Define Acetylcholine

Define Acetylcholine Neurotransmitter. Acetylcholine (chemical formula C 7 H 16 N O 2) is an organic, polyatomic cation that acts as a neurotransmitter in both the peripheral nervous system and central nervous system in many organisms including humans.  Acetylcholine (ACh) carries nerve impulses across a gap between neurons, known as a synapse. When a nerve impulse arrives at the nerve ending, acetylcholine, which is stored there in vesicles, is released and combines with a receptor molecule in the postsynaptic membrane or the end-plate membrane of a muscle fibre. Once released from a nerve terminal, it reacts instantly to a specific receptor, producing a particular response. Acetylcholine plays a critical task in the peripheral nervous system by activating muscle cells.

There are 2 Important Types of Acetylcholine receptor (AChR);

There are 2 basic types of cholinergic receptors, mAChR (muscarinic acetylcholine receptors) and nAChR (nicotinic acetylcholine receptors). Both of these receptors respond to acetylcholine. Nicotinic receptors are located at synapses between 2 neuron and at synapses between neurons and skeletal muscle cells. Upon activation a nicotinic receptor acts as a channel for the movement of ions into and out of the neuron, directly resulting in depolarization of the neuron. Muscarinic receptors, located at the synapses of nerves with smooth or cardiac muscle, trigger a chain of chemical events referred to as signal transduction.

Acetylcholine Food Sources

Acetylcholine is not found in foods; body synthesizes it from a molecule named Acetyl CoA, which combines with choline. Foods that contain choline; Raw egg yolks, beef liver, milk, low-fat cheese, wheat germ, shrimp,  salmon,  soy protein, oat bran, pine nuts. An approximate diet supplies 200 mg-600 mg of choline daily. Choline supplement dosage; Researchers recommend 550 mg per day for men and 425 mg a day for women.

Acetylcholine Function in The Body

BrainAcetylcholine is a substance that transmits nerve impulses in both the peripheral nervous system and central nervous system. In the central nervous system (CNS), acetylcholine acts as part of a neurotransmitter system and plays a role in attention and arousal. In the peripheral nervous system (PNS), this neurotransmitter is a important part of the autonomic nervous system and works to activate muscles. As a neuromodulator, it can exist in the cerebrospinal fluid and regulate a series of neurons directly as opposed to through a single synaptic connection.

ACh is a chemical messenger, a neurotransmitter, released by nerve cells in numerous parts of the peripheral nervous system. As a essential neurotransmitter, acetylcholine helps nerve impulses communicate with one other by moving messages across the synaptic cleft. Acetylcholine is closely associated with cognitive functions, most especially memory. Also, acetylcholine is necessary in both voluntary and involuntary processes in the body such as slowing the heart beat and contraction in the skeletal muscle. ACh is responsible for opening several sodium channels in the cell membrane by binding the skeletal muscles and the acetylcholine receptors. Subsequently the sodium ions are then triggered to penetrate the muscle cells which cause the muscles to contract.

Alzheimer’s Disease

Alzheimer’s, first described by the German neurologist Alois Alzheimer, is a physical disease affecting the brain. Symptoms generally develop slowly and get worse over time, becoming severe enough to interfere with daily work. During the course of the disease, protein plaques and tangles develop in the structure of the brain, leading to the death of brain cells. Short-term memory fails when Alzheimer’s disease first destroys nerve cells in the hippocampus, and language skills and judgment decline when neurons die in the cerebral cortex. Today, 26 million people worldwide have this dementia, and over 15 million Americans will be affected by the year 2050.

The level of acetylcholine decreases as you age. In Alzheimer’s disease, acetylcholine reduces much faster than normal because of the accumulation of 2 abnormal proteins. These proteins kill acetylcholine-transmitting cells. The gradual death of cholinergic brain cells, cells that transmit acetylcholine, results in a progressive and important loss of brain function. ACh lack can display as Alzheimer’s, MS, dementia, speech problems, slow movement, learning disorders, verbal memory problems, memory lapses, attention problems, carelessness, and decreased creativity. A 1998 research in the “Journal of Clinical Psychiatry” found that individuals who do not have sufficient level of acetylcholine have an increased possibility of developing Alzheimer’s disease.

Though there is no cure for Alzheimer’s disease, there are a few medicine on the market which can help to ease some of the symptoms of the disease. Cholinesterase inhibitors are designed to protect the cholinergic system, which is necessary for memory and learning and is progressively destroyed in Alzheimer’s disease. Cholinesterase inhibitors slow the metabolic breakdown of acetylcholine and make more of this chemical available for communication between cells. It helps slow the progression of cognitive impairment and can be useful for some Alzheimer’s patients in the early to middle stages. The first cholinesterase inhibitor drug, tacrine, was approved in 1993, but is rarely prescribed at the present time  due to safety concerns. The 3 most commonly prescribed cholinesterase inhibitors are donepezil, rivastigmine, and galantamine.

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