"The neurotransmitter (and hormone) induces an increase in intracellular cyclic adenosine monophosphate (cAMP) which is also associated with an increase in intracellular concentration, which ultimately increases heart rate

Norepinephrine

Messenger

Explanation:

Norepinephrine ( NE ), also called noradrenaline ( NA ) or noradrenalin ,

is an organic chemical in the catecholamine family that functions in

the brain and body as a hormone and neurotransmitter.

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.

Intracellular

concentrations

of cAMP play an

important

second

messenger role

in regulating

cardiac muscle

contraction.

Activation of the

sympathetic

nervous system

releases the

neurotransmitter

norepinephrine

and increases

circulating catecholamines (epinephrine and norepinephrine).

step 1: nitrogen fixation- conversion of atmospheric no₂ into forms useful to plants by lightning, bacteria, and cyanobacteria.

step 2: nitrification-process of converting ammonia to nitrite or nitrate.

step 3: assimilation-plant roots absorb new form of nitrogen.

step 4: ammonification-conversion of organic nitrogen to ammonia by bacteria involved in decomposition.

step 5: denitrification-bacteria turns the decomposed matter back into n₂o, which is released into atmosphere; repeat cycle.