The key difference between neurotransmitters and hormones is that neurotransmitters are the chemical messengers used by the nervous system to transmit nerve impulse across the synapses while hormones are the chemical messengers used by the endocrine system to stimulate or communicate with specific targets cells.
Nervous system and endocrine system are very important organ systems in our body that regulate various activities. Both systems are dependent on the release of special chemicals either as neurotransmitters or as hormones respectively. These neurotransmitters and hormones act as chemical messengers and facilitate the nerve impulse transmission and the regulation of physiological activities in our body.
CONTENTS
1. Overview and Key Difference
2. What are Neurotransmitters
3. What are Hormones
4. Similarities Between Neurotransmitters and Hormones
5. Side by Side Comparison – Neurotransmitters vs Hormones in Tabular Form
6. Summary
What are Neurotransmitters?
Neurotransmitters are chemical messengers of our nervous system. They can be small amine molecules, amino acids, or neuropeptides. Neurotransmitters facilitate the transmission of a nerve impulse or action potential across the synaptic cleft. Synaptic cleft is the region where two neurons come closer but do not touch with each other. Hence, neurons use neurotransmitters to pass the action potential from the presynaptic membrane to the postsynaptic membrane (from the axon of one neuron to the dendrites of the second neuron).
Figure 01: Neurotransmitters
Therefore, the presynaptic neuron membrane creates vesicles filled with neurotransmitters and release into the synaptic cleft. They diffuse through the cleft and reach the postsynaptic membrane and bind with the receptors located on the membrane surface. The binding of neurotransmitters with receptor proteins will stimulate postsynaptic neuron and continue the nerve transmission. This action of neurotransmitters can be three ways; excitatory, inhibitory or modulatory. Some common examples of neurotransmitters are acetylcholine, dopamine, glutamate, glycine, serotonin, histamine and noradrenaline.
What are Hormones?
Hormones are the chemical messengers produced by the endocrine system. Endocrine system secretes hormones into the blood, and via the circulatory system, they reach the distant target cells. Glands are the organs that produce and secrete hormones while target organs are the organs they affect. Hormones are able to stimulate a specific set of cells that locate somewhere else and have no direct connection with their glands. Hormones affect many different processes in our body including, growth, sexual function, reproduction, mood, metabolisms, etc.
Figure 02: Hormones
Chemically, there are four types of hormones; (1) amino acid derivatives, (2) Peptide, protein, or glycoprotein. (3) Steroids and (4) Eicosanoid. The main endocrine glands that release hormones are pituitary, pineal, thyroid, parathyroid, adrenal, ovaries (in females) and testes (in males). Each gland releases a specific hormone or several hormones, which help to regulate body activities. For example, parathyroid gland releases PTH, which is able to raise the blood calcium level and stimulate calcium absorption.
Moreover, some examples of hormones are Estradiol, testosterone, melatonin, vasopressin, insulin and growth hormone, luteinizing hormone, follicle-stimulating hormone, thyroid-stimulating hormone, etc.
What are the Similarities Between Neurotransmitters and Hormones?
- Both neurotransmitters and hormones are chemical messengers.
- They release form vessels into the surrounding fluid by similar mechanisms.
- Some neurotransmitters and hormones have a similar
- Several hormones, as well as the neurotransmitters, are produced by the tissues in the Central Nervous System.
- Some molecules act as both hormones and neurotransmitters.
What is the Difference Between Neurotransmitters and Hormones?
Neurons produce neurotransmitters while endocrine system produces hormones. Both work as chemical messengers in two different organ systems. Neurotransmitters facilitate signal transmission between neurons. On the other hand, hormones affect many processes in our body, including growth and development, mood, metabolism, sexual function, reproduction, etc. Similarly, the organ system that produces neurotransmitters is the nervous system while it is the endocrine system for hormones.
The below infographic presents more details on the difference between neurotransmitters and hormones in tabular form.
Summary – Neurotransmitters vs Hormones
Neurotransmitters and hormones are two types of chemical messengers that work in our body. Neurotransmitters work for the nervous system and facilitate impulse transmission between neurons while hormones affect many different processes of our body including growth and development, metabolism, sexual function, mood, reproduction, etc. Endocrine system produces hormones. Pituitary, pineal, thyroid, parathyroid, adrenal, ovaries (in females) and testes (in males) are the main sites of hormone production. The action of neurotransmitters is very fast, unlike hormonal action, which is very slow. This is the difference between neurotransmitters and hormones.
Reference:
1.“What Are Neurotransmitters?” Queensland Brain Institute, 9 Nov. 2017. Available here
2.“Hormone.” Wikipedia, Wikimedia Foundation, 8 Aug. 2018. Available here
Image Courtesy:
1.”Synapse Illustration2 tweaked”By Nrets (CC BY-SA 3.0) via Commons Wikimedia
2.”Hormone”By संताजी बबन चवरे (CC BY-SA 4.0) via Commons Wikimedia