Respiration

• What is respiration?

  Occurs in every cell in the body, and it is the process of transferring energy from glucose so living processes can occur. All living things undergo respiration.

  • It is exothermic as energy is transferred to the environment
  • It can take place aerobically (with oxygen) or anaerobically (without oxygen)
• What is aerobic respiration?

  This uses oxygen. It yields the most energy. Most of the reactions that make up aerobic respiration occurring the mitochondria.
• What is anaerobic respiration?

  Occurs when there is not enough oxygen. It does not yield as much energy as anaerobic respiration. It is only used as a last resort, for example during a spring where it is difficult to breathe in enough oxygen. The oxidation of glucose is incomplete.

  In animals: Glucose (C6H1206)-> Lactic

  In plant and yeast cells it is called fermentation: Glucose (C6H12O6)->Ethanol+Carbon dioxide (CO2)

  This reaction is used to make bread and alcoholic drinks.
• What is response to exercise?

  During exercise, more energy is needed in order for the muscles to contract. This means respiration has to occur faster, and therefore more oxygen needs to be supplied to cells (and more CO2 removed). This is done by:

  • Heart rate increasing
  • Breathing rate increasing
  • Breath volume increasing
• What is oxygen debt?

  If there is not enough oxygen supplied anaerobic respiration takes place instead. As lactic acid is a byproduct of this reaction, it builds up creating an oxygen debt. Oxygen debt is the amount of extra oxygen the body needs after exercise to react with the accumulated lactic acid and remove it form the cells.

  Blood flowing through the muscles transports the lactic acid to the liver where it is converted back to glucose.
• What is metabolism?

  The sum of all the reactions in a cell or the body. The energy transferred in the cells by respiration is used in the processes of metabolism to make new molecules. These processes are controlled by enzymes.
• Give some examples of metabolic reactions.

  1. Glucose molecules converted into starch, glycogen and cellulose by being joined together
  2. A glycerol molecule and three molecules of fatty acids forming a lipid molecule
  3. Glucose and nitrate ions forming amino acids, used to form proteins
  4. The reactions in respiration
  5. Urea forming from the breakdown of proteins for excretion