7.1 The Respiratory Process in energy Production

What is Respiration?Respiration refers to the process of

obtaining oxygen and delivering it to the cells for cellular respiration and removing carbon dioxide produced by the cells.

Occurs in two main stages:1. External respiration

Mechanical process that maintains a continuous exchange of gases between the respiratory surfaces of an organism and its environment.

2. Internal respiration (cellular respiration)

Biochemical process in which energy is made available to all living cells.

Energy requirement in living process• Energy required in:– Muscle contraction– Active transport of biochemical substances– Transmission of nerve impulses– Synthesis of proteins– Formation of new protoplasm for growth– Cell division

• Heat released during cellular respiration helps maintain body temperature.

What is the main substrate to produce energy?

Glucose.

How is the chemical energy stored within glucose made available to

living cells?• The energy is released during cellular respiration.• Two types of cellular respiration:

1. AErobic respiration2. ANAErobic respiration

Aerobic respirationRequires continuous supply of oxygen

which is obtained from the air during external respiration.

Occurs in mitochondria in cells.Summary for aerobic respiration:

C6H12O6 + 6O2 6CO2 + 6H2O + 2898 kJ

Release all available energy stored in glucose molecule.

CO2 and H2O are produced as waste products.

glucose oxygen carbon dioxide water energy

Energy released is used to synthesize adenosine triphosphate (ATP) from adenosine triphosphate (ADP) and inorganic phosphate.

ATP acts as an instant sources of energy which drives cellular processes as and when needed.

ATP consists of phosphate bonds which can be easily broken down to release energy when required by the body.

How do cells overcome the shortfall in oxygen supply?Cells undergo anaerobic respiration, a

process in which the cells continue to generate ATP without utilizing oxygen.

Anaerobic respirationOrganisms that respire anaerobically

known as anaerobes.Eg: bacteria, yeastOccurs in cytoplasm.Temporary anaerobic respiration may occur

in our own body in the fast working skeletal muscles, as in fast running, walking, swimming etc.

Anaerobic respiration in human musclesDuring vigorous activity, blood cannot

supply enough oxygen to meet demand for ATP.

Muscles are in a state of oxygen deficiency and said to incur oxygen debt and obtain extra energy from anaerobic respiration.

Glucose molecules break down partially into intermediate substance called lactic acid.

Energy released much less than aerobic respiration.

When acid lactic concentration reach high level causing muscular cramps and fatigue.

Body need to rest and recover.Getting rid of lactic acid:

Lactic acid has to be oxidised to CO2 and water after exercise but this step requires O2.

Extra O2 is absorbed from the air we breath in.Oxygen debt is the amount of O2 needed to

remove the lactic acid from the muscle cells.This is why we breath heavily after strenuous

exercise.

Oxidation of lactic acid occurs in liver.Oxygen debt is said to “have been

paid” when all lactic acid has been eliminated through increased breathing.

Anaerobic respiration in yeastProduces ethanol.Process known as fermentation and

catalyzed by enzyme zymase.

Application:Wine and beer production (production of

ethanol)Bread making (CO2 causes dough to rise)

Comparison between aerobic and anaerobic respiration