave or non-REM sleep, where the body relaxes, cerebral cortex activity is minimal, and energy use declines by up to $30\,$.

Rapid Eye Movement (REM) Sleep

Active dreaming state characterized by fluctuating heart and respiratory rates, decreased muscle tone, and an EEG resembling wakefulness.

Reticular Activating System (RAS)

A network in the brainstem reticular formation that regulates arousal and wakefulness by projecting to the cerebral cortex.

Huntington’s Disease

An inherited disorder marked by the destruction of $ACh$-secreting and $GABA$-secreting neurons in the basal nuclei, leading to motor and intellectual decline.

Lipofuscin

An intracellular granular pigment with no known function that accumulates in neurons as a common sign of aging.

Neurofibrillary Tangles

Intracellular masses of neurofibrils that form dense mats inside the cell bodies and axons of aging neurons.

Plaques

Extracellular accumulations of fibrillar proteins, such as serum amyloid ($A$) protein, often found in brain regions associated with memory processing.