Transport of nutrients - circulation

Target Language or Knowledge:

Digested food molecules such as  glucose, amino acids, minerals and some  vitamins are soluble in water and can be transported by the circulation system - these food molecules are absorbed into  the blood capillaries in the villi and taken  directly to the liver in the hepatic portal  vein. The liver acts as a sorting area - storing some molecules, modifying others  and allowing some to continue on in the circulation system. The hepatic portal  system is unusual in that it contains two  sets of capillaries - one in the digestive system and one in the liver. In almost  all other parts of the circulation system,  the blood is returned to the heart after  travelling through one set of capillaries. Food molecules from the liver travel  in veins to the heart, from where the blood is pumped into the lungs to be oxygenated. Once oxygenated, blood returns to the heart and is pumped through arteries to all areas of the body. The blood supplies the body cells with nutrients and oxygen. Insoluble digested food molecules, such as fatty acids and some vitamins, are absorbed into the lacteals inside the villi and transported to the thoracic duct of the lymph system - a series of tubes throughout the body that collect fluid from around the body cells and return it to the blood. The thoracic duct returns the food molecules and fluid to the circulation system just above the vena cava, which leads to the heart.

 glucose soluble circulation capillaries villi liver portal liver storing modifying circulation hepatic capillaries liver liver heart lungs oxygenated digested fatty acids vitamins lacteals thoracic lymph blood thoracic heart