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.
Norepinephrine Synthesis and Release. Norepinephrine (NE) is the primary neurotransmitter for postganglionic sympathetic adrenergic nerve s. It is synthesized inside the nerve axon, stored within vesicles, then released by the nerve when an action potential travels down the nerve.