Respiration

1. Respiration

2. Why does the body needs to breathe? We know that we breathe constantly throughout life. Also, we know that if we stopped breathing we would eventually die. So, breathing in oxygen (O2) must be linked to something that we need constantly and without it our bodies would die. The answer is ENERGY making.

3. Imagine a fire... FUEL OXYGEN Energy-making process The energy-making process depends on the breathing system and the digestive system. This will produce energy in the form of heat but only if it is supplied with 2 main ingredients.

4. the oxygen is supplied by the breathing system and the fuel (in the form of digested food) comes courtesy of the digestive system. + 2 Energy-making process The bodies energy-making reaction needs similar things to the energy-making process of fire. Like the fire, the body needs oxygen and a fuel.

5. food oxygen breathing system digestive system BLOOD Energy-making process If we now think back over the journey of oxygen and digested food through the human body, we will realise that they both end up in the same place. these substances eventually arrive at the body cells

6. capillary blood + oxygen food muscle cell Energy-making process Therefore, the raw materials for the energy-making process eventually arrive at the bodycells. This energy-making process is known as... R E S P I R A T I O N Each living cell is supplied with food and oxygen in order to generate energy.

7. These waste products must be removed from the body. Waste products No chemical reaction is 100% efficient. Therefore, as well as producing the useful energy, respiration also produces waste products. If the process of breathing in is used to obtain the O2 for respiration, it would make sense for the body to use the process of breathing out to remove these waste products of this reaction. This is exactly what happens!

8. Test One Before you start exhaling, the lime water is a clear liquid Blow gently through a straw into a test tube filled with lime water. After a short while, the lime water becomes cloudy. straw lime water Waste products If we study the composition of the air that is breathed out, we will identify the waste products of respiration. Two tests help us identify these waste products.

9. carbon dioxide (CO2) Waste products If a gas is bubbles through lime water and the liquid becomes cloudy, the gas is identified as…. This is the first of our wasteproducts of respiration.

10. On a freezing cold day, watch what happens when you breathe out. The air you breathe out is visible because the mystery waste product condenses back into a liquid. Waste products Test Two

11. water Waste products This waste product is water vapour and so our final waste product of the process of respiration is...

12. FOOD (GLUCOSE) + + + CARBON DIOXIDE OXYGEN WATER ENERGY from digestive system from breathing system waste product exhaled waste product exhaled USEFUL! Waste products Using this information, we can now write out the full equation for respiration.

13. Think about what you do in an average day. Let us try to understand why….. sometimes you are resting low energy requirements What is respiration? However, to call this reaction just ‘respiration’ is not quite correct.

14. sometimes you are active high energy requirements What is respiration?

15. the process of respiration must be able to ‘speed up’ and ‘slow down’ this will mean that we need different amounts of food to feed the reaction our rate of breathing will change the blood will have to flow at different speeds according to demand What is respiration? Your body requires different amounts of energyat different times. Therefore… this is exactly what happens it will also mean that we need different amounts of oxygen to feed the reaction

16. 1. sleeping 2. running a marathon What is respiration? It seems that the process of respiration changes during the course of the day. Let’s take two extreme examples human activity and see how the process of respiration change... This may not represent the daily activities of an average human, but this scenario will help us understand this process of respiration in more depth.

17. low demand for food and oxygen blood flow does not have to be rapid low energy demand the breathing rate remains normal What is respiration? SLEEPING When we sleep, our body is at rest. There is a low demand for energy. In other words, the body has plenty of time to inhale the oxygen that it needs. It also has time to completely digest the food to release the important chemicals (e.g glucose). The blood can efficiently transport these substances to the cells without increasing its rate of flow.

18. O2 Aerobic respiration When the body is performing respiration in such a way, it is given a special name. When the body… • has plenty of oxygen • is able to completely digest food • can supply the cells with the oxygen and food that they need We say it is performing AEROBIC respiration.

19. Glucose + Oxygen Carbon Dioxide + Water + Energy Aerobic respiration So our original equation for the process of respiration is actually the equation for aerobic respiration. This is an efficient process... enough energy is made to supply the whole body. Our bodies perform aerobic respiration for much of the day. In fact, as long as the supply of oxygen remains high enough, we will continue to perform aerobic respiration. Of course, the amount of energy we produce will drop if the level of oxygen drops.

20. remember the runners? before during after Aerobic respiration So, now we know that there is a form of respiration which is performed when there is a supply of oxygen to the body. But, what happens in situation 2? Are they performing aerobic respiration? Well, in order to answer that question, we have to think about what their bodies are doing during the race.

21. low high aerobic before aerobic (but slowing) low / none high during dropping none / low after ? What is respiration? Energy demands Oxygen available Form or respiration What’s happening?

22. ? How can the body perform aerobic respiration in this situation? Glucose + Oxygen Carbon Dioxide + Water + Energy What is respiration? Aerobic respiration requires oxygen but when you have been running a race or doing strenuous exercise, you cannot inhale enough oxygen for this reaction. This process fails! But, if this process fails when the oxygen levels drop, the body would be left with absolutely no energy.

23. No energy would lead to stop working! This would mean that the body would stop working whenever it became short of oxygen. The problem is that we often do exercise and our bodies continue working. What must be happening when our oxygen levels drop to zero? The body must be able to keep working through short periods of low/no oxygen. But how?

24. When this supply is cut off, the cell is left with excess food and lacks energy. With aerobic respiration, the cells supply of oxygen and food is relatively constant. oxygen food blood cell It solves this problem by making energy from just the food alone!

25. Anaerobic respiration Now because it is releasing energy from food, it is still performing respiration. But it is not aerobic respiration because there is no oxygen present. (aero- means of air) Therefore we call it ANAEROBIC respiration. The energy being made by breaking down the food without oxygen. This seems a better process! To be able to make energy without needing oxygen would be very beneficial. However, there is a problem.

26. Anaerobic respiration Remember the last time you ran a race, carried a heavy weight or swam under water for too long and ran short of breath. It probably felt uncomfortable. Well, if anaerobic respiration was as efficient as it sounds, this lack of comfort would not happen.

27. Anaerobic respiration So, what is the problem with anaerobic respiration? When the cell breaks down the food to release the energy, it also makes a potentially harmful waste product. The breakdown of the food is also incomplete. It is not an efficient process.

28. Glucose Lactic Acid + (some) Energy not as much energy as with aerobic respiration waste product from the digestive system Anaerobic respiration This waste product is known as LACTIC ACID. Therefore the equation for anaerobic respiration is… You will notice that this reaction is only an option for short periods of time. This is because the waste product is harmful and not enough energy is made to satisfy the body.

29. relaxation contraction Why is lactic acid so harmful? Well, this chemical can stop muscles within the body, from contracting and relaxing. The lactic acid soaks the muscle cells and prevents the muscle cell from doing its job. If the muscles in your body stop contracting and relaxing they are said to be fatigued. They eventually seize and you experience cramp.

30. YES NO We want the energy that anaerobic respiration produces But we don’t want the lactic acid waste product Why is lactic acid so harmful? If you want to consider the full impact of damage caused by the presence of lactic acid, just remember that the heart is made of muscle cells! This leaves us with a problem... if we want to do exercise So the answer is for anaerobic respiration to be a ‘gap-fill’ during periods of very low / no oxygen availability.

31. rest exercise stops exercise Anaerobic respiration aerobic anaerobic oxygen levels time Anaerobic respiration keeps our bodies going until we can breathe in more oxygen again. Whilst we are performing anaerobic respiration, our bodies are building up a ‘debt’ of oxygen.

32. Lactic acid This is rather like owing the bank some money. Once you get some money, you have to pay off that debt. We can think of that debt as being the presence of lactic acid in the body.

33. Lactic acid When our bodies convert from aerobic to anaerobic respiration, we start making lactic acid. As soon as this begins, the body starts building an oxygen debt. This is equivalent to the amount of oxygen it would have used if aerobic respiration had continued.

34. In this way, the process of aerobic respiration can be converted into The process of anaerobic respiration which can then turn back into... Lactic acid This oxygen debt will have to be repaid when the exercise stops. Oxygen will be used to break down the lactic acid that is present in the body. The oxygen ‘oxidises’ the lactic acid. In fact, the lactic acid is oxidised into carbon dioxide and water.

35. glucose + oxygen carbon dioxide + water + energy glucose + oxygen carbon dioxide + water + lactic acid + little energy Summary The body has the ability to produce energy, despite changes in the supply of oxygen. Here are the two forms of respiration. Aerobic respiration(complete breakdown of food) Anaerobic respiration(incomplete breakdown of food) Aerobic respiration is performed when oxygen is present. Anaerobic respiration is performed when oxygen is absent.

36. B Aerobic Respiration _______ + ______ _______ _______ + ______ + ______ A The body can perform two types of respiration. These are: 1. ____________ respiration (performed in plenty of O2) 2. ____________ respiration (performed in little or no O2) Respiration….do I really need oxygen? Work through the following tasks, filling the missing words or crossing out the wrong words where necessary.

37. C Aerobic respiration is performed when the supply of oxygen to the cells is HIGH / LOW. It is the COMPLETE / INCOMPLETE breakdown of food and so is very INEFFICIENT / EFFICIENT. It is a method of respiration that produces LOTS / LITTLE energy for the body. If the body does not get enough oxygen to the cells it CAN / CAN’T perform aerobic respiration. Instead it has to perform __________ respiration for a LONG / SHORT period of time.

38. D • HEAVY / LIGHT exercise for LONG / SHORT periods of time. • HEAVY / LIGHT exercise for LONG / SHORT periods of time. E Anaerobic Respiration _______ + ______ _______ _______ + ______ waste product useful Why would the body be short of oxygen? Two common reasons for the body being short of energy would be if a human was performing…

39. F Anaerobic respiration is performed when the supply of oxygen of the cells is HIGH / LOW. It is the COMPLETE / INCOMPLETE break down of food and so is very INEFFICENT / EFFICIENT. It is a method of respiration that produces LOTS / LITTLE energy for the body.

40. Lactic acid muscle fatigued aerobic anaerobic oxygen contracting broken This is poisonous. It can build up in _________ cells and stop them ___________ and relaxing. We say the cell is tired or __________. If we then relax and breathe again the body recovers. The supply of ___________ increases and the lactic acid is ___________ down. The body can now stop performing ___________ respiration and go back to performing __________ respiration.

41. Multiple choice questions

42. 1. Which of the following is a definition of respiration? A breathing B the release of energy from food C obtaining oxygen and releasing carbon dioxide D exchanging gases

43. 2. Aerobic respiration is a type of respiration that uses up… A oxygen. B energy. C carbon dioxide. D water.

44. 3.   Which of the following are the raw materials for the process of aerobic respiration? A carbon dioxide, water and glucose B glucose and carbon dioxide C oxygen, water and energy D oxygen and glucose

45. 4.   Which of the following are the waste products of aerobic respiration? A oxygen and carbon dioxide B glucose and energy C carbon dioxide and water D oxygen, water and energy

46. 5.   Which of the following is a useful product of aerobic respiration? A oxygen B energy C carbon dioxide D glucose

47. 6.   Which of the following is an accurate equation for this process of aerobic respiration? A Glucose + Carbon Dioxide Water + Energy + Oxygen B Oxygen + Carbon Dioxide  Glucose + Sugar + Energy C Water + Energy + Sugar  Carbon Dioxide + Oxygen D Glucose + Oxygen  Carbon Dioxide + Water + Energy

48. 7.   Animals perform anaerobic respiration when the body is short of… A energy. B carbon dioxide. C food. D oxygen.

49. 8.   The main waste product from the process of anaerobic respiration is… A lactic acid. B carbon dioxide. C urea. D water.

50. 9. Which of the following statements accurately describes one use of the energy released during respiration? A The breakdown of protein into muscle from which amino acids are made. B The building of amino acids from proteins. C The building of protein from amino acids, with these proteins then being used to make muscle. D The building of carbohydrates from fatty acids to make organs.