Excretion - OCR A-Level Biology | Questions with 100% correct Answers | Verified

What is excretion? - The removal of waste from the body that may build up and become toxic What are the main excretory products? - CO2, nitrogenous compounds and compounds such as bile pigments Why do we get rid of metabolic waste products? - They can alter the pH interfering with cell processes so the normal metabolism is affected, they may also inhibit enzymes Why is excess CO2 a problem? - It is mostly transported as hydrogen carbonate ions the formation of which releases H ions that affect the pH of the cytoplasm of RBC's changing the bonds and shape of haemoglobin reducing its affinity for oxygen Why must we excrete nitrogenous compounds? - Amino acids can't be stored because they contain a toxic amino group that needs removing Through which vessels does blood flow into the liver? - The hepatic artery (oxygenated blood from the heart) and the hepatic portal vein (deoxygenated blood from the digestive system) What is the bile duct? - Duct that carries the bile secreted in the liver from the liver to the gall bladder How is the liver further divided from lobes? - Lobes are divided into lobules In what vessel does blood from the vein and arteries mix? - A sinusoid What is the purpose of blood passing through sinusoids? - They put the blood in close contact with liver cells that alter the concentrations of substances in itWhat do kupfer cells in sinusoids do ? - They recycle and break down RBC's producing bilirubin as well