What is a chemical message that travels through the blood to regulate target cells?
Neurotransmitters carry chemical signals (“messages”) from one neuron (nerve cell) to the next target cell.
What are neurotransmitters?
Neurotransmitters are chemical messengers that your body can’t function without. Their job is to carry chemical signals (“messages”) from one neuron (nerve cell) to the next target cell. The next target cell can be another nerve cell, a muscle cell or a gland.
Your body has a vast network of nerves (your nervous system) that send and receive electrical signals from nerve cells and their target cells all over your body. Your nervous system controls everything from your mind to your muscles, as well as organ functions. In other words, nerves are involved in everything you do, think and feel. Your nerve cells send and receive information from all body sources. This constant feedback is essential to your body’s optimal function.
What body functions do nerves and neurotransmitters help control?
Your nervous system controls such functions as your:
How do neurotransmitters work?
You have billions of nerve cells in your body. Nerve cells are generally made up of three parts:
Neurotransmitters are located in a part of the neuron called the axon terminal. They’re stored within thin-walled sacs called synaptic vesicles. Each vesicle can contain thousands of neurotransmitter molecules.
As a message or signal travels along a nerve cell, the electrical charge of the signal causes the vesicles of neurotransmitters to fuse with the nerve cell membrane at the very edge of the cell. The neurotransmitters, which now carry the message, are then released from the axon terminal into a fluid-filled space that’s between one nerve cell and the next target cell (another nerve cell, muscle cell or gland).
In this space, called the synaptic junction, the neurotransmitters carry the message across less than 40 nanometers (nm) wide (by comparison, the width of a human hair is about 75,000 nm). Each type of neurotransmitter lands on and binds to a specific receptor on the target cell (like a key that can only fit and work in its partner lock). After binding, the neurotransmitter then triggers a change or action in the target cell, like an electrical signal in another nerve cell, a muscle contraction or the release of hormones from a cell in a gland.
What action or change do neurotransmitters transmit to the target cell?
Neurotransmitters transmit one of three possible actions in their messages, depending on the specific neurotransmitter.
What happens to neurotransmitters after they deliver their message?
After neurotransmitters deliver their message, the molecules must be cleared from the synaptic cleft (the space between the nerve cell and the next target cell). They do this in one of three ways.
How many different types of neurotransmitters are there?
Scientists know of at least 100 neurotransmitters and suspect there are many others that have yet to be discovered. They can be grouped into types based on their chemical nature. Some of the better-known categories and neurotransmitter examples and their functions include the following:
Amino acids neurotransmitters
These neurotransmitters are involved in most functions of your nervous system.
These neurotransmitters play a lot of different roles in your nervous system and especially in your brain. Monoamines neurotransmitters regulate consciousness, cognition, attention and emotion. Many disorders of your nervous system involve abnormalities of monoamine neurotransmitters, and many drugs that people commonly take affect these neurotransmitters.
Peptides are polymers or chains of amino acids.
This excitatory neurotransmitter does a number of functions in your central nervous system (CNS [brain and spinal cord]) and in your peripheral nervous system (nerves that branch from the CNS). Acetylcholine is released by most neurons in your autonomic nervous system regulating heart rate, blood pressure and gut motility. Acetylcholine plays a role in muscle contractions, memory, motivation, sexual desire, sleep and learning. Imbalances in acetylcholine levels are linked with health issues, including Alzheimer’s disease, seizures and muscle spasms.
Why would a neurotransmitter not work as it should?
Several things can go haywire and lead to neurotransmitters not working as they should. In general, some of these problems include:
Problems with other parts of nerves, existing diseases or medications you may be taking can affect neurotransmitters. Also, when neurotransmitters don’t function as they should, disease can happen. For example:
How do medications affect the action of neurotransmitters?
Scientists recognized the value and the role of neurotransmitters in your nervous system and the importance of developing medications that could influence these chemical messengers to treat many health conditions. Many medications, especially those that treat diseases of your brain, work in many ways to affect neurotransmitters.
Medications can block the enzyme that breaks down a neurotransmitter so that more of it reaches nerve receptors.
Medications can block the neurotransmitter from being received at its receptor site.
Medications can block the release of a neurotransmitter from a nerve cell.
A note from Cleveland Clinic
Neurotransmitters play a role in nearly every function in your body. More specifically, neurotransmitters are the chemical communicators that carry a nerve’s message from one nerve cell to the next cell. Without neurotransmitters, your body can’t function. Too high of a level or too low of a level of specific neurotransmitters results in specific health problems. Medications work by increasing or decreasing the amount of or the action of neurotransmitters.
What is the term given to chemical messengers that travel in the blood to a target cell and cause that cell to change its activity?
Hormones are the body's chemical messengers. They carry information and instructions from one set of cells to another.
Which type of hormone travels through the blood to its target cell?
Steroids generally travel to their target cells attached to a special carrier protein that "likes" water (such as, sex steroid hormone binding globulin and serum albumin). The hormones detach before passing into the cell where they bind to receptors. To get a better picture of this, think of oil and water.
What is the name of the chemical messengers that travel through our blood?
Hormones are your body's chemical messengers. They travel in your bloodstream to tissues or organs.
What are chemical signals that travel through the bloodstream?
The endocrine system uses chemical signals called hormones to convey information from one part of the body to a distant part of the body. Hormones are released from the endocrine cell into the extracellular environment, but then travel in the bloodstream to target tissues.