Glossary
Here, you will find a collection of all the definitions from various pages, as well as a few more. This list will always be growing. Also, since this site is about paralysis, the definitions are in the context of how they relate to movement or the lack thereof.
NOTE - These are MY definitions in my own words. If you want the "official" definition, use a dictionary.
UNDER CONSTRUCTION!
Definitions A-Z
(A)
Acetylcholine (ACh) - a neurotransmitter molecule with many functions. It is involved in learning, memory, and most importantly for this site, muscle movement. In muscle movement, when the action potential reaches the end of a motor neuron, acetylcholine is released from the end of the neuron (called the synaptic terminal), diffuses across the synaptic cleft, and binds to its receptors on the muscle cell membrane.
Acetylcholine receptor (AChR) - A protein that binds to the molecule acetylcholine. There are two main categories of acetylcholine receptor - nicotinic receptors, which control voluntary muscle movement, and muscarinic receptors, which control smooth muscle movement as well as many of the functions of the parasympathetic nervous system. Both nicotinic and muscarinic receptors also have several sub-types, which are found in different parts of the body. The most important receptor regarding this site is the muscle nicotinic receptor, which is located on the surface of muscle cells.
Acetylcholinesterase (AChE) - An enzyme that breaks down acetylcholine. In terms of movement, it's needed so that acetylcholine is not just out there binding to your receptors and causing muscle movement when you don't want to move or causing prolonged depolarization. If this enzyme is inhibited, there will be an increased amount of acetylcholine in the neuromuscular junction, which can help counteract the effects of neuromuscular blocking agents.
Agonist - something that activates a receptor and causes its effect. For example, succinylcholine is a nicotinic acetylcholine receptor agonist because, like acetylcholine, it causes the receptors to open when it binds to them.
Antagonist - something that blocks or opposes the effect of something else. For example, dTC is an nicotinic acetylcholine receptor antagonist because it competitively binds to acetylcholine receptors and blocks the action of acetylcholine there.
(C)
Competitive inhibition - when a substance binds to the active site of a protein where another substance would usually bind, preventing the usual substance from binding there.
Contraindication - from "contra" meaning opposite, a sign or reason you should NOT give a medication or do a procedure. For example, a contraindication of succinylcholine is muscular dystrophy. That means, if the patient has muscular dystrophy, DO NOT give succinylcholine.
(D)
Depolarizing Agent - A neuromuscular blocking agent that binds to and opens acetylcholine receptors, causing an initial depolarization. It keeps the receptors open and does not allow the muscle to repolarize to be able to depolarize again and send another action potential after the first one. Succinylcholine and decamethonium are the two main examples of depolarizing agents.
(I)
Indication - in medical terms when giving medication, a sign or reason that you should give a medication or do a procedure.
Inhibition - When a substance binds to a protein in such a way to prevent the protein from performing its normal function
(N)
Nicotinic acetylcholine receptor (nAChR) - An ion channel that spans the cell membrane of neurons and muscles. When acetylcholine binds to it, it opens, allowing sodium (and some calcium) to enter the cell, causing depolarization of the cell and possibly initiating an action potential. Neuromuscular blocking agents work by binding to the nicotinic receptors on the surface of muscle cells and preventing acetylcholine from binding there. As a result, a muscle cannot generate an action potential needed for contraction to occur, and so muscle contration does not occur.
Noncompetitive inhibition - when a substance binds to an area of the protein that is not where another substance would usually bind to, but it changes the shape of the protein in such a way that the original substance that would bind there can no longer fit into the active site and bind to it.
Non-Depolarizing Agent - A neuromuscular blocking agent that binds to and blocks nicotinic acetylcholine receptors on the motor end plate of skeletal muscles. Unlike acetylcholine, it does not cause the receptor to open when it binds, and it is not broken down by acetylcholinesterase. It just stays there and prevents acetylcholine from binding to and activating the receptor. When acetylcholine is unable to bind to its receptors, you don't move.
(S)
Succinylcholine (SCh) - The only depolarizing neuromuscular blocker used in the US. It has a very rapid onset (30 seconds to a minute) and a short duration (about 5 minutes). Because of its speed and short length, it is commonly used at the beginning of surgeries or in emergency situations to allow a patient to be quickly intubated. However, it also has some dangerous side effects, namely hyperkalemia (elevated potassium levels) and malignant hyperthermia.
(T)
d-Tubocurarine (dTC) - A non-depolarizing neuromuscular blocking agent and an active ingredient in curare, an arrow poison used by South American tribes to paralyze and kill their prey. It was used clinically for the first time in 1942 as a muscle relaxant during surgeries, and now has many derivatives which are still used in medicine today. Tubocurarine is a classic example of something that's been used as both poison and medicine. This molecule has really seen it all.
Abbreviations
ACh - Acetylcholine
AChE - Acetylcholinesterase
AChR - Acetylcholine receptor
dTC - d-Tubocurarine (may also be written as DTC, dTc, or d-Tc, but dTC is what I see most often)
mAChR - Muscarinic acetylcholine receptor
nAChR - Nicotinic acetylcholine receptor
NDMR - Non-depolarizing muscle relaxant
NMB - Neuromuscular blocker
NMBA - Neuromuscular blocking agent
NMBD - Neuromuscular blocking drug
(NMB, NMBA, and NMBD all refer to the same thing and are generally interchangeable. Just use whichever one you like best. I personally like "NMB" best, so that's the one that is used on the website, but you can use whichever one you want.)
SCh - Succinylcholine
SP - Sleep Paralysis
NOTE - These are MY definitions in my own words. If you want the "official" definition, use a dictionary.
UNDER CONSTRUCTION!
Definitions A-Z
(A)
Acetylcholine (ACh) - a neurotransmitter molecule with many functions. It is involved in learning, memory, and most importantly for this site, muscle movement. In muscle movement, when the action potential reaches the end of a motor neuron, acetylcholine is released from the end of the neuron (called the synaptic terminal), diffuses across the synaptic cleft, and binds to its receptors on the muscle cell membrane.
Acetylcholine receptor (AChR) - A protein that binds to the molecule acetylcholine. There are two main categories of acetylcholine receptor - nicotinic receptors, which control voluntary muscle movement, and muscarinic receptors, which control smooth muscle movement as well as many of the functions of the parasympathetic nervous system. Both nicotinic and muscarinic receptors also have several sub-types, which are found in different parts of the body. The most important receptor regarding this site is the muscle nicotinic receptor, which is located on the surface of muscle cells.
Acetylcholinesterase (AChE) - An enzyme that breaks down acetylcholine. In terms of movement, it's needed so that acetylcholine is not just out there binding to your receptors and causing muscle movement when you don't want to move or causing prolonged depolarization. If this enzyme is inhibited, there will be an increased amount of acetylcholine in the neuromuscular junction, which can help counteract the effects of neuromuscular blocking agents.
Agonist - something that activates a receptor and causes its effect. For example, succinylcholine is a nicotinic acetylcholine receptor agonist because, like acetylcholine, it causes the receptors to open when it binds to them.
Antagonist - something that blocks or opposes the effect of something else. For example, dTC is an nicotinic acetylcholine receptor antagonist because it competitively binds to acetylcholine receptors and blocks the action of acetylcholine there.
(C)
Competitive inhibition - when a substance binds to the active site of a protein where another substance would usually bind, preventing the usual substance from binding there.
Contraindication - from "contra" meaning opposite, a sign or reason you should NOT give a medication or do a procedure. For example, a contraindication of succinylcholine is muscular dystrophy. That means, if the patient has muscular dystrophy, DO NOT give succinylcholine.
(D)
Depolarizing Agent - A neuromuscular blocking agent that binds to and opens acetylcholine receptors, causing an initial depolarization. It keeps the receptors open and does not allow the muscle to repolarize to be able to depolarize again and send another action potential after the first one. Succinylcholine and decamethonium are the two main examples of depolarizing agents.
(I)
Indication - in medical terms when giving medication, a sign or reason that you should give a medication or do a procedure.
Inhibition - When a substance binds to a protein in such a way to prevent the protein from performing its normal function
(N)
Nicotinic acetylcholine receptor (nAChR) - An ion channel that spans the cell membrane of neurons and muscles. When acetylcholine binds to it, it opens, allowing sodium (and some calcium) to enter the cell, causing depolarization of the cell and possibly initiating an action potential. Neuromuscular blocking agents work by binding to the nicotinic receptors on the surface of muscle cells and preventing acetylcholine from binding there. As a result, a muscle cannot generate an action potential needed for contraction to occur, and so muscle contration does not occur.
Noncompetitive inhibition - when a substance binds to an area of the protein that is not where another substance would usually bind to, but it changes the shape of the protein in such a way that the original substance that would bind there can no longer fit into the active site and bind to it.
Non-Depolarizing Agent - A neuromuscular blocking agent that binds to and blocks nicotinic acetylcholine receptors on the motor end plate of skeletal muscles. Unlike acetylcholine, it does not cause the receptor to open when it binds, and it is not broken down by acetylcholinesterase. It just stays there and prevents acetylcholine from binding to and activating the receptor. When acetylcholine is unable to bind to its receptors, you don't move.
(S)
Succinylcholine (SCh) - The only depolarizing neuromuscular blocker used in the US. It has a very rapid onset (30 seconds to a minute) and a short duration (about 5 minutes). Because of its speed and short length, it is commonly used at the beginning of surgeries or in emergency situations to allow a patient to be quickly intubated. However, it also has some dangerous side effects, namely hyperkalemia (elevated potassium levels) and malignant hyperthermia.
(T)
d-Tubocurarine (dTC) - A non-depolarizing neuromuscular blocking agent and an active ingredient in curare, an arrow poison used by South American tribes to paralyze and kill their prey. It was used clinically for the first time in 1942 as a muscle relaxant during surgeries, and now has many derivatives which are still used in medicine today. Tubocurarine is a classic example of something that's been used as both poison and medicine. This molecule has really seen it all.
Abbreviations
ACh - Acetylcholine
AChE - Acetylcholinesterase
AChR - Acetylcholine receptor
dTC - d-Tubocurarine (may also be written as DTC, dTc, or d-Tc, but dTC is what I see most often)
mAChR - Muscarinic acetylcholine receptor
nAChR - Nicotinic acetylcholine receptor
NDMR - Non-depolarizing muscle relaxant
NMB - Neuromuscular blocker
NMBA - Neuromuscular blocking agent
NMBD - Neuromuscular blocking drug
(NMB, NMBA, and NMBD all refer to the same thing and are generally interchangeable. Just use whichever one you like best. I personally like "NMB" best, so that's the one that is used on the website, but you can use whichever one you want.)
SCh - Succinylcholine
SP - Sleep Paralysis