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Excretion: Removable of metabolic waste from the body: two products: co2 and urea.Co2: is produced by every living cell, in aerobic respiration. co2 is toxic and can have effects:

Reduce o2 transport: co2 diffuses into RBC combines with h2o forms carbomnmic acid. This dissociates to form hydrogencarbonate. h2 com[petes with o2 on heam, and forms haemoglobinic acid.

C02: combine directly with heam, forming carbaminohaemoglobin. Lowers affinity of o2

Carbonic acid dissiates the h2 ions released makes blood more acidic, ph changes is small then detected by the respiratpory centre, Rate of breathing increases to remove excess co2. ph lowered below 7.35 respiratory acidosis (sdifficult in breathing, headache, drowsiness, tremor, confusion incraeses heart rate and changes in blood pressure.

Urea: produced via liver: excess amino acids cant be stored, and contain useful energy, broken down via liver cells in deaminatioin. The potenially toxic and highly soluble ammonia group: reacts with co2 oin the orthine cycle. and produces less toxic and less soluble urea. Urea carried by the plasma in blood stream to thye kidney where it is removed as urine. Keto acid can then be respired/ converted into carbs/ fat for storage.

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The liver is supplied by two main blood vessels: hepatic artery carrieso2 blood from heart. Hepativc portal vein: d02 blood, absorbed nutrientts and toxicx subtanses absorbed in the intestines. Blood leaves the liver via hepatic vein, and returned via vena cava to the heart. Liver also makes bile which is carried to the bile duct to the gall bladder, where it is stored. secreted into the duodenum to aid digestion of fats.

The liver is divided inot lobes whuich are further divided into lobules. Running through each lobule are branches of hepatic artery and hepat portal vein. The blood mixes andf passes through the chamber called SINUSOID lined via liver cells, called hepatocytes, where tyhey exchange materials, amnd site of the intense metabolic acticity. Function of the hepatocytes is to produce bile. whic is then released in the bile canaliculi which then form the bile duct and drain the bileinto the gall bladder for storage.

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Liver diagram:


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Liver continued:

Hepatocytes:Cuboidal shaped contains Microvilli. Site of metabolicc reactions; Detoxification synthesis of cholestrol and bile salts.

Kuffer Cells: Specialised macrophages move around the sinusoids and breakdown/ recycke RBC. Heam breakdown results in the production of bilirubin, excreted in bile and faeces.

Detoxification: Liver is able to detoxify many compounds. Compunds are prooduced in the body such as h2 peroxide. Broken down by catalase into harmless h20 and 02 Toxins are consumed such as alcohol and others are taken for medical/ recreational use. The liver can detoxify toxins through reactions such as oxidation, reduction, meythylation.

Detoxification of alcohol: (ethanOl) is broken down by hepatocytes into ethanAl by enzyme ethanol dehydrogenase it is further oxidised to ethanoic acid which can then enter krebs cycle to be respired.

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Kidney suppiled with blood renal artery, drained by the renal vein. Kidney removes waste products from the blood, to produce urine. Passes through the ureters to the bladder (store) released out of the body through urethra. Outer region: cortex. Inner region: medulla.

Structure of the nephron: Kidneys contain thousands of tubles called nephrons. it starts with Renal (Bowmans) Capsukes, followed by the PCT, Loop of henle and then DCT, which then joins to the collecting duct, blood flowing throiugh afferent arteriole which has branched from renal artery forms cappillary network, Glomerulus.

Ultrafiltration:(renal capsule): blood flows ibot the glomerus from affernt arteriole, wider than efferent, where the blood is carried away. Increases the pressure in glomerulus, compared to renal capsule, forces blood plasma through pores in cappillary, through the basement membrane and epithelial cells, renal capsule forming glomerular filtrate.

Endothethial cells: narrow gaps allowing blood plasma through. Basement membrane: mesh of collagen and glycoprotein fibres acts as a filter only allowing molecules through the molecular, large proteins and cells are NOT filteredout. Presence of proteins lowers in water potenial. Epithelial cells: renal capsule called podocytes have finger like projections: fluid passes between these processes inot the lumen of bowmans capsule.

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Selective reabsorption:

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how come there's nothing on selective reabsorption?

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