What Conditions Does the ANS Cover?

The autonomic nervous system is the pair of "automatic" control lines — sympathetic (the accelerator) and parasympathetic (the brake) — that reach almost every organ. When either line fires too hard, too weakly, or at the wrong time, symptoms appear in whatever territory that line was supposed to regulate. Below is a working map of common conditions (grouped by the specialty that usually sees them) and the usual ANS involvement. Use this as a "why ANS?" reference.

Specialty / condition	Typical ANS issue	Primary branch(es)	What that means
Cardiology – Hypertension	Chronic sympathetic overactivity with inadequate parasympathetic restraint elevates BP	Sympathetic ↑, Parasympathetic ↓	Vessels stay constricted and baroreflex has less braking power → persistent high pressure
Cardiology – Atherosclerosis / ischemic tendency	Sympathetic tone stays high, feeding endothelial stress and inflammation	Sympathetic ↑	Constant “go” signal on vessels → stiffer arteries, easier plaque formation, higher demand on heart
Cardiology – Cardiac dysrhythmias	Either bursts of sympathetic drive or loss of parasympathetic buffering around the SA/AV nodes	Both (pattern-dependent)	Accelerator launches or sustains an abnormal rhythm because the brake wasn’t there at the right instant
Cardiology – Congestive heart failure	Compensatory sympathetic activation becomes chronic; parasympathetic fades	Sympathetic ↑, Parasympathetic ↓/low	Body keeps telling the heart to push harder even when it’s tired → fluid retention, worse remodeling over time
Neurology – Orthostatic hypotension	Sympathetic outflow on standing is too weak or too slow to tighten vessels	Sympathetic ↓	Blood falls to the legs → lightheadedness, near-fainting, need to sit/lie down quickly
Neurology – Anxiety disorders	Resting sympathetic tone is high; sometimes parasympathetic also misfires during challenges	Sympathetic ↑ (± Parasympathetic ↑)	Body stays in “alert” mode → palpitations, sweat, GI upset, poor recovery after stress
Neurology – Depression	Parasympathetic activity is relatively dominant in a way that blunts perfusion and energy	Parasympathetic ↑	System slows instead of flexing → fatigue, low drive, autonomic symptoms that look “slowed”
Neurology – Migraine / headache with autonomic features	Mismatch in vascular tone control, sometimes parasympathetic-then-sympathetic swings	Mixed / region-specific	Vessels dilate or constrict at the wrong time → pain generation and associated autonomic symptoms
Pulmonology – Sleep disturbances (sleep apnea)	Airway collapses when parasympathetic support is low; repeated arousals spike sympathetic tone	Sympathetic ↑, Parasympathetic ↓	Each apneic event is a mini “fight-or-flight” → nonrestorative sleep, higher CV risk
Pulmonology – Asthma	Bronchial obstruction and β-agonist rescue drive sympathetic activation	Sympathetic ↑	Lungs and heart get more adrenergic exposure → HR/BP variability, higher stress load
Pulmonology – COPD	Similar to asthma: therapies and chronic work of breathing keep sympathetic tone high	Sympathetic ↑	Autonomic system is busy just keeping ventilation adequate → less reserve for posture, GI, sleep
Endocrinology – Diabetes	Early: parasympathetic changes around insulin/glucose handling; later: sympathetic overactivity and small-fiber loss	Parasympathetic ↑ → Sympathetic ↑ (progressive)	As nerves are stressed, fine control of heart, vessels, and gut declines → “diabetic autonomic neuropathy” picture
Endocrinology – Thyroid disorders (hypo / hyper)	Thyroid hormones modulate baseline metabolic tone; too high pushes sympathetic features, too low blunts parasympathetic flexibility	Hyper: Sympathetic ↑; Hypo: Parasympathetic ↑/rigid	Hyperthyroid → palpitations, heat intolerance, BP variability; Hypothyroid → slowed GI, cold intolerance, more rigid HR/BP control
Internal Medicine – Morbid obesity	Stress-linked parasympathetic patterns plus intermittent sympathetic pushes	Parasympathetic ↑ (rest), Sympathetic ↑ (stress)	Regulation of BP, GI motility, even temperature is working harder than it should for baseline tasks
Internal Medicine – GERD	Parasympathetic imbalance alters gastric motility and sphincter tone	Parasympathetic mis-timed	Stomach/LES open or move at the wrong time → reflux, chest/throat symptoms, worse with stress
Internal Medicine – Irritable bowel syndrome	Some patients have parasympathetic withdrawal (IBS-C), others parasympathetic excess (IBS-D); sympathetic can amplify	Parasympathetic ↑ or ↓, ± Sympathetic ↑	Gut gets the wrong autonomic pattern for the content inside → pain, bloating, constipation/diarrhea cycling
Internal Medicine – Gastroparesis	Vagal (parasympathetic) drive to the stomach is too low	Parasympathetic ↓	Stomach empties slowly → early satiety, nausea, interplay with glucose control
Rheumatology / Pain – Fibromyalgia, chronic pain states	Sympathetic “always on” with secondary parasympathetic fatigue	Sympathetic ↑ → Parasympathetic ↓	No true off-switch → pain amplification, poor sleep, worse orthostatic tolerance, high fatigue burden
Women’s Health – (Premature) menopausal symptoms	Loss of ovarian hormones reduces autonomic buffering → sympathetic surges and thermoregulatory instability	Sympathetic ↑, Parasympathetic ↓	Hot flashes, palpitations, sleep fragmentation, BP variability become more common because the ANS has less hormonal damping

This table is deliberately high-level; the same person can sit in more than one row, because it is the same two wires going to many organs.