Liver Anatomy

Figure 21-19: The hepatic portal system

IB ASSESSMENT STATEMENT

H.4.1 Outline the circulation of blood through liver tissue, including the hepatic artery, hepatic portal vein, sinusoids and hepatic vein.

Blood and Bile Flow

Through the Liver

Blood flow of the Liver

• Hepatic Artery delivers oxygenated blood to the liver.

• Blood leaves the liver by the hepatic Vein

• Hepatic portal vein bring blood to the liver from the small intestine.

Blood Flow in the Liver

• Arterial blood mixes with that from the hepatic portal vein as it flows through the blood-filled channels known as the sinusoids.

• Sinusoids differ from capillaries because there are no walls separating the blood from the liver cells.

• Thus blood are indirect contact with the blood cells

• The sinusoids are lined with phagocytic cells that ingest old red blood cells

Blood flow in the Liver Animation

• https://www.youtube.com/watch?v=P5_BxsbmXcA

Structure of Liver Animation

• https://www.youtube.com/watch?v=Gn-ibhGE7PI

• http://www.healthline.com/human-body-maps/liver#1/8

IB Assessment Statements

• H.4.3 Explain the role of the liver in regulating levels of nutrients in the blood.

• H.4.4 Outline the role of the liver in the storage of nutrients, including carbohydrate, iron, vitamin A, and vitamin D.

Functions of the Liver• Storage

– Glycogen, fat, vitamins, copper and iron. Hepatic portal blood comes to liver from small intestine.

• Nutrient interconversion– Amino acids to energy producing

compounds– Hydroxylation of vitamin D. Vitamin D

then travels to kidney where it is hydroxylated again into its active form

Liver as a storage organ

• Liver stores:– Iron– Carbohydrates (glycogen)– Fat Soluble Vitamins (A, B12, D, and K)

IB Assessment Statement

• H.4.5 State that the liver synthesizes plasma proteins and cholesterol

Functions of the Liver• Synthesis

–Albumins, fibrinogen, globulins, heparin, clotting factors

IB Assessment Statement

• H.4.7 Describe the process of erythrocyte and hemoglobin breakdown in the liver, including phagocytosis, digestion of globin and bile pigment formation.

Composition of Bile

• A yellow-green, alkaline solution containing bile salts, bile pigments, cholesterol, neutral fats, phospholipids, and electrolytes

• Bile salts are cholesterol derivatives that:– Emulsify fat– Facilitate fat and cholesterol absorption– Help solubilize cholesterol

Regulation of Bile Release

Figure 23.25

Bile Flow around the Liver

• Bile is completely isolated from the blood via bile channels

• Bile channels are composed of two rows of liver cells

• Bile is produced in the liver and brought to the gall bladder for storage via the bile ducts.

• Bile ducts are channels that carry bile.

IB Assessment Statement

• H.4.8 Explain the liver damage caused by excessive alcohol consumption

H.4.7: Liver damage caused by excessive alcohol consumption

• Liver damage occurs as a result of excessive and prolonged alcohol use.

• There are three stages of liver damage which includes fat accumulation leading to liver inflammation then cirrohsis of the liver.

• The breakdown of alcohol occurs in the liver and the resulting breakdown products of alcohol are toxic to the liver cells.

IB Assessment Statement

• H.4.6 State that the liver has a role in detoxification.

Functions of the Liver• Bile production: 600-1000 mL/day. Bile salts (bilirubin), cholesterol, fats, fat-

soluble hormones, lecithin– Neutralizes and dilutes stomach acid– Bile salts emulsify fats. Most are reabsorbed in the ileum.– Secretin (from the duodenum) stimulates bile secretions, increasing water

and bicarbonate ion content of the bile• Storage

– Glycogen, fat, vitamins, copper and iron. Hepatic portal blood comes to liver from small intestine.

• Nutrient interconversion– Amino acids to energy producing compounds– Hydroxylation of vitamin D. Vitamin D then travels to kidney where it is

hydroxylated again into its active form• Detoxification

– Hepatocytes remove ammonia and convert to urea• Phagocytosis

– Kupffer cells phagocytize worn-out and dying red and white blood cells, some bacteria

• Synthesis– Albumins, fibrinogen, globulins, heparin, clotting factors