Define Excretion  The removal of metabolic waste from the body.

Name the main 2 substances excreted by the body  Carbon dioxide from respiration  Nitrogen-containing compounds such as urea

Complete the following sentences:  Carbon dioxide combines with water in the blood to form Carbonic acid  This dissociates to form hydrogencarbonate ions and Hydrogen ions  This occurs under the influence of the enzyme carbonic anhydrase

Label the following Hepatic Vein Hepatic Portal Vein Hepatic Artery Bile Duct Sinusoid Kupffer Cell

What is the role of the Kupffer cells  Kupffer cells are specialised macrophages. They move within the sinusoids and are involved in the breakdown and recycling of old red blood cells

Name 3 functions of the liver  Control of blood glucose levels, amino acid levels, lipid levels  Synthesis of red blood cells in the fetus, bile, plasma proteins, cholesterol  Storage of vitamins A, D and B12, Iron, glycogen  Breakdown of hormones  Destruction of red blood cells

Outline what happens during deamination  Reacts with oxygen  Produces Ammonia and Keto acid

Have a go at the following past exam question

Fill in the gaps  Alcohol is broken down by hepatocytes by the action of the enzyme ethanol dehydrogenase. This produces ethanal which is dehydrogenated further by the enzyme ethanal dehydrogenase. The final compound is ethanoate which combines with coenzyme A to form acetyl coenzyme A. The hydrogen ions produced in this process combine with NAD to produce reduced NAD.

Label the following Efferent Arteriole Renal Vein Glomerulus Afferent arteriole Loop of Henle Proximal Convoluted tubule Bowman’s Capsule Collecting Duct

Where is most of the water reabsorbed? a) Proximal Convoluted tubule b) Loop of Henle c) Distal Convoluted tubule d) Collecting duct.

Past exam question

Why does the water potential decrease as you go down the descending limb?  Loss of water by osmosis to surrounding tissue  Diffusion of sodium and chloride ions into the tubule

State 3 sources where water is gained  Food  Drink  Metabolism

Fill in the boxes for the following flow diagram: Increase in water potential Decrease in water potential Detected by osmoreceptors in hypothalamus Less ADH produced Collecting duct wall less permeable Less water reabsorbed More ADH produced Collecting duct wall more permeable More water reabsorbed Decrease in water potential Increase in water potential Normal Water potential in blood

Explain how kidney Dialysis works  Removes wastes, excess fluid and salt from the blood  Dialysis membrane is partially permeable  The dialysis fluid contains the correct concentration of salts, urea, water and other substances in blood plasma  Any substance in excess diffuses across