Excretion

Description

3 Biology Mind Map on Excretion, created by Rob Pettit on 23/03/2015.
Rob Pettit
Mind Map by Rob Pettit, updated more than 1 year ago
Rob Pettit
Created by Rob Pettit over 9 years ago
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Resource summary

Excretion
  1. Liver
    1. Regulates blood glucose
      1. Blood glucose increase control by insulin from pancreas
        1. Stores to glycogen (glycogenesis), fatty acids and triglycerides in liver, muscle and adipose tissue
          1. Uses glucose in glycolysis to release energy
          2. Blood glucose decrease control by glucagon from pancreas
            1. Releases glucose from glycerol stored in liver
              1. Releases glucose from amino acids in muscle by gluconeogenesis.
            2. Regulation of amino acids (excess toxic)
              1. Excess transferred to liver by hepatic portal vein from intestine
                1. Deamination
                  1. Converts to ammonia (toxic) which combines with carbon dioxide to form UREA in the ORNITHINE cycle
                  2. Transamination
                    1. The twelve amino acids which can be made by the body are produced by converting one type of amino acid into another – transamination.
                    2. Production of plasma proteins
                  3. Regulation of body temp
                    1. Other functions
                    2. Pancreas
                      1. Islets of Langerhans produce insulin
                        1. Alpha cells
                          1. Detects low blood sugar
                            1. Glucagon causes release of glucose from glycerol stored in liver and converts amino acids from proteins in muscle into glucose by gluconeogenesis (non-carbs). Glucagon releases energy from fatty acids in muscle to provide energy for process.
                          2. Beta cells
                            1. Detects high blood sugar
                              1. Insulin causes take up of glucose in liver, muscle and adipose tissue (converts to glycogen).
                        2. Kidney
                          1. Removal of nitrogenous and other waste from the body
                            1. Urea from liver (ornithine cycle)
                              1. Bowmans cup contains glomerulus. The high pressure forces small molecules such as water, glucose, amino acids, sodium chloride and urea through the filter i.e. from the blood in the glomerular capsule across the basement membrane of the Bowman's capsule and into the nephron. Ultrafiltration: The fluid formed in this way is called glomerular filtrate. Large molecules such as plasma proteins and blood cells do not pass through the filter because they are too big.
                                1. The filtrate contains toxic substances such as urea which it is necessary toremove from the body but it also contains substances such as glucose which are required by the body. The function of the proximal convoluted tubule is to reabsorb these useful substances.
                                  1. Similar mechanisms result in the re-absorption of many of the amino acids and up to 90% of the sodium ions from the tubule fluid. The removal of all these soluble substances results in an osmotic gradient between the fluid in the tubule and the cells which line it. Water is therefore drawn out of the tubule fluid by osmosis, and passes into blood. This process is responsible for 85-90% of water re-absorption in the Nephron. It is only the remaining 10-15% which is regulated in the loop of Henle and collecting duct.
                                    1. The ability to produce concentrated urine is important in allowing terrestrialmammals to conserve water. The loop of Henle and the collecting ductform a system known as a countercurrent multiplier whose function isto remove water from the fluid in the tubule and produce a concentratedurine.
                              2. Uric acid from deamination of purines (adenine and guanine)
                                1. Ammonia from deamination of amino acids. Ammonia is secreted into the urine by cells in the kidney tubule.
                                2. Maintaining constant internal environment by helping to regulate pH, water and sodium ionconcentrations in the blood and tissues
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