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Removal of Materials from the Blood. Liver, Lungs, Kidneys. Role of the Liver. Conserves useful substances by the liver. It breaks down plasma proteins and synthesises new ones.
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Removal of Materials from the Blood Liver, Lungs, Kidneys
Role of the Liver • Conserves useful substances by the liver. It breaks down plasma proteins and synthesises new ones. • Detoxifies toxic materials by altering chemically, by chemical breakdown, by chemical attachment and by the uptake by macrophages.
Chemical Alteration • Active molecules are rendered inactive by being chemically altered. • Products are excreted in bile or released into the bloodstream and removed by the kidneys.
Chemical Breakdown • Hydrogen peroxide broken down into water and oxygen by the enzyme catalase. • Alcohol is broken down by a series of enzyme controlled reactions into Acetyl CoA which is respiratory substrate. • High alcohol levels cannot be broken down and the liver becomes damaged – cirrhosis.
Chemical Attachment • Conjugation • Molecular label is added to the waste product. • The label is the amino acid glycine. • Liver cells then recognise the substance as waste and is excreted by the kidneys.
Uptake by Macrophages • Macrophages line the liver’s blood vessels and remove unwanted substances by phagocytosis.
Jaundice • Bilirubin accumulates in the bloodstream if • The liver suffers a disease e.g. hepatitis • Bile duct becomes blocked • Excessively high rate of RBC destruction As the conc of bilirubin increases the skin and the whites of the eyes become yellow and the person suffers from jaundice.
Urea Production • Urea is produced when excess amino acids are broken down by a process called DEAMINATION. • They are broken down into ammonia and an organic acid. • The highly toxic ammonia enters the ornithine cycle where it reacts with carbon dioxide to produce less toxic urea. • The organic acid enters the Kreb’s cycle and is used in respiration.
Deamination Amino acid Organic acid enters Krebs Cycle Ammonia enters ornithine cycle Urea
Bilirubin • Haemoglobin from RBC is broken down into a yellow pigment called bilirubin. • It is released into the blood giving plasma it’s faint yellow colour. • Bilirubin is then removed from blood plasma by liver cells. • A molecule of another substance is attached and the conjugated form of bilirubin is added to bile and becomes bile pigment.
Bilirubin Excretion • Bile pigment does not aid digestion • It is released in bile as a form of excretion. • It is converted by bacteria to a brown pigment which gives faeces it’s colour. • Complete the diagram in your sheets.
Role of the Lungs • Carbon dioxide is produced in cells by respiration. • It is carried to the lungs by the circulatory system. • CO2 is carried in the blood plasma in the form of bicarbonate ions. • The bicarbonate ions enter the RBC and combine with H ions to form carbonic acid. • This is then broken down by an enzyme…
Removal of Carbon Dioxide This is an example of excretion (elimination of waste metabolic products)
Role of the Lungs • H2CO3 H2O + CO2 • The conc of carbon dioxide is now higher in the blood plasma than in the alveoli and so diffuses into the lungs.
Role of Kidneys • ULTRAFILTRATION OF BLOOD • REABSORPTION OF USEFUL SUBSTANCES FROM FILTRATE
KIDNEY RENAL ARTERY RENAL VEIN URETER BLADDER URETHRA
cortex medulla
GLOMERULUS DISTAL CONVOLUTED TUBULE RENAL ARTERY BOWMAN’S CAPSULE PROXIMAL CONVOLUTED TUBULE RENAL VEIN LOOP OF HENLE BLOOD CAPILLARY COLLECTING DUCT
Ultrafiltration • Renal artery carries blood containing waste products. • It branches into the tiny capillaries of the glomerulus. • Products such as water, glucose, urea and salt are filtered out into the Bowman’s capsule due to blood being at high pressure.
Basement Membrane Filter • Pores in the basement membrane allow the rapid passage of glucose, salts, water and urea into the Bowman’s Capsule. • Large molecules such as plasma proteins are prevented from leaving the bloodstream.
Reabsorption • Most water is reabsorbed back into the bloodstream along with glucose and any salts that are needed. • Urea is not reabsorbed and passes into the collecting duct with excess water and salt. • Urea is carried away from the body in urine.
Proximal Convoluted Tubule • Reabsorption of • Glucose • Salts • water
Loop of Henle • Water reabsorbed by osmosis in both the descending and ascending limbs.
Distal Convoluted Tubule • Reabsorption of • Salts (sodium chloride) • Water (small quantities)
Collecting Duct • Reabsorption of • Water to bring blood water conc back to normal Controlled by the hormone ADH (anti-diuretic hormone) Nitrogenous Excretion!!
ADH • Anti-diuretic Hormone • Increases the permeability of the proximal convoluted tubule and the collecting ducts to water. • More ADH, more reabsorption, less urine. • This is a form of homeostasis.