Why does a lumbar puncture take place in the lower lumbar region of the spinal cord?

Explanation:

Lumbar puncture is a process usually used to collect cerebro-spinal fluid.  This process is often used to detect diseases of the central nervous system.  Sometimes it is also used to inject medication.Lumbar puncture takes place in the lower lumbar region of the spinal chord because spine contains the cerebrospinal fluid and it becomes safe to collect CSF from this region without any major side effects.

enzyme active site and substrate specificity

enzymes bind with chemical reactants called substrates. there may be one or more substrates for each type of enzyme, depending on the particular chemical reaction. in some reactions, a single-reactant substrate is broken down into multiple products