Question

What is Noradrenaline ? Explain with an example ?

Answer 1

Noradrenaline is a hormone that is produced naturally by the body. It is given by injection to treat life-threatening drops in blood pressure. (NB. Noradrenaline is sometimes also referred to as norepinephrine.)



Noradrenaline produces wide ranging effects on many areas of the body and is often referred to as a 'fight or flight' chemical, as it is responsible for the body's reaction to stressful situations.

Noradrenaline normally produces effects such as increased heart rate, increased blood pressure, widening of pupils, widening of air passages in the lungs and narrowing of blood vessels in non-essential organs. This enables the body to perform well in stressful situations.

Noradrenaline works by stimulating receptors called adrenoceptors, which are found all over the body. When injected into a vein, noradrenaline acts mostly on a type of adrenoceptor known as an alpha receptor. These are found on muscle inside the walls of peripheral blood vessels. Stimulating these alpha receptors causes the muscle to contract, which makes the blood vessels constrict and narrow.

By narrowing the blood vessels in the extremities, noradrenaline redirects blood to essential organs such as the heart and brain. It also produces greater resistance for the heart to beat against, and this increases blood pressure.

Noradrenaline is used to restore blood pressure to normal in emergency situations when blood pressure has dropped dangerously low.

For example
if any fight-or-flight response. (stress full condition like when a dog follow). In the brain, norepinephrine increases arousal and alertness, promotes vigilance, enhances formation and retrieval of memory, and focuses attention; it also increases restlessness and anxiety. In the rest of the body, norepinephrine increases heart rate and blood pressure, triggers the release of glucose from energy stores, increases blood flow to skeletal muscle, reduces blood flow to the gastrointestinal system, and inhibits voiding of the bladder and gastrointestinal motility.