Autonomic Nervous System and Visceral Reflexes

Flashcards covering key concepts related to the autonomic nervous system and its functions.

Autonomic Nervous System (ANS)

A special motor nervous system that controls glands, cardiac muscle, and smooth muscle involuntarily.

Homeostasis

The state of steady internal conditions maintained by living things, a term coined by Walter Cannon.

Visceral Reflexes

Unconscious, automatic responses to stimulation involving visceral receptors and effectors.

Fight-or-Flight Response

The sympathetic division's preparation of the body for physical activity by increasing heart rate, blood pressure, and airflow.

Rest-and-Digest Response

The parasympathetic division's calming effect that promotes bodily maintenance processes such as digestion and waste elimination.

Denervation Hypersensitivity

Exaggerated responses in cardiac and smooth muscle if autonomic nerves are severed.

Sympathetic Division

The part of the ANS that prepares the body for stressful or active situations.

Parasympathetic Division

The part of the ANS that calms bodily functions and reduces energy expenditure.

Preganglionic Neurons

Neurons that originate in the central nervous system and synapse with postganglionic neurons.

Postganglionic Neurons

Neurons that synapse with effector organs, extending from autonomic ganglia to target tissues.

Neural Divergence

A characteristic of the sympathetic division where one preganglionic neuron branches to synapse on multiple postganglionic neurons.

Cholinergic Fibers

Autonomic fibers that release acetylcholine as a neurotransmitter.

Adrenergic Fibers

Sympathetic fibers that release norepinephrine as a neurotransmitter.

Dual Innervation

Most visceral organs receive nerve fibers from both the sympathetic and parasympathetic divisions.

Vasomotor Tone

The baseline firing frequency of sympathetic fibers that keeps blood vessels partially constricted.

Cerebral Cortex

Part of the brain that can influence the ANS through emotions like anger and fear.

Enteric Nervous System

The nervous system of the digestive tract, which operates independently of the CNS.

Hirschsprung Disease

A hereditary defect causing the absence of the enteric nervous system, leading to severe constipation.

Catecholamines

Hormones such as epinephrine and norepinephrine released by the adrenal medulla.

Muscarinic Receptors

Cholinergic receptors found in all cardiac muscle, smooth muscle, and gland cells.

Nicotinic Receptors

Cholinergic receptors found on all ANS postganglionic neurons and at neuromuscular junctions.

Alpha-adrenergic Receptors

Receptors that are usually excitatory and respond to norepinephrine.

Beta-adrenergic Receptors

Receptors that are usually inhibitory and also respond to norepinephrine.