An ICD may describe: 1  The inputs and outputs of a single system, e.g.  2 The Wikipedia Interface Control Document.. 3  The interface between two systems or subsystems, e.g.  4 The Doghouse to Outhouse Interface Control Document..n application programming interface is a form of ICD for a software system, in that it describes how to access the functions and services provided by a system via an interface. If a system producer wants others to be able to use the system, an ICD (or equivalent) is a worthwhile investment.
Lesson Summary. Norepinephrine is a neurotransmitter secreted by neurons in the sympathetic nervous system. This chemical is secreted in response to stress, which triggers the 'fight or flight response.' The release of norepinephrine causes several changes that help our body to work more efficiently.esson Summary. Norepinephrine is a neurotransmitter secreted by neurons in the sympathetic nervous system. This chemical is secreted in response to stress, which triggers the 'fight or flight response.' The release of norepinephrine causes several changes that help our body to work more efficiently.
The first cell then quickly absorbs any serotonin or norepinephrine that remains in the gap between cells. This is called reuptake.. Normally, this process works without any problems. When the levels of serotonin or norepinephrine become unbalanced, however, it can cause a variety of conditions, including depression. SNRIs help to block the reuptake of serotonin and norepinephrine so more remains in the space between the brain's nerve cells.