LO5

Bile reaches the gallbladder through a series of ducts.
Pathway of bile flow:
- Leaves the liver through the right and left hepatic ducts.
- These two ducts converge to form the common hepatic duct.
- The common hepatic duct becomes the common bile duct.
Bile from the liver fills the common bile duct before backing up into the gallbladder through the cystic duct.

The bile duct merges with the pancreatic duct to form the hepatopancreatic ampulla (ampulla of Vater).
The ampulla enters the duodenum at a raised area called the major duodenal papilla.
Flow of bile and pancreatic juice into the duodenum is controlled by a sphincter called the hepatopancreatic sphincter (sphincter of Oddi).

Daily secretion by the liver: Up to 1 liter of bile.
Components of bile:
- Yellow-green fluid containing minerals, phospholipids, bile salts, bile pigments, and cholesterol.
- Main bile pigment: Bilirubin (resulting from the breakdown of hemoglobin).
- Most important component: Bile salts (formed in the liver from cholesterol).
Function of bile salts:
- Aid in the digestion and absorption of fat in the small intestine.
Reabsorption of bile salts:
- 80% reabsorbed in the ileum (final section of the small intestine) and returned to the liver.
- 20% not reabsorbed is excreted in feces, giving feces its brown color.
- If bile secretion is obstructed, feces may become grayish-white, indicating lack of bile.

Hard masses that can form inside the gallbladder, often due to excessive cholesterol in the bile.
Symptoms: Gallstones may cause no signs but can lead to excruciating pain if lodged within a duct.
Consequences of blocked bile flow:
- Backward flow of bile to the liver.
- Absorption of bile into the bloodstream leads to jaundice (yellow discoloration of the skin, mucous membranes, and sclerae).
Treatment options for symptomatic gallstones:
- Surgery to remove the gallbladder.
- Medications to dissolve gallstones.

The liver, gallbladder, and pancreas are accessory organs of the digestive system.
The liver plays a crucial role in digestion by secreting digestive fluids or enzymes into the digestive tract at the junction of the stomach and small intestine.
Size and location:
- The largest gland in the body, located in the upper right abdomen beneath the diaphragm.
Functions:
- Performs more than 250 tasks, including:
  - Storing and releasing glucose.
  - Processing vitamins and minerals.
  - Filtering toxins and recycling old blood cells.
Additional functions discussed in Chapter 22, Nutrition & Metabolism.

Composed of four lobes:
- Right lobe.
- Left lobe.
- Two additional lobes visible from behind:
  - Caudate lobe (near the inferior vena cava).
  - Quadrate lobe (next to the gallbladder).
The right and left lobes are separated by the falciform ligament, anchoring the liver to the abdominal wall.

The functional units of the liver are called hepatic lobules.
Structure of lobules:
- Tiny, six-sided cylinders filled with a central vein that passes through each lobule.
- Hepatic cells (hepatocytes) fan out from the center of the lobule.
- Sinusoids (blood-filled passageways) are present between sheets of hepatic cells.
- Canaliculi are tiny canals that transport bile secreted by hepatocytes.

Each liver lobule receives two types of blood:
- Nutrient-rich venous blood from the intestines via small branches of the portal vein.
- Oxygenated blood from the hepatic artery, delivering it from the aorta.
The blood filters through sinusoids, allowing the hepatocytes to:
- Remove nutrients (glucose, amino acids, iron, vitamins) as well as hormones, toxins, and drugs.
- Secrete substances (clotting factors, albumin, angiotensinogen, glucose) into the bloodstream for distribution throughout the body.
Kupffer cells (phagocytic cells) are present to remove:
- Bacteria,
- Worn-out red blood cells,
- Debris.
The central vein carries processed blood out of the liver.

Hepatic: Pertaining to the liver.
Hepatitis: Swelling and inflammation of the liver, often used to refer to a viral infection of the liver.