🔥 Basics

• Respiration is the breaking down of organic substances viz. carbohydrates, fats and proteins into carbon dioxide, water & energy.
• Energy output is the chief product of respiration.
• Energy outut through
  • Slow oxidation of organic food
  • Exothermic
  • Release of energy = conserved in chemical energy.
  • Respiration = oxidation of foods in living cells.
  • Nature of respiration: Amphibolic means both catabolic and anabolic.

👉🏻 Conclusion: Respiration is a special type of combustion.

Respiration Means

• Oxidation of food
• Complex compound to simple compound
• Exothermic (Release of heat)
• Release of hydrogen
• Output of H in phases
• Energy conserved
• Enzymatically controlled
• At low temp
• In living cells

👉🏻 Respiratory subtract may be carbohydrates, fats and in certain condition proteins.

• Proteins are utilized only when carbohydrates or fats are not available.
• The first phase of respiration during which carbohydrates were used up had been termed by Blackman as the Floating respiration.
• The second phase of respiration in which protoplasmic proteins were used up had been termed by Blackman as the Protoplasmic respiration.
• Most common respiratory substrate is glucose:

C₆H₁₂O₆ + 6O₂ + 6H₂O → 6CO₂ + 12H₂O + Energy 🔥

Types of Respiration

• Aerobic
• Anaerobic = Fermentation
• Animal respiration is essentially aerobic process and ceases altogether if oxygen is absent.
• Fermentation is the form of anaerobic respiration carried on by some fungi and bacteria. Substrate of fermentation is present outside the cell and is in the liquid medium.
• According to pfeffer, ordinary aerobic respiration occurs in two stages:

1. Splitting of sugar by a no. of steps into alcohol and CO₂

Sugar → → → → Alcohol + CO₂

2. Oxidation of alcohol or some intermediate product by atmospheric oxygen into CO₂ and H₂O oxidation.

   

• Here, first stage is independent of O₂ and in fact it is anaerobic respiration. It means anaerobic respiration is the first part of aerobic respiration.

• Anaerobic Respiration is also called intra-cellular respiration. ^{UPPSC 2021}