What is norepinephrine?
Norepinephrine is a neurotransmitter that is used by the sympathetic nervous system to send messages to other nerves and also muscle tissue.
Norepinephrine is also a hormone that is produced and secreted by the medulla (inner part) of the adrenal glands in direct response by nervous stimulation.
Norepinephrine causes blood pressure to rise, the heart to beat faster, increases metabolism and blood glucose levels, and increases energy production and blood flow to the extremities.
Important norepinephrine facts
- The amino acid tyrosine is a precursor to norepinephrine
- Dopamine needs to be synthesised to produce norepinephrine
- Norepinephrine is known as a neurohormone as it acts as both a neurotransmitter and hormone
- Norepinephrine is also known as noradrenaline
- Norepinephrine is a neurotransmitter of the adrenergic nervous system
- Norepinephrine stimulates the body systems to prepare to “fight or flight”, which is a well-known human preservation reaction to any dangerous situations
Why norepinephrine is important
Norepinephrine activates two types of cell membrane receptors:
- A-receptors – contracts smooth muscle (except in the intestines)
- B-receptors – relaxes smooth muscles; increases rate and force of heart muscle contractions
Norepinephrine is also an important neurotransmitter in many parts of the central nervous system, where it participates in blood pressure regulation, arousal and mood.
