ANS: Glossary

---

a-adrenergic receptors

Receptors that respond to norepinephrineA neurotransmitter involved in attention, arousal, and the fight-or-flight response. and epinephrineadrenaline): Fight-or-flight hormone from the adrenal medulla., primarily involved in vasoconstrictionThe narrowing of blood vessels due to contraction of smooth muscle, increasing blood pressure and re and increasing blood pressureThe force exerted by gases in the respiratory system, affecting airflow and gas exchange.. Found on smooth muscle and various organs.

acetylcholine

A neurotransmitterChemicals that transmit signals across synapses. released by cholinergic neuronsThe functional cells of the nervous system that transmit signals. that stimulates muscle contraction and plays a key role in both the somatic and parasympathetic nervous systems.

adrenal medulla

The inner part of the adrenal glandPaired endocrine glands above the kidneys producing stress-related hormones. that functions as a modified sympathetic ganglionA cluster of neuron cell bodies located in the peripheral nervous system (PNS).; it secretes epinephrine and norepinephrine into the bloodstream during stress.

adrenergic neurons

Neurons that release norepinephrine as their primary neurotransmitter, typically part of the sympathetic nervous systemThe organ system that controls body functions using electrical and chemical signals..

adrenergic receptors

Receptors that bind norepinephrine and epinephrine; divided into α (alpha) and β (beta) types with differing effects on target tissues.

afferent neurons

Sensory neurons that carry signals from sensory receptorsProteins located on the surface or inside cells that bind specific molecules (e.g., neurotransmitter toward the central nervous systemComposed of the brain and spinal cord; integrates and processes information. .

antagonistic effects

When two branches of the autonomic nervous systemThe part of the peripheral nervous system that controls involuntary functions such as heart rate, di (sympathetic and parasympathetic) exert opposite effects on the same organ (e.g., heart rate).

autonomic nervous system

The part of the peripheral nervous systemPNS All nervous tissue outside the CNS; includes nerves and ganglia. that controlsVariables that remain constant to ensure a fair test. involuntary functions such as heart rate, digestion, and respiratory rate; includes sympathetic and parasympathetic divisions.

autonomic tone

The baseline level of activity of the autonomic nervous system, maintained by continuous signaling, allowing for fine-tuned regulation of target organsOrgans affected by specific hormones..

B-adrenergic receptors

Receptors that generally respond to epinephrine and norepinephrine by stimulating heart rate, dilating bronchiThe large airways that branch from the trachea into the lungs, dividing into smaller bronchioles., and relaxing smooth muscle (especially in blood vessels and lungs).

catechol-O-methyltransferase (COMT)

An enzyme that breaks down catecholamines (e.g., norepinephrine and epinephrine) outside of nerve endings.

cholinergic neuron

A neuron that releases acetylcholinealso know as ACh A neurotransmitter that stimulates muscle contraction. as its neurotransmitter, common in the parasympathetic nervous system and somatic motor pathways.

cooperative effects

When the sympathetic and parasympathetic systems work together to produce a single, unified physiological effect (e.g., salivation).

dual innervation

A situation in which most target organs receive input from both the sympathetic and parasympathetic divisions of the autonomic nervous system.

efferent neurons

Motor neurons that carry signals from the central nervous system to effectors such as muscles or glands.

enteric plexus

A network of neurons within the walls of the gastrointestinal tract that regulates digestion independently of the central nervous system, though influenced by it.

epinephrine

A hormone (also called adrenaline) secreted by the adrenal medullaInner part of adrenal glands producing catecholamines (epinephrine, norepinephrine). that enhances the fight-or-flight response by increasing heart rate, blood pressure, and blood flow to muscles.

integrating center

A part of the central nervous system that processes sensory information and determines the appropriate response in a reflex arc.

micturition reflex

A reflex involving the contraction of the bladderA muscular organ that stores urine before excretion. and relaxation of the sphincter muscles that leads to urination; controlled by both autonomic and somatic pathways.

monoamine oxidase (MAO)

An enzyme that breaks down monoaminesA class of neurotransmitters including dopamine, serotonin, norepinephrine, and epinephrine. like norepinephrine and serotoninA monoamine neurotransmitter involved in mood, sleep, and sensory perception. within nerve endings, helping regulate their levels.

muscarinic receptors

Cholinergic receptors found on the effector organs of the parasympathetic nervous system; they mediate slower, prolonged responses to acetylcholine.

nicotinic receptors

Cholinergic receptors found on postganglionic neurons and skeletal muscle; they respond to acetylcholine and mediate fast synaptic transmission.

norepinephrine

A neurotransmitter released primarily by sympathetic postganglionic neurons; also acts as a hormone when released from the adrenal medulla.

parasympathetic division

The branch of the autonomic nervous system responsible for “rest-and-digest” functions, promoting maintenance and conservation of energyThe capacity to do work or cause change..

parasympatholytic

A drug or agent that inhibits or blocks the effects of the parasympathetic nervous system.

parasympathomimetic

A drug or agent that mimics or enhances the effects of the parasympathetic nervous system.

postganglionic fiber

The axon of a neuron that originates in an autonomic ganglion and extends to a target organ or tissue.

preganglionic fiber

The axon of a neuron that originates in the central nervous system and synapses in an autonomic ganglion.

receptors

Proteins located on the surface or inside cellsThe basic structural and functional units of life. that bind specific moleculesGroups of atoms bonded together. (e.g., neurotransmittersChemicals released by neurons to transmit signals across a synapse. or hormones) to initiate a physiological response.

sympathetic division

The branch of the autonomic nervous system responsible for the “fight-or-flight” response, preparing the body for stress or physical activity.

sympatholytic

A drug or agent that inhibits the effects of the sympathetic nervous system.

sympathomimetics

Agents that mimic the effects of the sympathetic nervous system by stimulating adrenergic receptorsReceptors that bind norepinephrine and epinephrine; divided into α (alpha) and β (beta) types with or promoting norepinephrine release.

vasomotor tone

The baseline level of vasoconstriction maintained by sympathetic nerve activity, allowing rapid adjustments to blood pressure.

visceral motor system

Another name for the autonomic nervous system; it controls the involuntary motor functions of the internal organs.

visceral reflexes

Reflexes that control involuntary functions of visceral organs (e.g., blood pressure, digestion) through autonomic pathways.

---