(vii) It starts with acetyl Co-A which is then converted into several
intermediate compounds with the release of NADPH 2 , FDH 2 , ATP,
hydrogen atoms and then Acetyl Co-A is regenerated back.8.1 (i) Electron Transport System or ETS :
(i) In this hydrogen atoms produced during oxidation of various
intermediates during Kreb cycle are first broken into protons and
electrons.
(ii) These protons and electrons after passing through a series of
coenzymes and cytochromes combine with oxygen to form water
molecules.
(iii) During these series of events 1NADPH 2 releases 3ATP molecules
and 1FADH 2 gives 2ATP molecules which were produces during kreb
cycle and glycolysis.
NOTE : The net gain of ATP molecules during respiration in 38ATP
molecules among them,
8ATP from glycolysis
6ATP from conversion of pyruvic acid into acetyl CO. A
24ATP from kreb cycle
besides this CO 2 and H 2 O are also released.
Some important points :
(i) Diaphragm becomes flat during inspiration and becomes convex
during expiration.
(ii) Tidal volume : Volume of air inspired or expired in relaxed
position. It is around 500 ml.
(iii) Residual volume : Air left in the whole reparatory tract after
forceful expiration. It is 1.5 liters.
(iv) Total lung capacity : Maximum amount of air the lungs can hold
after forceful inspiration. It is about 5-6.0 litres.
(v) Vital capacity : Maximum amount of air which can be breathed out
through forceful expiration after a forceful inspiration. It is 3.4-4.8
litres.- Vital Capacity is more in athletes, mountain dwellers, non smokers.
- The total area for gas exchange provided by our 750 million alveoli in