Difference Between Adrenergic and Cholinergic (With Table)

The autonomic central nervous system is among the most important aspects of our central nervous. It is in charge of regulating actions that do not require cognitive acknowledgment or action on the part of the organism. The sympathetic nervous system includes the adrenergic receptor and the parasympathetic nervous system includes the cholinergic receptor, which are the two significant sections of the autonomic nervous system.

Adrenergic vs Cholinergic

The main difference between adrenergic and cholinergic is that adrenergic receptors are present in different pathways of the nervous system along with neurotransmitter use. Adrenaline and noradrenaline attach to them. Cholinergic receptors, on the other hand, are prevalent in the parasympathetic nervous system. They interact with the amino acid acetylcholine. There are two different types of adrenergic receptors (alpha and beta), as well as nicotinic and muscarinic cholinergic synapses.

Noradrenaline (norepinephrine) and adrenaline bind to and activate adrenergic transmitters in the body (epinephrine). G protein-coupled sensors are primarily engaged in the sympathetic nerves. There are also two types of adrenergic receptors: -receptors (Alpha 1 and 2) and -receptors (Alpha 2 and 3). (beta 1, 2, and 3). Adrenaline has greater specificity for beta 2 receptors, while noradrenaline has a higher affinity for alpha receptors. Excitation is carried out by receptors 1 and 1, whereas inhibition is carried out by receptors 2 and 2.

Cholinergic receptors are another kind of autonomic nervous system receptor. Acetylcholine is released by cholinergic neurons. These are inotropic and metabotropic sensors. They also connect to acetylcholine and react to it, making communication easier. The nervous system is also involved with cholinergic receptors. Muscarinic and nicotinic receptors are the two types of cholinergic receptors. All internal organs have muscarinic receptors.

Comparison Table Between Adrenergic and Cholinergic

Parameters for ComparisonAdrenergicCholinergic
DefinitionAutonomic receptors that bind
to adrenaline and noradrenaline.
Autonomic receptors that bind
acetylcholine.
Associated Nervous
System
Sympathetic Nervous system
Parasympathetic nervous
system.
NeurotransmittersAdrenline and noradrenalineAcetylcholine
TypeAlpha and BetaNicotinic and muscarinic
ResponsibilityIncreases heart activity during
binding.
Regulates heart activity during
stimulation.
AssociationIncrease blood pressure, lung cavity
expansion, pupil dilation, and
redirection of blood flow into
skeletal muscles.
Blood vessel dilation,
contracting muscles smoothly,
enhanced body secretions.

What is Adrerengic?

The adrenergic receptors are housed in adrenergic nerves, which are constituents of the Sympathetic system. These receptors are G-protein coupled and bind to a variety of catecholamines released by the adrenal gland. Epinephrine (adrenaline) and norepinephrine (noradrenaline) are the main two neurotransmitters involved in adrenergic receptor binding. These are also in charge of the body’s fight-or-flight reaction.

When sympathetic nerve endings in the heart bind with these neurotransmitters, they affect the heart, myocardial contractibility, and conduction velocity, all of which significantly raise the activity of the heart.

Besides their influence on the heart, they also improve the body’s momentary efficiency by directing blood away from non-essential organs and toward skeletal muscles. Other implications include pupil dilation, increased blood pressure, and lung cavity expansion, among others.

Adrenergic neurotransmitters (adrenoceptors) connect agonists like the sympathetic neurotransmitter NE and the circulatory hormone epinephrine (EPI). The 1-adrenoceptor is the most important adrenoceptor in the heart (excluding coronary vascular adrenoceptors). Heart rate goes up (positive chronotropic), conduction velocity is enhanced (positive homotopy), contractility is expanded (positive inotropy), and the rate of myocyte relaxation is increased when stimulated by a 1-agonist such as NE or EPI (positive lusitropy).

The alpha and beta forms of adrenoceptors are further divided based on their function and impact on health. When adrenaline unites to these receptors, it causes alpha vasoconstriction and beta vasodilation.

What is Cholinergic?

The parasympathetic nervous system is linked to the cholinergic route, which involves the functions of cholinergic receptors. The neurotransmitter Acetylcholine activates these receptors, which are both inotropic and metabotropic (ACh). Acetylcholine neurotransmitters carry out their functions by binding to the muscarinic and nicotinic receptors, which are the 2 major cholinergic receptors. The body’s metabolize and rest responses are controlled by the cholinergic system.

The cholinergic influences on the heart are caused by the vagus or parasympathetic nerve endings. These receptors in the heart are liable for suppressing the heart’s capabilities when acetylcholine unites them. The body’s acetylcholine binding effect, which lowers heart rate and blood pressure, is a fine balance. Acetylcholine also has other effects such as dilation of blood vessels, increased bodily secretions, and smooth muscle contraction.

These neurotransmitters can be discovered throughout the body, but they’re most frequent in organ systems like sensory glands, respiratory tracts. The site can be witnessed in the heart and eyes, and gastrointestinal tract. Cholinergic receptors are found in both Somatic and Autonomic nervous systems and are classified as Nicotinic and Muscarinic receptors. Nicotine ties to nicotine receptors, while muscarine unites to muscarinic receptors.

Choline derivatives (acetylcholine, methacholine, carbachol, bethanechol) and alkaloids are examples of primary cholinergic intermediaries (muscarine, pilocarpine, cevimeline).

Main Differences Between Andrergenic and Cholinergic

  1. The main difference between the both is their involvement with different parts of the nervous system. The adrenergic system belongs to the sympathetic nervous system whereas the cholinergic pave its way to the parasympathetic system.
  2. Unlike adrenergic that bind itself to two: adrenaline and noradrenaline, cholinerage unites acetylcholine.
  3. Neurotransmitters in both differ by adrenergic having adrenaline and noradrenaline while cholinergic has acetylcholine.
  4. While adrenergic is responsible for increasing heart rate, cholinergic is responsible for regulation.
  5. Alpha and Beta are sub-divisions of adrenergic whereas nicotinic and muscarinic belong to cholinergic.
  6. The responsibility of adrenergic involves blood pressure increase, pupil dilation whereas muscle contraction and blood vessel dilation are the responsibilities of the latter.

Conclusion

Adrenergic and cholinergic receptors are found in our body’s autonomic nervous system. They are controlled by the neurotransmitters binding to them, which regulate their different functions.
When adrenergic nerve endings and specific receptors in the heart bind to adrenaline neurotransmitters, they cause an increase in heart activity, whereas when cholinergic receptors in the heart are stimulated, they cause a decrease in heart activity.

Dilation of pupils, increased blood pressure, expansion of the lung cavity, and rerouting blood flow into skeletal muscles to enhance glucose availability are all impacts of binding with adrenergic receptors.

References

  1. https://www.sciencedirect.com/science/article/pii/S0022202X15330402
  2. https://academic.oup.com/endo/article-abstract/80/5/975/2696051