🪨 Biliary Colic Fat-Meal Trigger Simulator

Fatty Meal Consumed

A fatty meal reaches the small intestine and triggers hormone release.

• Set by slider: Meal fat content (trigger strength)
• CCK: I-cell hormone (released from duodenal mucosa)
• ~5 min: CCK plasma half-life (rapid clearance)
• 15–60 min: Onset to symptoms (after eating)

Fat sensing in the duodenum

Fatty acids trigger I-cells to release cholecystokinin into blood.

Meal composition matters

Higher fat content produces a stronger, longer hormone surge.

Individual trigger threshold

Some patients react to even modest amounts of dietary fat.

CCK Stimulates Gallbladder Contraction

Cholecystokinin travels through blood and binds gallbladder smooth muscle receptors.

• CCK1R: CCK receptor type (smooth muscle target)
• ~10 min: Signal transit time (blood to gallbladder)
• Relaxes: Sphincter of Oddi (allows bile to flow out)
• Dose-dependent: Contraction trigger (scales with CCK level)

CCK receptor binding

CCK binds CCK1R receptors on gallbladder smooth muscle cells.

Coordinated motor response

Gallbladder contracts while the sphincter of Oddi relaxes.

Neural reinforcement

Vagal nerve activity further amplifies the contraction signal.

Gallbladder Contracts and Bile Moves

Smooth muscle squeezes stored bile toward the narrow cystic duct.

• 50–75%: Normal ejection fraction (healthy gallbladder emptying)
• ~1–3 mm: Cystic duct diameter (narrowest bile pathway)
• 30–60 min: Contraction duration (per meal response)
• 30–50 mL: Bile volume stored (typical fasting gallbladder)

Wall muscle shortens

Circular smooth muscle fibers shorten, raising internal pressure.

Bile pushed toward the neck

Fluid concentrates and flows toward the cystic duct opening.

Pressure rises against resistance

A narrow duct means pressure builds faster than outflow.

Gallstone Obstructs the Cystic Duct

A stone lodges in the duct, blocking bile from escaping.

• ~10–15%: Gallstone prevalence (adults, mostly asymptomatic)
• ~80%: Cholesterol stone share (of all gallstones)
• Transient: Obstruction type (stone often dislodges later)
• Stone ≥ duct: Critical size ratio (triggers blockage)

Size relative to duct matters

Obstruction occurs only when the stone exceeds duct width.

Bile has nowhere to go

Trapped bile raises pressure inside the contracting gallbladder.

Often self-resolving

The stone frequently dislodges back into the gallbladder lumen.

Biliary Colic Pain Peaks

Stretched gallbladder walls fire pain signals felt under the ribs.

• RUQ / epigastric: Typical pain location (right upper quadrant)
• 30 min–6 hrs: Episode duration (classic biliary colic)
• Right shoulder blade: Referred pain site (via phrenic nerve)
• Stone dislodges: Resolution (pain subsides gradually)

Wall tension drives pain

Stretch receptors in the gallbladder wall signal visceral pain.

Colicky, waxing pattern

Pain rises and falls as the gallbladder keeps contracting.

Radiates to the back

Pain often refers to the right shoulder or scapula.