Human Digestion and Nutrition Liver – Organ of many functions

Liver Overview Football-sized in upper right abdomen Largest organ by weight (~3 lbs.) “Swiss Army Knife” Performs functions related to: Digestion Excretion Metabolism Carbohydrates Fats Proteins

Liver and Blood Blood enters liver from two sources From intestines through portal vein Includes all absorbed nutrients Some are processed/altered Some are released directly From heart through hepatic artery Includes oxygen/nutrients for liver cells to perform their functions

Liver Functions – Digestion Liver makes/ secretes bile To gall bladder Gall bladder makes/secretes bile salts To small intestine Bile salts break up large fat globules Mechanical Digestion Lipase breaks up small fat globules Chemical Digestion Glycerol and fatty acids Absorbed to blood

Liver Functions – Carbohydrate Metabolism High glucose – Glucose converted to glycogen Low glucose - Glycogen converted to glucose High glycogen – glucose stored as fat Low glycogen – fat and protein converted to glucose Regulated by hormones Used primarily for cell respiration/energy production in all cells

Liver Function – Lipid/Fat Metabolism Fatty acids converted to molecules used in cell respiration Glycerol converted to molecules used in cell respiration Fatty acid and glycerol are put together to make fat molecules for energy storage Fatty acid and glycerol are put together to make fat molecules used in cell membranes Used primarily for cell respiration and cell membranes in all cells

Liver Function – Protein Metabolism Amino acids go directly to cells for protein synthesis Amino acids used by liver to make proteins for blood Amino acids converted to different amino acids as needed by cells Amino acids converted to molecules for energy Amino acids broken down for nitrogen to build DNA/RNA Used primarily for protein synthesis in all cells

Liver Function - Excretion Removes nitrogen compounds from amino acids and converts to urea Removes and breaks down old/damaged red blood cells from blood Removes toxins from blood – including alcohol and drugs (legal and illegal) All of these products are filtered from blood by the kidneys and excreted in urine

Liver Functions Liver Functions Video Liver Ted Talk