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Discuss the Transport of Gases by the Bloodstream.

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Introduction

Discuss the Transport of Gases by the Bloodstream All animals need certain gases such as oxygen to survive and they also produce waste carbon dioxide, which must be transported around and eventually out of the body. As a result, gas carriage around the body is essential to organisms. There are two main sections to gas carriage - the carriage of oxygen and the carriage of carbon dioxide. Although the two gases can be carried using entirely different methods, they work together to keep constant gradients for efficient transport. Oxygen needs to be transported from the lungs to all parts of the body as all respiring tissues need it (C6H12O6 + 6O2 --> 6CO2 + 6H2O). It is carried round the bloodstream with the aid of haemoglobin. Haemoglobin is a protein with a quaternary structure and a prosthetic group. Each gram of gram of haemoglobin can combine with approximately 1.34cm3 of oxygen to create oxyhaemoglobin. Therefore the total amount of oxygen that can be carried in the blood is dependant on the amount of haemoglobin present. ...read more.

Middle

Foetal haemoglobin has a higher affinity for oxygen than normal haemoglobin which is important so that mother's blood brought to the foetus will be able to be taken by the foetus' blood when the two types of haemoglobin meet. Myoglobin is found in muscle tissue and takes up oxygen more readily than normal haemoglobin so that the Myoglobin can act as a temporary store for oxygen inside muscles. In all types of oxygen carrying proteins, the presence of carbon dioxide decreases affinity for oxygen. In terms of the graph, the line would be shifted to the right - this is known as the Bohr Shift. The Bohr shift occurs due to the decreased pH of the blood when carbon dioxide is present. In biological terms, this means that the more carbon dioxide present, the more oxygen is released. Carbon dioxide levels most be controlled in order to keep a constant blood pH level. CO2 is carried around the blood using three methods. Firstly, approximately 7% of the gas can be dissolved in the plasma section of blood in water. ...read more.

Conclusion

The remaining 70% is dissolved in water at a rate 5000 times faster than normal with the aid of the enzyme carbonic anhydrase. The hydrogen carbonate then dissociates into hydrogen carbonate ions: CO2 + H2O --> H+ + H2CO3 The H+ then combines with Haemoglobin to produce H2Gb. This occurs because proteins are made of amino acids which have a buffer effect and combine with H+ ions. The remaining HCO3+ ions diffuse out of the cell and water and Cl- ions also diffuse in to balance out charges. In conclusion, oxygen is transported around the body using the protein Haemoglobin. There are various types of haemoglobin but they all have similar uses. The structure of these proteins allows them to release oxygen at low partial pressures only, so it is released in areas that need it most. Various factors including carbon dioxide presence can affect haemoglobin's affinity for oxygen. Carbon dioxide is transported round the blood using 3 main methods - the main method involves storage in red blood cells as hydrogen carbonate ions. 1 The position of the graph is dependant on the partial pressure of CO2, temperature, pH. 2 Oxygen = Diatomic (O2 - HbO8) 3 Hgb = Hb = Haemoglobin ...read more.

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