LO – Level 3 – To state what substance is used as the main energy resource in the body. Level 4 –To describe what happens in aerobic respiration. Level 6 – To write the word equation for aerobic respiration. To write the word equation for anaerobic respiration.
How is digested food used by the body? Glucose, from digested carbohydrates, is an important substance that contains stored chemical energy. When glucose reacts with oxygen, a lot of energy is released. In the body’s cells, glucose and oxygen react to release energy. Some of this is released as heat and the rest is used by the cells. What is the release of energy from glucose called? The body needs a constant supply of energy which comes from digested food.
What is respiration? Respiration is the process that the body uses to release energy from digested food (glucose): This type of respiration is called aerobic respiration because energy is released in the presence of oxygen. How do the glucose and oxygen needed for aerobic respiration get to the all the body’s cells? oxygen carbon dioxide glucose ++ water ( energy) + from the digestive system from the respiratory system waste product (exhaled)
Respiration and combustion Burning is the reaction between a fuel and oxygen. This reaction is called combustion: During combustion, heat and light energy are released and carbon dioxide and water are also produced, so combustion is similar to respiration. The difference between combustion and respiration is that combustion is not a controlled reaction. Respiration is a controlled reaction that slowly releases energy from food in the body’s cells and the cells do not catch fire! fueloxygencarbon dioxidewater + +
Aerobic and anaerobic respiration When the body is able to supply its cells with the oxygen and glucose that they need, it carries out aerobic respiration. When the body cannot supply the cells with the oxygen needed to break down glucose, then it has to carry out anaerobic respiration. Energy is released without oxygen: lactic acidglucoseenergy + oxygen carbon dioxide glucose ++ water( energy) + Clip
Not enough oxygen! When anaerobic respiration takes place, lactic acid is also produced. glucoselactic acidenergy + After exercise the body needs to remove the lactic acid before it causes damage to cells. Lactic acid builds up in the muscle cells and prevents the muscles doing their job. This is thought to cause fatigue and sometimes cramp.
Oxygen debt The amount of oxygen needed to remove all the lactic acid after exercise is called an oxygen debt. oxygenwaterlactic acidcarbon dioxide ++ After activity that has lead to anaerobic respiration, the person involved breathes heavily and their heart rate remains high to supply the body with the oxygen it needs. Lactic acid is broken down by oxygen.