Respiration

• Respiration


  • high-energy drinks give us an extra burst of energy when we are getting tired
  • Respiration is the release of energy from food

  1. If this process needs oxygen, it is called aerobic respiration
  2. If oxygen is not needed, the process is called aerobic respiration

  Respiration is summarised by the equation:

  
• Aerobic Respiration


  • living things need energy to allow them to move, grow, stay warm and repair damaged parts.
  • They get their energy from food in a process called respiration.
  • Respiration for the majority of living things is aerobic.
  • Aerobic respiration can be summarised by the word equation:

  
• To allow aerobic respiration to take place, cells need a supply of glucose and oxygen. In humans:


  • Glucose is carried by blood plasma from the small intestine to all the cells of the body
  • Oxygen is carried by haemoglobin in red blood cells from the lungs to all the cells of the body
• Aerobic Respiration pt. 2


  • In all living cells glucose combines with oxygen to release energy and the waste products (end products) carbon dioxide and water (vapour).
  • Some of the energy is used by the cells, while some is lost as heat.
  • The waste products are carried by blood plasma to the lungs, where they pass out of (are excreted from the body.
• Aerobic Respiration 


  • As well as taking place in all the living cells in the human body, aerobic respiration also takes place in most animal and plant cells.
  • Aerobic respiration starts in the cytoplasm of a cell but finishes (and releases most of the energy) in the mitochondria.
• Factors Affecting Respiration


  • Temperature
  • Oxygen
  • Water
• Temperature 


  • Respiration is a process that occurs in living things. This means it is a biological process. Most biological reactions are controlled by enzymes.
  • These are proteins that speed up reactions without being used up in the reaction.
  • Above a certain temperature enzymes change shape, which means they do not work so well.
  • This means that the rate of the reaction slows down and the enzyme becomes denatured.
• Temperature pt. 2

  • Human enzymes have their maximum rate of reaction at 37°C, while plant enzymes work best between 20°C and 30°C. This means the rate of respiration is highest at these temperatures in humans or in plants.
• Oxygen - Respiration

  • Oxygen is essential for aerobic respiration. When we exercise we breathe faster and deeper to take in more oxygen and release more energy and carbon dioxide.
  • If there is a shortage of oxygen (e.g. when we exercise vigorously, or if a plant's roots are in waterlogged soil) the rate of respiration may not supply enough energy.
• Anaerobic Respiration

  • In cases such as those mentioned above, cells can respire anaerobically; this means they break down glucose in the absence of oxygen. This supplies a small amount of extra energy to the cells.
  • However, it also produces harmful waste products. In humans, anaerobic respiration produces lactic acid and some energy, as shown in the equation below:

  
• Water - Respiration


  • Water is essential to allow enzymes to work. This means a lack of water in cells will slow down the rate of respiration. This is why we must ensure that we drink enough water, especially when we lose water as sweat (e.g. in hot weather or during exercise).
• Products of Respiration

  1. Energy: this is why all living things carry out respiration. The more active organism is, the more respiration it needs to carry out
  2. Carbon dioxide: this is a waste product of respiration

  • animals release carbon dioxide into the air
  • plants may use some of the carbon dioxide they produce for photosynthesis; any carbon dioxide not used in photosynthesis is released into the air

  3. Water (vapour): this is another waste product of respiration. Both plants and animals release water vapour into the air
• Lactic Acid

  • Causes muscles to cramp, which forces us to stop the exercise
  • In yeast cells, anaerobic respiration produces alcohol, carbon dioxide and some energy:

  
• Chemical Equation for Respiration