Excretion

Kidney Failure

Liver Structure

Liver Function

Kidney Function II

Osmoregulation

Excretion

Kidney Structure

Kidney Function I

The removal of metabolic waste from the body

Metabolic waste is substance produced in excess by metabolic processes

Products

Carbon Dioxide

Nitrogen-containing products (e.g. urea)

Other compounds (e.g. bile)

Excretory Oragns

Liver

Lungs

Kidneys

Skin

Carbon dioxide produced from respiration is transported to the lungs

Directly involved in excretion

Breaks down amino acids by deamination, combining the N-containing part with carbon dioxide to make urea

Urea removed from the blood and into urine

Sweat contains salts, water and excretory products urea, uric acid and ammonia

Carbon Dioxide

Nitrogenous Compounds

Haemoglobonic acid and carbaminohaemoglobin are both unable to combine with oxygen, reducing oxygen transport

The body cannot store excess amino acids

H+ ions in the plasma lower pH, potentially dangering numerous proteins in the blood. There are proteins within the blood acting as a pH buffer

If the pH change is small, the change is detected by the respiratory centre in the brain, causing an increase in breathing rate to help remove excess carbon dioxide

If pH drops below 7.35, it can cause headaches, drowsiness, rapid heart rate and changes in blood pressure, respiratory acidosis

Amino acids are deaminated, removing the potentially toxic amino group, forming ammonia, which is toxic

Ammonia is converted into urea via the ornithine cycle while the keto acid produced is used as energy in respiration or can be converted to a carbohydrate or fat for storage

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Formation of Urea

Deamination

Ornithine Cycle

Orange Ants Can Count Apples And Umbrellas

2NH3 + O2 --> CO(NH2)2 + H2O

Ornithine (an amino acid) combines with carbon dioxide and ammonia, producing water and citrulline.

Citrulline combines with ammonia and produces water and arginine

Water is added and splits arginine up into urea and ornithine

2RCH(NH2)COOH + O2 --> 2RC(O)COOH + 2NH3

Detoxification

Alcohol

These reactions are catalysed by ethanol dehydrogenase and ethanal dehydrogenase

During the break down of ethanol and ethanal, 2H ions are released in each reaction, combining with NAD to produce reduced NAD

NAD is required to break down fatty acids, with less NAD available, fatty acids are converted to lipids and stored in the hepatocytes, enlarging the liver (fatty liver)

ethanol --> ethanal --> ethanoate --> acetyl coemzyme A (used in respiration)

(2) amino acid + oxygen --> (2) keto acid + (2) ammonia

Keto acid can be used in respiration to release energy or stored as a carbohydrate or fat

Catalase is an enzyme which converts hydrogen peroxide into hydrogen and water, it has a high turnover number

Cytochrome P450 are usually used in aiding electron transport in respiration, it also breaks down drugs which can interfere with their roles in respiration

Glycogen Storage

Sugars are stored as glycogen

The glycogen forms granules in the cytoplasm of the hepatocytes

This can be broken down to release glucose into the blood as required

Metabolic Functions

Synthesis of bile, plasma proteins, cholesterol

Synthesis of red blood cells in fetus

Break down of hormones

Destruction of red blood cells

Storage of vitamins, iron, glycogen