B9 - Respiration

• Aerobic respiration


  Cellular respiration that uses oxygen
• Aerobic respiration


  • It takes place all the time in plant and animal cells
  • It transfers energy that cells can use
• Aerobic respiration


  1. Glucose reacts with oxygen

  2. Carbon dioxide and water are produced as waste products
• Aerobic respiration is an exothermic reaction
• Some of the energy transferred in respiration is used for reactions inside the cell, the rest is transferred to the environment
• Mitochondria


  • Tiny rod-shaped parts (organelles) found in almost all plant and animal cells
  • They have a folded inner membrane that provides a large surface area for the enzymes involved in aerobic respiration
  • The number of mitochondria in a cell shows how active the cell is
• Uses of energy from respiration


  • Building up large molecules from smaller ones
  • Breaking down larger molecules to smaller ones
  • Muscle contraction
  • Maintaining constant internal body temperature
  • Moving mineral ions into root hair cells
  • Converting sugars, nitrates, and other nutrients into amino acids
• Glycogen


  A carbohydrate that muscles can store and convert rapidly back to glucose to use during exercise
• Response to exercise


  1. Heart rate increases and arteries supplying blood to muscles dilate

  2. Breathing rate and depth increase

  3. Glycogen stored in muscles is converted back to glucose
• The increase in heart rate and breathing rate during exercise is to supply the muscles with what they need and remove the extra waste produced
• Cellular respiration increases during exercise to supply the muscle cells with the increased levels of energy needed for contraction
• Anaerobic respiration


  Cellular respiration that does not use oxygen
• Anaerobic respiration takes place in lots of different organisms
• Less energy is transferred by anaerobic respiration than by aerobic respiration
• Oxygen debt


  The extra oxygen needed after anaerobic respiration to break down the lactic acid produced
• Anaerobic respiration


  Respiration without oxygen
• Anaerobic respiration in animal cells

  • Glucose is incompletely broken down to form lactic acid
  • Transfers less energy than aerobic respiration
• Anaerobic respiration in plant cells and some microorganisms

  Glucose is broken down to form ethanol and carbon dioxide
• If muscles work hard for a long time

  They become fatigued and don't contract efficiently
• If muscles don't get enough oxygen

  They will respire anaerobically
• Oxygen debt


  The amount of oxygen needed to convert the accumulated lactic acid into glucose after exercise
• After exercise, oxygen is still needed to convert the accumulated lactic acid into glucose
• Metabolism


  The sum of all the reactions in a cell or the body of an organism
• Common metabolic reactions


  • Conversion of glucose to starch, glycogen, and cellulose
  • Formation of lipid molecules from glycerol and fatty acids
  • Use of glucose and nitrate ions to form amino acids for proteins
  • Reactions of respiration
  • Reactions of photosynthesis
  • Breakdown of excess proteins in the liver to form urea
• Role of the liver


  • Detoxifying poisonous substances
  • Passing breakdown products into the blood for excretion
  • Breaking down old blood cells and storing iron
• Removing lactic acid


  1. Blood transports lactic acid to the liver

  2. Liver converts lactic acid back to glucose

  3. Glucose is then completely broken down in aerobic respiration
• If the glucose from lactic acid is not needed, it may be converted to glycogen and stored in the liver