as 1 2 2 the bohr effect
DESCRIPTION
Regular exercise and a balanced diet are needed to keep the body healthy. Too little food leads to a person being underweight and prone to certain types of illness, while too much food and not enough exercise leads to a person being overweight and other types of ill health.NutrientsA mixture of different types of food in the correct amounts is needed to maintain health.The main food groups are carbohydrates, fats and proteins.This table summarises some typical sources of these nutrients and why our bodies need them.The main food groupsFood group Found in Needed by our bodies for:Carbohydratespotato, banana, pastapotatoes, pasta, bread, bananas, sugar and rice a source of energy for life processesFatscheesecheese, butter, margarine and oils a source of energy for life processes: fats are also needed to make cell membranes and to insulate our bodiesProteinsmeatmeat, fish, eggs and cheese growth and repair - building cellsMineral ions and vitamins are also important in a healthy diet. They are needed in small amounts for healthy functioning of the body.Imbalanced dietsAn imbalanced diet causes a person to become malnourished. For example:too little food may lead to a person being underweighttoo much food may lead to a person being overweight.A poor diet may also lead to deficiency diseases. For example, too little vitamin D in the diet can lead to rickets, which affects the proper growth of the skeleton. Type 2 diabetes is also a problem related to poor diet. Note that you do not need to know how the nutrients work or the effects of any particular deficiency in the diet for your exam.Regular exercise and a balanced diet are needed to keep the body healthy. Too little food leads to a person being underweight and prone to certain types of illness, while too much food and not enough exercise leads to a person being overweight and other types of ill health.NutrientsA mixture of different types of food in the correct amounts is needed to maintain health.The main food groups are carbohydrates, fats and proteins.This table summarises some typical sources of these nutrients and why our bodies need them.The main food groupsFood group Found in Needed by our bodies for:Carbohydratespotato, banana, pastapotatoes, pasta, bread, bananas, sugar and rice a source of energy for life processesFatscheesecheese, butter, margarine and oils a source of energy for life processes: fats are also needed to make cell membranes and to insulate our bodiesProteinsmeatmeat, fish, eggs and cheese growth and repair - building cellsMineral ions and vitamins are also important in a healthy diet. They are needed in small amounts for healthy functioning of the body.Imbalanced dietsAn imbalanced diet causes a person to become malnourished. For example:too little food may lead to a person being underweighttoo much food may lead to a person being overweight.A poor diet may also lead to deficiency diseases. For example, too little vitamin D in the diet can lead to rickets, which affects the proper growth of the skeleton. Type 2 diabetes is also a problem related to poor diet. Note that you do not need to know how the nutrients work or the effects of any particular deficiency in the diet for your exam.TRANSCRIPT
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The Bohr effect
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The Bohr effectLearning outcome:To describe and explain the effects of raised carbon dioxide concentrations on the haemoglobin dissociation curve.To learn how carbon dioxide is transported in blood.
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What determines the loading and unloading of oxygen by haemoglobin?The amount of oxygen that haemoglobin carries is affected by:
The partial pressure of oxygen andThe partial pressure of carbon dioxide
The presence of a high partial pressure of carbon dioxide causes haemoglobin to release oxygen. This is called the Bohr effect
High pC02Haemo-globin releases oxygen
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The Bohr effectDuring respiration, CO2 is produced. This diffuses into the blood plasma and into the red blood cells.
Inside the red blood cells are many molecules of an enzyme called carbonic anhydrase *. It catalyses the reaction between CO2 and H2O.
Red cellplasmaCO2H2CO3HCO3- + H+.The resulting carbonic acid then dissociates into HCO3- + H+. (Both reactions are reversible). *H2O
HCO3-
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The Bohr effect (continued)Haemoglobin very readily combines with hydrogen ions forming haemoglobinic acid. As a consequence haemoglobin releases some of the oxygen it is carrying.By removing hydrogen ions from the solution, haemoglobin helps to maintain the pH of the blood close to neutral. It is acting as a buffer.
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The Bohr effectThree Oxygen Dissociation curves illustrating the Bohr Effect. Increased carbon dioxide in the blood causes a right-shift in the curves, such that the haemoglobin more easily unloads the oxygen it is carrying.
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Why is the Bohr effect useful?High concentrations of carbon dioxide are found in actively respiring tissues, which need oxygen. Due to the Bohr effect, these high carbon dioxide concentrations cause haemoglobin to release its oxygen even more readily than it would do otherwise.
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How is carbon dioxide transported?Carbon dioxide is mostly carried as hydrogencarbonate ions in blood plasma, but also in combination with haemoglobin in red blood cells (carbamino-haemoglobin) and dissolved as carbon dioxide molecules in blood plasma.
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Carbon dioxide transportAbout 5% of the CO2 produced simply dissolves in the blood plasma. Some CO2 diffuses into the red blood cells but instead of forming carbonic acid, attaches directly onto the haemoglobin molecules to form carbaminohaemoglobin.
Since the CO2 doesnt bind to the haem groups the Haemoglobin is still able to pick up O2.About 85% of the CO2 produced by respiration diffuses into the red blood cells and forms carbonic acid under the control of carbonic anhydrase. The carbonic acid dissociates to produce hydrogencarbonate ions (HCO3-) The HCO3- diffuses out of the red blood cell into the plasma