Roles of ATP

ATP is mostly involved in:

  • Active Transport – About 50% of the ATP used by resting mammals is devoted to maintaining the ionic content of the cells. The Sodium-Potassium pump acts as ATPase , catalysing the hydrolysis of ATP to ADP. The energy released is used to move 3Na ions out of the cells, and 2K ions in the cell creating a potential difference across the membrane. Keep in mind that this has to do with the anaerobic respiration.
  • Muscle Contraction – The energy for muscle contraction comes from the hydrolysis of ATP to ADP and inorganic Phosphate. During muscle contraction ATP is continually regenerated by a system that involves Creatine (A nitrogenous waste product of the body) Phosphate or PCr. The ADP produce during the hydrolysis is re-converted to ATP by the transfer of the phosphate group from PCr. However, the supply of PCr is short and runs out in a few seconds. It is then that the lactate pathway starts to take place.

Composition of muscles

  • Muscles can be divided into more fibres. A muscle fibre is a single cell with more nuclei composed by the stacking of myofibrils. A myofibril is a stack of sacromeres. Sacromeres are units of alternating thick filaments ( protein myosin) and thin filaments (protein actin).


I know that knowledge about muscles isn’t necessary, but I’m summarising it justin’ case.


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