15 - GI Accessory Organs

Liver lobes

Right lobe, left lobe, quadrate lobe (square-shaped), caudate lobe

Falciform ligament

Separates right and left lobes of liver

Porta hepatis

"Door" containing portal vein, hepatic artery, and common bile duct

Hepatopancreatic ampulla

Dilated region with sphincter where bile and pancreatic secretions enter duodenum

Liver blood supply

Hepatic artery (from celiac trunk) and hepatic portal vein (to IVC)

Hepatocytes

Main liver cells responsible for metabolism, detoxification, protein synthesis, and storage

Liver macrophages functions

• Phagocytose microbes, toxins

• Break down old RBCs and WBCs

• Secrete cytokines

Liver lobule

Functional unit of liver with hexagonal structure

Portal triad

Bile duct, portal venule, portal arteriole

Functions of the Liver

1. Processes and / or stores dietary nutrients

2. Synthesize all major plasma proteins

3. Processes / eliminates many drugs and hormones

4. Stores some body iron and excretes bilirubin

5. Aids in digestion through the production of bile

Vitamin A

Converted to retinyl esters for vision

Vitamin D (function and synthesis)

• Promotes calcium absorption and bone metabolism

• Can be synthesized but require UV exposure

Vitamin K

Used by hepatocytes to form coagulation factors

what type of proteins does the liver synthesize

most plasma proteins including:

• albumin, coagulation factors, complement proteins, most drugs

Iron storage

Liver stores iron as ferritin and transports via transferrin

Bilirubin

The heme from damaged RBC returns to the liver and discarded as bilirubin

Bile functions

• Lipid digestion and absorption

• Cholesterol metabolism

• Excretion of lipid-soluble drugs

Gallbladder

Thin green sack with a muscular wall that stores bile

Gallbladder Removal

• Cholecystectomy for gallstone removal

• Occur mainly in female, fertile, over forty because estrogen promotes cholesterol synthesis

parasympathetic stimulation effect on bile production and storage

• enhances hepatic bile production

• only can cause weak contractions of the gallbladder

CCK effect on bile production

causes intense contractions of the gallbladder

secretin effect on bile production

Enhances hepatic production of bicarbonate rich bile

Sympathetic stimulation of pancreas

• Sympathetic stimulation stimulates releases of glucagon to release glucose in alpha cells

• Also decreases release of insulin